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Influence of preservative treatment on durability of ACA-treated white spruce poles Kim, Won Jang 1984

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INFLUENCE OF PRESERVATIVE TREATMENT ON DURABILITY OF ACA-TREATED WHITE SPRUCE POLES  by WON  JANG KIM  B.Sc.F., U n i v e r s i t y o f Toronto, 1981  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  in THE FACULTY OF GRADUATE STUDIES (FACULTY OF FORESTRY)  We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard  THE UNIVERSITY OF BRITISH COLUMBIA April,  1985  ® Won Jang Kim, 1985  In p r e s e n t i n g  t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of  requirements f o r an advanced degree a t the  the  University  o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make it  f r e e l y a v a i l a b l e f o r reference  and  study.  I  further  agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may  be granted by the head o f  department o r by h i s o r her r e p r e s e n t a t i v e s .  my  It i s  understood t h a t copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l gain  s h a l l not be  allowed without my  permission.  Department of  Forestry  The U n i v e r s i t y of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date  A p r i l 25,  1985  written  ABSTRACT  In 1977, s i x t y - t w o white spruce p o l e s e c t i o n s were i n s t a l l e d a t the Western F o r e s t Products Island test f i e l d  site.  Laboratory's  They had been commercially  impregnated w i t h amirioniacal copper arsenate chlorophenol  (PCP).  Westham pressure-  (ACA) o r penta-  Twenty-four o f the ACA-treated  spruce  p o l e s were s t u d i e d t o determine the i n f l u e n c e o f p r e s e r v a t i v e p e n e t r a t i o n , r e t e n t i o n , and n i t r o g e n l e v e l on decay r e s i s t a n c e o f spruce p o l e s a f t e r seven years o f f i e l d  testing.  Such i n f o r m a t i o n was c o n s i d e r e d o f great v a l u e i n e s t a b l i s h i n g t r e a t e d spruce  as v i a b l e p o l e m a t e r i a l i n Canada.  S t u d i e s u s i n g a 0.5% s o l u t i o n o f chrome a z u r o l S i n d i cated t h a t f o r the ACA-treated  spruce p o l e s a f t e r seven  years  i n t e s t , average p r e s e r v a t i v e p e n e t r a t i o n o f 1.14 i n .  (2.90  cm) was g e n e r a l l y g r e a t e r than that r e q u i r e d by Cana-  d i a n standards.  However, a n a l y s i s using  X-ray spectrometry lb./ft.  3  energy-dispersive  showed t h a t the mean r e t e n t i o n o f 0.50  (8.06 kg/m ) was l e s s than the l e v e l o f 0.6 l b . / f t . 3  (9.6 kg/m ) f o r ACA, r e q u i r e d by the CSA standard. 3  a l s o found arsenic, ACA  that copper was present  I t was  i n greater quantity  than  i n s p i t e o f t h e i r equal presence i n t h e o r i g i n a l  treating  solution.  3  In m i c r o b i o l o g i c a l s t u d i e s , a t o t a l o f seventy-one f u n g a l i s o l a t e s belonging  to seventeen genera and  were i d e n t i f i e d  to genus, w i t h  f i f t e e n o f these  as to s p e c i e s .  U n l i k e the untreated  wood-decaying Basidiomycetes were not  four  taxa  identified  c o n t r o l poles,  true  found a s s o c i a t e d  with  the ACA-treated spruce p o l e s . A n a l y s i s employing an O r i o n ammonia-specific coupled  to an O r i o n M i c r o p r o c e s s o r  that n i t r o g e n content increased  due  to ACA  i o n a l y s e r 901 treatment was  i n the t r e a t e d zone and  electrode revealed  significantly  a l s o beyond the  penetra-  t i o n l i m i t of p r e s e r v a t i v e .  A linear relationship existed  between n i t r o g e n content  chemical  and  r e t e n t i o n i n the  first  a n a l y t i c a l zone. V a r i a t i o n i n m o i s t u r e content  above the f i b e r  satura-  t i o n p o i n t produced marked changes i n e l e c t r i c a l r e s i s t a n c e as detected  by Shigometer measurements.  The  practical  a p p l i c a t i o n o f the Shigometer f o r d e t e c t i o n o f decay i s l i m i t e d by such  inconsistences.  internal  iv  TABLE OF CONTENTS Page ABSTRACT  i i  TABLE OF CONTENTS  iv  LIST OF TABLES  viii  LIST OF FIGURES  X  ACKNOWLEDGEMENTS  1.0  x i i  INTRODUCTION  1  1.1  CHEMICAL DISTRIBUTION STUDY  5  1.2  BIOLOGICAL STUDY  6  1.3  NITROGEN ENHANCEMENT STUDY  8  1.4  SHIGOMETER STUDY  2.0  10  LITERATURE REVIEW  12  2.1  SUPPLY AND DEMAND FOR UTILITY POLES IN CANADA .  12  2.2  WHITE SPRUCE AS POTENTIAL POLE SPECIES  22  2.2.1  CHEMICAL, PHYSICAL AND MECHANICAL PROPERTIES OF WHITE SPRUCE 23  2.2.2  PROBLEMS ASSOCIATED WITH WHITE SPRUCE  2.3  ....  FACTORS AFFECTING THE TREATABILITY OF SPRUCE ROUNDWOOD  30  35  2.3.1  MICROBIOLOGICAL STUDIES  35  2.3.2  PHYSICAL STUDIES  39  2.3.2.1  INCISING  39  Page 2.3.2.2 2.3.3 2.4  VARIATION OF THE TREATING CONDITIONS  . 41  CHEMICAL STUDIES  43  PROTECTION OF POLES WITH WATERBORNE CHEMICALS . 45  2.4.1  CHROMATED COPPER ARSENATE (CCA)  47  2.4.2  AMMONIACAL COPPER ARSENATE (CCA)  51  2.4.2.1  CHEMICAL COMPOSITION AND FORMULATION  2.4.2.2  MECHANISM OF FIXATION  2.5  FACTORS INFLUENCING THE EFFECTIVENESS OF PRESERVATIVE SYSTEMS  . 51 53  ... 55  2.5.1  PENETRATION  56  2.5.2  RETENTION  59  2.5.3  TREATMENT RESULTS OF SPRUCE WITH AMMONIACAL WOOD PRESERVATIVES 61  2.6 2.6.1  2.6.2  BIODETERIORATION OF CHEMICALLY TREATED WOOD  .. 69  DETOXIFICATION OR REMOVAL OF PRESERVATIVE CHEMICALS BY MICROORGANISMS  70  PRESERVATIVE TOLERANCE BY WOOD DECAYING FUNGI  73  2.7  NITROGEN ENHANCEMENT DUE TO ACA TREATMENT  2.8  FUNGAL METABOLISM OF NITROGEN  78  2.9  FUNCTION OF THE SHIGOMETER IN RELATION TO ELECTRICAL PROPERTIES OF INFECTED WOOD  85  3.0  MATERIALS AND METHODS  ....  76  93  3.1  MATERIALS  93  3.2  METHODS  93  vi  Page 3.2.1  SAMPLING METHODS  93  3.2.1.1  BIOASSAY  93  3.2.1.2  CHEMICAL ASSAY AND NITROGEN  97  3.2.1.3  SHIGOMETER  97  3.2.2  3.2.3  ANALYSIS OF CHEMICAL PENETRATION AND RETENTION MICROBIOLOGICAL STUDIES  99 101  3.2.3.1  ISOLATION PROCEDURES  101  3.2.3.2  IDENTIFICATION AND GROUPING OF THE ISOLATES  106  3.2.4  DETERMINATION OF NITROGEN  108  3.2.5  SHIGOMETER MEASUREMENTS  109  4.0  RESULTS AND DISCUSSION  4.1  CHEMICAL DISTRIBUTION STUDY  I l l I l l  4.1.1  PENETRATION  I l l  4.1.2  RETENTION  115  4.1.3  DISTRIBUTION OF CHEMICAL COMPONENTS  123  4.2  BIOLOGICAL STUDY  127  4.3  NITROGEN ANALYSIS  138  4.4  EVALUATION OF THE SHIGOMETER  152  4.4.1  MOISTURE MEASUREMENTS  152  4.4.2  SHIGOMETER MEASUREMENTS  156  I.  vii  Page 4.4.3  5.0  EFFECT OF MOISTURE CONTENT ON THE SHIGOMETER MEASUREMENTS  CONCLUSIONS  168  170  5.1  CHEMICAL STUDY  170  5.2  BIOLOGICAL STUDY  170  5.3  NITROGEN STUDY  171  5.4  SHIGOMETER STUDY  172  5.5  GENERAL  172  REFERENCES  174  6.0  APPENDIX A  195  viii  LIST OF  TABLES  Table 1.  2.  3.  4.  5.  Page F o r e s t resources comparison o f F o r e s t s , 1979).  (B.C. M i n i s t r y  Trend i n u t i l i t y p o l e exports (Sugden, 1979).  14 from  B.C. 15  Trend i n t o t a l annual Canadian imports, e x p o r t s , payments and r e c e i p t s o f u t i l i t y poles.  17  Chemical composition ous woods (Isenberg,  24  o f s i x common c o n i f e r 1980).  P h y s i c a l p r o p e r t i e s o f s i x common c o n i f e r ous woods.  26  M e c h a n i c a l p r o p e r t i e s o f s i x common c o n i f e r s (Jessome, 1977).  28  7.  Summary o f p o l e s t r e n g t h t e s t s .  31  8.  Composition o f the CCA  49  9.  H i s t o r i c a l development o f ACA  6.  10.  11.  preservatives. composition.  Summary o f n i t r a t e r e d u c t i o n (Nason, 1962; Nason and Takahashi, 1958; N i c h o l a s , 1963).  52  81  P r e s e r v a t i v e p e n e t r a t i o n values determined f o r the ACA-treated spruce p o l e s a f t e r seven years i n t e s t .  112  12.  A n a l y s i s o f ACA  116  13.  Student t - t e s t between the mean c u r r e n t and p r e v i o u s ( p r i o r to i n s t a l l a t i o n ) t o t a l s .  122  M u l t i p l e r e g r e s s i o n a n a l y s i s o f the r a t i o o f copper t o a r s e n i c f o r the r e t e n t i o n i n the f i r s t a n a l y t i c a l zone.  125  14.  chemical  retention.  ix  Table 15.  16.  17.  18.  19.  20.  21.  22.  23.  24.  25.  26.  Page I d e n t i f y and frequency o f f u n g i i s o l a t e d from 24 white spruce p o l e s at Westham I s l a n d test f i e l d s i t e .  128  Fungi i d e n t i f i e d from b a s i d i o c a r p s on unt r e a t e d spruce c o n t r o l p o l e s at Westham I s l a n d t e s t s i t e ( C s e r j e s i , 1984).  131  R e l a t i o n s h i p between i s o l a t i o n frequency and c o r e p o s i t i o n f o r the genera o f major f u n g i i s o l a t e d from 24 white spruce p o l e s .  132  Frequency o f i s o l a t i o n o f the major f u n g i i n the p i t h zone from both k e r f e d and nonkerfed poles.  136  A n a l y s i s o f n i t r o g e n percentage i n t r e a t e d white spruce p o l e s .  139  ACA-  Analysis of variance of residual nitrogen i n the ACA-treated white spruce p o l e s , using s p l i t - p l o t design.  140  Range t e s t s f o r n i t r o g e n i n f o u r d i f f e r e n t zones.  140  Least squares r e g r e s s i o n a n a l y s i s f o r the n i t r o g e n content and chemical r e t e n t i o n i n the f i r s t a n a l y t i c a l zone.  143  M o i s t u r e contents o f the ACA-treated test poles.  153  spruce  E l e c t r i c a l r e s i s t a n c e r e a d i n g (kP_) w i t h the Shigometer i n ACA-treated spruce p o l e s .  157  E l e c t r i c a l r e s i s t a n c e readings o f p o l e s c l a s s i f i e d t o i d e n t i f y those g r e a t e s t def l e c t i o n readings ( i n d i c a t i v e o f decay).  161  Examples o f t e s t measurements o b t a i n e d from seven suspect spruce p o l e s .  164  X  LIST OF FIGURES Figure 1.  2.  3.  4a.  4b.  5.  6.  7.  8.  9.  Page Changes i n annual Canadian imports, exports, payments and r e c e i p t s o f u t i l i t y p o l e s .  19  Battery-powered p u l s e d - c u r r e n t meter, Shigometer Model 7950, and t w i s t e d w i r e probe.  87  C r o s s - s e c t i o n a l view o f the p o l e at the g r o u n d l i n e showing the p o s i t i o n o f t h r e e b i o l o g i c a l cores.  95  Using flamed f o r c e p s , sampled core i s i n s e r t e d i n a s t e r i l i z e d g l a s s tube.  96  Sample cores i n the s t e r i l i z e d g l a s s tubes w i t h cork caps at both ends.  96  Sampling o f cores f o r the study o f d i s t r i b u t i o n and n i t r o g e n c o n t e n t .  98  S t o r i n g a p i e c e o f the core f o r moisture measurement.  98  S e c t i o n i n g procedures o f a b i o l o g i c a l core, p r o v i d i n g f o u r zones f o r the i s o l a t i o n o f fungi.  103  Two r e p l i c a t i o n s o f two d i f f e r e n t types o f media, r e p r e s e n t i n g each s e c t i o n o f f o u r s e l e c t e d zones.  105  P o s i t i o n i n g about 3/4 the medium s u r f a c e .  105  o f each p i e c e above  10.  Histogram o f average ACA  11.  R a t i o o f copper t o a r s e n i c versus retention.  12.  chemical  penetration.  Mean r e s i d u a l n i t r o g e n content  113  total  versus zone.  124 142  Regression l i n e o f n i t r o g e n content over c h e m i c a l r e t e n t i o n i n the f i r s t a n a l y t i c a l zone.  ACKNOWLEDGEMENTS  I am deeply supervisor,  t o Dr. R.W. Kennedy, my graduate  f o r h i s v a l u a b l e a s s i s t a n c e i n suggesting the  experimental for  indebted  s u b j e c t and p r e p a r i n g  his conscientious  past three years  the t h e s i s , as w e l l as  and understanding guidance over the  at this University.  I should  l i k e to  express p a r t i c u l a r g r a t i t u d e t o Drs. J.N.R. Ruddick and R..S.  Smith f o r t h e i r p r o f e s s i o n a l a s s i s t a n c e i n s u p e r v i s i n g  the experimental criticism appreciate  phases and f o r t h e i r v a l u a b l e  and c o n t i n u i n g  encouragement.  advice,  A l s o , I deeply  the guidance o f the remaining member o f my  committee, Dr. van der Kamp. S p e c i a l thanks a r e due t o Dr. E.C. S e t l i f f  for h i s  d i r e c t i o n and a s s i s t a n c e throughout b i o a s s a y work, Ms. J . E. C l a r k , Ms. W.C. Chung, Ms. J.K. Ingram and Mr. N.A. Ross f o r p r o v i d i n g t e c h n i c a l guidance and f a c i l i t i e s f o r the experimental  works, and t o Dr. A. Kozak and Mr. J .  Emanuel f o r the s t a t i s t i c a l  analysis.  I should  like to  extend my s p e c i a l thanks t o Mr. B.E. Dawson-Andoh, my colleague,  and Mr. A. Byrne f o r the b e n e f i t d e r i v e d  many d i s c u s s i o n s w i t h thesis.  from  them a t the time o f w r i t i n g t h i s  I would l i k e t o express my J.W.  Wilson and R.M.  agement through my the Canadian  s i n c e r e thanks t o Drs.  K e l l o g g f o r t h e i r continuous  graduate study.  encour-  F i n a n c i a l support  from  E l e c t r i c a l A s s o c i a t i o n i s very s i n c e r e l y  acknowledged. Finally,  I am extremely g r a t e f u l to my w i f e ,  f o r the e x c e l l e n t t y p i n g job and, above a l l ,  Sharon,  f o r her warm  encouragement, support and endless p a t i e n c e , without which t h i s study would not have been p o s s i b l e .  1.0  INTRODUCTION Wood u t i l i t y p o l e s i n t r a n s m i s s i o n and d i s t r i b u t i o n  systems represent a l a r g e annual c a p i t a l Canadian e l e c t r i c a l and telephone  investment.  companies have a c o n s i d -  e r a b l e f i n a n c i a l investment i n wooden poles  i n service,  amounting t o an annual r a t e i n excess o f $80 m i l l i o n 1984b).  (Ruddick,  Every year over $29 m i l l i o n i s i n v e s t e d i n B r i t i s h  Columbia alone  through the i n s t a l l a t i o n o f p r e s e r v a t i v e  t r e a t e d wooden p o l e s . Canada has an uneven d i s t r i b u t i o n o f c o n i f e r o u s capable  o f being used as p o l e m a t e r i a l .  species  In p a r t i c u l a r , the  regions between the P a c i f i c Coast and the Rocky Mountains are endowed w i t h s e v e r a l softwoods which produce t r e e s o f g r e a t q u a l i t y and h e i g h t . and p o p u l a t i o n pressures  At the same time the i n d u s t r i a l on e a s t e r n and c e n t r a l Canadian  f o r e s t s have long ago removed almost a l l the b e s t material  (Sugden, 1979).  T r a d i t i o n a l l y , Canada has been a net p o l e due  pole  to i t s vast f o r e s t resource.  exporter  The p r o v i n c e o f B.C. i s  p a r t i c u l a r l y f o r t u n a t e s i n c e i t c o n t a i n s commercial q u a n t i t i e s o f D o u g l a s - f i r (Pseudotsuga m e n z i e s i i  (Mirb.)  Franco),  western red cedar (Thuja p l i c a t a Donn) and lodgepole (Pinus c o n t o r t a Dougl.),  pine  f o r the supply o f the u t i l i t y  poles.  2  S i n c e the e a r l y 1970's, however, t h e r e has been a number o f comments concerning  the shortage o f these p o l e s .  1974 meeting o f the Western F o r e s t Products  At the  Laboratory's  (WFPL) Research Program Committee on Treated Wood Products, i t was r e v e a l e d t h a t Canada was importing a c o n s i d e r a b l e number o f u t i l i t y p o l e s mainly (Dobie,  1976).  from the U.S.A. and F i n l a n d  As a consequence, a study was conducted  to  analyze the supply-demand s i t u a t i o n , and to i d e n t i f y and understand  the v a r i o u s problems p l a g u i n g the i n d u s t r y .  P o s s i b l e ways o f s o l v i n g o r e l i m i n a t i n g some o f the problems were suggested.  The simple, short-term s o l u t i o n was t o  import p o l e s from o t h e r c o u n t r i e s , such as the U.S.A. However, i t became obvious  that a more a p p r o p r i a t e , l o n g -  term s o l u t i o n would be t o u t i l i z e some o f the o t h e r wood s p e c i e s , c u r r e n t l y not used f o r p o l e s i n Canada. Although western red cedar and lodgepole p i n e a r e the two wood s p e c i e s most w i d e l y used, the B.C. f o r e s t s a l s o c o n t a i n l a r g e q u a n t i t i e s o f western hemlock (Tsuga phylla  (Raf.) Sarg.), a m a b i l i s f i r (Abies a m a b i l i s (Doug.)  Forbes) and white spruce 1974,  hetero-  (Picea g l a u c a  (Moench) V o s s ) .  In  the WFPL proposed t o the Research Program Committee  on Wood P r e s e r v a t i o n a study t o determine the s t r e n g t h and t r e a t a b i l i t y o f three a l t e r n a t i v e pole species a v a i l a b l e i n B.C.  Among these s p e c i e s , there was c o n s i d e r a b l e i n t e r e s t  3  i n the p o t e n t i a l o f spruce f u t u r e demand. it  f o r s a t i s f y i n g some o f the  Spruce i s p a r t i c u l a r l y a t t r a c t i v e because  is available in relatively  l a r g e q u a n t i t i e s and  p o l e produced from t h i s s p e c i e s would meet the  the  requirements  o f the p o l e c l a s s e s i n g r e a t e s t demand. In 1977,  s i x t y - t w o white spruce p o l e s e c t i o n s were  i n s t a l l e d at the WFPL's Westham I s l a n d t e s t f i e l d Vancouver.  They had been commercially  i n c i s e d and  impregnated w i t h ammoniacal copper arsenate chlorophenol  (PCP)  in o i l .  s i t e near  (ACA)  pressureor  As a consequence o f the  pentatreating  c o n d i t i o n s used f o r the p o l e s , those t r e a t e d w i t h ACA  were  w e l l p e n e t r a t e d but the p r e s e r v a t i v e r e t e n t i o n s were  low,  whereas the PCP-treated high chemical content  p o l e s had poor p e n e t r a t i o n but a  i n the t r e a t e d zone (Ruddick,  1978).  T h i s m a t e r i a l t h e r e f o r e p r o v i d e s an unique o p p o r t u n i t y t o i n v e s t i g a t e the i n f l u e n c e o f the parameters o f p r e s e r v a t i v e p e n e t r a t i o n and spruce p o l e s . ACA-treated  r e t e n t i o n on the long-term  d u r a b i l i t y of  T h i s present study i n v e s t i g a t e d o n l y the  poles.  S i n c e i t was  intended t h a t a number o f the spruce  s e c t i o n s would be i n s t a l l e d their service l i f e ,  one  i n a graveyard  pole  t e s t to evaluate  additional factor, kerfing,  i n c l u d e d i n the d e s i g n o f the o r i g i n a l study i n Twenty-two o f the f o r t y - o n e spruce p o l e s to be  was  1977. later  installed  at Westham I s l a n d t e s t f i e l d  s i t e were t h e r e f o r e  l e n g t h k e r f e d 0.32  cm)  i n . (0.81  i n width extending  p i t h o f p o l e s , to minimize the formation s e r v i c e and process.  t r e a t e d w i t h ACA  fullto  the  o f deep checks i n  using the Lowry  empty-cell  I n s t a l l a t i o n o f r e p r e s e n t a t i v e samples o f a l l  treatments i n the graveyard t e s t permitted  monitoring  f u n g a l c o l o n i z a t i o n , decay, p r e s e r v a t i v e l e a c h i n g and  of check*  ing c h a r a c t e r i s t i c s o f the ACA-treated pole s e c t i o n s . Four main o b j e c t i v e s have been i d e n t i f i e d  for this  study: a)  To determine the ACA  preservative penetration  r e t e n t i o n o f the p o l e s  i n t e s t and  p r e s e r v a t i v e d i s t r i b u t i o n and  r e p o r t on  and the  possible leaching of  ACA; b)  c)  To determine whether decay f u n g i have become established  i n the t r e a t e d and  To c o n f i r m  or deny p r e v i o u s  untreated  wood;  observations  of  enhanced n i t r o g e n l e v e l s i n the untreated commodities t r e a t e d w i t h ACA d)  To e v a l u a t e  the u s e f u l n e s s  of  preservative;  o f a Shigometer f o r  the d e t e c t i o n o f decay i n p o l e s , by Shigometer data w i t h  core  comparing  the r e s u l t s obtained  from  fungal i s o l a t i o n studies. Such i n f o r m a t i o n  i s r e q u i r e d to e s t a b l i s h the  viability  o f ACA-treated spruce as p o l e m a t e r i a l i n Canada.  1.1  CHEMICAL DISTRIBUTION STUDY Preservative  systems must perform t h e i r  functions  throughout the s e r v i c e l i f e o f the product under a v a r i e t y o f exposure c o n d i t i o n s .  Thus, wooden p o l e s must be  a t i v e - t r e a t e d to p r o t e c t both the above- and portions  preserv-  below-ground  f o r s e v e r a l decades, i n a v a r i e t y o f c l i m a t e s  and  soils. Because o f the r e l a t i v e l y high c o s t o f o r g a n i c much work has been d i r e c t e d to developing than o i l - s o l u b l e f o r m u l a t i o n s poles.  ACA  i s one  (e.g. PCP)  years.  This formulation  contains,  equal amounts o f copper and AS2O5.  In ACA,  water-soluble  rather  f o r p r o t e c t i o n of  waterborne p r e s e r v a t i v e  w e l l e s t a b l i s h e d f o r treatment o f poles  solvents,  that has  during  become 20  the past  as a c t i v e i n g r e d i e n t s ,  a r s e n i c , expressed as CuO  and  the ammonia i n the s o l v e n t r e a c t s w i t h  the  copper a r s e n a t e to form a s o l u b l e complex which, although s t a b l e i n ammonium hydroxide s o l u t i o n , r e a d i l y breaks down to form an i n s o l u b l e copper arsenate when the s o l v e n t i s removed.  Inorganic  s a l t s of copper-arsenic-zinc  i n ammonium hydroxide have been formulated  and  wood f o r t o x i c i t y t o f u n g i , water r e p e l l e n c y glowing combustion r e s i s t a n c e , and  dissolved  tested i n  (Rak,  leach resistance  1975), (Rak  6  and  Clarice, 1974) .  Rak,  In recent  studies  (Krzyzewski, 1978a?  1977a; Ruddick, 1978) , the outstanding  penetration  of  ammoniacal p r e s e r v a t i v e s o l u t i o n s i n t o spruce roundwood has been shown. The  f i x a t i o n o f ammoniacal copper compounds depends  on the v o l a t i l i z a t i o n o f ammonia and o f the p r e s e r v a t i v e . proven to be one  The  o f the most durable o f the  wood  preservative  i s highly  t e s t f o r s e v e r a l years and obtained  and  effective.  o b j e c t i v e o f t h i s p a r t o f the study was  i n i t i a l values  has  I t i s r e l a t i v e l y non-leachable  mine the p r e s e r v a t i v e p e n e t r a t i o n in  insolubilization  Copper a r s e n a t e - t r e a t e d  treatments used today. the p r e s e r v a t i v e  the  and  to  deter-  r e t e n t i o n o f the  poles  to compare these r e s u l t s w i t h  i n 1977  p r i o r to graveyard  installa-  tion.  1.2  BIOLOGICAL STUDY The  s e r v i c e l i f e o f wood poles can be  by decay, i n s e c t a t t a c k ,  and  drastically  reduced  even automobile c o l l i s i o n s .  The  most s e r i o u s o f these i s undoubtedly decay. During recent p o l e shortages, s e v e r a l wood-treating companies examined the s u i t a b i l i t y o f spruce as a p o l e material.  In v a r i o u s  i t has been reported  experiments conducted on spruce, however, t h a t p o t e n t i a l problems e x i s t e d due  to  7  excessive  checking and d i f f i c u l t y i n o b t a i n i n g an adequate  treatment.  I t i s a l s o known that spruce wood i s very low  i n n a t u r a l decay r e s i s t a n c e , and as such must be p r e s e r v a t i v e t r e a t e d f o r a p p l i c a t i o n s i n v o l v i n g ground c o n t a c t . poles  fungal attack  i s favoured i n the s u r f a c e  above and below the g r o u n d l i n e , regions.  In u t i l i t y  layers just  and a l s o i n the core o f these  Both o f these l o c a t i o n s a r e c r i t i c a l w i t h  t o the s e r v i c e a b l e l i f e o f the p o l e ,  respect  since i t s strength i s  dependent on i t s c a n t i l e v e r beam c o n f i g u r a t i o n , where the maximum moment i s developed about the g r o u n d l i n e . The  i d e n t i t y and the e f f e c t s on microorganisms c o l o n i z i n g  wood have been the s u b j e c t o f many major i n v e s t i g a t i o n s . I n f o r m a t i o n on the i d e n t i t i e s ,  frequencies,  and the r o l e o f  the major f u n g i a s s o c i a t e d w i t h d e g r a d a t i o n i n u t i l i t y i s e s s e n t i a l f o r c o n t r o l programs.  poles  An understanding o f the  s u c c e s s i o n a l r e l a t i o n s h i p s among microorganisms i n the i n i t i a t i o n and development o f wood decay, and t h e i r e f f e c t s on p r e s e r v a t i v e s t a b i l i t y and p o l e s t r e n g t h  i s required t o devise  the b e s t p r o t e c t i o n s t r a t e g i e s . T h i s p o r t i o n o f the study was designed t o o b t a i n the identity,  frequency, and r o l e o f the major f u n g i  involved  i n d e g r a d a t i o n i n the ACA-treated white spruce p o l e s a f t e r s e v e r a l years i n f i e l d  testing.  8  1.3  NITROGEN ENHANCEMENT STUDY Wood-degrading microorganisms  have the same b a s i c growth  requirements as do the green p l a n t s .  These i n c l u d e a source  of  f a v o u r a b l e temperature,  food, an adequate  supply o f water,  oxygen, and a s u i t a b l e pH. Optimal n u t r i t i o n a l needs o f wood-damaging  microorganisms  vary, but a l l s p e c i e s o b v i o u s l y can e x i s t on what i s a v a i l a b l e i n wood i t s e l f .  Energy and most o f the c e l l - b u i l d i n g m a t e r i a l s  f o r microorganisms  a r e s u p p l i e d mainly by the carbohydrate  f r a c t i o n c o n s i s t i n g o f h o l o c e l l u l o s e , s t a r c h e s , and sugars, and  f o r some organisms, by the l i g n i n f r a c t i o n .  m i n e r a l s are a v a i l a b l e , though  N i t r o g e n and  i n c o m p a r a t i v e l y s m a l l amounts.  A t r a c e amount o f thiamin, the v i t a m i n B l o f animal n u t r i t i o n , a p p a r e n t l y i s needed by most decay  fungi.  C e l l u l o s e , h e m i c e l l u l o s e and l i g n i n comprise more than 90 p e r c e n t o f the d r y weight o f most woods, so are s u f f i c i e n t l y abundant t o meet the requirements o f microorganisms utilizing  them.  However, n i t r o g e n i s extremely sparse, being  p r e s e n t i n amounts no g r e a t e r than about 0.03 t o 0.10 percent (Cowling, 1970). for  N e v e r t h e l e s s , these q u a n t i t i e s are adequate  r a p i d decay o f wood, i n d i c a t i n g unique  e f f i c i e n c y by the a t t a c k i n g f u n g i .  nitrogen-utilizing  I t has been suggested by  Cowling t h a t t h i s e f f i c i e n c y may d e r i v e i n p a r t from an a b i l i t y o f the f u n g i t o s o l u b i l i z e the n i t r o g e n i n the protoplasm  9  o f t h e i r o l d e r hyphae and t r a n s p o r t i t t o new zones o f a t t a c k , where i t supplements the n i t r o g e n e x i s t i n g i n the zones. Several researchers 1965;  (Cowling,  1970; Cowling and M e r r i l l ,  F i n d l a y , 1934; M e r r i l l and Cowling, 1965 and 1966) have  shown t h a t i n c r e a s i n g the n i t r o g e n content  o f wood  frequently  i n c r e a s e s the r a t e o f decay by wood-inhabiting f u n g i .  Moder-  a t e l y g r e a t e r r a t e s o f decay have been observed t o be c o r r e l a t e d w i t h g r e a t e r amounts o f n a t u r a l n i t r o g e n , b u t there i s still  c o n f l i c t i n g evidence as t o whether decay can be increased  a p p r e c i a b l y by a r t i f i c i a l l y  adding n i t r o g e n t o wood  (Cowling,  1970). It  i s g e n e r a l l y assumed t h a t , d u r i n g the f i x a t i o n o f  the ammonia-based wood p r e s e r v a t i v e , such as ACA, the ammonia is  l o s t from the wood.  However, i t has p r e v i o u s l y been  r e p o r t e d by Ruddick (1979) t h a t the treatment o f wood w i t h ammoniacal type p r e s e r v a t i v e s r e s u l t s i n c e r t a i n enhancement o f the n i t r o g e n content the q u e s t i o n  i n the untreated  core.  Therefore,  o f whether the l o s s o f ammonia from ACA-treated  wood i s complete c o u l d w e l l prove t o be important,  particu-  l a r l y i n spruce when inadequate treatment combined w i t h the easy formation  o f deep checks i s encountered.  Comparison o f the ACA- and non-ACA-treated spruce woods would a l l o w c o n c l u s i o n s enhancement.  t o be made on p o s s i b l e n i t r o g e n  Thus the o b j e c t i v e o f t h i s p a r t o f the study  10  was  t o measure the r e s i d u a l n i t r o g e n  w i t h ACA  and  nitrogen  l e v e l i n wood was  l e v e l i n wood t r e a t e d  t o determine a l s o to what extent,  i f any,  enhanced by the treatment.  p o s s i b l e n i t r o g e n enhancement was  the Any  c o r r e l a t e d w i t h the presence  o f f u n g i i n h a b i t i n g the wood.  1.4  SHIGOMETER STUDY E a r l y r e c o g n i t i o n of an a t t a c k and  the degree o f  any  wood d e t e r i o r a t i o n are important to the p o l e producers to minimize p o s s i b l e l o s s e s . i s not  readily identified  mycelium and  fungal  have become w e l l  Unfortunately, i n the  biological  i n i t i a l stages.  attack  Superficial  f r u i t bodies are o n l y produced a f t e r f u n g i  established.  Some o f the key  elements i n a long-term decay c o n t r o l  program f o r u t i l i t i e s p o l e s e l e c t i o n and  are proper p o l e s p e c i f i c a t i o n s , c a r e f u l  handling,  r e l i a b l e i n s p e c t i o n s , and a n c i l l a r y preservative  effective preservative  treatment,  p o l e maintenance programs i n v o l v i n g  treatment.  d e t e c t i o n o f e a r l y decay i n poles nomical remedial treatment has  However, the followed  reliable  by e f f e c t i v e eco-  been o f p a r t i c u l a r importance.  E x i s t i n g methods f o r i n t e r n a l decay d e t e c t i o n , such as boring,  sounding, s o n i c d e t e c t o r s ,  and X-rays, are e i t h e r  i n s e n s i t i v e t o i n c i p i e n t decay a t t a c k or u n r e l i a b l e .  Recently,  the Shigometer has been proposed f o r d e t e c t i o n o f decay i n  11  l i v i n g hardwood t r e e s .  The Shigometer i s a r e s i s t a n c e meter,  which measures changes i n the c o n d i t i o n o f the wood a s s o c i a t e d w i t h changes i n e l e c t r i c a l r e s i s t a n c e .  A pulsed d i r e c t c u r r e n t ,  p a s s i n g through wood i n p r o g r e s s i v e stages o f decay, meets with decreasing  resistance.  Such changes caused by f u n g a l  a t t a c k are, f o r example, s p e c i f i c g r a v i t y , pH, moisture and the c o n c e n t r a t i o n o f c a t i o n s (Brudermann, 1977). D e s p i t e c o n s i d e r a b l e r e s e a r c h conducted on wood  utility  p o l e s , t h e r e i s no c l e a r i n d i c a t i o n o f the value o f the Shigometer i n d e t e c t i n g e a r l y decay i n p o l e s under conditions.  The o b j e c t i v e o f t h i s f i n a l  field  segment o f the study  was t o determine whether a Shigometer c o u l d be used f o r detect i o n o f e a r l y decay i n p o l e s having been i n f i e l d several years.  test for  Shigometer readings were, t h e r e f o r e ,  taken  i n wood adjacent t o the l o c a t i o n s sampled f o r the f u n g a l s t u d i e s , and the r e s u l t s i n t e r p r e t e d i n terms o f presence or absence o f a c t i v e decay f u n g i .  12  2.0  LITERATURE REVIEW  2.1  SUPPLY AND DEMAND FOR UTILITY POLES IN CANADA S i n c e the b u i l d i n g o f the n a t i o n ' s r a i l w a y and the i n -  v e n t i o n o f the t e l e g r a p h , wood u t i l i t y p o l e s have been w i d e l y used i n Canada.  With the growing p o p u l a t i o n and i n d u s t r y ,  the demand f o r e l e c t r i f i c a t i o n spread through areas a c r o s s the n a t i o n .  During  urban and r u r a l  the p e r i o d between the l a t e  1950s and the e a r l y 1970s, there was a s i g n i f i c a n t i n the e l e c t r i c a l d i s t r i b u t i o n f a c i l i t i e s ,  increase  particularly in  the P r a i r i e p r o v i n c e s o f A l b e r t a , Saskatchewan and Manitoba. For example, a c t u a l purchases approximately procured 1975).  o f these p r o v i n c e s i n c r e a s e d  15% a year from 1970 when 50,800 p o l e s were  t o 1973 when 77,600 poles were obtained With r i s i n g d i s p o s a b l e incomes and more  purchased,  (Karaim, automobiles  t h e r e have been p r e s s u r e s t o improve road t r a n s -  p o r t a t i o n networks, o f t e n n e c e s s i t a t i n g r e l o c a t i o n o f e x i s t ing  pole l i n e s .  The requirement  f o r p o l e replacement,  at  the r a t e o f anywhere from 0.5 t o 2.5% depending on the u t i l i t y reporting  (Sugden, 1979), has a l s o been an important  a f f e c t i n g a constant demand f o r new p o l e s .  factor  There have been  some c o u n t e r a c t i n g e f f e c t s on the demand f o r wooden p o l e s due to  a e s t h e t i c reason, development o f new technology  such as  microwave systems i n t e l e g r a p h p o l e l i n e , and encroachment  i n t o the market by c o n c r e t e and s t e e l p o l e s (Karaim, Sugden, 1979).  1975;  N e v e r t h e l e s s , such types o f n a t u r a l , economic  and environmental  f a c t o r s have maintained a steady p r e s s u r e  on the e l e c t r i c a l ,  telephone and t e l e g r a p h u t i l i t y  companies  and, by e x t e n s i o n , on the s u p p l i e r s o f wooden p o l e s .  Thus,  n a t u r a l wooden p o l e s have been a unique product o f Canada's f o r e s t s , s i n c e they have been e f f e c t i v e l y used  i n the form  i n which they grew. Historically,  the u t i l i t y p o l e i n d u s t r y i n Canada  e s t a b l i s h e d around western  red cedar mainly due t o i t s  n a t u r a l decay r e s i s t a n c e , s t r a i g h t n e s s , l e n g t h and weight, and  was  light  c o m p a r a t i v e l y t h i n sapwood, s u i t a b i l i t y o f c l i m b i n g  finally  i t s abundance r e l a t i v e t o demand.  treatment, an average western  red cedar p o l e l i f e somewhat  l e s s than 20 years can be expected e a r l y 1970s, the requirements  (USDA, 1974).  S i n c e the  f o r u t i l i t y p o l e s have been  g r a d u a l l y i n c r e a s i n g a c r o s s Canada.  However, because  c o n t a i n s h a l f o f the n a t i o n ' s t o t a l softwood (Table 1), and a l l i t s western  Even without  growing  B.C. stock  red cedar, the p r o v i n c e  t r a d i t i o n a l l y has been a net p o l e e x p o r t e r , as w e l l as a steady s u p p l i e r t o the r e s t o f the c o u n t r y . The t r e n d i n u t i l i t y p o l e exports from B.C. p e r i o d 1963  to 1978  i s shown i n Table 2.  One  f o r the  significant  f e a t u r e o f the data i s that exports o f p o l e s from B.C.  since  TABLE 1.  Forest  F o r e s t resources comparison (B.C. M i n i s t r y o f F o r e s t s ,  Region  British  Columbia(1)  Canada(2) World(3)  F o r e s t Land ( m i l l i o n ha.)  Softwood Growing Stock (million m )  Hardwood Growing Stock (million m )  1979).  Total Growing Stock ( m i l l i o n m^)  52.1  7,871  211  8,082  342.0  15,202  4,079  19,281  2,795.0  107,000  180,000  287,000  O r i g i n a l sources: (1) B r i t i s h Columbia M i n i s t r y o f F o r e s t s , Inventory S t a t i s t i c s , 1978 (2) Canadian F o r e s t r y S e r v i c e , Canada's F o r e s t s , 1978 (3) FAQ, World Pulp and Paper Demand, Supply and Trade, 1977; Royal C o l l e g e o f F o r e s t r y , Stockholm, Sweden, World F o r e s t Resources, 1974 Note:  The q u a l i t y o f f o r e s t land and growing stock s t a t i s t i c s i s not uniform amongst regions o f the world due t o the use o f d i f f e r e n t d e f i n i t i o n s and measurements standards.  TABLE 2.  Trend i n u t i l i t y p o l e exports from B.C. (Sugden, 1979).  T o t a l Q u a n t i t y Exported ( L i n e a l Feet)  Year  To o t h e r Provinces  1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978  3,894,070 2,909,059 5,958,518 3,358,961 2,252,050 1,271,184 815,305 1,407,227 2,073,375 2,069,189 2,693,753 3,912,525 2,027,878 1,788,082 1,018,076 2,865,669  Original Note:  1.  2.  source:  To U.S.A.  7,797,268 6,566,569 3,750,672 8,026,637 6,496,834 5,917,141 4,700,716 6,059,181 3,699,385 4,183,636 2,205,397 3,483,773 1,574,975 1,602,261 2,352,849 3,132,550  B.C. M i n i s t r y  To o t h e r Countries  1,014,324 677,201 473,529 1,005,065 3,128,154 4,281,641 2,088,801, 1,583,584 271,502 213,192 638,317 49,784 522,624 67,600 80,225 1,800  Total  12,705,662 10,172,829 10,182,719 12,390,663 11,877,038 11,469,966 7,604,822 9,049,992 6,044,262 6,466,017 5,537,467 7,446,082 4,125,477 3,457,943 3,451,150 6,000,019  o f F o r e s t s , Annual  Reports  Due t o the use o f d i f f e r e n t measurement u n i t s , i . e . p i e c e s and l i n e a l f e e t , and no c a t e g o r i z a t i o n between p o l e s and p i l e s i n some B.C. f o r e s t d i s t r i c t s , the above data u n t i l 1976 do not c o i n c i d e w i t h those a v a i l a b l e i n o t h e r l i t e r a t u r e sources such as B.C. Annual Reports and Dobie (1976). F u r t h e r data a f t e r 1978 a r e omitted because o f their unavailability.  1971 were seldom more than h a l f o f those from 1963 But  l o g p r o d u c t i o n i n B.C.  c u n i t s i n 1966  i n c r e a s e d from 16.02  t o 24.77 m i l l i o n i n 1973,  cedar output jumped from 2.09 1976).  to 3.10  to  1968.  million  and western  red  m i l l i o n cunits  (Dobie,  Thus the probable s i t u a t i o n , as Dobie (1976) p o i n t s  out, was  one o f a d i m i n i s h i n g p o r t i o n o f the h a r v e s t b e i n g  utilized  as p o l e s t o c k .  At the same time, demand f o r B.C.  p o l e s from the r e s t o f the c o u n t r y i n c r e a s e d s u b s t a n t i a l l y s i n c e 1969,  consequently p u t t i n g p r e s s u r e on the a v a i l a b l e  supply. As i n d i c a t e d above, the u t i l i t y p o l e market which had been t r a d i t i o n a l l y s t a b l e changed markedly i n the e a r l y 1970s.  As a r e s u l t , Canada became a net p o l e importer f o r  the f i r s t time i n 1974.  The  trends i n t o t a l annual  Canadian  imports and exports o f u t i l i t y p o l e s f o r the p e r i o d 1963 1983  to  are presented i n Table 3, and are shown g r a p h i c a l l y i n  F i g u r e 1.  The most s t r i k i n g  f e a t u r e about  the f i g u r e i s  t h a t c o n s i d e r a b l e f l u c t u a t i o n s i n p o l e imports were apparent, p a r t i c u l a r l y f o r s e v e r a l years s i n c e 1973. it  On the o t h e r hand,  l e a v e s no doubt that the trend i n exports has been s t e a d i l y  downward.  I t i s c l e a r l y noted t h a t t h e r e was  i c i n c r e a s e i n imports i n 1973, about 4.4  a fairly  dramat-  so that net p o l e imports were  m i l l i o n l i n . f t . i n 1974.  T h i s had an  adverse  e f f e c t on the b a l a n c e o f payments f o r p o l e s , which i n  1974  TABLE  3.  Trend  in  payments  total and  annual  receipts  Canadian of  imports,  u t i l i t y  Exports  Year  Value in  1000  Total of  $  exports,  poles.  Imports  Quantity in  Lin.  (To  U.S.A.)  Ft.  Value in  1000  Total of  $  Quantity in  (From  U.S.A.)  Lin. Ft.  5,377  8,126,327  (8,088,705)  6,935,318 6,733,764  (6,910,411) (6,687,930)  459 1,398  1,176,180 2,129,111  (1,176,180)  1965  4,866 5,025  1966  5,538  6,895,309  (6,890.656)  3,049,932  [3,049,932)  1967 1968  5,324  (5,979,833)  [1.388.683)  1969 1970  6,281  6,092,943 7,520,449 5,897,501  1,616 791  6,384  6,357,994  1971  5,707  5,632,980  1972  6,040  1973  5,892 7.230  1963 1964  [2,129.111)  (7.341.056)  504  1,388,683 492,465  [  492,465)  (5,791,219) (5,928.918)  399  354,778  [  354,778)  932 811 900  664,846 620,994  [ (  664,846) 620,994)  5,217,016  (5,204,439) (5,180,081)  4,886,554  [4,803.287)  7,644  5,102,732 4,269,435  (4,281,274) (2,768.079)  3,629 12,105  1976  9,262  5,223,450  (2,288,718)  4,030  1977 1978  6,859 7,618  3,564.042  (2,892,867) (2,673,636)  1,505,536 4,478,659  (1,561,373) (1,503,536) (3,166,689)  1979 1980  7,802 8,587  2,813.173 2,863,510  (2,570,840)  3,031 8,076 10,459  3,593,119  (3,205,059)  (2,769.414)  10,530  3,614,124  (3,110,277)  1974 1975  6,435  3,311,452  11,980  1,007,187  (1,007,187)  3,874,716  (3,422,716)  9,475,269  (8,831,674)  7,818,437 2,029,880  (7,415,837)  TABLE  3.  (cont.)  Exports  Year  Value in  1000 o f  Total $  Imports  Quantity i n L i n .  (To  Value  U.S.A.)  Ft.  in  1000 o f  Total $  Quantity (From in L i n . Ft.  1981  8,990  3,135,880  (2,719,137)  6,668  2,192,383  1982  10,853  2,632,950  (1,701,762)  7,032  2,102,410  1983  13,876  3,122.047  (2,634,065)  2,629  825,085  Sources  Statistics  Canada  Catalogues  65-202,  65-203  U.S.A.)  (1,839,471) (1.729,646) (  825,085)  -10-  H LU LU  r-8-  A  LU  < LU U. O 0)  z o  L-6• IMPORTS  -4-  EXPORTS  — \ -2-  (0  -15-  oc <  • PAYMENTS  o M01  RECEIPTS  /  ' \ z  h5-  -o-  ^  —i'"" i 1963  '64  '66  -1— '66  >  I  '67  '68  I  '69  _ 1 _ _ L _ _L_ _L_  '70  '71  -1  1  '72  '73  _l  L_  ~i  '74  r~  '76  r  '76  -  —T— '77  '78  i '79  _ L _ _L_  '80  —r—  '82  '83  _ L _ '81  _l_  Figure 1. Changes in annual Canadian imports, exports, payments and receipts of utility poles.  20  was $2.3  a d e f i c i t o f $4.9  m i l l i o n compared w i t h a s u r p l u s o f  m i l l i o n i n the p r i o r  year.  The p r i n c i p a l reason that Canada became a net o f p o l e s during the years 1974 1980  and  1975  importer  and again i n 1978  -  i s t h a t , as noted p r e v i o u s l y , very h i g h lumber p r i c e s  r e s u l t e d i n the d i v e r s i o n o f some p o l e s t o c k to sawmills, thus c r e a t i n g a r e d u c t i o n i n p o l e i n v e n t o r i e s . reason was  Another  the sudden i n c r e a s e i n demand i n c o n j u n c t i o n w i t h  an extremely  low supply s i t u a t i o n .  t h a t t h i s change was  I t should a l s o be  noted  a r e s u l t o f heavy forward buying  f o r the f o l l o w i n g y e a r s .  in  1973  F u r t h e r d e t a i l e d d i s c u s s i o n and  a n a l y s i s are a v a i l a b l e elsewhere (Dobie,  1976;  Karaim,  1975;  Sugden, 1979). As most p o l e s u p p l i e r s a n t i c i p a t e d , Canada returned s h o r t l y t o i t s former p o s i t i o n as a net p o l e e x p o r t e r . t o a dramatic  i n c r e a s e i n p o l e imports  Due  from the U.S.A. (Table  3), however, t h i s p o s i t i o n was  reversed again f o r the s h o r t  p e r i o d between 1978  The  was  and  1980.  large proportion of  southern y e l l o w p i n e from southern U.S.  c e n t r a l and  e a s t e r n Canada.  imports  destined f o r  As Dobie (1976) i n d i c a t e d , t h i s  t r e n d appeared to be mainly because o f p r i c e advantage and e q u i v a l e n t f r e i g h t c o s t s f o r p o l e s from Alabama t o O n t a r i o compared w i t h those  from B.C.  southern  In s p i t e o f the major  f l u c t u a t i o n t h a t o c c u r r e d from the e a r l y 1970s u n t i l  1980,  21  it  i s c l e a r l y shown t h a t the t r a d e trend f o r p o l e s i n recent  years has been f a i r l y s t a b l e , w i t h the i n c r e a s e d s u r p l u s of r e c e i p t s commencing i n 1981  and p e r s i s t i n g t o the p r e s e n t .  In a recent study conducted demand and  by Sugden (1979),  the f u t u r e  supply o f wooden u t i l i t y p o l e s i n Canada has been  e x t e n s i v e l y analysed on the b a s i s o f c a l c u l a t e d p o l e usage r a t e s and  estimated p r o v i n c i a l p o p u l a t i o n s .  e r i n g the e v e n t u a l i t y o f imports  Without c o n s i d -  of p o l e s from f o r e i g n coun-  t r i e s , what h i s analyses have shown i s t h a t p r o j e c t e d demands f o r wooden u t i l i t y p o l e s t o the year 2000 i s s u f f i c i e n t be met  to  by p r o j e c t e d domestic s u p p l i e s .  S i n c e the e a r l y 1970s, as noted,  t h e r e has been the  danger t h a t southern y e l l o w p i n e s u p p l i e r s c o u l d m a i n t a i n o r e n l a r g e t h e i r p r o p o r t i o n o f the p o l e market.  Regardless  o f the Canadian supply s i t u a t i o n , t h e r e w i l l always be a l i k e l i h o o d o f p o l e s being  imported.  T h e r e f o r e , Canada should  compete s u c c e s s f u l l y i n p r i c e to c o n t i n u e t o be a net p o l e e x p o r t e r , as w e l l as to s a t i s f y i t s domestic  demands.  i n o r d e r t o a v o i d the n e c e s s i t y o f having to import commodate i n c r e a s e d p o l e requirements, out, an obvious  to ac-  as Dobie (1976) p o i n t s  need e x i s t s f o r c l o s e r l i a i s o n between buyer  and s e l l e r r e g a r d i n g f u t u r e supply. f o r a g r e a t e r lead-time allowance and  But  f o r manufacturers  There are a l s o needs  on the p a r t o f p o l e  to check comparative  p o l e and  buyers,  lumber  22  v a l u e s c a r e f u l l y b e f o r e c o n s i g n i n g p o l e s t o c k to a s a w m i l l . In agreement w i t h the l i t e r a t u r e Ruddick, 1978;  (Dobie,  1976;  Karaim,  1975;  Sugden, 1979), i t i s b e l i e v e d t h a t a more  a p p r o p r i a t e , long-term  s o l u t i o n would be t o u t i l i z e some o f  the l i t t l e - u s e d p o l e s p e c i e s a v a i l a b l e i n Canada. an urgent  need e x i s t s f o r r e s e a r c h data on the  treatment  o f n o n - t r a d i t i o n a l s p e c i e s such as white  Therefore,  satisfactory spruce  f o r use as u t i l i t y p o l e s , w i t h the o b j e c t i v e o f making p o l e supply more e l a s t i c .  2.2  WHITE SPRUCE AS POTENTIAL POLE SPECIES White spruce,  r e g i o n , can be approximately  a c h a r a c t e r i s t i c t r e e o f the b o r e a l  found  almost everywhere i n Canada, making  up  40% o f the c o n i f e r o u s volume and o n e - t h i r d o f  the t o t a l volume o f a l l s p e c i e s grown i n t h i s country 1979).  forest  Even i n B.C.  (Sudgen,  where the number o f c o n i f e r s are found,  a number o f s p e c i e s o f spruce again predominates, c o n s i s t i n g o f 25% o f the mature volume i n the p r o v i n c e .  This species  i s w i d e l y used f o r r e f o r e s t a t i o n and p l a n t i n g , and s i z e d timber  i s abundant i n l a r g e q u a n t i t i e s .  (Hosie, 1975; t a l l and  24 i n . (61 cm)  h e i g h t s o f 120 (122  cm).  Isenberg,  1980), white spruce i n diameter,  On  i s 80  i t s polethe average f t . (24  but some t r e e s a t t a i n  f t . (36 m) w i t h a diameter o f up t o 48 i n .  m)  23  The w i t h an  wood i s l u s t r o u s , n e a r l y white to p a l e brown  i n d i s t i n c t heartwood, i s u s u a l l y s t r a i g h t g r a i n e d ,  l i g h t to moderately l i g h t red c e d a r ) ,  2.2.1  and  (e.g. a l i t t l e denser than western  v e r y uniform i n appearance.  CHEMICAL, PHYSICAL AND WHITE SPRUCE The  chemical p r o p e r t i e s  MECHANICAL PROPERTIES OF  of coniferous  woods are  i n g l y s i m i l a r w i t h only minor v a r i a t i o n s o c c u r r i n g species.  Wood o f a l l s p e c i e s  cellulose  (alpha  and  coloured  i s chemically  c e l l u l o s e and  extractives.  The  surpris-  among  composed o f h o l o -  hemicellulose),  lignin,  ash  proximate v a l u e s f o r the chemical com-  p o s i t i o n o f white spruce wood are shown i n T a b l e 4. o f comparison, the t a b l e a l s o i n c l u d e s  several  For  sake  coniferous  woods which are e i t h e r dominant o r p o t e n t i a l s p e c i e s  f o r pole  p r o d u c t i o n i n Canada.  conif-  Of  the chemical p r o p e r t i e s  of  erous woods, e x t r a c t i v e content i s p r o b a b l y the only o f consequence, and  as Panshin and  De Zeeuw (1970) p o i n t  the e x t r a c t i v e s g e n e r a l l y  c o n s t i t u t e a few p e r c e n t o f  oven-dry weight o f wood.  The  c o n t a i n s acetone- and  on  f a t t y a c i d s and  out,  the  heartwood o f white spruce  petroleum e t h e r - s o l u b l e  (Rogers et a l . , 1969), and  variable  Swan (1973) reported  resin acids.  For  extractives information  the p e r c e n t composition  o f heartwood e x t r a c t i v e s are a v a i l a b l e elsewhere (Drew and Pylant,  1966).  However, the e x t r a c t i v e s , such as t h u j a p l i c i n s  TABLE  4.  Chemical composition of  six  common  coniferous  woods  (Isenberg,  1980)  Solubility  White  spruce  Amabilis  f i r  Doualas-fir Lodqepole  (%)  (%)  Lignin  pentosan  Alcohol  Hot  benzene  water (%)  (%)  (%)  (%)  i%)  11.8  0.3  2.0  2.6  qlauca)  42.6  16.4  29.4  (Abies  amabilis)  43.8  -  28.2  9.8  0.5  2.6  3.2  (Pseudotsuqa  pine  hemlock  Western  red  A l l  cellulose  (Picea  Western  Note:  cellulose  Ash  Total  Hemi-  AlphaSpecies  in  (Pinus (Tsuga  cedar  menziesii)  contorta) heterophylla)  (Thuia  percentages  plicata)  based  49.6  14.1  27.7  7.9  0.2  4;i  5.0  45.7  -  27.2  12.4  0.2  3.5  2.7  49.2  15.5  29.4  9.2  0.3  2.6  2.0  44.0  14.6  30.9  9.0  0.3  on m o i s t u r e - f r e e  14.1  11.0  wood.  to 4*  25  responsible  f o r the n a t u r a l decays r e s i s t a n c e o f western red  cedar (Kurth,  1950;  Rennerfelt,  1948), are not present  in  spruce wood. The  p h y s i c a l p r o p e r t i e s o f wood normally i n c l u d e spe-  c i f i c g r a v i t y , shrinkage,  anatomy.  These p r o p e r t i e s c l o s e l y  r e l a t e to the mechanical s t r e n g t h p r o p e r t i e s o f the wood to i t s a b i l i t y to be  and  impregnated by p r e s e r v a t i v e s o l u t i o n s .  To i l l u s t r a t e the p h y s i c a l p r o p e r t i e s o f white spruce, Table 5 has  been prepared t o i n c l u d e white spruce and  other s p e c i e s there  listed  is a little  i n Table 4.  Of these s p e c i e s  five presented,  d i f f e r e n c e i n most o f the p h y s i c a l p r o p e r -  t i e s examined, though D o u g l a s - f i r has s p e c i f i c g r a v i t y value. of r e s i n canals  the  a significantly  higher  I t c o u l d be argued that the presence  i s b e n e f i c i a l f o r the d i s t r i b u t i o n o f  a t i v e s o l u t i o n s both i n the t r a n s v e r s e  and  A t t r i b u t e s such as t r a c h e i d diameter and  preserv-  radial directions.  ray volume would  i n f l u e n c e the ease o f p e n e t r a t i o n both i n v e r t i c a l and directions.  lateral  Thus the s m a l l average t r a c h e i d diameter w i t h  the presence o f blocked  bordered p i t s o f white spruce  may  account f o r some o f the d i f f i c u l t i e s  i n preservative treat-  ment r e p o r t e d  p r o c e s s o f heartwood  formation blocking  for this species.  The  o r d r y i n g causes the p i t membrane t o s h i f t the p i t a p e r t u r e  by the torus  (Stamm, 1970).  thereby This  s i t u a t i o n , which i s w e l l known i n the i n t e r i o r v a r i e t y o f  TABLE  Specific  5.  Physical properties  Gravity  Tracheid  of  s i x common  coniferous  Dimensions  woods.  Shrinkage Ave.  Ray Species  Green Volume  Ring  Oven-dry  Volume^  Length  Diameter  Resin Canals  Volume  (*)  (mm)  On)  (normal)  2  Green  to  O v e n -d r y ( % )  TangenRadial  White  t i a l  Width  Latewood  (mm)  (%)  Volumetric  0.37  0.42  7.0  3.3  35  present  4.7  8.2  13.7  1.7  21  6.35  6.42  7.0  3.3  60  absent  4.6  9.8  13.8  1.7  22  0.45  0.51  7.3  3.4  55  present  5.0  7.8  11.8  1.7  35  0.38  0.43  5.7  3.2  55  present  4.5  6.7  11.5  1.0  23  0.38  0.44  8.0  3.0  50  absent  4.3  7.9  11.9  1.3  31  0.31  0.34  6.9  3.1  45  absent  2.4  5.0  6.8  1.7  27  spruce Amabilis f i r Douglasf i r Lodgepole pine Western hemlock Western red cedar  Sources t 1.  Isenberg  2. 3.  Panshin Jessome  (1980) a n d De Z e e u w (1977)  (1970)  D o u g l a s - f i r , a l s o occurs i n white spruce (Sebastian  et a l . ,  1965). The mechanical p r o p e r t i e s o f wood obtained  from  small  c l e a r specimens a r e extremely u s e f u l i n determining the r e l a t i v e s t r e n g t h between s p e c i e s .  These p r o p e r t i e s a r e  dependent on a number o f f a c t o r s * such as the m o i s t u r e cont e n t and p h y s i c a l p r o p e r t i e s o f the wood, which may v a r y among s p e c i e s and even w i t h i n the same s p e c i e s .  Table 6  summarizes the mechanical p r o p e r t i e s o f the s i x s p e c i e s i n both green and a i r - d r y c o n d i t i o n s . green data g i v e n  On the b a s i s o f the  i n the t a b l e , these s p e c i e s c o u l d be ranked  i n order o f increasing f i b r e s t r e s s at p r o p o r t i o n a l l i m i t i n s t a t i c bending as f o l l o w s : amabilis  white spruce, lodgepole  pine,  f i r , western r e d cedar, western hemlock and Douglas-  fir. Although the r e s u l t s o f mechanical t e s t s made on s m a l l c l e a r specimens can be used t o s e l e c t wood s p e c i e s g i v e n end-use, i t should  be noted that i n very  for a  few cases  i s the end-use s a t i s f i e d e x a c t l y by such specimens.  Wooden  u t i l i t y p o l e s a r e normally t e s t e d f o r s e v e r a l purposes, i n accordance w i t h e s t a b l i s h e d t e s t procedures such as those published  by the American S o c i e t y  (ASTM) i n t h e i r s t a n d a r d :  f o r T e s t i n g and M a t e r i a l s  ASTM D 1036-83 Standard Methods  o f S t a t i c T e s t s o f Wood Poles  (ASTM, 1984).  The s t r e n g t h  TABLE  6.  Mechanical properties  of  s i x common  conifers  (Jessome,  1977).  Species Test  Attribute  White spruce  Static  Bending  Stress  at  Limit  Proportional  (psi)  Modulus  of  Impact  Bending  Compression Parallel  to  6ra in  Compression Perpendicular to  Grain  Stress Limit  cedar  4,110 7,800  3.100 4.990  5,650  6,960  5,300  11,020  11,760  7.800  Elasticity  1,610  1,270  1,480  1,440  1,650  1,960  1,580  1,790  1,050 1.200  8,350  8,680  10,360  7,760  9,000  7.580  10,920  12,000  14,340  10,780  11,200  9,700 1,380  of  Elasticity  Stress  at  Limit  of  Pro(psi)  Stress  Elasticity  psi) at  red  7,500  portional  (1000  Western  12,850  Maximum C r u s h i n g (psi) Modulus  2,970 7,050  Western hemlock  5,480  psi)  Crushing  4,320 7,740  pine  9,990 1,350  Stress at Proportional Limit (psi) (1000  2,990 5,810  Lodgepole  5.100  psi)  Modulus  f i r  9,090 1,150  of  (1000  Douglas-  f i r  Rupture  (psi) Modulus  2.780 5.320  Amabilis  Proportional  (psi)  1,370  1.610  2,000  1,370  1,970  2,000  2,260  2,810  1,830  2,310  1,490  1,820  2,140  2.810  2,220  2,980  2.310  3.710 2,470  4,150  4,950  4,450  5,290  3,970  2,770  3.610  2,860  3,580  2.780  5,350  5,920  7,270  6,270  6,780  4,920  1,310 1,650  1,460 1,750  1,670  1,420  1,620  1.170  1,970  1,660  1,750  1.320  245  234  460  276  373  278  500  523  871  529  657  497  TABLE  6.  (cont.)  Species Attribute  Test  White  Amabilis  spruce Load  Hardness  Required  Imbed  0.444  Sphere  to  to  P a r a l l e l  Maximum  Side  i n .  Half  Diameter Shear  to  End  (lb)  Stress  (psi)  Grain  Cleavage  Splitting in.  Tesion dicular  Maximum  Perpen-  3  Stress  i n .  f i r  Lodgepole pine  Western  Western  hemlock  red  cedar  279  322  481  362  468  265  423  672 589  49a  617  330  320  442 406  339  561  431  555  835  903  673  992  674  670  714  922  724  752  696  985  1,093  1,382  1,238  940  809  (lb./  156  168  216  186  202  136  long)  221  210  222  297  214  145  307 475  274  407  238  444  332 548  390  444  425  357  Strength  width,  Douglas-  f i r  (psi)  to  Grain  Note:  Values  in  condition;  the  f i r s t  those  in  line the  for  each  second  property  line  are  are  the  adjusted  s p e c i e s means to  12  percent  i n  the  moisture  unseasoned condition.  30  p r o p e r t i e s o f whole p o l e from white spruce have been obtained from a v a i l a b l e l i t e r a t u r e sources 1979), and data  are presented  (Eggleston, 1952;  i n Table 7.  from western red cedar,  Sugden,  For sake o f comparison,  lodgepole p i n e , a m a b i l i s f i r  and western hemlock p o l e s are a l s o i n c l u d e d .  On  the b a s i s  o f the data g i v e n i n the t a b l e , i t i s e v i d e n t t h a t both a m a b i l i s f i r and western hemlock are p o t e n t i a l as s u b s t i t u t e s f o r western red cedar and  candidates  lodgepole  pine  p o l e s , at l e a s t i n terms o f mechanical s t r e n g t h p r o p e r t i e s . On  the o t h e r hand, white spruce  appears to have lower s t r e n g t h  p r o p e r t i e s than any o f the s p e c i e s l i s t e d . cause f o r concern,  T h i s might be a  p a r t i c u l a r l y when c o n s i d e r i n g t h i s  species  as a source o f longer p o l e s .  2.2.2  PROBLEMS ASSOCIATED WITH WHITE SPRUCE During  Laboratory  the p a s t decade, the E a s t e r n F o r e s t  Products  (EFPL) conducted numerous s t u d i e s on the  treat-  ment o f white spruce w i t h waterborne p r e s e r v a t i v e s (Krzyzewski, and  1978;  Rak,  1977a,b and c; Rak  S h i e l d s , 1984a and b ) .  and C l a r k e , 1975a; Ralph  However, because o f the  diffi-  c u l t y i n penetrating t h i s species with preservatives, l i m i t e d use has been made o f i t f o r the p r o d u c t i o n o f preserved wood products. Due  to the p o l e shortage  i n the e a r l y 1970s, s e v e r a l  TABLE  7.  Summary o f  pole  strength  Treatment  Modulus Pole  Species  Origin  Drying  Preservation  tests.  Length  of  Mo. of  (ft.)  Poles  Rupture3 Coeff.  Average (psi)  Std. of Dev.  Var.  {%)  5%  Source  Fractile  White  B.C.  Air  Bethel-PCP  35  53  4961  3562  1  B.C.  Air  Bethel-ACA  35  53  4911  951 684  19.2  spruce  13.9  3872  1  Amabilis  B.C.  Kiln  Bethel-PCP  35  52  5642  1032  18.3  4118  1  f i r  B.C.  Kiln  Bethel-ACA  35  51  5194  781  15.0  4016  1  Western  B.C.  25  52  6135  739  12.0  4999  1  B.C.  None Air  None  hemlock  Creosote  25  50  6432  975  15.2  4963  B.C.  Kiln  Bethel-PCP  35  52  7483  1026  13.7  5922  1 1  B.C.  Kiln  Bethel-ACA  35  50  6967  1034  14.8  5407  1  -  Lodgepole  U.S.A.  pine  B.C. B.C. Alta.  None Air  Alta.  None  U.S.A.  None  None None  U.S.A.  Air  Rueping-Creosote  U.S.A.  Air  U.S.A.  None  Rueping-Creosote None  None  CCA None Rueping-Creosote None  -  9  5836  25 25  23 24  5809 6671  -  2  627  25 25  23 25  25  6  25 30 45  -  10.8  -  4839  1  12.9  6604  862 667  1 1  6581  527  4955  542  10.1 8.0 10.9  5353 5567  6  5174  492  21  5150  5  4220  5752  1  4116  1  9.5  4406  684  13.3  4106  1 1  648  15.3  3245  1  0  TABLE  7.  (cont.)  Treatment  Species  Origin  Drying  Modulus  Preservation  Pole  No.  Length  of  (ft.)  Poles  Std.  (psi)  Dev.  30  51  5229  25  4694  885  18.9  4587 5787  599  13.1  CCA  2  4395  -  CCA  U.S.A.  -  CCA  3 5  5207 4882  None -  None Butt  Treated  B.C.  None  None  30  51  B.C.  None  None  30  B.C.  None  None  30  40 40  U.S.A.  None  None  30  U.S.A.  None  None  30  The  groundline  1)  Sugden  2)  Eggleston  MOR v a l u e s  (1979) (1952)  were  9  Var.  (%)  30  -  U.S.A.  B.C.  of  763  U.S.A.  red  B.C.  Rupture Coeff.  Average  Western cedar  of  14.6  5%  -  4075 3391 3672  877  15.2  4466  827  14.7  4370  26  5620 5550  514  9.3  4746  25  5325  505  9.5  4536  determined approximately at  6  feet  above  Source*3  Fractile  the  butt.  2 2 2  wood-treating companies examined the s u i t a b i l i t y o f spruce as p o l e m a t e r i a l .  I t has been r e p o r t e d by R u t h e r f o r d (1977)  o f Domtar t h a t , i n experiments  conducted  on spruce, p o t e n t i a l  problems e x i s t e d due t o e x c e s s i v e checking formation and f i c u l t y i n o b t a i n i n g an adequate treatment. ent w i t h the world  dif-  This i s consist-  l i t e r a t u r e i n which the r e f r a c t o r y behav-  i o u r o f s e v e r a l s p e c i e s o f spruce i s d e s c r i b e d (Banks,  1973?  Dunleavy et a l . , 1973a and b? Hauffe, 1970? Hackbarth,  1975?  L i e s e and Bauch, 1967; S i a u and Shaw, 1971?  Rak,  1977a? Rak  Unligil,  1971).  and C l a r k e , 1975a? I t i s g e n e r a l l y known  t h a t spruce wood i s v e r y low i n n a t u r a l decay r e s i s t a n c e (MacLean, 1935? N i c h o l a s and S i a u , 1973? Panshin and Zeeuw, 1970? USDA, 1974).  F o r example, u n t r e a t e d fence  p o s t s o f white spruce have an average 3.2  years i n e a s t e r n Canada  De  service l i f e of only  (Krzyzewski and Sedziak,  1974).  Thus any damage by checking a f t e r s h a l l o w treatment c o u l d expose spruce wood w i t h low n a t u r a l d u r a b i l i t y t o h i g h decay hazard. D e s p i t e e x t e n s i v e s t u d i e s (Hackbarth,  1975?  and L i e s e , 1975? L i e s e and Bauch, 1967? Rak,  Hackbarth  1977a? S i a u ,  1970), the reasons f o r the r e f r a c t o r y nature o f spruce are not f u l l y understood.  L i e s e and Bauch (1967) have proposed  t h a t the low p e r m e a b i l i t y o f the ray c e l l s relatively  i s due t o the  s m a l l p r o p o r t i o n o f ray t r a c h e i d s .  However, i n  a more recent study conducted by Hackbarth and on spruce  L i e s e (1975)  t r e a t e d w i t h two waterborne p r e s e r v a t i v e s , copper  chrome f l u o r i d e and  copper chrome borate,  they  concluded  t h a t n e i t h e r the number nor the area o f ray c e l l s i n f l u e n c e d the p r e s e r v a t i v e p e n e t r a t i o n , and and  rather increasing density  the p r o p o r t i o n o f latewood both reduced the p r e s e r v a t i v e  absorption.  Sapwood was  heartwood and  found t o be more permeable than  a x i a l p e n e t r a t i o n i n sapwood was  thirty-four  times g r e a t e r than t h a t i n e i t h e r the r a d i a l o r t a n g e n t i a l directions.  The o n l y chemical  i n f l u e n c e was  detected was  f a c t o r f o r which a p o s i t i v e  the s o l u t i o n c o n c e n t r a t i o n ,  sug-  g e s t i n g t h a t i n c r e a s i n g the s o l u t i o n s t r e n g t h caused a r e d u c t i o n i n the amount o f s o l u t i o n absorbed L i e s e , 1975).  Recently Rak  (1977a) has  (Harkbarth  and  a l s o suggested t h a t  s t r u c t u r a l reasons f o r the low p e r m e a b i l i t y o f spruce fewer bordered  p i t s w i t h s m a l l e r margo pores,  c i e n t c a p i l l a r y connections  and  are  less  effi-  between ray parenchyma on c r o s s -  f i e l d s than i n permeable s p e c i e s such as p i n e s . White spruce heartwood i s undoubtedly one d i f f i c u l t woods to t r e a t .  Although the range o f p e r m e a b i l i t y  i s thought to be r e l a t i v e l y narrow i n spruce, t h i s may  exceptions  occur depending on the s p e c i e s o f spruce,  geographic l o c a t i o n and 1984b).  o f the most  r a t e o f growth (Ralph and  In a d d i t i o n p e r m e a b i l i t y may  to  their Shields,  be a f f e c t e d by  such  f a c t o r s as the method o f l o g storage,  time o f year the  m a t e r i a l i s c u t , as w e l l as s e v e r a l o t h e r v a r i a b l e s . m e a b i l i t y a l s o d i f f e r s w i t h i n a s i n g l e annual r i n g  Per-  with  earlywood bands o f t e n b e i n g more permeable than latewood. T h i s phenomenon i s f r e q u e n t l y observed as a banding i n some p r e s s u r e - t r e a t e d spruce  2.3  effect  (Ralph and S h i e l d s , 1984b).  FACTORS AFFECTING THE TREATABILITY OF SPRUCE ROUNDWOOD The  Canadian wood p r e s e r v a t i o n i n d u s t r y has r e l i e d  h e a v i l y on s p e c i f i c wood s p e c i e s f o r p r e s s u r e  treatment.  Consequently, more permeable wood s p e c i e s f o r use i n p r e s e r v a t i v e - t r e a t e d commodities have become depleted Thus spruce  can be a convenient  abundant l o c a l resources  i n Canada.  replacement f o r them from  provided  t h a t i t can be t r e a t e d t o  l e v e l s adequate t o p r o t e c t commodities i n ground  contact.  In g e n e r a l , the problem o f t r e a t i n g d i f f i c u l t l y t r a b l e s p e c i e s such as spruce b a s i c methods.  These a r e :  pene-  has been a t t a c k e d by three  (1) the use o f enzymes, molds,  o r b a c t e r i a ( m i c r o b i o l o g i c a l ) ; (2) i n c i s i n g and v a r i a t i o n o f the t r e a t i n g c o n d i t i o n s type and f o r m u l a t i o n  2.3.1  ( p h y s i c a l ) ; and (3) p r e s e r v a t i v e  (chemical).  MICROBIOLOGICAL STUDIES  A number o f r e s e a r c h e r s have shown t h a t microorganisms and  enzymes ean i n c r e a s e the p e r m e a b i l i t y o f wood.  Work i n  36  t h i s area was  i n i t i a t e d by Lindgren  and  Harvey (1952) when  they found t h a t Trichoderma mold improved the o f southern p i n e sapwood sprayed w i t h  permeability  fluoride solutions.  S e v e r a l subsequent s t u d i e s  (Dunleavy et a l . , 1973a and  b;  Ellwood and  Greaves and  Knuth  Ecklund, 1959;  and McCoy, 1962; reported crease  Schulz,  1968;  t h a t b a c t e r i a and  Barnacle,  Unligil,  other  1971  and  1970;  1972a) have  fungi also e f f e c t i v e l y i n -  the p e r m e a b i l i t y o f wood, i n d i c a t i n g t h a t the  permeability c e l l s and  i s p r i n c i p a l l y due  p i t membranes.  to degradation  increased  o f the  ray  For example, s t e e p i n g spruce p o l e s  f o r two months i n stagnant water caused a breakdown o f  the  p i t membranes, r e s u l t i n g i n an improved p e r m e a b i l i t y o f ray c e l l s  (Dunleavy et a l . , 1973b).  The  the  degree o f improve-  ment depends upon both the time o f year and  the d u r a t i o n  of  ponding, r e f l e c t i n g the e f f e c t o f water temperature on bacterial activity.  Schulz  (1968) a l s o observed t h a t  penetra-  t i o n o f fluor-chrome a r s e n i c phenol (FCAP) p r e s e r v a t i v e i n c r e a s e d up to 67% i n the sapwood r e g i o n o f ponded spruce poles. S i m i l a r l y , when t r e a t i n g ponded white spruce p o l e w i t h CCA  preservative, U n l i g i l  solution absorption. i n p e r m e a b i l i t y was up t o 179%  (Unligil,  (1971) r e p o r t e d  For c r e o s o t e  treatment, the  even more marked, w i t h 1971  and  a 50%  1972a).  greater  improvement  increased  According  sections  retentions  to U n l i g i l ,  the e f f e c t s o f ponding are l i m i t e d t o the sapwood zone. Although b a c t e r i a were detected  throughout the sapwood, o n l y  the r e s i n c a n a l s , e p i t h e l i a l c e l l s and  ray parenchyma were  p a r t i c u l a r l y a f f e c t e d i n the i n n e r r e g i o n .  He a l s o suggested  t h a t a t t a c k o f the s u r f a c e o f the p o l e s e c t i o n by s o f t r o t f u n g i may  have c o n t r i b u t e d t o the improved p e r m e a b i l i t y .  S i n c e i t i s known t h a t microorganisms degrade wood by enzymatic a c t i o n , i t i s l o g i c a l t o assume t h a t p e r m e a b i l i t y c o u l d be  i n c r e a s e d by treatment w i t h enzymes.  t i o n was  verified  i n a study by N i c h o l a s and  This'assumpThomas (1968)  which showed t h a t s e v e r a l enzymes a t t a c k the p i t membranes i n l o b l o l l y p i n e sapwood, r e s u l t i n g i n a s i g n i f i c a n t in permeability.  increase  U n l i g i l and Krzyzewski (1972) attempted  to  improve the p e r m e a b i l i t y o f spruce by enzymatic decomposition o f the p e c t i c substances i n the l i q u i d - f & o w - c o n t r o l l i n g t o r i . Dunleavy and h i s co-workers (1973b) have a l s o conducted a s i m i l a r study on w a t e r - s t o r e d s t o r e d spruce  spruce  logs to examined water-  logs f o r enzymatic a c t i v i t y , p a r t i c u l a r l y t h a t  involving pectate  l y a s e , s i n c e degradation  p e c t i c substances  ( i . e . p i t membranes) would enhance f u r t h e r  lyase a c t i v i t y . m a t e r i a l may  products  While the enzymatic pretreatment  from  of pole  improve the o v e r a l l p e r m e a b i l i t y , i t remains  u n c l e a r whether any  s i g n i f i c a n t improvement i n p e n e t r a t i o n  i n the r a d i a l d i r e c t i o n i s o b t a i n e d .  Indeed Adolph (1976)  has  suggested  cult  than  Assuming  that  impregnation  in either  the  that bordered  destroyed,  this  would  because of bordered The  use  permeability tive ing  to U n l i g i l  loss  clear  spruce any  b e i n g on  static  an  sitchensis  (Bong.) from  they  the  are  selec-  treatment  roundwoods such problems.  for drying.  to  d r y and  the  of  his on  a  was  as  slight  co-workers full-sized  negligible.  o f p o l e s was  with oil-borne utility  Sitka  the poles are  during the  drying  that They  the  However, leads  and  carried  w i t h enzyme t r e a t m e n t s  out m o s t l y on  s m a l l wood  have so  specimens.  to  later  difficult  process i n -  creases. Experiments  clean  preserva-  poles,  placed i n water  Furthermore decay  air-dried  Water storage of poles  t h e y must be  stacked  on  Accord-  poles indicated  of ponding  Concerning  risk  movement  faces.  indicated  and  ponding  tives.  be  tests  Carr)  after  handling since  partially  to improve  because  spruce  appearance  extra  radial  bending  surface  are c e r t a i n  are  tangential  strength tests  added b e n e f i t  there  direction.  tori  enzymes  However, Dunleavy  have r e p o r t e d t h a t  that  the  and  of white  reduction resulting  found  t o improved  diffi-  thus m i n i m i z i n g s t r e n g t h l o s s .  specimens  (Picea  or axial  i s advantageous  (1972a),  i n strength.  (1973b)  lead  attack,  i s much more  p i t membranes and  of microorganisms  in their  small,  tangential  pits  o f wood  radially  f a r been  Therefore,  39  s t u d i e s on the a p p l i c a b i l i t y o f enzyme treatments to roundwoods are r e q u i r e d . still  At present,  the enzyme p r e p a r a t i o n s  too expensive to have a p r a c t i c a l use.  Although  are use  o f the mould fungus Trichoderma i s a simple method t o improve p e r m e a b i l i t y o f softwood practice.  (Bergman, 1984), i t i s not used i n  Presumably t h i s i s because a mould a t t a c k i s s t i l l  regarded as a gateway to wood decay.  2.3.2  PHYSICAL STUDIES  2.3.2.1  INCISING  While n a t u r a l seasoning normally  or a r t i f i c i a l  preconditioning  improve r e s u l t s o f treatment, some r e f r a c t o r y s p e c i e s  require a d d i t i o n a l preparation  i n order  treating results.  the most commonly imployed  method o f p r e p a r i n g  At present,  these s p e c i e s  formed on both sawn and one  i s i n c i s i n g , which i s per-  round m a t e r i a l .  o f the most e f f e c t i v e and  to o b t a i n s a t i s f a c t o r y  I n c i s i n g has  l e a s t c o s t l y methods o f iroprove-  i n g the t r e a t a b i l i t y o f wood (Nicholas and mechanically along  and  been  Siau,  1973).  By  r u p t u r i n g the wood c e l l s at p e r i o d i c i n t e r v a l s  across the p i e c e , the s t r u c t u r e i s rendered  suffi-  c i e n t l y porous to permit the flow o f p r e s e r v a t i v e s o l u t i o n s i n t o the i n c i s e d zone. A number o f r e p o r t s i n d i c a t e t h a t the p e r m e a b i l i t y spruce to p r e s e r v a t i v e s can be  improved by i n c i s i n g  of  (Banks,  1973;  Horn et a l . ,  Mohler,  1969;  1977;  Krzyzewski and S h i e l d s ,  Ralph and S h i e l d s , 1984a).  1977;  Banks (1973) has  r e p o r t e d the development o f a c l o s e - s p a c e d i n c i s i n g p a t t e r n f o r use on spruce lumber, and i n a very r e c e n t study  (Ralph  and S h i e l d s , 1984a) i n c i s i n g o f spruce lumber proved benef i c i a l by i n c r e a s i n g p r e s e r v a t i v e p e n e t r a t i o n i n the h e a r t wood areas o f boards, even when t r e a t e d by the thermal fusion process.  Horn and h i s co-workers  dif-  (1977) have shown  that i n c i s i n g spruce p o l e s c l e a r l y enhances both the penet r a t i o n and r e t e n t i o n o f waterborne by p r e s s u r e impregnation.  preservatives applied  They a l s o noted that an a d d i t i o n -  a l b e n e f i t r e s u l t i n g from i n c i s i n g was  the dramatic lowering  o f the c o n c e n t r a t i o n g r a d i e n t over the o u t e r 1.2 a n a l y t i c a l zone, w i t h the p a t t e r n o f 1.2 i n c i s i o n s staggered 0.4 (3 cm).  i n . (1 cm)  i n . (3 cm)  deep  l a t e r a l l y 1.2 i n .  Thus by choosing a s u i t a b l e spacing and depth o f  incisions,  i t i s p o s s i b l e t o p r o v i d e p o l e s w i t h a more  uniform p r e s e r v a t i v e treatment. treatment  and  i n . (3 cm)  In a d d i t i o n to improving  r e s u l t s , a secondary b e n e f i t p r o v i d e d by  i s the r e d u c t i o n o f deep checks  incising  (Krzyzewski and S h i e l d s ,  1977)  The main disadvantages o f i n c i s i n g are t h a t i t produces a rough s u r f a c e and r e s u l t s i n some s t r e n g t h l o s s 1969)  N i c h o l a s and S i a u , 1973).  (Mohler,  However, f o r most products  such as p o l e and timber, these disadvantages are not too  41  s e r i o u s and i n c i s i n g undoubtedly p r i n c i p a l method o f improving  2.3.2.2  w i l l continue to be  the  treatability.  VARIATION OF THE TREATING CONDITIONS  To a c e r t a i n extent, the treatment by u s i n g d i f f e r e n t t r e a t i n g c y c l e s .  r e s u l t s can be  altered  For example, i t i s gen-  e r a l l y known that the f u l l - c e l l process can be used t o maximize r e t e n t i o n .  Furthermore,  the Lowry and Rueping processes  can be used t o reduce r e t e n t i o n w h i l e o b t a i n i n g b e t t e r penet r a t i o n compared w i t h the f u l l - c e l l process t u t e o f Timber C o n s t r u c t i o n , 1971). w i t h o i l b o r n e s o l u t i o n s may  (Canadian  Insti-  P r e s s u r e processes  used  be e i t h e r f u l l - c e l l o r empty-  c e l l , w h i l e the f u l l - c e l l process i s almost always used w i t h the waterborne s o l u t i o n s  (Kennedy, 1981).  Although  these  p r e s s u r e - t r e a t i n g processes have proven t o be e f f e c t i v e means of  impregnating wood w i t h p r e s e r v a t i v e s o l u t i o n s i n most  cases, they do not p r o v i d e adequate treatment of r e f r a c t o r y wood.  T h i s i s mainly the r e s u l t o f i n s u f f i c i e n t p r e s s u r e t o  overcome the a i r - l i q u i d  i n t e r f a c e s i n the extremely s m a l l  pores o f t h i s type o f wood (Nicholas and S i a u , 1973). it  i s a n t i c i p a t e d t h a t s i g n i f i c a n t l y b e t t e r r e s u l t s c o u l d be  obtained by a l t e r i n g the t r e a t i n g schedule and  Thus  (e.g. p r e s s u r e  temperature). The work by MacLean (1935) c l e a r l y showed that  increasing  the p r e s s u r e from 100 t o 250 p s i (689 t o 1723 kPa) improved the treatment o f r e f r a c t o r y wood. Siau  However, the r e s e a r c h by  (1970) and Walters and W h i t t i n g t o n (1970) has i n d i c a t e d  that c o n s i d e r a b l y h i g h e r p r e s s u r e s are r e q u i r e d t o o b t a i n complete  impregnation o f t h i s type o f wood.  Although an i n c r e a s e i n p r e s s u r e appears  to be a means  o f a c h i e v i n g b e t t e r treatment o f r e f r a c t o r y wood, i n c r e a s i n g the d u r a t i o n o f a p p l i e d p r e s s u r e r a t h e r than i t s magnitude was found t o be more b e n e f i c i a l t o improving p e n e t r a t i o n (Hackbarth, 1975).  These r e s u l t s a r e i n agreement w i t h those  o f an e a r l i e r study by Hauffe  (1970), who a l s o noted the  b e n e f i c i a l e f f e c t o f i n c r e a s i n g the temperature s o l u t i o n when t r e a t i n g b l a c k spruce B.S.P.).  Both Hauffe and Bosshard  (Picea mariana  tar o i l , kPa)  (Mill.)  (1968), who i n v e s t i g a t e d  the use o f h i g h p r e s s u r e s and temperatures t i o n o f Norway spruce  of creosote  on the impregna-  (Picea a b i e s (L.) Karst.) w i t h c o a l -  concluded that p r e s s u r e s g r e a t e r than 150 p s i (1032  and temperatures  the wood s t r u c t u r e . o f squared  i n excess o f 100°C caused damage t o I t was a l s o observed d u r i n g treatment  timbers o f white spruce that c o l l a p s e occurred  at about 65°C i n some timbers, mostly on heartwood faces (Krzyzewski, 1978).  T h i s e f f e c t has not been observed i n  the treatment o f roundwood, but u n t i l such time as the i n f l u e n c e o f temperature  i s determined,  Krzyzewski has recom-  mended t h a t the temperature  should not be h i g h e r than t h a t  indicated. A number o f p i l o t p l a n t s t u d i e s (Krzyzewski, 1978; 1975 and  and  1977c) have been conducted  roundwood t o determine  on white spruce  lumber  optimum t r e a t i n g c o n d i t i o n s .  Using a m o d i f i e d t r e a t i n g schedule,  i . e . flow i n p r e s e r v a -  t i v e a t 57°C w i t h p r e s s u r e s up to 150 p s i (1032 Krzyzewski  Rak,  kPa),  (1978) obtained good p e n e t r a t i o n s and r e t e n t i o n s  i n a l a r g e number o f spruce roundwood t r e a t e d w i t h ammoniacal salt preservatives.  T h i s o b s e r v a t i o n i s i n agreement w i t h  that r e p o r t e d by Rak  (1975>.  The  t r e a t i n g schedule p l a y s an important  ing a s a t i s f a c t o r y p r e s e r v a t i v e treatment.  role i n achiev-  However, i t should  be noted t h a t c e r t a i n f a c t o r s p l a c e r e s t r i c t i o n s on the p r e s sure and temperature  used.  As N i c h o l a s and S i a u (1973) p o i n t  out, s u s c e p t i b i l i t y o f wood t o c o l l a p s e v a r i e s w i t h the p r e s sure, p e r m e a b i l i t y , wood s p e c i e s , s i z e o f the specimen,  type  o f p r e s e r v a t i v e , r a t e of p r e s s u r e i n c r e a s e , and p r e s e r v a t i v e temperature.  Consequently,  a l l these f a c t o r s must be  s i d e r e d when the use o f h i g h e r p r e s s u r e i s  2.3.3  con-  contemplated.  CHEMICAL STUDIES The  t h i r d area o f r e s e a r c h a c t i v i t y t o i n c r e a s e the  p e n e t r a b i l i t y o f spruce i s the proper s e l e c t i o n o f chemicals  and  additives for formulations.  Since  the c h a r a c t e r i s t i c s  o f the t r e a t i n g s o l u t i o n have an e f f e c t on the treatment of wood, the problem o f t r e a t i n g d i f f i c u l t l y p e n e t r a b l e such as spruce has been attacked preservatives experience  (e.g. ACA)  and  species  by using more p e n e t r a t i v e  their modifications.  Long  w i t h aqueous ammonia as a s o l v e n t f o r i n o r g a n i c  p r e s e r v a t i v e s a l t s as o r i g i n a l l y used i n the U.S.A. ( F r i t z , 1947? Gordon, 1947)  f o r the treatment of a  t r e a t white f i r (Abies c o n c o l o r  difficult-to-  (Gord. & Glend.) L i n d l . )  prompted t r i a l s of t h i s s o l v e n t f o r the treatment o f Canadian spruce  (Rak,  1977a).  Since then, ammonia has been used  in preservative formulation of a copper-zinc-arsenic ment o f spruce Clarke, Rak  s t u d i e s and  (CZA)  (Clarke and  i n the development  p r e s e r v a t i v e system f o r t r e a t -  Rak,  1974;  Rak,  1976;  (1977a) r e p o r t e d  that the p e r m e a b i l i t y o f spruce improved using  aqueous ammoniacal s o l u t i o n o f i n o r g a n i c s a l t s , w i t h o r d i n a r y aqueous s o l u t i o n s . v a t i o n , experimental (CAA)  oped by Rak provided  and  1975a).  roundwood i n the r a d i a l d i r e c t i o n was  additive  Rak  and  (1976  On  copper-zinc-arsenic-additive  high chemical  1977c) and  Rak  r e t e n t i o n s and  t r a t i o n i n white spruce.  compared  the b a s i s o f t h i s obser-  ammoniacal p r e s e r v a t i v e s ,  and  an  and  Unligil  copper-arsenic (CZAA),  devel  (1977), have  e x c e l l e n t sapwood pene-  These p r e s e r v a t i v e s have improved  f i x a t i o n p r o p e r t i e s i n the wood compared t o c o n v e n t i o n a l ACA, are t o x i c t o a wide range o f f u n g i , and a t the same time reduce the amount o f a r s e n i c necessary f o r t h e i r f o r m u l a t i o n . CAA i s now i n c l u d e d i n the Canadian  Standards  Association  p r e s e r v a t i o n standard CS'A 080 as a m o d i f i c a t i o n o f ACA, w h i l e CZAA has been accepted p r o v i s i o n a l l y as ammoniacal copper z i n c arsenate  (ACZA).  A commercial  schedule f o r treatment o f spruce w i t h the  new p r e s e r v a t i v e , copper-ammonia-additive,  was prepared by  Krzyzewski and Rak (1973) i n which a p r e s s u r e o f 150 p s i (1032 kPa) and temperatures employed.  ranging from 52°C t o 75°C were  Encouraging r e s u l t s w i t h t h i s t r e a t i n g  were r e p o r t e d by Rak (1977c), Ralph and S h i e l d s U n l i g i l and Krzyzewski  schedule  (1984a) and  (1978) w i t h both p r e s s u r e treatments  and d i f f u s i o n treatments o f the g r o u n d l i n e bandage-type on spruce having moisture contents above the f i b e r point.  saturation  P o s i t i v e economic b e n e f i t s o f ACA o r ACZA systems  i n c l u d e a wider y e t l e s s expensive range o f woods (e.g. P i c e a and Populus s p e c i e s ) that can be t r e a t e d Shields,  2.4  (Ralph and  1984a).  PROTECTION OF POLES WITH WATERBORNE CHEMICALS With i n c r e a s i n g importance o f communications and power  supply i n everyday  life,  experience has l e d u t i l i t y  companies  t o s p e c i f y p r e s e r v a t i v e treatment t o ensure continued and  e l i m i n a t e the high c o s t o f replacement.  strength  F o r these reasons,  p r e s e r v a t i v e treatment o f most s p e c i e s o f p o l e s has been employed  by means o f pressure  impregnation f o r many y e a r s .  Although c r e o s o t e was the f i r s t p r e s e r v a t i v e t o become established  i n Canada, a number o f o t h e r p r e s e r v a t i v e s have  since followed  and the wood-preserving i n d u s t r y has s e t t l e d  on a few b a s i c m a t e r i a l s and f o r m u l a t i o n s the t e s t o f time.  Wood p r e s e r v a t i v e s can be arranged  two broad c a t e g o r i e s : and w a t e r - s o l u b l e  organie-solvent  inorganic s a l t s  borne p r e s e r v a t i v e s a r e d e s c r i b e d for  bis  1983a).  into  (oilborne) Five o i l -  i n the Canadian Standard processes  They a r e c r e o s o t e ,  ( t r i b u t y l t i n ) oxide,  naphthenate.  substances  (waterborne).  wood p r e s e r v a t i o n u s i n g p r e s s u r e  Preservation,  which have stood  (CSA-080 Wood  pentachlorophenol,  copper-8-quinolinolate  and copper  On the o t h e r hand, o f the common waterborne  p r e s e r v a t i v e s , two systems such as CCA and ACA a r e most used i n Canada (Smith, 1977) and p r o v i d e  widely  e x c e l l e n t and l o n g -  l a s t i n g p r o t e c t i o n o f t r e a t e d wood a g a i n s t  biodegradation  (Gjovik and Davidson, 1972). Three p r e s e r v a t i v e s have been i n common use f o r u t i l i t y poles pressure-treated  i n accordance w i t h  i f i c a t i o n s , namely c r e o s o t e , still  PCP and CCA.  the CSA 080.4 specAlthough PCP i s  the main p r e s e r v a t i v e employed f o r u t i l i t y p o l e s , the  47  waterborne p r e s e r v a t i v e s are g a i n i n g more acceptance by some utility  companies.  S i n c e the e a r l y 1970s, c o n s i d e r a b l e e f f o r t has been devoted towards the development o f new wood p r e s e r v a t i v e s (Butcher e t a l . , 1977? C l a r k e and Rak, 1974? Johnson and Gutzmer, 1978? Rak and C l a r k e , 1975a? Sparks,  1978) and,  because o f the r e l a t i v e l y high c o s t o f o r g a n i c s o l v e n t s , much o f t h i s a c t i v i t y has been d i r e c t e d t o developing r a t h e r than o i l - s o l u b l e f o r m u l a t i o n s .  water-soluble  These waterborne p r e -  s e r v a t i v e s i n v o l v e chemicals  which are t o x i c t o f u n g i , and  p r e f e r a b l y show some a b i l i t y  f o r f i x a t i o n i n the wood,  preventing with water.  thereby  t h e i r subsequent l e a c h i n g from wood when i n c o n t a c t Approved f o r m u l a t i o n s o f p r e s e r v a t i v e s used i n  Canada a r e covered by Standard  CSA-080 Wood P r e s e r v a t i o n .  Good examples o f such f o r m u l a t i o n s a r e CCA, ACA and CAA, the first  two o f which form the bulk o f waterborne p r e s e r v a t i v e s  c u r r e n t l y used i n Canada.  ACA i s p a r t i c u l a r l y  attractive  s i n c e the p e n e t r a t i o n o f ammonia i n t o a l l components o f wood substance, tified  and i t s a c t i o n on the s t r u c t u r e o f wood are i d e n -  as f a c t o r s a f f e c t i n g the t r e a t a b i l i t y o f spruce.  2.4.1  CHROMATED COPPER ARSENATE (CCA) The  chromated copper arsenates  a r e known i n the American  Wood-Preservers' A s s o c i a t i o n (AWPA, 1984) and CSA (1983b) as  Type A, B, and C, l i s t e d AWPA s t a n d a r d s .  i n t h e i r o r d e r o f acceptance  as  These f o r m u l a t i o n s d i f f e r p r i n c i p a l l y i n  the p r o p o r t i o n s o f a r s e n i c and chromium present i n each mulations  for-  d i f f e r p r i n c i p a l l y i n the p r o p o r t i o n s o f a r s e n i c  and chromium present i n each f o r m u l a t i o n . the oxide b a s i s , c o n t a i n about 19% CuO.  A l l three, on  Type A i s h i g h i n  chromium, Type B h i g h i n a r s e n i c , w h i l e Type C i s i n t e r m e d i ate.  Type C i s c l o s e i n composition t o the numerical  o f Types A and B, and a l s o c l o s e to the two w i d e l y British  f o r m u l a t i o n s , T a n a l i t h C and C e l c u r e A.  s i t i o n o f each type o f CCA CCA  averag  used  The  compo-  p r e s e r v a t i v e s i s shown i n Table 8  p r e s e r v a t i v e s have been used w i d e l y f o r many years  throughout  the world  f o r t r e a t i n g permeable s p e c i e s .  though a l l three types o f CCA  c o u l d be used,  Al-  o n l y Types B  and C have found e x t e n s i v e use s i n c e the i n t r o d u c t i o n o f p r e s e r v a t i v e s i n t o the Canadian standards.  However, the  s i t u a t i o n has changed such that Type C f o r m u l a t i o n i s favoured by CCA  t r e a t e r s , mainly due  major c h a i n o f Type B users and due  CCA  now  to i t s adoption by a i n p a r t to a d e s i r e by  t r e a t e r s to use a p r e s e r v a t i v e w i t h a lower a r s e n i c content (Ruddick,  1982).  Research a s p e c t s o f CCA  i n v a r i o u s c o u n t r i e s has  looked i n t o many  p r e s e r v a t i v e system f o r t r e a t i n g wood, thus  e n a b l i n g p r o p e r t i e s such as f i x a t i o n o f t o x i c  chemicals,  TABLE 8.  Composition o f the CCA  preservatives.  AWPA standards^ CSA 2 Type A  Type B  Type C  Standards  Cr0 (%)  59.4(65.5)69.3  33.0(35.3)38.0  44.5(47.5)50.5  36-65  CuO(%)  16.0(18.1) 20.9  18.0(19.6)22.0  17.0(18.5) 21.0  As 0 (%)  14.7(16.4)19.7  42.0(45.1)48.0  30.0(34.0)38.0  3  2  5  19 16-45  Sources: 1. American Wood-Preservers' A s s o c i a t i o n (1984). 2. Canadian Standards A s s o c i a t i o n 080, Wood P r e s e r v a t i o n (1983b). Note:  F i g u r e s i n parentheses represent nominal composition on the o x i d e b a s i s others represent range.  t h e i r r e s i s t a n c e t o l e a c h i n g , water r e p e l l e n c y , resistivity, and  Clarke,  electrical  p a i n t a b i l i t y , and c o s t t o be c o n t r o l l e d (Rak 1975a).  T h i s has been p o s s i b l e by v a r y i n g the  nature and the r a t i o o f the copper, chromium and a r s e n i c components.  I n CCA s o l u t i o n , these three components a r e a l l  water-soluble.  When the s o l u t i o n i s impregnated i n t o wood,  f i x a t i o n depends on an o x i d a t i o n - r e d u c t i o n  r e a c t i o n between  chromium components i n the p r e s e r v a t i v e and reducing i n the wood substance, thereby p r e v e n t i n g l e a c h i n g from wood (Rak and C l a r k e , o f the r e d u c t i o n - o x i d a t i o n  1975b).  compound and temperature, the  by the AWPA and CSA  A p r o t r a c t e d schedule necessary f o r t r e a t i n g  difficult-to-treat  species  leads t o problems with  c i p i t a t i o n o f t o x i c chemicals  (Rak and C l a r k e ,  has been a l s o r e p o r t e d by Rak and C l a r k e t i o n o f the chemical not p r o v i d e  achieved.  e a r l y pre-  1975a).  It  (1975b) that v a r i a -  components i n the p r e s e r v a t i v e s o l u t i o n  s u f f i c i e n t c o n t r o l over the r a t e s o f the  oxidation-reduction to be  both  F o r t h i s reason, maximum t r e a t i n g  temperatures o f o n l y 49°C a r e allowed  did  Since the r a t e  o f the p r e s e r v a t i v e system i s l i m i t e d during  treatments and s t o r a g e .  standards.  t h e i r subsequent  r e a c t i o n s i s a f u n c t i o n o f the  c o n c e n t r a t i o n o f the reducing stability  groups  r e a c t i o n s t o enable adequate p e n e t r a t i o n  51  2.4.2  AMMONIACAL COPPER ARSENATE  (ACA)  Information i n support o f ACA, "Chemonite", was i n 1949  submitted  under the trade name  to the AWPA P r e s e r v a t i v e s Committee  (Baechler, 1949), f o l l o w i n g the papers presented  the A s s o c i a t i o n i n 1947  (Fritz,  The o r i g i n a l patent was  i s s u e d to Gordon i n  ACA  was  was  1947? Gordon, 1947? O t t , 1947). 1939.  o r i g i n a l l y prepared at the t r e a t i n g p l a n t by  mixing a copper hydroxide.  to  chemical with a r s e n i c t r i o x i d e i n ammonium  Because o f the components used,  i n c o r r e c t l y c a l l e d ammoniacal copper  i n the mid-1970s, i t was  the p r e s e r v a t i v e  arsenite.  r e a l i z e d that t h i s was  However,  erroneous,  s i n c e d u r i n g the mixing p r o c e s s , the a i r o x i d i z e d the a r s e n i c to the p e n t a v a l e n t form  (Ruddick,  changed t o ammoniacal copper  1982).  arsenate.  Thus the name was ACA  has been used  f o r many years on the west c o a s t o f the United S t a t e s and i s now  w i d e l y used  2.4.2.1  i n Canada.  CHEMICAL COMPOSITION AND  FORMULATION  The h i s t o r i c a l development o f the s p e c i f i c a t i o n s f o r ACA  composition  i n a l standards  i s shown i n Table 9.  A c c o r d i n g t o the o r i g -  (Beachler, 1949? Gordon, 1947), ACA  was  mulated from copper hydroxide, a r s e n i c t r i o x i d e , a c e t i c and ammonia. it  foracid,  Although no d e f i n i t e i n f o r m a t i o n i s a v a i l a b l e ,  i s u n l i k e l y t h a t copper hydroxide  i s used  i n the f o r m u l a t i o n  TABLE  9.  Historical  development  AWPA 1949 Proposal  Acceptance  Oxide  Cu  as  Cu(OH)2(%)  60  +  5  55.7(57.7)59.7  as  As2O3O6)  40  +  5  38.7(40.7)42.7  Cu  as  CuO(%)  As  as  A&205(%) 2.0-3.0%  NH3 Acetic  acid(*)  Carbonate  as  0.05  in  soln.  -  1.5-2.0xCu(OH)2 116  soln.  -  CO 2  composition.  1969  As  -i n  ACA  Standards  1953  l  of  CSA  1984  Basis  -  Oxide  4  Standards  Basis  -  -  (49.8)47.7  min.  (49.8)47.7  min.  (50.2)47.6  min.  (50.2)47.6  min.  1.5-2.0xCuO 1.7  -  1.5  max.  min.xCuO  1.7  -  49.8-63.0 37.0-50.2 1.5-3.5xCu0  -  max.  -  0.0-0.8xCuO  Sources t 1.  Baechler  2. 3.  (1953) American Wood-Preservers'  (1949) Association  4. 5. Note:  Canadian Figures  in  Standards  A s s o c i a t i o n 080,  parentheses  represent  (1971)  (1984) Wood P r e s e r v a t i o n  nominal  composition;  (1983b)  other  figures  represent  range.  o f ACA, because o f i t s h i g h e r c o s t i n the p r e p a r a t i o n than the s u l f a t e o r b a s i c carbonate  (Winter  rather  e t a l . , 1965).  However, the d i r e c t use o f copper s u l f a t e may be somewhat undesirable  i f the r e s u l t i n g ACA s o l u t i o n i s t o be used i n  the treatment o f u t i l i t y p o l e s , where r e s i d u a l c o n d u c t i v i t y i s unwanted  1973).  (Hartford  Over the past 30 years,  the ACA p r e s e r v a t i v e system has  become w e l l e s t a b l i s h e d , and i t s f o r m u l a t i o n p r e s e n t l y cont a i n s equal weights o f c u p r i c and a r s e n i c oxides,  p l u s op-  t i o n a l s m a l l amounts o f ammonium a c e t a t e o r b i c a r b o n a t e , a l l dissolved  i n 4-6% o f aqueous ammonia.  copper s o l u b i l i t y ,  Acetate  ions enhance  and carbonate ions render the s u r f a c e o f  the t r e a t e d wood more water r e p e l l e n t (Kennedy, 1981).  Un-  l i k e CCA, the ammoniacal p r e s e r v a t i v e i s not marketed as a prepared  formulation.  With the o x i d a t i o n o f the s o l v e n t r e a c t s w i t h  to  AS2O3  AS2O5,  the copper arsenate  the ammonia i n t o form a s o l u b l e  complex: 3CuO + A s 0 2  3  +  I2NH3  + 4H 0  »  2  3Cu(NH ) 3  2 + 4  + 2 H A s 0 4 + 40H~ 2  _  (1)  T h i s s o l u b l e complex i s s t a b l e i n ammonium hydroxide s o l u t i o n .  2.4.2.2 The  MECHANISM OF FIXATION f i x a t i o n o f ammoniacal copper systems i n wood has  been reported  by Eadie and Wallace  (1974) and Sundman (1984).  (1962), Rak and C l a r k e  While the CCA p r e s e r v a t i v e  depends  on a r e a c t i o n between the p r e s e r v a t i v e components and the wood, the f i x a t i o n o f ammoniacal copper compounds depends on the v o l a t i l i z a t i o n o f ammonia and the i n s o l u b i l i z a t i o n o f the p r e s e r v a t i v e . Following  impregnation o f the ACA i n t o the wood, the  ammonia i n the s o l v e n t evaporates. plex  i n ammonium  reaction  hydroxide s o l u t i o n i s s t a b l e as shown i n  (1), i t r e a d i l y breaks down t o form i n s o l u b l e copper  a r s e n a t e when the s o l v e n t 3Cu(NH ) 3  Although the s o l u b l e com-  o+ z  4  + 2H As0 2  _ 4  i s removed: » ^  + 40H~  1 2 N H  3  >  Cu (As0 ) 3  For t h i s reason, the ACA system  4  2  • 4H 0 2  (2)  i s r e l a t i v e l y r e s i s t a n t to  l e a c h i n g when the t r e a t e d wood i s placed  i n s e r v i c e and the  formulation  to be v a r i e d w i t h -  enables time and temperature  out danger o f premature p r e c i p i t a t i o n o f t o x i c chemicals, provided  that l o s s o f ammonia from the t r e a t i n g s o l u t i o n i s  prevented co-workers  (Rak and C l a r k e , (1955) reported  lower a r s e n i c  1974).  t h a t the ACA-treated wood has  fixation.  Copper a r s e n a t e - t r e a t e d  wood has proven to be one o f the  most durable o f the p r e s e r v a t i v e though  However, Wilson and h i s  treatments used today. A l -  i t i s r e l a t i v e l y non-leachable and the ACA p r e s e r v a t i v e  is highly e f f e c t i v e , considerable  e f f o r t has been devoted  towards the development o f s e v e r a l ammonia-based  preserva-  t i v e s that make use o f the method o f f i x a t i o n a p p l i e d (Butcher et a l . , 1977; 1975a).  In a c c e l e r a t e d  C l a r k e and  Rak,  1974;  Rak  l a b o r a t o r y and  field  tests,  been shown that these m o d i f i e d ant  to l e a c h i n g compared w i t h ACA.  (ACB) and  2.5  Gutzmer, 1978;  ACA  Clarke, i t has  are more r e s i s t -  Ammoniacal copper b o r a t e  i s another s i m i l a r l y p r e c i p i t a t e d p r e s e r v a t i v e  (Johnson  Vinden and McQuire, 1984).  FACTORS INFLUENCING THE SYSTEMS Preservative  out  preservatives  and  in  EFFECTIVENESS OF  PRESERVATIVE  systems must perform t h e i r f u n c t i o n through-  the s e r v i c e l i f e o f the product under a v a r i e t y o f expo-  sure c o n d i t i o n s .  Thus, u t i l i t y p o l e s must be t r e a t e d w i t h  systems that p r o t e c t both the a e r i a l and below-ground for  s e v e r a l decades i n a v a r i e t y o f c l i m a t e s ,  ing  conditions. In g e n e r a l ,  portions  s o i l s and  leach-  the e f f e c t i v e n e s s o f a wood-preservative  treatment i n p r e v e n t i n g  d e t e r i o r a t i o n i s dependent on  treatment r e s u l t s , as w e l l as the p r e s e r v a t i v e system.  the The  two main c r i t e r i a used to e s t a b l i s h the e f f e c t i v e n e s s o f a preservative  treatment are depth o f p e n e t r a t i o n  chemical r e t e n t i o n . are  inspected  and  level  of  Almost a l l wood products purchased today  f o r conformance w i t h a r e s u l t s - t y p e  specifica-  t i o n , because an a c c u r a t e measure o f both p e n e t r a t i o n and r e t e n t i o n would i n d i c a t e whether the wood was p r o p e r l y t r e a t e d .  2.5.1  PENETRATION I t has been recognized t h a t there a r e a number o f f a c t o r s  a f f e c t i n g p e n e t r a t i o n o t h e r than t r e a t i n g techniques.  These  are s p e c i e s , p i t a s p i r a t i o n , sapwood depth,  incis-  ing technique,  dryness,  sap s t a i n ,  and season o f the year.  Regardless  o f what causes l a c k o f p e n e t r a t i o n , i t a f f e c t s s e r v i c e l i f e . F o r example, p o l e s which do not r e c e i v e adequate p e n e t r a t i o n are s u b j e c t to decay i n the untreated sapwood and low-retent i o n zones near the p o i n t o f t e r m i n a t i o n o f seasoning  checks.  These checks normally c l o s e a t o r near the g r o u n d l i n e , and r a i n water running  down the i n s i d e o f checks accumulates dust,  spores and m o i s t u r e .  T h e r e f o r e , the wood should be adequately  t r e a t e d w e l l beyond the p o i n t o f p e n e t r a t i o n o f these checks to prevent  i t from decay  hazard.  While i t i s o f t e n observed t i o n i s approximately  t h a t the depth o f p e n e t r a -  uniform on a l l s i d e s o f the m a t e r i a l ,  not i n f r e q u e n t l y the p e n e t r a t i o n i s much deeper a t some p o i n t s than o t h e r s , showing an u n t r e a t e d core o f wood o f i r r e g u l a r o r star-shaped  c r o s s s e c t i o n (Best, 1974; Bramhall,  1966).  The causes o f t h i s n a t u r a l l y vary, but are known t o i n c l u d e f a c t o r s such as o f f - c e n t e r p i t h , t h i c k n e s s o f the growth  57  rings, density,  sap s t a i n , moisture content d i f f e r e n c e s ,  checking p a t t e r n Since should  be  general, tion  (Arsenault,  and  1973).  sapwood i s p e r i s h a b l e ,  i t i s important that i t  thoroughly t r e a t e d to prevent e a r l y f a i l u r e s .  In  the depth o f sapwood c o n t r o l s the depth o f p e n e t r a -  (Arsenault,  1966;  Hearn, 1951).  sapwood i s t h i n , as w e l l as  In s p e c i e s where the  i n l a r g e poles and  timbers,  in-  c i s i n g procedures have been p r a c t i s e d f o r more thorough penetration Estep,  1966;  formation  (Banks, 1973;  Best and M a r t i n ,  Ruddick, 1978).  1969;  Graham  Although i n c i s i n g may  of s e v e r a l s h a l l o w checks r a t h e r than one  check, i t i s i n s u f f i c i e n t  i n preventing  formation  that extend beyond the zone o f t r e a t e d wood. u l a r l y true when the depth o f p e n e t r a t i o n  Estep,  1966).  Thus the use o f saw  This  1981;  Estep,  Ruddick and  1966;  H e l s i n g and  Ross, 1979).  is partic-  (Graham  k e r f s has been employed  Graham, 1976;  I t has  major  i s shallow, as i n  to reduce deep checking through the t h i n sapwood Graham and  encourage  o f checks  d i f f i c u l t - t o - t r e a t s p e c i e s having a narrow sapwood and  and  (Graham, Ruddick,  been concluded  k e r f i n g i s much more e f f e c t i v e than i n c i s i n g  1973;  that  in controlling  checking i n roundwood, p a r t i c u l a r l y when t r e a t e d w i t h waterborne p r e s e r v a t i v e s . Some aspects o f v a r i a b i l i t y  i n penetration  above, namely, s p e c i e s , o f f - c e n t e r p i t h , and  are  described  sapwood depth.  Other f a c t o r s a f f e c t i n g p e n e t r a t i o n , e s p e c i a l l y l a c k o f penet r a t i o n i n the i n n e r sapwood, may areas o f s a t u r a t i o n due  i n c l u d e water pockets or  to the presence o f mold f u n g i or  b a c t e r i a , or i n c i p i e n t decay  ( A r s e n a u l t , 1973).  more i m p o r t a n t l y , causes o f v a r i a b i l i t y p r a c t i c e s i n c l u d e t r e a t i n g p o l e s and  However,  r e l a t e d t o treatment  lumber o f w i d e l y  differ-  ent m o i s t u r e c o n t e n t s , f o l l o w i n g v a r i o u s p e r i o d s and methods of a i r drying.  S e v e r a l r e s e a r c h e r s (Coetzee and Laar,  Krzyzewski, 1978;  Rak,  1977a; Ruddick,  when m a t e r i a l i s impregnated  1978)  1976;  have shown that  w i t h a waterborne  preservative,  i n c r e a s i n g the moisture expedites the spread o f p r e s e r v a t i v e and r e s u l t s  i n deeper p r e s e r v a t i v e p e n e t r a t i o n .  to Krzyzewski  According  (1978), the optimum p r a c t i c a l c o n d i t i o n i s the  medium range o f 28 to 35% moisture c o n t e n t .  However, s i n c e  the worst checks i n a p o l e f r e q u e n t l y extend more than inches i n t o the p o l e , Ruddick  two  (1978) recommended to conduct  the treatment o f roundwood at moisture contents not exceeding 25%.  Indeed,  t h e r e i s even concern that the c u r r e n t commer-  c i a l p r a c t i c e o f d r y i n g the m a t e r i a l t o j u s t l e s s than m o i s t u r e content does not e s t a b l i s h adequate p r i o r t o treatment.  checking p a t t e r n s  To a c e r t a i n extent, t h i s may  ated by pretreatments such as i n c i s i n g and/or  be  allevi-  kerfing.  Complete p e n e t r a t i o n o f the sapwood should be the i n a l l p r e s s u r e treatments.  25%  ideal  Although long experience has  59  shown t h a t even s l i g h t p e n e t r a t i o n s penetrations  have some value,  deeper  a r e h i g h l y d e s i r a b l e t o avoid exposing  wood when checks occurs i n s e r v i c e , p a r t i c u l a r l y  untreated  f o r important  members o f h i g h replacement c o s t .  Whatever the cause, i f  wood i s not adequately penetrated,  e a r l y f a i l u r e s would  2.5.2  result.  RETENTION The  second c r i t e r i o n used i n e s t a b l i s h i n g the e f f i c a c y  of preservative i n wood.  treatment i s the amount o f chemical r e t a i n e d  The r e t e n t i o n o f p r e s e r v a t i v e  i s an e q u a l l y  impor-  t a n t f a c t o r i n f l u e n c i n g the e f f e c t i v e n e s s o f p r e s e r v a t i v e systems i n extending the s e r v i c e l i f e o f t r e a t e d wood p r o ducts.  However, i t should  be noted that net r e t e n t i o n o f  p r e s e r v a t i v e by the t r e a t e d wood alone i s not an adequate index o f the e f f i c i e n c y o f treatment.  As mentioned  previously,  t h i s i s because the p r e s e r v a t i v e can be concentrated  in certain  areas o f the wood, l e a v i n g wide v a r i a t i o n s i n depth o f penetration. In g e n e r a l ,  the frequency d i s t r i b u t i o n o f r e t e n t i o n i n  a group o f t r e a t e d poles it  shows a normal d i s t r i b u t i o n .  Thus  i s obvious that many o f the t r e a t e d poles w i l l have below-  average r e t e n t i o n s .  Also,  i t i s obvious that some o f them  w i l l be i n the r i s k r e t e n t i o n l e v e l c a t e g o r y s p e c i f i e d i n the a p p r o p r i a t e  standards.  These l o w - r e t e n t i o n  poles a r e  candidates Not  for early failure.  only are poles d i f f e r e n t  from each other, but  r e t e n t i o n s w i t h i n a p o l e a r e as v a r i a b l e as those among poles. while  M i l l s and h i s co-workers (1965) have suggested  that  30 t o 40% o f the v a r i a t i o n i n r e t e n t i o n can be explained  by measured p h y s i c a l c h a r a c t e r i s t i c s , 60 t o 70% o f p o l e - t o p o l e v a r i a t i o n i s normal due t o other ducted by A r s e n a u l t i n standard is  factors.  A study con-  (1966) on the penta r e t e n t i o n v a r i a t i o n  p o l e s p e c i e s reported  t h a t percentage v a r i a t i o n  l e s s near the s u r f a c e o f the wood than a t g r e a t e r  where p e r m e a b i l i t y d i f f e r e n c e s add t o the v a r i a t i o n . more r e f r a c t o r y s p e c i e s such as D o u g l a s - f i r and  depths, The  lodgepole  pine have g r e a t e r v a r i a t i o n between p o l e s compared w i t h red and  southern As  pines.  described  earlier,  the r e t e n t i o n o f p r e s e r v a t i v e i n  wood i s i n f l u e n c e d by s e v e r a l f a c t o r s , i n c l u d i n g p e r m e a b i l i t y and  surface-to-volume r a t i o .  These two f a c t o r s account f o r  the l a r g e d i f f e r e n c e s i n a b s o r p t i o n between small-diameter and  large-diameter  poles  (Arsenault,  1973).  Varying  surface-  to-volume r a t i o s e x p l a i n the f a c t t h a t the top o f p o l e s r e c e i v e c o n s i d e r a b l y more treatment than the b u t t s , and s m a l l diameter p o l e s  i n a c y l i n d e r charge tend  t o be o v e r t r e a t e d  when the l a r g e p o l e s a r e adequately t r e a t e d . In a study o f the causes o f v a r i a t i o n i n r e t e n t i o n s ,  M i l l s e_t a l . (1965) found t h a t the r e t e n t i o n s on a weight per c u b i c f o o t b a s i s were not s i g n i f i c a n t l y a f f e c t e d by e i t h e r d e n s i t y o r r i n g count.  A l s o , i t has been reported by C s e r j e s i  et al.(1967) that there  i s apparently  s p e c i f i c g r a v i t y and a b s o r p t i o n  no c o r r e l a t i o n between  o f p r e s e r v a t i v e on a weight  per s u r f a c e area b a s i s from waterborne s o l u t i o n s o f a n t i s t a i n chemicals  (e.g. copper s u l f a t e o r sodium pentachlorophenate)  a p p l i e d t o western hemlock and D o u g l a s - f i r lumber. as a p r a c t i c a l matter, a uniform  Therefore,  method o f a s s i g n i n g weight  per u n i t volume r e t e n t i o n s t o s p e c i e s and products should be used  (Arsenault,  1966), a v o i d i n g any c o n s i d e r a t i o n o f d e n s i t y  d i f f e r e n c e s between s p e c i e s .  2.5.3  TREATMENT RESULTS OF SPRUCE WITH AMMONIACAL WOOD PRESERVATIVES Extensive  experimentation  and i n d u s t r i a l t r i a l s  ammoniacal p r e s e r v a t i v e s o l u t i o n s have y i e l d e d results  favourable  i n d i c a t i n g t h a t spruce roundwood, lumber and plywood  can be t r e a t e d s u c c e s s f u l l y by pressure 1978;  with  process  (Krzyzewski,  Krzyzewski and Rak, 1973; Krzyzewski et a l . , 1978;  Krzyzewski and S h i e l d s , 1977; Rak, 1977a, b, and c; Rak and Clarke,  1975a).  Ralph and S h i e l d s  Encouraging r e s u l t s were a l s o reported by (1984a and b) w i t h non-pressure treatments  (e.g. thermal d i f f u s i o n process) o f spruce w i t h m o i s t u r e contents  above the f i b e r s a t u r a t i o n p o i n t .  C s e r j e s i (1984)  has  r e p o r t e d improvements i n p o l e r e s i s t a n c e t o c e r t a i n  o f decay organisms  types  when t r e a t e d w i t h ammoniacal wood p r e s e r v -  atives. The CSA  (1983c) p r e s e n t l y allows f o r the use o f spruce  p o l e s t r e a t e d w i t h ACA  a t 0.6  lb./ft.  3  (9.6 kg/m ) o x i d e 3  r e t e n t i o n w i t h a minimum p e n e t r a t i o n o f 0.5 100% sapwood up t o a depth o f 0.75 even these minimum requirements,  i n . ( 1 3 mm)  i n . ( 1 9 mm).  particularly  and  However, for retention,  are o f t e n not achieved w i t h spruce roundwood, i n s p i t e o f pretreatments  to improve p r e s e r v a t i v e uptake.  In a study o f  p r e s e r v a t i v e treatment o f white spruce p o l e s w i t h ACA,  Ruddick  (1978) found t h a t they showed e x c e l l e n t p e n e t r a t i o n o f p r e s e r v a t i v e , but the chemicals r e t a i n e d were not s u f f i c i e n t s a t i s f y the l e v e l e s t a b l i s h e d by the CSA  standard.  These  o b s e r v a t i o n s c o r r e l a t e c l o s e l y w i t h those r e p o r t e d by investigators 1978;  Rak,  (Coetzee and Laar, 1976;  Gohre, 1958;  to  several  Krzyzewski  1977a), i n that e x c e l l e n t p r e s e r v a t i v e - p e n e t r a t i o n  v a l u e s were o b t a i n e d , w h i l e the chemical r e t e n t i o n s were much lower than  anticipated.  As mentioned p r e v i o u s l y , the problem  of treating  diffi-  c u l t l y p e n e t r a b l e s p e c i e s such as spruce has been s o l v e d i n two ways:  by i n c r e a s i n g the p e r m e a b i l i t y o f the wood, and  by u s i n g more p e n e t r a b l e p r e s e r v a t i v e s . S e v e r a l r e s e a r c h e r s (Banks,  1973;  Horn e_t a l . ,  1977)  63  have shown that i n c i s i n g spruce wood c l e a r l y enhances the permeability  o f waterborne p r e s e r v a t i v e s  a p p l i e d by  impregnation, thus improving the p e n e t r a t i o n  of preservatives.  I t has a l s o been reported by numerous i n v e s t i g a t o r s et a l . . 1973a and b; Krzyzewski, 1973; Schulz, 1971  pressure  (Dunleavy  1968; U n l i g i l ,  and 1972a) t h a t the improvement i n the p e r m e a b i l i t y  was  s i g n i f i c a n t l y marked when t r e a t i n g ponded spruce m a t e r i a l with  preservatives. Considerable  e f f o r t has a l s o been made t o study the e f f e c t  o f ammonia on v a r i o u s  components o f the wood substance and some  p h y s i c o - c h e m i c a l p r o p e r t i e s o f ammonia-treated wood and  Popper, 1971 and 1975; B a r i s k a et_ a l . ,  Baumgardt, 1970; Rak, 1977a). by s a y i n g  that p e n e t r a t i o n  (Bariska  1969; Davidson and  These s t u d i e s can be summarized  o f ammonia i n t o a l l components o f  wood substance, and i t s a c t i o n on the substance o f wood are i d e n t i f i e d as f a c t o r s a f f e c t i n g the t r e a t a b i l i t y . (1977a) has i n d i c a t e d , i n h i s p e r m e a b i l i t y u s i n g a method p r e v i o u s l y developed  Indeed Rak  s t u d i e s o f spruce  (Rak, 1964), that an ammo-  n i a c a l s o l u t i o n o f copper a r s e n a t e i s an e x c e l l e n t candidate f o r the treatment o f s p r u c e . spruce sapwood m i c r o s e c t i o n s  Studies  o f the p e r m e a b i l i t y o f  t o ACA and CCA p r e s e r v a t i v e s  proved t h a t the ammoniacal system p e n e t r a t e s  1.7 t o 1.8 times  f a s t e r i n the r a d i a l d i r e c t i o n than the CCA system.  The p e r -  m e a b i l i t y i n the t a n g e n t i a l d i r e c t i o n was 3.8 times b e t t e r on  the average (Rak and C l a r k e , 1975a). firmed by p r e s s u r e spruce  roundwood  p o r t i n g evidence  These r e s u l t s were con-  treatments o f spruce  lumber (Rak, 1975) and  (Rak, 1977c) w i t h both p r e s e r v a t i v e s . f o r these o b s e r v a t i o n s  Sup-  i s a l s o p r o v i d e d by  the f a c t d e s c r i b e d by Rak (1977a) that the p e r m e a b i l i t y o f spruce  sapwood t o an aqueous ammoniacal s o l u t i o n o f i n o r g a n i c  s a l t s was found t o be b e t t e r than a p l a i n water s o l u t i o n .  He  a l s o found t h a t t h i s improved r a t e o f p e n e t r a t i o n was i n d e pendent o f the nature The  o f the s a l t s i n ammoniacal s o l u t i o n .  e f f e c t o f ammonia on v a r i o u s components o f the wood  substance has been i n v e s t i g a t e d on model systems w i t h drous l i q u i d ammonia by many r e s e a r c h e r s  anhy-  ( B a r i s k a and Popper,  1975;  B a r i s k a e t a l . , 1969; Fukada, 1968; M a r r i n a n and Mann,  1956;  Rak, 1964; Schuerch, 1964; W e l l a r d ,  o f t e n compared w i t h stance.  1954).  I t was  the i n t e r a c t i o n o f water w i t h wood sub-  M a r r i n a n and Mann (1956) suggested t h a t anhydrous  l i q u i d ammonia converts  c e l l u l o s e I ( n a t i v e c e l l u l o s e ) at  about 55°C i n t o c e l l u l o s e HI (ammonium c e l l u l o s e ) which may be r e v e r t e d back t o c e l l u l o s e I by water a t room temperature. I t i s g e n e r a l l y known t h a t the c r y s t a l l o g r a p h i c u n i t o f c e l l u l o s e HE i s g e o m e t r i c a l l y d i f f e r e n t I.  from t h a t o f c e l l u l o s e  Of the r e p o r t e d e f f e c t s o f ammonia on wood, Rak (1977a)  concluded spruce  t h a t o n l y two appeared t o be c l o s e l y r e l a t e d t o  treatability.  F i r s t , anhydrous l i q u i d ammonia can  65  penetrate  a l l components o f the wood substance i n c l u d i n g  c r y s t a l l i n e c e l l u l o s e , i n the b e t t e r and f a s t e r  absorption  o f aqueous ammonia than o f water by spruce sapwood. ammonia changes the m i c r o s t r u c t u r e ,  reducing  the c e l l  Secondly, wall  dimensions and forming a new system o f c a p i l l a r i e s made up of i n t e r t r a c h e a l separations  i n the compound middle l a m e l l a  o f c e l l w a l l s and a l s o s e p a r a t i o n s longitudinal tracheids.  between r a y c e l l s and  The other p r o p e r t i e s o f ammonia and  i t s e f f e c t s on wood, such as i t s p l a s t i c i z i n g e f f e c t , changes i n h e m i c e l l u l o s e s  chemical  a f f e c t i n g the f i b e r s a t u r a t i o n p o i n t ,  s o r p t i o n and e q u i l i b r i u m moisture content, and d e n s i f i c a t i o n of wood, are r a t h e r r e l a t e d t o the p r o p e r t i e s o f t r e a t e d wood itself  (Rak, 1977a).  However, i t i s b e l i e v e d  that they  illu-  s t r a t e the nature o f the treatment w i t h ammoniacal s o l u t i o n s . Since  the s t r u c t u r e o f wood i s o b v i o u s l y  a very  t a n t f a c t o r i n i t s impregnation w i t h p r e s e r v a t i v e ,  impor-  i t would  seem that i t s r e l a t i o n s h i p to wood p r e s e r v a t i o n would have < been i n v e s t i g a t e d very the case.  intensively.  However, t h i s i s not  The l i t e r a t u r e c o n t a i n s many more r e f e r e n c e s t o  s p e c i f i c a t i o n s , p r a c t i c e and technique than t o the c r i t i c a l f a c t o r o f wood anatomy.  In the r e p o r t s on the e f f e c t o f  wood s t r u c t u r e , more d e a l w i t h the bordered p i t p a i r s , s i n c e these p i t s a r e the most c r i t i c a l ,  s i n g l e feature influencing  l i q u i d movement i n the r e l a t i v e l y simple o r g a n i z a t i o n o f  t i s s u e s i n c o n i f e r o u s woods.  Spruce i s p a r t i c u l a r l y  diffi-  c u l t to t r e a t w i t h waterborne p r e s e r v a t i v e s i f the moisture content i n the wood i s allowed ration point.  to f a l l below the f i b e r s a t u -  Under these c o n d i t i o n s , i t i s g e n e r a l l y known  t h a t c o n t i n u i t y o f the c a p i l l a r y system i s impaired by r a t e d t o r i i n bordered p i t s ,  and  the secondary w a l l o f t r a -  c h e i d s has r a t h e r h i g h e r a f f i n i t y to hydrophobic to  aspi-  the water (Rak and C l a r k e , 1975).  liquids  than  Thus i t i s p o s s i b l e  that the anatomical f e a t u r e s o f spruce, forming the pathways by which a chemical p e n e t r a t e s r a d i a l l y i n the sapwood, cont a i n c o n s t r i c t i o n s which cause premature p r e c i p i t a t i o n o f the p r e s e r v a t i v e , r e s u l t i n g i n an enhanced chemical and  l e s s chemical p e n e t r a t i o n .  microscope  coupled to an X-ray  Ruddick (1978) f a i l e d  Using a scanning  retention  electron  energy a n a l y z e r , however,  to l o c a t e any c o n s i s t e n t h i g h concen-  t r a t i o n s o f copper arsenate i n a r e g u l a r p a t t e r n which would have confirmed in  t h i s hypothesis.  Gross c e l l u l a r  the form o f c r y s t a l l i n e d e p o s i t s o f copper  inclusions,  arsenate , were  l o c a t e d i n s e v e r a l v e r t i c a l e p i t h e l i a l c e l l s o f samples o f the ACA-treated  spruce, although the a d j o i n i n g l o n g i t u d i n a l  r e s i n c a n a l s were devoid o f copper a r s e n a t e .  However, the  n e i g h b o r i n g h o r i z o n t a l r e s i n c a n a l s and a s s o c i a t e d e p i t h e l i a l c e l l s c o n t a i n e d no l a r g e d e p o s i t s . it  Thus he concluded  that  i s not p o s s i b l e to i n t e r p r e t the poor r e t e n t i o n as being  67  mainly due to a blockage o f the pathways by which the p r e s e r v a t i v e permeates the wood. As mentioned e a r l i e r ,  the e m p t y - c e l l process i s known  to produce an enhanced chemical p e n e t r a t i o n and l e s s While  retention.  there may be o t h e r p o s s i b l e i n t e r p r e t a t i o n s , a t the  present time h i g h moisture content appears  to be the most  p l a u s i b l e e x p l a n a t i o n f o r the o b s e r v a t i o n s o f ACA-treated spruce m a t e r i a l w i t h s a t i s f a c t o r y p e n e t r a t i o n s but low r e t e n tions . Rak  (1977a) has suggested  that the i n i t i a l  moisture  content o f spruce roundwood a f f e c t s the gross a b s o r p t i o n s and depth o f p e n e t r a t i o n o f ammoniacal s o l u t i o n s ,  i n that  i n c r e a s i n g the moisture e x p e d i t e s the spread o f p r e s e r v a t i v e and  r e s u l t s i n deeper ^chemical p e n e t r a t i o n w h i l e d e c r e a s i n g  the chemical r e t e n t i o n .  Indeed Krzyzewski  t h a t i n h i s study o f the treatment  (1978) r e p o r t e d  o f white spruce p o l e s w i t h  ammoniacal s a l t p r e s e r v a t i v e , h i g h r e t e n t i o n s were o b t a i n e d at low moisture content  (20 t o 30%)  w h i l e deep p e n e t r a t i o n s  were secured a t h i g h moisture content  (above 75%) .  These  g e n e r a l o b s e r v a t i o n s c o r r e l a t e c l o s e l y w i t h those r e p o r t e d by o t h e r i n v e s t i g a t o r s  (Coetzee and Laar, 1976; Gohre, 1958;  Ruddick, 1978), i n t h a t an i n c r e a s e i n m o i s t u r e causes a r e d u c t i o n i n chemical r e t e n t i o n . be accounted  f o r by the d i l u t i n g  content  T h i s may e a s i l y  i n f l u e n c e o f the water  68  a l r e a d y present i n the wood.  On  the o t h e r hand, the chemical  would be a b l e to d i f f u s e r e a d i l y from the p r e s e r v a t i v e s o l u t i o n t o the water p r e s e n t i n the c e l l  lumens, r e s u l t i n g i n  b e t t e r p e n e t r a t i o n a t h i g h moisture c o n t e n t .  Indeed Ruddick  (1978) has used moisture v a r i a t i o n p r e s e n t i n s i d e the p o l e s to  e x p l a i n the r e s u l t s from h i s spruce p o l e study.  The s h o r t  a i r - d r y i n g p e r i o d o f about f i v e months, w h i l e a l l o w i n g the outer sapwood to dry to l e s s than 25% moisture content, would have a s m a l l e r e f f e c t on the moisture s i t i o n zone and of  l e v e l o f both the t r a n -  the heartwood, which were indeed i n excess  30% moisture content f o r 86% of a l l p o l e  tests.  The e f f e c t i v e n e s s o f a wood-preservative  treatment  may  a l s o depend on the uniform d i s t r i b u t i o n o f a l l c h e m i c a l components, p a r t i c u l a r l y  i n waterborne p r e s e r v a t i v e systems.  Good performance of the s a l t  treatments  is partially  attrib-  uted to the f a c t t h a t they are absorbed  i n t o the c e l l w a l l  and u n i f o r m l y d i s t r i b u t e d  Very r e c e n t l y , however,  i n the wood.  Ruddick and h i s co-workers (1981, 1984a) have r e p o r t e d a d i s p r o p o r t i o n a t e uptake o f chemical components, such as and a r s e n i c , i n ACA-treated b e i n g due  T h i s can be e x p l a i n e d as  to the a d a p t a b i l i t y o f these components to the  f i x a t i o n process. in  woods.  copper  The  importance  o f these o b s e r v a t i o n s  lies  the f a c t t h a t the a r s e n i c content i n the wood should not  be allowed to f a l l  to unacceptably  low l e v e l s  (Ruddick,  1984a)  which might permit decay by any c o p p e r - t o l e r a n t as Phialophora  f u n g i such  spp.  Although spruce can be t r e a t e d w i t h p r e s e r v a t i v e t o s a t i s f a c t o r y l e v e l s by u s i n g aqueous ammonia s o l u t i o n s , studies o f pressure  treatments o f spruce roundwood have showed  an i n f l u e n c e o f i n i t i a l m o i s t u r e content on p r e s e r v a t i v e penet r a t i o n and r e t e n t i o n . penetrations  With the o b s e r v a t i o n s  but low r e t e n t i o n s , t h i s i s a fundamental,  order problem t o overcome. beyond the q u e s t i o n of penetration  I t should  and r e t e n t i o n i s the q u e s t i o n  of s e r v i c e l i f e of a pole  first-  that levels  of service l i f e ,  i n deciding  the l o n g e v i t y  i s the degree and s e v e r i t y o f check-  in service.  2.6  BIODETERIORATION OF CHEMICALLY TREATED WOOD Various  s p e c i e s o f wood have c e r t a i n unique c h a r a c t e r i s -  t i c s that a l l o w one s p e c i e s and  be a l s o noted  o f t r e a t a b i l i t y to conventional  s i n c e the p r i n c i p a l f a c t o r i n v o l v e d  ing  of excellent  t o be d i f f e r e n c i a t e d from another,  the same i s t r u e o f an abundance o f microorganisms which  i n h a b i t and degrade both untreated wood.  Microscopical patterns  and p r e s e r v a t i v e - t r e a t e d  o f such d e g r a d a t i o n a r e a r e -  s u l t a n t o f the combination o f these two p a r t i c i p a t i n g components, as w e l l as the e f f e c t i v e n e s s o f p r e s e r v a t i v e in  the t r e a t e d wood  products.  systems  Differences and c h e m i c a l l y  i n decay s u s c e p t i b i l i t y between  untreated  t r e a t e d wood have long been s t u d i e d .  In  a d d i t i o n t o substandard treatment o f wood, however, i t has been recognized  that there a r e the two other b a s i c  f o r the premature  f a i l u r e of chemically  reasons  t r e a t e d wood, namely  d e t o x i f i c a t i o n o r removal o f p r e s e r v a t i v e chemicals by woodi n h a b i t i n g and wood-destroying microorganisms, and p r e s e r v a t i v e t o l e r a n c e by c e r t a i n f u n g i .  2.6.1  DETOXIFICATION OR REMOVAL OF PRESERVATIVE CHEMICALS BY MICROORGANISMS Laboratory t e s t s have shown that Fusarium sp. i s able  to break down the d i n i t r o p h e n o l component o f FCAP t i v e , allowing  t r e a t e d wood to be attacked  f u n g i such as Coprinus sp. (Madhosingh, and O ' N i e l l creosoted  (1966) reported  by  preserva-  non-tolerant  1961a and b ) .  t h a t some microorganisms  Drisko found on  p i l e s m e t a b o l i z e d naphthalene, phenanthrene and  neutral f r a c t i o n s of creosote.  Losses o f a r s e n i c from FCAP-  t r e a t e d wood and o f PCP have been noted when the t r e a t e d wood was exposed 1964).  to non-wood-destroying  fungi  (Duncan and D e v e r a l l ,  S i m i l a r r e s u l t s have been obtained  t r e a t e d wood t o Trichoderma v i r i d e  on exposure o f PCP-  (Unligil,  1972b).  Numerous l a b o r a t o r y t e s t s have a l s o shown the e f f e c t s o f wood-destroying  f u n g i on p r e s e r v a t i v e s .  Osborne (1968) reported  that L e n z i t e s  DaCosta and  sp. a f f e c t e d the water  s o l u b i l i t y and/or t o x i c i t y o f CCA p r e s e r v a t i v e wood without causing  any decay.  Coniophora sp. caused con-  s i d e r a b l e l o s s o f PCP from pine b l o c k s amounts o f the p r e s e r v a t i v e reported  by L e v i  i n treated  (Unligil,  treated with 1968).  subtoxic  I t has been  (1976) that s e v e r a l wood-decaying f u n g i such  as P o r i a spp. s o l u b i l i z e d and absorbed copper, chromium and a r s e n i c components from the wood t r e a t e d w i t h CCA t i v e , suggesting  preserva-  that the presence o f even s m a l l amounts o f  mycelium i n wood may r e s u l t i n the s o l u b i l i z a t i o n o f CCA components. B a c t e r i a have long been known t o be a s s o c i a t e d wood i n s e r v i c e (Levy, 1975; Smith, 1975). s e v e r a l researchers 1982;  Nilsson,  (Drysdale  In r e c e n t  years  and Hedley, 1984; L e i g h t l e y ,  1982) have i n t e n s i v e l y s t u d i e d  the e f f e c t o f  b a c t e r i a on t r e a t e d wood products such as posts and  with  and p o l e s ,  as the t h i r d major type o f decay, b a c t e r i a l degrade has  been f r e q u e n t l y observed i n such products.  I t i s believed  t h a t the c o l o n i z a t i o n by b a c t e r i a i n a s s o c i a t i o n w i t h  fungi  is  initial  the i n i t i a l p a r t o f the process o f decay, and t h i s  c o l o n i z a t i o n o f wood by b a c t e r i a i s e s t a b l i s h e d p a r t l y by random a c t i o n on the s u r f a c e zones o f the samples, b u t mostly by  i n v a s i o n through the r a y parenchyma c e l l s  Greaves, 1975).  ( L i e s e and  D e t a i l e d d i s c u s s i o n s on b a c t e r i a l degrade  have been o f f e r e d i n s e v e r a l works (Drysdale  and Hedley, 1984;  Leightley,  1982; N i l s s o n and H o l t ,  1983; Schmidt and L i e s e ,  1982) . In the absence o f good p r e s e r v a t i o n p r a c t i c e , there can be  l i t t l e doubt t h a t the major cause o f wood degradation i n  s e r v i c e i s due t o organisms.  Even where b i o d e g r a d a t i o n i s  adequately c o n t r o l l e d by the c a r e f u l a p p l i c a t i o n o f known wood p r e s e r v a t i o n technology, i t i s now recognized forms o f degradation wood i n s e r v i c e . 1984;  that  other  may p l a y a s i g n i f i c a n t r o l e i n damaging  In very r e c e n t s t u d i e s  (Banks and Evans,  Carey, 1982; V o u l g a r i d i s and Banks, 1981), i t has been  observed t h a t s u r f a c e l a y e r s o f wood were degraded by the a c t i o n o f water.  As Carey  (1982) p o i n t s out, the i n c r e a s e d  moisture contents  may p l a y another r o l e i n encouraging sub-  sequent c o l o n i z a t i o n by wood d e s t r o y i n g Despite  organisms.  these numerous s t u d i e s , very  l i m i t e d data i s  a v a i l a b l e on the p r a c t i c a l s i g n i f i c a n c e o f such In f a c t , the r e l e v a n c e the f i e l d  observations.  o f some o f the l a b o r a t o r y r e s u l t s t o  s i t u a t i o n has been questioned  (Leutritz,  F i e l d e v a l u a t i o n s o f p r e s e r v a t i v e performance,  1965).  particularly  i n u t i l i t y p o l e s , have been concerned s o l e l y w i t h  the l e n g t h  o f time the t r e a t e d m a t e r i a l remains s e r v i c e a b l e .  A number  of studies  (Duncan and Lombard, 1965; E s l y n , 1970; Z a b e l e t  al.,  1980 and 1982) have simply  examined the f u n g i a s s o c i a t e d  with  decay i n such t r e a t e d p o l e s .  I t i s now recognized  that  73  field  t e s t s o f wood p r e s e r v a t i v e s  should  determine not o n l y  the performance l i f e o f t r e a t e d wood products but a l s o the f a t e o f the p r e s e r v a t i v e  i n the wood.  The i d e n t i t y and the  e f f e c t s o f organisms c o l o n i z i n g wood, both untreated and t r e a t e d , have a l s o been the v i t a l  subject  gations  E f f e c t i v e studies of f i e l d  (Clubbe and Levy, 1982).  performance should life,  incorporate  o f many i n v e s t i -  a l l the elements, i . e . s e r v i c e  a t t a c k i n g organisms and b i o d e g r a d a t i o n  of preservatives,  In t h i s way, i t would be p o s s i b l e to determine the importance o f d e t o x i f i c a t i o n o r removal o f p r e s e r v a t i v e and thus p r e d i c t more a c c u r a t e l y the performance o f the p r e s e r v a t i v e  2.6.2  system.  PRESERVATIVE TOLERANCE BY WOOD_DECAYING FUNGI In the same manner as f u n g i e x e r t s e l e c t i v e i n f l u e n c e s  on v a r i o u s  types o f media, i . e . a c i d i f i e d , benomyl and/or  t e t r a c y c l i n e , o r phenol-added malt agar, due to t h e i r rance t o such substances  tole-  (Clubbe and Levy, 1977; Hale and  Savory, 1976; Hunt and Cobb, 1971; Smith, 1983), s e r v i c e e x p e r i e n c e and l a b o r a t o r y t e s t s have shown that tolerance varies with fungal species a l s o been found that w i t h i n - s p e c i e s greater  and s t r a i n .  preservative I t has  d i f f e r e n c e s are often  than between-species d i f f e r e n c e s  ( L e v i , 1973).  The  frequency w i t h which t o l e r a n t f u n g i o c c u r i n the f i e l d , and the economic f e a s i b i l i t y  o f impregnating s u f f i c i e n t  preserv-  74  a t i v e i n t o wood t o p r o t e c t a g a i n s t t o l e r a n t f u n g i may mine the l i k e l i h o o d o f f u n g a l decay o f c h e m i c a l l y  deter-  treated  wood. I t has been thought t h a t s o f t r o t f u n g i may be the u l t i m a t e cause o f f a i l u r e o f p r e s e r v a t i v e - t r e a t e d (Hulme and Butcher, 1977a and b; Smith, 1977).  softwoods  Certainly  many s p e c i e s have the a b i l i t y t o t o l e r a t e q u i t e high l e v e l s o f commonly used wood p r e s e r v a t i v e s , which r e s u l t s i n p r e mature  f a i l u r e o f t r e a t e d wood products i n s e r v i c e  1976).  (Dale,  The dominant s o f t r o t f u n g i belong t o the genus  Phialophora.  Members o f t h i s genus have shown very  soft rot a b i l i t y  ( N i l s s o n , 1973) and prominent  active  tolerances  t o copper ( L e i g h t l e y , 1979 and 1980; N i l s s o n and Henningsson, 1978).  Very r e c e n t l y , L e i g h t l e y and h i s co-workers  and L e i g h t l e y ,  1983; L e i g h t l e y and Armstrong, 1980) reported  that transmission Phialophora  e l e c t r o n microscopy o f the c o p p e r - t o l e r a n t  species  revealed  l a y e r around hyphae. charides  (Francis  a distinctive extracellular  The presence o f e x t r a c e l l u l a r p o l y s a c -  on the hyphae o f wood decay f u n g i suggests some  physiological role.  As Green  (1980) suggested, i t i s b e l i e v e d  t h a t these l a y e r s a c t as m a t r i c e s and subsequent enzymic  f o r hyphal s u b s t r a t e  contact  activity.  Some o f the Basidiomycetes, t r u e wood-destroying f u n g i , have a l s o shown high  tolerance  to c e r t a i n p r e s e r v a t i v e s .  For  example, L e n t i n u s l e p i d e u s and  i s known t o be t o l e r a n t t o c r e o s o t e  the fungus i s widespread i n n a t u r e .  Thus i t i s necessary  to t r e a t wood products, such as r a i l r o a d t i e s and u t i l i t y poles,  treated with s u f f i c i e n t creosote  species,  even though c o n s i d e r a b l y  Duncan and Lombard  that f a i l u r e t o do t h i s had l e d t o premature  to many c r e o s o t e - t r e a t e d  t i e s and p o l e s .  (DaCosta and K e r r u i s h ,  t r o n microscopy, L e v i arsenic  I t has a l s o been  1964; L e v i , 1975).  Using e l e c -  (1975) found that copper, chromium and  i n and/or onto the hyphae o f P_. m o n t i c o l a ,  the c o n c e n t r a t i o n  o f these three components v a r i e d  g r e a t l y from hypha t o hypha.  He e x p l a i n e d  a t i o n may have been due t o d i f f e r e n c e s ities  preserv-  i n CCA-treated p i n e wood were absorbed from the S2  layers of tracheids but  (1965)  failure  known that some P o r i a spp. a r e h i g h l y t o l e r a n t t o CCA ative  fungal  s m a l l e r q u a n t i t i e s would  c o n t r o l o t h e r wood-destroying f u n g i . reported  to control this  o f the v a r i o u s  c e l l sites  that t h i s v a r i -  i n the b i n d i n g  capac-  f o r copper, chromium and  arsenic. It to a v o i d  i s g e n e r a l l y known that  laboratory  tests are e s s e n t i a l  the problem o f decay s u s c e p t i b i l i t y o f c h e m i c a l l y  t r e a t e d wood i n s e r v i c e by t o l e r a n t f u n g i Laboratory tolerance fore, f i e l d  (Unligil,  t e s t s a r e not always f e a s i b l e .  t e s t s on p r e s e r v a t i v e s  decay f u n g i so that l a b o r a t o r y  1972b). There-  should i d e n t i f y t o l e r a n t  t e s t data can be r e l a t e d to  76  service experience.  2.7  NITROGEN ENHANCEMENT DUE TO ACA TREATMENT N i t r o g e n i s p r e s e n t i n wood i n r e l a t i v e l y s m a l l amounts,  comprising more than about 0.03% but u s u a l l y l e s s than 0.1% of  the dry weight o f wood ( A l l i s o n et a l . ,  1970;  1963; Cowling,  Heck, 1929; M e r r i l l and Cowling, 1966; Rennie, 1965;  Young and Guinn,  1966).  Little  i s known c o n c e r n i n g the n i -  trogenous m a t e r i a l s i n wood, l a r g e l y because the s m a l l amounts present a r e commercially unimportant.  But t o w o o d - i n h a b i t i n g  microorganisms and i n s e c t s t h a t d e r i v e t h e i r nourishment m a r i l y from the wood i t s e l f , are  o f paramount importance.  1970;  Cowling and M e r r i l l ,  1976;  King e t a l . ,  pri-  these s m a l l amounts o f n i t r o g e n Numerous r e s e a r c h e r s (Cowling,  1966; F i n d l a y ,  1934; Henningsson,  1980; M e r r i l l and Cowling, 1965 and 1966)  have shown that the r a t e o f decay o f wood by f u n g i i s r e l a t e d d i r e c t l y to i t s nitrogen content. As mentioned  previously,  i t i s g e n e r a l l y assumed that,  d u r i n g the f i x a t i o n o f the ammonia-based wood p r e s e r v a t i v e , the  ammonia i s l o s t from the wood.  been v e r i f i e d y e t . of  However, t h i s has not  T h e r e f o r e , the q u e s t i o n o f whether l o s s  ammonia from the ACA-treated wood i s complete o r not,  c o u l d w e l l prove important, p a r t i c u l a r l y when inadequate treatment o f d i f f i c u l t - t o - t r e a t and non-durable woods, such  as spruce, i s Very  encountered.  l i t t l e work has been conducted  enhancement o f ACA-treated  wood.  on the n i t r o g e n  Based on the method d e v e l -  oped by Rennie (1955), Ruddick (1979) determined content o f wood w i t h ACA  treatment,  the n i t r o g e n ,  using an O r i o n M i c r o p r o -  c e s s o r i o n a l y s e r , as d e s c r i b e d i n the O r i o n o p e r a t i n g manuals (1977  and  1978).  ACA-treated  In h i s study o f the n i t r o g e n content of  wood, the enhancement o f n i t r o g e n was  easily  d e t e c t a b l e a f t e r nine months o f s t o r a g e o f t r e a t e d ponderosa pine  (Pinus ponderosa Laws.) sapwood stakes i n d o o r s , and  a f t e r two years o f s t o r a g e outdoors spruce p o l e m a t e r i a l . spruce samples was  o f d i s c s cut from t r e a t e d  However, the n i t r o g e n content o f the  much l e s s  stakes, p o s s i b l y i n d i c a t i n g  (< 50%)  l o s s o f chemical due  From the spruce samples, he concluded t r a t i o n was  than t h a t o f the p i n e to l e a c h i n g .  t h a t the ammonia pene-  s i g n i f i c a n t l y g r e a t e r than t h a t o f the p r e s e r v a -  t i v e s o l u t i o n i n some o f the wood where no copper or a r s e n i c c o u l d be  detected.  There are a l s o i n d i c a t i o n s from the ACA ment o f c e r t a i n wood s p e c i e s , which darken treatment,  t h a t the ammonia may  wood than the p r e s e r v a t i v e .  treat-  i n colour during  p e n e t r a t e f a r t h e r i n t o the  For example, when D o u g l a s - f i r  wood i s p r e s s u r e - t r e a t e d w i t h ACA, The cause o f t h i s darkening  pressure  i t darkens i n c o l o u r .  i s presumably r e l a t e d to the  78  use o f ammonium hydroxide i n the p r e s e r v a t i v e , s i n c e the treatment with o t h e r waterborne p r e s e r v a t i v e s  (e.g. CCA) which  a l s o c o n t a i n copper and a r s e n i c does not g i v e t h i s r e a c t i o n . Because ammonia i s r e a d i l y l i b e r a t e d from ammonium hyd r o x i d e . Ruddick  (1979) has suggested t h a t , during  the p r e s -  sure treatment o f wood w i t h ACA, the ammonia penetrates the wood c e l l s p r i o r t o the p r e s e r v a t i v e s o l u t i o n .  Indeed Rak  (1977a) has used t h i s f a c t to e x p l a i n the improved permeab i l i t y o f spruce t o ACA compared w i t h CCA. suggested by Ruddick (1979) t h a t , during  I t has been a l s o  the f i x a t i o n  some o f the ammonia d i f f u s e s f u r t h e r i n t o the wood. on these two suggestions, has  Based  which have not been v e r i f i e d , he  concluded t h a t an enhancement o f the n i t r o g e n  could r e s u l t i n n o n - p r e s e r v a t i v e - t r e a t e d  2.8  process,  level  wood.  FUNGAL METABOLISM OF NITROGEN Although the previous  study  (Ruddick, 1979) has proven  that the wood t r e a t e d w i t h ACA p r e s e r v a t i v e i s enhanced i n i t s nitrogen  level,  i t i s s t i l l questionable  c a l form t h i s enhanced n i t r o g e n i s present  i n which chemi-  i n the wood, and  a l s o whether f u n g i a r e capable o f m e t a b o l i z i n g o f n i t r o g e n t o promote t h e i r growth. content  t h i s source  Increasing  the n i t r o g e n  o f wood f r e q u e n t l y i n c r e a s e s the r a t e o f decay by  wood-destroying f u n g i .  However, there  is conflicting  evidence  79  as to whether decay can be  i n c r e a s e d a p p r i c i a b l y by  c i a l l y adding n i t r o g e n to wood.  To date,  has been performed on these q u e s t i o n s . may  be  artifi-  l i t t l e o r no work  Nevertheless,  answers  i n f e r r e d p a r t l y on the b a s i s o f more recent knowledge  o f f u n g a l metabolism o f n i t r o g e n , d e r i v e d chemical  and  from combined b i o -  genetical studies.  Fungal n i t r o g e n sources are q u i t e v a r i e d and may o r g a n i c or i n o r g a n i c i n n a t u r e .  be  In the same manner as  the  degree o f s p e c i a l i z a t i o n depends p a r t l y on whether the  fungus  possesses enzymes to degrade i n s o l u b l e carbon sources  (e.g.  starch, cellulose,  only  lignin),  o r whether i t can u t i l i z e  s o l u b l e carbon compounds, the n i t r o g e n can e x e r t a s e l e c t i v e influence.  For example, the a b i l i t y to a s s i m i l a t e n i t r a t e  confers a higher  degree o f n u t r i t i o n a l independence  (autotropy)  than does the need f o r ammonia or ammonia-compounds, and even s t r o n g e r dependence (heterotropy)  e x i s t s when s p e c i f i c  n i t r o g e n compounds, i . e . a p a r t i c u l a r amino a c i d , are ( M u l l e r and  Loeffler,  1976).  n i t r o g e n sources w i t h equal a requirement f o r n i t r o g e n utilize  In g e n e r a l , f a c i l i t y , and  A few  a fungus may Fungi  i n o r g a n i c n i t r o g e n i n the form o f n i t r a t e s ,  f u n g i may  use have  may  nitrites  i n the form o f amino a c i d s .  be a b l e to o b t a i n n i t r o g e n v i a the  u t i l i z a t i o n of molecular  required  not a l l f u n g i  i n a s p e c i f i c form.  o r ammonia, o r o r g a n i c n i t r o g e n  an  nitrogen  (Smith, 1970).  direct However,  80  It  i s q u e s t i o n a b l e whether the f i x a t i o n o f atmospheric  n i t r o g e n , which i s so well-known among b a c t e r i a ( S e i d l e r et  a l . , 1972), occurs w i t h  fungi.  and N i l s s o n (1976) reported grated  I n t e r e s t i n g l y , Henningson  that n i t r o g e n compounds had mi«  t o t r e a t e d t r a n s m i s s i o n poles  from surrounding  Having shown that during d r y i n g o f wood, s o l u b l e and  carbohydrate  o f wood.  nitrogenous  m a t e r i a l s accumulate a t e v a p o r a t i v e  King and h i s co-workers  soil.  faces  (1974, 1976, 1979 and 1980)  a l s o showed that such s o l u b l e m a t e r i a l s not o n l y enhanced decay rate o f wood i n s o i l by s o f t r o t , but s t i m u l a t e d  con-  s i d e r a b l e movement o f n i t r o g e n t o wood which was a t t r i b u t e d to m i c r o b i a l biomass. Most f u n g i can use n i t r a t e s as a s o l e o r s i g n i f i c a n t source o f n i t r o g e n , but as Moore-Landecker (1972) p o i n t s out, inabilities  t o u t i l i z e n i t r a t e s a r e common among the h i g h e r  Basidiomycetes to which most wood-decaying f u n g i belong. presented  i n Table  researchers 1963)  As  10, i t has been p o s t u l a t e d by s e v e r a l  (Nason, 1962; Nason and Takahashi,  t h a t n i t r a t e i s reduced v i a n i t r i t e  1958; N i c h o l a s ,  and hydroxylamine  to ammonia i n a s e r i e s o f steps which a r e e s s e n t i a l l y e l e c t r o n transfer reactions.  The enzymes i n v o l v e d c o n t a i n a number  o f c o f a c t o r s and metals, 10)  as a hydrogen donor.  and u t i l i z e NADH o r NADPH (see Table There i s s t i l l  some doubt about  the p o s s i b l e e x i s t e n c e o f an o r g a n i c r e d u c t i v e route  from  TABLE 10.  Summary o f N i t r a t e Reduction (Nason, 1962; Nason and Takahashi, 1958; N i c h o l a s , 1963).  Possible pathway  Oxidation/ reduction state of N +5  NOr  +2e NO  Cofactors  Enzyme  NADH or NADPH  FAD" Fe  Nitrate reductase  MO  NADH or NADPH  FAD Cu Fe  2  +3  2  Hydrogen donor  +2e  Nitrite reductase  (HNO)  n i t r o x y l group or  +1  (N20)  n i t r o u s oxide group or N02NH2  nitramide or H2N 0 2  Hyponitrite reductase  2  hyponitrous a c i d + 2e NH2OH  -1  hydroxylamine  NADH or NADPH  FAD Mg Mn  Hydroxylamine reductase  NH.  Reduced n i c o t i n a m i d e adenine d i n u c l e o t i d e 2 Reduced n i c o t i n a m i d e adenine d i n u c l e o t i d e phosphate F l a v i n adenine d i n u c l e o t i d e  nitrite  to  inorganic  ammonia, b u t reductive  (Pateman and Table  10,  of  pathway  Kinghorn,  oxidation  the  postulated  state  ion  may  1963;  potassium, m u s t be the  nitrogen  or  is  utilized  nitrite can  used  gillus  spp.,  Ustilago  other  to  can  the  be  i s formed by  hand,  as  oxidation  majority  of  fungi  can  This  has  been observed  sp.,  A s p e r g i l l u s spp.,  and  use  i n numerous  a  before  and  sense  Although bacteria, i t i.e.  Asper-  Penicillium 1976). that  sole  fungi,  B o t r y t i s sp.,  then  i n one  nitrate.  i t is likely  ammonia as  and  compounds.  thus  spp.  Kinghorn,  nitrate  ammonium,  some f u n g i ,  Neurospora  nitrate,  The as  oxide  1962;  ammonia  t o x i c t o many f u n g i  sp.  nitrous  1958),  of  at  nature  (Nason,  into organic  s o u r c e by  in  nitroxyl,  1976).  use  shown  The  and  wood c e l l s  from n i t r a t e ,  ( P a t e m a n and  with  atom.  (NC^)  level  fungi  hydroxylamine  n i t r a t e (Cochrane,  a nitrogen  sp. as  i n t o the  the  intermediate  possibilities  a l l f u n g i w h i c h can  Fusarium  and  Kinghorn,  in  equation  o r more  dioxide  that  one  is uncertain;  assimilated  i s known t o be  be  and  calcium  reduced  Nitrite  as  P a t e m a n and  incorporated  nitrogen  the  nitrogen  intermediates  (N2O2),  be  one  f o r the  have a l l been considered Nicholas,  From  that  accepted  important  formed between n i t r i t e  +1  hyponitrite  i s the  1976).  i t i s probable  compounds a r e the  i t is generally  On  the  the  great  nitrogen  s u c h as  Cladosporium  spp.  source.  Alternaria sp.,  83  Coprinus s p i , Dip loci i a sp. , Mucor sp., Neurospora spp., P e n i c i I l i u m spp. and U s t i l a g o sp. (Lewis and Fincham, 1970; Morton and Macmillan,  1954; Pateman et a l . , 1967).  It is  g e n e r a l l y r e c o g n i z e d that the form i n which the ammonia i s supplied  i s important.  form o f ammonium  The f u n g i may use n i t r o g e n i n the  i o n (NH^"") which can be s u p p l i e d as ammonium 1  hydroxide o r ammonium s a l t s .  Although the f u n g i a r e capable  of m e t a b o l i z i n g both n i t r a t e o r n i t r i t e and ammonium i o n , ammonium  i o n i s known t o be p r e f e r r e d because  i t requires  l e s s energy expenditure by the fungus t o use t h i s  reduced  form o f n i t r o g e n . I t i s i n t e r e s t i n g to note that some n i t r o g e n sources f u n c t i o n as a t o x i c substance i n the form o f ammonium hydroxide s o l u t i o n . NaOH and N H 4 O H )  Because t r e a t i n g wood w i t h a l k a l i (e.g.  i n c r e a s e s decay r e s i s t a n c e i n both the  l a b o r a t o r y and the f i e l d  (Amburgey and Johnson, 1978;  Baechler, 1959; H i g h l e y , 1970 and 1973), have been proposed tion.  as an a l t e r n a t i v e method o f wood p r o t e c -  (Dwivedi and A r n o l d , 1973), which i s essen-  f o r treatment may a l s o i n c r e a s e decay r e s i s t a n c e i n wood  by reducing the a v a i l a b i l i t y for or  treatments  I t has been assumed that the a l k a l i treatment may  d e s t r o y thiamine tial  alkali  of other micronutrients e s s e n t i a l  f u n g a l growth (Baechler, 1959), ammoniacal n i t r o g e n content  o r by i n c r e a s i n g the pH  (Highley, 1973).  I f ammonium  salts,  i . e . ammonium n i t r a t e , a r e favoured over  hydroxide,  ammonium  as Moore-Landecker (1972) p o i n t s out, these  salts  are u t i l i z e d p o o r l y o r p o s s i b l y not a t a l l by some f u n g i (e.g. the B l a s t o c l a d i a l e s , Saprolegniaceae, Basidiomycetes).  y e a s t s , and the h i g h e r  I t was shown by Morton and M a c M i l l a n  (1954)  t h a t t h i s i n a b i l i t y i s due t o the pH e f f e c t i n the medium. When these s a l t s were used, they found  t h a t the pH o f the  medium r a p i d l y dropped due to the p r e f e r e n t i a l use o f ammonium i o n which occurs  i n many f u n g i , and consequently  f u n g a l growth  was r e t a r d e d . Although much i s known about the p h y s i o l o g y o f woodi n h a b i t i n g microorganisms, many areas  i n the fundamentals o f  t h e i r n i t r o g e n metabolism remain to be q u e s t i o n a b l e . p r e v i o u s study  (Ruddick,  1979) has proven t h a t the treatment  o f wood w i t h ACA i n c r e a s e s i t s n i t r o g e n content. comparatively  little  The  However,  i s known about the e f f e c t o f treatment  w i t h ammoniacal wood p r e s e r v a t i v e s on the c a p a b i l i t y o f m e t a b o l i z i n g enhanced nitrogenous m a t e r i a l s t o promote f u n g a l growth.  T h e r e f o r e , more e x t e n s i v e and p r e c i s e i n f o r m a t i o n  i s needed about the nature o f f u n g a l n i t r o g e n metabolism i n the wood t r e a t e d w i t h ammoniacal p r e s e r v a t i v e s , under v a r i o u s l a b o r a t o r y and f i e l d  tests.  2.9  FUNCTION OF THE SHIGOMETER IN RELATION TO ELECTRICAL PROPERTIES OF INFECTED WOOD The  e l e c t r i c a l p r o p e r t i e s o f wood a r e measured by i t s  r e s i s t i v i t y o r s p e c i f i c r e s i s t a n c e o r by i t s r e c i p r o c a l conductivity.  The c o n d u c t i v i t y o f a m a t e r i a l determines the  current that w i l l  flow when the m a t e r i a l  given voltage gradient. trical  i s placed  under a  Very d r y wood i s an e x c e l l e n t e l e c -  i n s u l a t o r , w i t h d i r e c t - c u r r e n t r e s i s t i v i t y i n the 1 fl  17  order o f 3 x 10 -' t o 3 x 10 1  perature  (Bannan, 1967).  ohm-centimeters at room tem-  I t i s g e n e r a l l y known t h a t the  e l e c t r i c a l r e s i s t a n c e o f wood i s lowered by i n c r e a s i n g moisture content.  E s p e c i a l l y below the f i b e r s a t u r a t i o n p o i n t ,  the d i r e c t - c u r r e n t e l e c t r i c a l r e s i s t a n c e o f wood decrease r a p i d l y as the m o i s t u r e content i n c r e a s e s . water i n c r e a s e  Even t r a c e s o f  the c o n d u c t i v i t y c o n s i d e r a b l y .  The mechanism  o f e l e c t r i c a l c o n d u c t i o n depends on the presence o f ions i n the wood.  A model f o r i o n i c conduction was proposed by L i n  (1965) t o e x p l a i n the e l e c t r i c a l conduction through the c e l l w a l l o f wood. carriers  He p o i n t e d  out that the number o f charges-  i n wood i s the major f a c t o r a f f e c t i n g the conduction  mechanism over the moisture content range from 0 t o 20%. At h i g h e r moisture contents,  the degree o f d i s s o c i a t i o n o f  absorbed ions i s s u f f i c i e n t l y h i g h so that the m o b i l i t y o f ions may become the major f a c t o r i n determining the e l e c t r i c a l  86  conductivity.  Therefore,  any change i n i o n c o n c e n t r a t i o n ,  d i s t r i b u t i o n , o r both, w i l l a l s o change the e l e c t r i c a l c o n d u c t i v i t y o f the wood. Research on the e l e c t r i c a l p r o p e r t i e s o f wood (Brown e t a l . , 1963; L i n , 1965 and 1967; Skaar, 1964), and o f t r e e s (Fensom, 1959, 1960 and 1963; Levengood, 1970) provided the basic information  f o r the development o f a number o f r e l a t i v e -  l y new techniques t o d e t e c t heartrot, and  of living  trees  Berry, 1975; T a t t a r ,  T a t t a r and S a u f l e y ,  the i n t e r n a l c o n d i t i o n , i . e .  (McGinnes and Shigo, 1975; Shigo 1974; T a t t a r e t a l . , 1972 and 1974;  1973).  One such technique i n v o l v e s the  measurement o f the e l e c t r i c a l r e s i s t a n c e o f wood to a pulsed current.  The o r i g i n a l equipment d e s c r i b e d  by Skutt  et: a l .  (1972) has been r e f i n e d s u b s t a n t i a l l y .  After further  opment o f the meter and the e l e c t r o d e s ,  the Shigometer  devel-  ( r e g i s t e r e d t r a d e mark Northeast E l e c t r o n i c s Corporation) Model 7950 ( F i g . 2 ) , d e s c r i b e d  by Shigo and Shigo (1974) and  Shigo e t a l . (1977), has been w i d e l y i n v e s t i g a t e d u t i l i t y poles Morris  f o r use i n  (Brudermann, 1977; Inwards and Graham, 1980;  e t a l . , 1984; P e r r i n , 1978 and 1979; S h o r t l e e t a l . ,  1978). The  Shigometer i s a meter which measures changes i n the  c o n d i t i o n o f the wood, a s s o c i a t e d resistance.  w i t h a change i n e l e c t r i c a l  The method i n v o l v e s the i n s e r t i o n o f a t w i s t e d  F i g u r e 2.  B a t t e r y - p o w e r e d p u l s e d - c u r r e n t meter, Shigometer Model 7950, and t w i s t e d w i r e probe.  88  w i r e probe w i t h bared k i n k s d r i l l e d hole. current  The  at the t i p s i n t o a r a d i a l l y -  degree o f r e s i s t a n c e to a pulsed  i s c l o s e l y governed by  the c o n c e n t r a t i o n  electric  of cations,  p a r t i c u l a r l y i n many deciduous woods ( S a f f o r d et. a l . , Shigo and  Sharon, 1970;  Shigo, 1973;  Shigo and  T a t t a r ejt a l . , 1972) .  decays, the c a t i o n s  manganese, McGinnes  Shigo (1975) s t a t e d more s p e c i f i c a l l y that the Shigometer  h i s co-workers  (1972  and  1974)  w i t h i n the t r e e . have recognized  Tattar that  p r e t a t i o n o f Shigometer r e s i s t a n c e i n v o l v e s many other such as c o n c e n t r a t i o n  o f hydrogen ions  s p e c i f i c g r a v i t y , and wood s t r u c t u r e . t h e i r s t u d i e s , Wilkes and was  and  As wood d i s c o l o r s and  r e s i s t a n c e decreases.  measures mobile i o n c o n c e n t r a t i o n and  Shortle  ( p r i m a r i l y potassium, calcium,  and magnesium) i n c r e a s e and and  Shigo, 1974;  1974;  interfactors  (pH), m o i s t u r e content, In agreement w i t h  Heather (1982a) found that  a r e l a t i v e l y weak c o r r e l a t i o n o f p u l s e  there  resistance with  pH and w i t h moisture content above the f i b e r s a t u r a t i o n p o i n t f o r s e v e r a l hardwood s p e c i e s .  However, i t has been  reported  that the weak p o s i t i v e c o r r e l a t i o n w i t h moisture content i s apparently  not c o n s i s t e n t among s p e c i e s ,  c o r r e l a t i o n was Wilcox, 1978) and b ) .  The  observed f o r Abies and  and  f o r Pinus and  since a  Sequoia  Dyera spp.  negative  (Piirto  (Thornton, 1979a  e f f e c t s o f d e n s i t y and wood s t r u c t u r e on  r e s i s t a n c e have been d i s c u s s e d  and  pulse  elsewhere (Skutt e_t a l . ,  1972;  Wilkes and Heather, 1982a and b ) , suggesting t h a t above the f i b e r s a t u r a t i o n p o i n t , an i n c r e a s e i n d e n s i t y c o u l d be expected  t o r e s u l t i n a decrease  r e s i s t a n c e may  in conductivity.  Shigometer  also vary with c e l l w a l l r e s i s t i v i t y ,  hole c h a r a c t e r i s t i c s , probe geometry, and measurement procedure  drill  some aspects o f  such as the p r e s s u r e , s u r f a c e area,  and q u a l i t y o f e l e c t r o d e c o n t a c t  (Wilson e_t a l . , 1982) .  Shigo and h i s co-workers (McGinnes and Shigo and B e r r y , 1975;  Shigo and Shigo,  Shigo,  1974)  1975;  have s t r e s s e d  the importance o f p a t t e r n s o f r e s i s t a n c e r a t h e r than v a l u e s f o r p r e d i c t i v e purposes. S h o r t l e et al.(1978) v a l s along one  absolute  I t has been emphasized  t h a t the p a t t e r n o f readings at  by  inter-  hole and not i n d i v i d u a l readings should  be  taken to i n d i c a t e the c o n d i t i o n o f the wood, w i t h a drop o f 75% i n the reading i n d i c a t i n g decay. were taken as 500  Ka because the o r i g i n a l analogue d i s p l a y s  were pegged at 500 Ksa. est  r e a d i n g was  They a l s o s t a t e d t h a t where the h i g h -  over 500 Ysi, a reading o f l e s s than 250 Ksz  would i n d i c a t e decay. Wood P r e s e r v i n g Co., these two  Readings o f over 500 Ksi  criteria  However, the Shigometer manual (Osmose 1980)  o n l y s t a t e s the f i r s t (75% drop)  f o r p r e d i c t i n g decay.  S i n c e the i n t r o d u c t i o n o f the Shigometer, a number o f investigators McGinnes and  (Brudermann, 1977; Shigo,  1975;  Inwards and Graham,  M o r r i s et a l . , 1984;  Perrin,  1980; 1978  of  and  1979;  P i i r t o and Wilcox,  Shortle,  1982;  Thornton  et a l . ,  1978;  Shigo and Berry,  S h o r t l e e t a l . , 1978; 1981;  Wilson et a l . , 1982;  Thornton,  Wilkes and Heather,  Z a b e l et a l . , 1982)  1975;  1979a and  1982a and  have  b;  critically  examined t h i s instrument as a d e c a y - d e t e c t i n g d e v i s e . a l l o f them adhered  t o the p r i n c i p l e s o f two  above, f o r p r e d i c t i n g decay. flicting  The  b;  criteria  Not given  l i t e r a t u r e c o n t a i n s con-  views as to the e f f e c t i v e n e s s o f the Shigometer f o r  d e t e c t i n g d i s c o l o r a t i o n and decay i n both s t a n d i n g t r e e s and converted  timber.  McGinnes and Shigo  (1975) claimed t h a t the technique i s  capable o f d e t e c t i n g r i n g shake and d i s c o l o u r e d heartwood i n b l a c k walnut  (Juglans n i g r a L . ) .  Shigo and B e r r y  (1975) con-  cluded t h a t the Shigometer d e t e c t s decay i n Pinus r e s i n o s a Ait.  S h o r t l e e_t a l . (1978) r e p o r t e d l y worked out  c r i t e r i a which i n d i c a t e d 93% accuracy.  predictive  i n t e r n a l i n telegraph poles with  In agreement w i t h t h e i r study,  i t has been  shown by Inwards and Graham (1980) t h a t the Shigometer c o u l d d e t e c t the c o n d i t i o n o f p o l e i n t e r i o r s at a r e l i a b i l i t y 76% compared t o increment b o r i n g s .  Recently Thornton  of  et a l .  (1981) and Z a b e l et: a l . (1982) a l s o p l a c e d a c e r t a i n amount of  c o n f i d e n c e i n Shigometer methods f o r d e t e c t i o n o f  decay i n p o l e s , but not f o r s o f t r o t . responses,  internal  D e s p i t e these p o s i t i v e  f u r t h e r assessments o f the Shigometer i n both  91  l i v i n g t r e e s ( P i i r t o and Wilcox, Wilkes and Heather, timber and  Thornton,  1979a and  Wilson e_t a l . ,  1982)  and  (Brudermann, 1977; M o r r i s e_t a l . ,  1984;  Perrin,  1979)  1982;  1978;  have a l l been c r i t i c a l .  b;  converted  P i i r t o and Wilcox  1978  (1978)  r e p o r t e d low readings i n both sound and decayed  heartwood o f  Sequoia g i g a n t e a L i n d l . w i t h g r e a t v a r i a b i l i t y ,  especially  i n sound wood.  From s o i l - b l o c k t e s t s w i t h white- and brown-  r o t f u n g i on hardwoods and softwoods, concluded  that the Shigometer  the s e v e r i t y o f decay.  Thornton  (1979a and  d e t e c t e d the presence but not  As a t o o l f o r i d e n t i f y i n g s t a i n  e a r l y decay i n u t i l i t y p o l e s , i t has been r e p o r t e d by mann (1977) and P e r r i n Shigometer  (1978  and  1979)  and  Bruder-  that the r e s u l t s of  measurements are not c o n s i s t e n t enough t o judge  c o n c l u s i v e l y the e f f e c t i v e n e s s of t h i s instrument. r e c e n t l y s e v e r a l r e s e a r c h e r s (Morris e_t a l . , 1982;  b)  Wilkes and Heather,  a l s o demonstrated  1982a; Wilson e t a l . ,  no p r e d i c t i v e a b i l i t y  r e s i s t a n c e , and suggested  1984;  More Shortle,  1982)  have  f o r patterns of  t h a t the p r e v i o u s l y p u b l i s h e d e v i -  dence should be regarded as i n c o n c l u s i v e .  They a l l found  g r e a t n a t u r a l v a r i a t i o n i n e l e c t r i c a l r e s i s t a n c e without decay, thus s u g g e s t i n g that the method i s u n r e l i a b l e . In a very r e c e n t study o f the e f f e c t o f moisture content on e l e c t r i c a l r e s i s t a n c e , M o r r i s and h i s co-workers (1984) have concluded t h a t there i s a l a r g e d i f f e r e n c e between the  reading o f timbers below 38% and above 45% moisture  content.  These o b s e r v a t i o n s c o r r e l a t e c l o s e l y w i t h those r e p o r t e d by P i i r t o and Wilcox  (1978),  and Thornton  (1979a and b ) , i n  that moisture content alone c o u l d r e s u l t i n a marked lowering of  resistance.  However, some groups o f i n v e s t i g a t o r s  and Graham, 1980? S h o r t l e , 1982)  (Inwards  have r e p e a t e d l y a s s e r t e d  t h a t v a r i a t i o n s i n moisture content above the f i b e r s a t u r a t i o n p o i n t do not a f f e c t  the e l e c t r i c a l  resistance.  Another i n t e r e s t i n g area o f concern w i t h regard t o the e f f e c t i v e n e s s o f the meter f o r wood i n s e r v i c e i s the p o s s i b l e e f f e c t o f the presence  o f i o n i z e d m a t e r i a l i n the wood on  v a r i a b i l i t y i n meter r e a d i n g s .  Although  the Shigometer has  been shown to be e f f e c t i v e i n d e t e c t i n g decay i n c r e o s o t e treated u t i l i t y poles  (Shigo and Shigo,  1974), i t i s expected  t h a t i n o r g a n i c m a t e r i a l s present i n wood t r e a t e d w i t h r e t a r d a n t s or waterborne p r e s e r v a t i v e s a l t s c o u l d  fire  substan-  t i a l l y a f f e c t r e s i s t a n c e readings i n the same manner as i n c r e a s i n g ash content o f decaying wood appears the r e a d i n g s .  the  to a f f e c t  In t h i s regard, where very l i t t l e work has  been done, James (1965) r e p o r t e d t h a t w a t e r - s o l u b l e , type wood p r e s e r v a t i v e s had a s u b s t a n t i a l e f f e c t on accuracy o f e l e c t r i c moisture meters.  saltthe  3.0  MATERIALS AND METHODS  3.1  MATERIALS Twelve k e r f e d and twelve  were s e l e c t e d from those t e s t s i t e i n 1977.  unkerfed  ACA-treated  poles  i n s t a l l e d a t Westham I s l a n d  field  Based on r e t e n t i o n data obtained on each  pole p r i o r to i n s t a l l a t i o n ,  these k e r f e d and unkerfed  were c a t e g o r i z e d i n t o four equal groups:  3 than o r equal t o 0.60 l b / f t  poles  retention greater  3 (9.6 kg/m ); g r e a t e r than o r  equal t o 0.45 (7.2) and l e s s than 0.60 (9.6); g r e a t e r  than  o r equal t o 0.30 (4.8) and l e s s than 0.45 (7.2); and r e t e n t i o n l e s s than 0.30 (4.8).  In the s e l e c t i o n o f each p o l e ,  r e l a t i v e l y uniform p e n e t r a t i o n was c o n s i d e r e d based upon the data 3.2  available.  METHODS  3.2.1  SAMPLING METHODS  3.2.1.1 The  BIOASSAY s o i l around the p o l e was excavated  groundline  i n s p e c t i o n and core sampling.  to f a c i l i t a t e  The p o l e s u r f a c e s  were examined and probed around the g r o u n d l i n e zone. v a t i o n s were recorded as major checks, pockets,etc.  Obser-  on the e x t e r n a l wood c o n d i t i o n , such  t h e i r width and depth, any d e t e c t a b l e decay  94  Three increment c o r e s , approximately 5 mm  i n diameter,  were removed from the p o l e i n the r e g i o n o f the g r o u n d l i n e for at  biological about  investigation.  The f i r s t  c o r e s were sampled  3.0 cm away from the l a r g e s t major check  developed  i n non-kerfed p o l e s , o r from the k e r f o f k e r f e d p o l e s .  The  second and t h i r d c o r e s were taken a t p o s i t i o n s o f 120° and 240° c l o c k w i s e apart from the f i r s t , The cores extended  respectively  (Figure 3).  from the s u r f a c e o f the p o l e to the p i t h .  The core b o r e r and e x t r a c t o r were dipped i n 70% a l c o h o l , flamed and allowed to c o o l down.  Using flamed f o r c e p s , each  sampled core was immediately put i n t o a s t e r l i z e d g l a s s w i t h cork caps a t both ends (Figures 4a and b ) .  tube  The tube  was then wrapped t i g h t l y i n a p l a s t i c bag and kept out o f direct sunlight.  When sampling was completed,  h o l e s were f i l l e d w i t h copper naphthenate  the d r i l l e d  p r e s e r v a t i v e , and  then s e a l e d w i t h t r e a t e d plugs t o prevent subsequent  infection.  A f t e r r e t u r n i n g t o the l a b o r a t o r y , the cores were s t o r e d i n a c o o l chamber. sampling. in for  I s o l a t i o n s were made w i t h i n 24 hours o f  The d e t a i l s o f s u b d i v i s i o n f o r i s o l a t i o n are g i v e n  S e c t i o n 3,2.3.1.  Sampling  and examination o f removed cores  f u n g a l a t t a c k were c a r r i e d out i n p a r a l l e l i n o r d e r t o  prevent contamination o f the c o r e s .  Figure 3 . Cross-sectional view of the pole at the groundline, showing the position of three biological cores.  96  Figure  4b.  Sample tubes  cores with  i n the  cork  caps  sterilized at  both  glass  ends.  97  3.2.1.2  CHEMICAL ASSAY AND NITROGEN  F o l l o w i n g the removal o f cores f o r the b i o l o g i c a l i n v e s t i g a t i o n , a second s e t o f c o r e s , each  approximately  1.3 cm i n diameter was removed adjacent t o the s i t e o f the second b i o l o g i c a l core from each o f the s e l e c t e d p o l e s (Figure 5), f o r d e t e r m i n a t i o n o f the ACA p r e s e r v a t i v e r e t e n t i o n and p e n e t r a t i o n , and a l s o f o r measurement o f the n i t r o gen content.  The core extended from the s u r f a c e o f the p o l e  to the p i t h . The sampled core was c u t i n t o f o u r equal p i e c e s f o r d e t e r m i n a t i o n o f the moisture  content o f the p o l e , and  each  p i e c e was s t o r e d i n a g l a s s tube w i t h rubber cap (Figure 6) and  returned t o the l a b o r a t o r y where i t was weighed and oven-  d r i e d a t 103 ± 2° f o r 24 hours.  A f t e r weighing  the oven-  d r i e d sample, each p i e c e was s e a l e d w i t h i n a p l a s t i c bag and s t o r e d under r e f r i g e r a t i o n f o r l a t e r d e t e r m i n a t i o n o f the r e t e n t i o n and p e n e t r a t i o n , and f o r measurement o f the n i t r o g e n content. Upon completion  o f the core sampling,  a l l h o l e s were  i n j e c t e d w i t h copper naphthenate, and c a r e f u l l y s e a l e d w i t h a t r e a t e d p l u g t o prevent  3.2.1.3  subsequent i n f e c t i o n o f the p o l e .  SHIGOMETER  The experimental work f o r the e v a l u a t i o n o f the Shigo-  Figure  5.  Sampling  o f cores  f o r the study  chemical  distribution  and  of  nitrogen  content.  Figure  6.  Storing a piece measurement.  o f the core  f o r moisture  meter was  conducted u s i n g the same p o l e s as those  during the f u n g a l i s o l a t i o n and chemical A f t e r the i n i t i a l each o f the poles was  been completed,  examined u s i n g the Shigometer.  readings were made near the s i t e o f one sampled f o r b i o l o g i c a l  the Shigometer of the three  RETENTION  To determine p r e s e r v a t i v e p e n e t r a t i o n , the  solution ing  twenty-four  from the p o l e s were s t a i n e d w i t h a  0.5%  (weight/volume) o f chrome a z u r o l S prepared  accord  to the AWPA Standard A3-77 (AWPA, 1977), by a p p l y i n g a  few narrow s t r e a k s along  the l e n g t h o f each c o r e .  t r e a t e d wood s t a i n e d b l u e due and  cores  assay.  ANALYSIS OF CHEMICAL PENETRATION AND  cores c o l l e c t e d  Based  from p r e l i m i n a r y i s o l a t i o n o f  i . e . the number o f f u n g i present,  3.2.2  assay.  f u n g a l i s o l a t i o n had  on the i n f o r m a t i o n obtained fungi,  studied  to a r e a c t i o n w i t h  The  ACA-  the copper  the r a d i a l depth o f treatment i n each core was  measured  A f t e r the measurement o f p r e s e r v a t i v e p e n e t r a t i o n , s t a i n e d p o r t i o n was e l i m i n a t i n g any  removed w i t h a sharp k n i f e ,  between 2 mm specified  and  thereby  i n f l u e n c e from the chrome a z u r o l S.  remainder o f each core was 16 mm  i n the CSA  then trimmed to l e n g t h  measurement o f chemical  retention.  The  (the wood  from the s u r f a c e o f the pole)  Standard 080.4-M (CSA,  the  as  1983c) f o r the  In a d d i t i o n , two  addi-  100  t i o n a l p o r t i o n s o f each core, adjacent t o the f i r s t  sampled  and immediately beyond the t r e a t e d zone, were c u t t o a l e n g t h i d e n t i c a l t o the CSA mesh sawdust.  standard.  They were then ground  Three-tenths gram o f the ground  thoroughly mixed w i t h 0.2  sawdust  t o 20 was  g o f c e l l u l o s e powder which acted  as a b i n d i n g agent and the mixture c a r e f u l l y p l a c e d i n a d i e . The sawdust i n the d i e was 300 MPa,  then compressed f o r 3 minutes  to produce a p e l l e t  mately 1.5 mm  19 mm  at  i n diameter and a p p r o x i -  thick.  The p e l l e t s were analysed u s i n g a T r a c o r Northern  energy-  d i s p e r s i v e X-ray spectrometer w i t h an americium-241 source, a molybdenum t a r g e t and a l i t h i u m - d r i f t e d germanium d e t e c t o r . Each p e l l e t was  analysed on both s i d e s t o check t h a t they  were s i m i l a r , as i t had been observed t h a t the c e l l u l o s e powder tended t o s e t t l e out i n p r e p a r i n g the p e l l e t . X-ray spectrometer was A computerized  c o n t r o l l e d by an Apple IU  microcomputer.  standard c a l i b r a t i o n graph had p r e v i o u s l y been  prepared f o r v a r i o u s combinations o f chromium, copper a r s e n i c , and i n c l u d e d c o r r e c t i o n s due ferences and m a t r i x e f f e c t s . a weight/weight  The  and  to i n t e r - e l e m e n t i n t e r -  The r e s u l t s were converted  from  b a s i s t o weight/volume b a s i s by m u l t i p l y i n g  by a c o n v e r s i o n f a c t o r t h a t i n c l u d e s the sample s p e c i f i c gravity.  The s p e c i f i c g r a v i t y determined  t o i n s t a l l a t i o n was  f o r each p o l e p r i o r  taken approximately 1 m below the present  101  sampling s i t e .  T h i s was  deemed more a c c u r a t e than u s i n g a  mean s p e c i e s s p e c i f i c g r a v i t y .  The p r e s e r v a t i v e r e t e n t i o n s  were expressed on an oxide b a s i s , i . e . CuO X-ray spectrometer output. to make a p e l l e t m u l t i p l i e d by 4/3  3.2.3  and A S 2 O 5 ,  from  S i n c e 0.3 g o f sawdust was  i n s t e a d o f the u s u a l 0.4 t o o b t a i n the a c t u a l  used  g, the r e s u l t  was  retention.  MICROBIOLOGICAL STUDIES  3.2.3.1  ISOLATION PROCEDURES  The f u n g i r e s p o n s i b l e f o r decay and s t a i n i n g i n ACAt r e a t e d western white spruce have not been p r e v i o u s l y s t u d i e d . In g e n e r a l , i t i s known t h a t f a s t - g r o w i n g m i c r o f u n g i or bact e r i a o f t e n overgrow  and obscure the decay and s t a i n i n g  Thms a p r e l i m i n a r y review o f the l i t e r a t u r e 1977; was  Hale and Savory, 1976;  i s o l a t i o n o f decay f u n g i .  (Clubbe and Levy,  Hunt and Cobb, 1971;  done to s e l e c t media f a v o u r a b l e towards  fungi.  Smith,  the growth  1983)  and  The two s e l e c t i v e media chosen  were; 1)  malt agar a c i d i f i e d by the a d d i t i o n o f 0.5% m a l i c acid  2)  (mainly f o r i n h i b i t i n g b a c t e r i a l growth);  b e n o m y l / t e t r a c y c l i n e malt agar ( f o r s u p p r e s s i n g most m i c r o f u n g i such as Trichoderma and  Penicillium  spp.). Media  f o r m u l a t i o n and p r e p a r a t i o n s are presented i n Appendix  A.  102  Each c o r e provided fungi.  four zones f o r the i s o l a t i o n o f  The zones s e l e c t e d  f o r i n v e s t i g a t i o n were:  i ) the  o u t e r zone o f the t r e a t e d wood (defined as the wood between 2 mm and 7 mm from the s u r f a c e o f the p o l e ) ; i i )  the un-  t r e a t e d wood immediately adjacent t o the o u t e r t r e a t e d iii)  the heartwood r e g i o n ;  these s e l e c t e d regions,  iv)  the p i t h .  From each o f  a 5 mm-long s e c t i o n was taken f o r  c u l t u r i n g and i d e n t i f i c a t i o n o f the f u n g i . for isolation,  shell;  Before s e c t i o n i n g  a whole c o r e was b r i e f l y s u r f a c e - f l a m e d , and  b e f o r e every c u t a k n i f e and forceps were dipped i n a l c o h o l , flamed and allowed t o c o o l down. make s e c t i o n s ,  A l l materials  i . e . , glass p e t r i dishes,  wood c u t t i n g boards, were s t e r i l i z e d .  needed t o  f i l t e r papers and  A f t e r a 5 mm-long  s e c t i o n o f the t r e a t e d wood was c u t and placed  on s t e r i l i z e d  f i l t e r paper i n a s t e r i l e g l a s s p e t r i d i s h , a s m a l l  cutting  from the remainder o f the t r e a t e d zone was made and dipped i n a 0.5% s o l u t i o n o f chrome a z u r o l S.  The p e n e t r a t i o n o f  the copper component o f the ACA was d e f i n e d c o l o r produced.  T h i s procedure was used t o determine the  l i m i t o f the ACA p e n e t r a t i o n . was c u t ,  by the dark b l u e  A f t e r the second 5 mm  section  the t h i r d was removed from the heartwood a t the mid-  p o i n t between the second and the p i t h ,  and the l a s t  was made as near as p o s s i b l e t o the p i t h . up as shown i n F i g u r e  7.  section  The c o r e was c u t  Figure  7.  Sectioning core,  procedures  providing  isolation  of  four  fungi.  of  a  zones  biological for  the  104  Each 5 nun s e c t i o n prepared f o r f u n g a l i s o l a t i o n was then c u t i n t o four q u a r t e r s .  Two r e p l i c a t i o n s o f two d i f f e r -  ent media were prepared f o r the c u l t u r i n g o f f u n g i  (Figure 8 ) .  Each q u a r t e r was p o s i t i o n e d  i n the medium so about 3/4 the  p i e c e was above the s u r f a c e  (Figure 9 ) .  A coding  system was  developed t o r e l a t e a l l i s o l a t e s obtained  to a pole  (kerfed o r non-kerfed), p o l e number, core  location, radial  p o s i t i o n i n a core, The for  type  and i s o l a t e number o f media.  p l a t e s were incubated  s e v e r a l weeks.  a t about 22°C and monitored  When f u n g a l growth appeared from the  wood samples, they were examined d a i l y , both and m i c r o s c o p i c a l l y .  macroscopically  Frequent s u b c u l t u r i n g onto pure malt  agar p l a t e s was necessary f o r the i s o l a t i o n o f a s i n g l e fungus from the f r e q u e n t l y o c c u r i n g  b a c t e r i a l contamination  or from other  fungi.  In some cases,  as many as f i v e  were obtained  from the same core p o s i t i o n .  no f u n g i c o u l d be i s o l a t e d i n i t i a l l y , i s o l a t e d to confirm observation  period  numbers and k i n d s sheets.  fungi  Cores from which  were sometimes r e -  absence o f f u n g a l i n f e c t i o n .  The average  f o r a p l a t e was about e i g h t weeks. o f c o l o n i e s were recorded  on core  The  data  I s o l a t i o n s o f s e l e c t e d f u n g i were f i r s t made onto  pure malt agar p l a t e s , and s u b c u l t u r e d  r e p e t i t i v e l y , as  necessary from m y c e l i a l margins o r s t r e a k i n g t o e s t a b l i s h pure c u l t u r e s .  Pure i s o l a t i o n s o f s e l e c t e d f u n g i were then  Figure  8.  Two r e p l i c a t i o n s o f t w o d i f f e r e n t t y p e s o f media, r e p r e s e n t i n g each s e c t i o n o f four s e l e c t e d zones.  Figure  9.  Positioning the  medium  about  3/4  surface.  of  each  piece  above  106  made i n t o malt agar t e s t tubes and maintained i n a c u l t u r e bank f o r l a t e r i d e n t i f i c a t i o n , a n d Approximately one thousand the twenty-four p o l e s .  study.  f u n g i were i s o l a t e d  from  When t h e same fungus appeared  c o r e p o s i t i o n on the two s e l e c t i v e media o r r e p l i c a t e i t was recorded a l p h a b e t i c a l l y B, e t c . ) .  as one i s o l a t e  plates,  (e.g. Fungus A,  Because t h e r e was sometimes v a r i a t i o n  p a t t e r n observed on the media  i na  i n the growth  (e.g. Phoma s p . ) , the t e n t a t i v e  name o f the fungus was m o d i f i e d by a s e r i e s o f numbers (e.g. Fungus A l , A2, e t c . ) .  Fungi r e a d i l y i n d e n t i f i a b l e from c u l -  t u r a l and m i c r o s c o p i c c h a r a c t e r i s t i c s , were recorded o n l y after several culture  i s o l a t e s had been s t u d i e d and i n c l u d e d i n the  collection.  By t h i s method approximately n i n e t y i s o l a t e s were selected  f o r further  study as b e i n g r e p r e s e n t a t i v e o f the  p r i n c i p a l fungal population inhabiting treated  3.2.3.2  white spruce p o l e s .  IDENTIFICATION AND GROUPING OF THE ISOLATES  Pure i s o l a t i o n o f s e l e c t e d c u l t u r e bank f o r subsequent several  the twenty-four ACA-  i d e n t i f i c a t i o n and study.  months, malt agar p l a t e s  those f u n g i maintained i t y to exhibit  f u n g i were s t o r e d i n a After  were prepared t o t r a n s f e r  i n t e s t tubes.  Because o f t h e i r  abil-  d i f f e r e n t forms on d i f f e r e n t media, a l l f u n g i  107  were s u b - c u l t u r e d onto uniform medium o f 1.5% malt e x t r a c t , 2% agar and d i s t i l l e d  water.  Sub-cultured p e t r i d i s h e s were put i n p l a s t i c bags and kept at a temperature o f 22°C i n a dark growth chamber f o r approximately  two weeks depending on t h e i r growth r a t e s .  H e a v i l y s p o r u l a t i n g c u l t u r e s were kept s e p a r a t e l y to a v o i d cross-contamination. Macroscopic were determined  c u l t u r a l and m i c r o s c o p i c f o r each i s o l a t e .  characteristics  Using dichotomous keys,  some o f the f u n g i were i d e n t i f i e d r e a d i l y and s o r t e d i n t o taxa o f s i m i l a r unknowns.  the o t h e r s  For those unknown  f u n g i , semi-permanent microscope s l i d e s were prepared each i s o l a t e ,  for  using l a c t o p h e n o l as the mounting medium.  Some i s o l a t e s o f the known and  unknown f u n g i were sent  to B i o s y s t e m a t i c s Research I n s t i t u t e o f A g r i c u l t u r e Canada (Ottawa),  C e n t r a a l b u r e a u Voor Schimmelcultures  (Baarn,  N e t h e r l a n d s ) , or Commonwealth M y c o l o g i c a l I n s t i t u t e England),  f o r c o n f i r m a t i o n or i d e n t i f i c a t i o n .  The  of  the named f u n g i were a l s o confirmed  by Dr. E.C.  of  the Western L a b o r a t o r y o f F o r i n t e k Canada Corp.  (Kew, identities Setliff All  i s o l a t e s were then c a t e g o r i z e d i n t o three major groups o f pole-inhabiting  f u n g i as f o l l o w s :  f u n g i ; and m i c r o f u n g i .  Basidiomycetes;  soft-rot  108  3.2.4  DETERMINATION OF NITROGEN F o l l o w i n g a n a l y s i s o f a p o r t i o n o f the wood sawdust f o r  chemical r e t e n t i o n , the remainder  o f the t r e a t e d zone near  the p o l e s u r f a c e and the untreated zone immediately  adjacent  t o the t r e a t e d s h e l l were analyzed f o r t h e i r n i t r o g e n contents.  In a d d i t i o n , two o t h e r 1 cm p o r t i o n s from the h e a r t -  wood and p i t h o f each core were c u t and ground t o 20 mesh sawdust. The method used was based  on that d e s c r i b e d by Rennie"  (1965) f o r the d e t e r m i n a t i o n o f n i t r o g e n i n woody t i s s u e . Approximately  300 mg o f oven-dried wood, depending on the  a v a i l a b i l i t y o f sawdust sample, was weighed i n t o a 100 ml Kjeldahl flask, o f potassium  f o l l o w e d by 40 mg o f m e r c u r i c oxide and 4 g  sulphate.  F i v e ml o f a n a l y t i c a l - g r a d e concen-  t r a t e d s u l p h u r i c a c i d was added and the mixture g e n t l y s w i r l e d . I t was then l e f t t o stand f o r 10 minutes p r i o r t o h e a t i n g to b o i l i n g .  The h e a t i n g schedule depended upon the sample,  but i n g e n e r a l h e a t i n g on an e l e c t r i c rack was maintained f o r a h a l f hour a f t e r the s o l u t i o n was c l e a r . to minimize  Care was taken  foaming d u r i n g the i n i t i a l h e a t i n g .  ing, the f l a s k was r o t a t e d s e v e r a l times t o speed and  During  heat-  clearing  t o wash down any p a r t i c l e s s p a t t e r e d onto the s i d e o f  the f l a s k .  When the h e a t i n g was completed,  the s o l u t i o n was  allowed t o c o o l s l i g h t l y b e f o r e t r a n s f e r r i n g t o a 100 ml  109  volumetric flask. was  T h i s t r a n s f e r took p l a c e w h i l e the s o l u t i o n  s t i l l warm, because otherwise  i t could s o l i d i f y  readily.  5 ml o f 2M sodium i o d i d e s o l u t i o n was then added t o the d i g e s t a t e which was f i n a l l y d i l u t e d w i t h d i s t i l l e d water up t o 100 ml o f d i l u t e d The  solution.  d i l u t e d s o l u t i o n i n a v o l u m e t r i c f l a s k was p l a c e d  i n c o o l area o v e r n i g h t a f t e r which the n i t r o g e n content was measured u s i n g an O r i o n ammonia-specific 95-10) coupled T h i s instrument  e l e c t r o d e (Orion  to an O r i o n M i c r o p r o c e s s o r was operated  i o n a l y s e r 901.  i n the a n a l a t e - a d d i t i o n mode,  as d e s c r i b e d i n the O r i o n o p e r a t i n g manuals (1977 and 1978) and  the n i t r o g e n c o n c e n t r a t i o n i n percentage was read  from the a n a l y z e r d i s p l a y .  I n summary, the method i n v o l v e d  p i p e t t i n g 1 ml o f the ammonia standard hydroxide lize, and  i n t o a 0.4M sodium  s o l u t i o n and a f t e r a l l o w i n g the reading t o s t a b i -  adding  10 ml o f the d i l u t e d d i g e s t a t e t o the s o l u t i o n  r e c o r d i n g the r e s u l t s .  Two r e p l i c a t e d readings on each  s o l u t i o n were made t o p r o v i d e an average n i t r o g e n  3.2.5  directly  content.  SHIGOMETER MEASUREMENTS Measurements f o r i n t e r n a l decay were made with a s p e c i a l  t w i s t e d - w i r e probe; an abrupt supposedly  i n d i c a t e s decay.  drop i n e l e c t r i c a l r e s i s t a n c e R e s i s t a n c e measurements w i t h  the Shigometer on each p o l e i n v o l v e d d r i l l i n g , from s u r f a c e  to  p i t h , a r a d i a l l y o r i e n t e d h o l e , 3/32 i n . (2.4 mm) i n  diameter,  at groundline.  The h o l e was made w i t h 8 i n . (20.3  cm) long d r i l l b i t mounted i n a l i g h t w e i g h t b a t t e r y powered drill.  The time taken t o d r i l l  the h o l e was u s u a l l y 40 t o  60 seconds w i t h frequent removal o f the b i t from the h o l e t o e l i m i n a t e sawdust.  The measurement o f r e s i s t a n c e was begun  a couple o f minutes a f t e r d r i l l i n g had been completed. Meter readings were made at 1 cm i n t e r v a l s ,  as i n d i c a t e d  by p a i n t e d marks on the probe, t o p r o g r e s s i v e l y deeper p o s i t i o n s i n s i d e the p o l e .  These measurements e s t a b l i s h e d the  i n t e r n a l p r o f i l e o f the e l e c t r i c a l r e s i s t a n c e . ing tal.  the twisted-wired  When i n s e r t -  probe i n t o a hole, i t was kept  horizon-  The procedure followed was based on that d e s c r i b e d i n  the Shigometer method manual. The  e l e c t r i c a l r e s i s t a n c e readings  were p l o t t e d on s c a l e d sketches percentages  i n k i l o ohms (kS2)  o f the c o r e s .  were c a l c u l a t e d f o r the lowest  the h i g h e s t v a l u e f o r a c o r e .  Deflection  each reading  from  The core p o s i t i o n s where a  d e f l e c t i o n percentage was 75 o r greater"were  recorded  being  p o s s i b l y decayed. When the i n s p e c t i o n was completed, a l l d r i l l e d were f i l l e d  holes  w i t h copper naphthenate p r e s e r v a t i v e from a  p l a s t i c squeeze b o t t l e , and then c a r e f u l l y s e a l e d w i t h a t r e a t e d plug t o prevent  subsequent i n f e c t i o n o f the p o l e .  Ill  4.0  RESULTS AND DISCUSSION  4.1  CHEMICAL DISTRIBUTION STUDY The  e f f e c t i v e n e s s o f a wood-preservative treatment i n  preventing  d e t e r i o r a t i o n i s dependent on the degree o f t r e a t -  ment, as w e l l as the e f f e c t i v e n e s s o f the p r e s e r v a t i v e system itself.  Treatment v a r i a b l e s i n c l u d e depth o f p e n e t r a t i o n ,  l e v e l o f chemical  4.1.1  r e t e n t i o n , and p r e s e r v a t i v e  distribution.  PENETRATION Table  11 r e p r e s e n t s  the r e s u l t s o f p r e s e r v a t i v e pene-  t r a t i o n determined f o r the ACA-treated spruce poles a f t e r seven years  in test.  The histogram o f the average  t i o n values  (Figure 10) d e p i c t s a s l i g h t right-skewed  t r i b u t i o n w i t h the 50 percent  o f the observed  f a l l i n g w i t h i n the range o f 1.0 The  dis-  penetrations  (2.5) t o 1.2 i n . (3.0 cm).  s i g n i f i c a n c e of this large penetration  comparing the data obtained  penetra-  i s e v i d e n t when  i n t h i s study w i t h the c u r r e n t  ACA-penetration requirements f o r spruce poles d e s c r i b e d i n the CSA 080 Wood P r e s e r v a t i o n Standard, s e c t i o n 080.4. c u r r e n t standard  r e q u i r e s a minimum p r e s e r v a t i v e  o f 0.50 i n . (13 mm) (19 mm).  Results  penetration  and 100% sapwood up to a depth o f 0.75 i n .  from t h i s study c l e a r l y i n d i c a t e that a l l  the t e s t p o l e s achieved observations  The  the CSA-required p e n e t r a t i o n .  These  c o r r e l a t e c l o s e l y w i t h those reported by Ruddick  112  TABLE 11.  P r e s e r v a t i v e p e n e t r a t i o n values determined f o r the ACA-treated spruce poles a f t e r seven years in test.  Penetration (in.)  Pole Number  K-3-24 K-3-25 K-3-29 N-3-49 K-4- 1 N-4- 2 K-4- 5 K-4- 8 N-4-10 K-4-20 N-4-23 K-4-25 N-4-29 N-4-41 N-5-11 N-5-16 K-5-21 N-5-23 K-5-26 N-5-29 K-5-31 K-5-39 N-5-50 N-5-51  Mean S t d . Dev.  Min.  Max.  Ave.  1.14 1.26 1.02 0.79 1.33 0.96 1.06 1.27 1.45 1.14 0.91 1.04 1.17 1.05 0.97 0.88 0.93 1.08 1.01 1.34 1.04 0.99 1.04 1.06  1.17 1.39 1.20 1.03 1.42 1.09 1.12 1.34 1.54 1.19 0.98 1.07 1.33 1.15 1.56 0.92 0.99 1.12 1.03 1.51 1.08 1.14 1.15 1.10  1.16 1.33 1.11 0.91 1.38 1.03 1.09 1.31 1.50 1.17 0.95 1.06 1.25 1.10 1.27 0.90 0.96 1.10 1.02 1.43 1.06 1.07 1.10 1.08  1.14 0.19  113  10 • • • • • • • • • x'X'X'x* •  8 CO LU _l  %*X*X'X w;Xx";*x*;  OL  urn  o  U.  O  cr HI  IIP  CQ  j ^MEAN  (1.14" )  i i • i i i i • •ixVx-x.•V.W.Vi tf-XyXv .ix-x-x»;« ;*x*x*x*! *x*x-x*  ?**x*:"x*S ••I-X-X-X *-X'X;X; *;*X"X"X' «»x"x"x"5 5$x*:$ ».**x«x*> JL'X'X'X*  JSvxS:  x^Sx^  1$$$  Xx^^:  1 —  0.8  1.0  1.2  1.4  1.6  A V E R A G E PENETRATION (in.)  Figure 10. Histogram of average A C A penetration.  (1978) , i n t h a t e x c e l l e n t large  number o f t r e a t m e n t s  attributed  of incising  Indeed, incising  Banks spaced  a n d ACA  poles clearly  has a l s o  incising  Considerable  Ruddick to the  (1977) h a v e shown t h a t  enhances  the penetration of  by pressure  impregnation.  r e p o r t e d t h e development o f a  p a t t e r n f o r use on spruce  the p e n e t r a t i o n o f  i n a  treatment.  preservatives applied  (1973)  roundwood.  penetration values  Horn and h i s co-workers  spruce  waterborne  o f spruce  the satisfactory  combination  of  p e n e t r a t i o n were o b t a i n e d  close-  lumber t o  improve  preservatives. effort  h a s b e e n made t o s t u d y  ammonia o n v a r i o u s c o m p o n e n t s o f t h e wood  the effect  substance  and  some p h y s i c o - c h e m i c a l p r o p e r t i e s o f a m m o n i a - t r e a t e d  wood  (Bariska  and Popper,  1969;  Davidson  and Bangardt,  studies,  i t c a n be c o n c l u d e d  into  1971 and 1 9 7 5 ; B a r i s k a et. a l . , 1970; Rak, 1977a).  a l l c o m p o n e n t s o f wood  the  structure  o f wood  the  treatability.  substance,  treatments  Cu-As p r e s e r v a t i v e s d i s s o l v e d excellent these  a  and i t s a c t i o n  as f a c t o r s o f spruce  sapwood p e n e t r a t i o n .  Supporting  o f the ACA-treated  similar  poles w i t h those  group o f the PCP-treated  poles  on  affecting  poles  i n a q u e o u s ammonia  with  provided  evidence f o r  observations i s provided by a comparison  results  these  t h a t p e n e t r a t i o n o f ammonia  are identified  Thus,  From  of the  recorded f o r  (Ruddick,  1978).  The  i n f e r i o r p e n e t r a t i o n o f the l a t t e r was  obvious.  Rak  (1977a) has a l s o shown t h a t the p e r m e a b i l i t y o f spruce sapwood i n the r a d i a l d i r e c t i o n t o an aqueous ammoniacal s o l u t i o n o f i n o r g a n i c s a l t s was t h a t o f water.  Thus, i t may  v a t i o n s t h a t the use o f ACA of  found t o be b e t t e r than  be concluded  from these  s o l u t i o n s w i t h the  obser-  application  i n c i s i n g have both c o n t r i b u t e d towards the e x c e l l e n t  p e n e t r a t i o n s observed  4.1.2  f o r the ACA-treated  spruce p o l e s .  RETENTION The r e t e n t i o n o f p r e s e r v a t i v e i s one o f the most impor-  t a n t f a c t o r s i n f l u e n c i n g the e x t e n s i o n o f the s e r v i c e of  preservative-treated poles.  chemical r e t e n t i o n was  Thus, i n t h i s study,  determined  i n three d i f f e r e n t  life the assay  zones f o r each p o l e , by a n a l y z i n g the b o r i n g t h a t had been used t o assess the p e n e t r a t i o n . presented  i n Table 12.  The  analytical results  T h i s t a b l e a l s o shows the  chemical content and the r e l a t i v e percentage ponents,  Cu and As,  total  o f the two  i n the three a n a l y t i c a l zones,  are  com-  and f o r  comparison the r e t e n t i o n v a l u e s measured p r i o r t o  installa-  t i o n f o r the f i r s t  determined  for  zone o n l y .  The present v a l u e s  zone 1 a c c o r d i n g t o the CSA  standard method may  pared w i t h those d e s c r i b e d i n the CSA 3 0.6  lb./ft.  be com-  080.4 standard o f  3 (9.6 kg/m  ) f o r ACA,  on an element oxide b a s i s .  TABLE  12.  Analysis  o f ACA  chemical  retention.  Retention  Relative  Zone Pole  of  number  analysis  K-3-24  K-3-25  K-3-29  N-3-49  K-4-  K-4-  1  2  percentage Cu 3  As  (kg/m ) 3  Total  (kg/m ) 3  (kg/m ) 3  Total (lb./ft.  Retention to  )  prior  installation  Cu  As  (lb./ft. )  0.27  1  5.00  3.67  8.67  0.53  58  42  2  0.80  0.27  1.07  0.07  75  25  3  0.27  0.13  0.40  0.03  67  33  1  6.27  6.00  12.27  0.77  49  2  1.60  1.33  2.93  0.18  51 55  3  0.40  0.27  0.67  0.04  60  40  1  3.47  2.13  5.60  0.35  62  38  2  0.80  0.27  1.07  0.07  75  25  3  0.13  0.13  0.26  0.01  50  50  1  4.13  2.67  6.80  0.43  61  39  0.08  67  33  3  0.62  45  2  0.80  0.40  1.20  3  0.27  0.13  0.40  0.03  67  33  10.80  0.68  54  46  4.00  0.25  53  47  0.67  0.04  40  60  4.00  0.25  60  40  1  5.87  2  2.13  3  0.27  4.93 1.87 0.40  1  2.40  1.60  2  0.53  0.27  0.80  0.05  67  33  3  0.13  0.13  0.26  0.01  50  50  0.39  0.28  G.67  0.39  1 5  TABLE 12.  (cont.)  Retention  Relative percentage  Pole  of a  Cu / 3» (kg/m ) 4.67 1.73 0.27  As , , (kg/m ) 3.33 1.07 0.27  Total , . 3. (kg/m ) 8.00 2.80 0.54  number K-4- 5  analysis 1 2 3  K-4- 8  1 2 3  2.40 1.13 0.27  1.73 0.87 0.27  4.13 2.00 0.54  K-4-10  1 2 3  5.33 1.73 0.40  4.40 1.07 0.13  K-4-20  1 2 3  4.67 1.60 0.27  N-4-23  1 2 3  K-4-25  1 2 3  0  J  J  Total . 3, (lb./ft. ) 0.49 0.17 0.03  Retention p r i o r . ^ , „ . n I«-,-,^b to i n s t a l l a t i o n (lb./ft. ) 0.26 o4  J  =  3  C  u  A  s  58 62 50  42 38 50  0.25 0.12 0.03  58 57 50  42 43 50  0.54  9.73 2.80 0.53  0.61 0.17 0.03  55 62 75  45 38 25  0.62  2.40 1.20 0.27  6.93 2.80 0.54  0.43 0.17 0.03  65 57 50  35 43 50  0.55  4.53 0.67 0.27  2.40 0.27 0.13  6.93 0.94 0.40  0.43 0.05 0.03  65 71 67  35 29 33  0.35  5.73 0.67 0. 13  4.00 0.40 0.13  9.73 1.07 0.26  0.61 0.07 0.01  59 63 50  41 37 50  0.32  TABLE 12.  (cont.)  Retention Pole number  Zone of analysis  3  Cu (kg/m ) 3  As (kg/m ) 3  Relative percentage  Total Total ( l b./ft. ) (kg/m ) 3  3  Cu  As  Retention p r i o r to i n s t a l l a t i o n (lb./ft. ) 3  N-4-29  1 2 3  4.13 0.67 0.27  3.33 0.53 0.27  7.46 1.20 0.54  0.47 0.08 0.03  55 56 50  45 44 50  0.60  N-4-41  1 2 3  6.80 1.33 0.40  6.40 1.07 0.27  13.20 2.40 0.67  0.82 0.15 0.04  52 56 60  48 44 40  0.74  N-5-11  1 2 3  1.87 1.07 0.27  0.67 0.40 0.13  2.54 1.47 0.40  0.16 0.09 0.03  74 73 67  26 27 33  0.33  N-5-16  1 2 3  4.07 0.83 0.27  2.60 0.41 0.13  6.67 1.24 0.40  0.41 0.08 0.03  61 67 67  39 33 33  0.21  K-5-21  1 2 3  5.67 0.53 0.13  3.53 0.27 0.13  9.20 0.80 0.26  0.57 0.05 0.01  62 67 50  38 33 50  0.22  N-5-23  1 2 3  5.67 1.33 0.13  3.80 0.67 0.13  9.47 2.00 0.26  0.59 0.12 0.01  60 67 50  40 33 50  0.46  1 3  TABLE 12.  (cont.)  Retention Pole number  Zone of analysis  3  Cu (kg/m ) 3  As (kg/m ) 3  Total Total (kg/m ) ( l b . / f t . ) 3  3  Relative percentage Cu  As  Retention p r i o r to i n s t a l l a t i o n (lb./ft. ) 3  K-5-26  1 2 3  4.40 0.67 0.13  3.47 0.40 0.13  7.87 1.07 0.26  0.49 0.07 0.01  56 63 50  44 37 50  0.33  N-5-29  1 2 3  4.53 1.73 0.13  2.80 0.93 0.27  7.33 2.67 0.40  0.45 0.16 0.03  62 65 33  38 35 67  0.29  K-5-31  1 2 3  4.27 2.27 0.40  3.60 2.13 0.53  7.87 4.40 0.93  0.49 0.28 0.05  54 52 43  46 48 57  0.45  K-5-39  1 2 3  6.00 0.80 0.27  5.33 0.53 0.13  11.33 1.33 0.40  0.71 0.08 0.03  53 60 67  47 40 33  0.70  N-5-50  1 2 3  3.07 1.07 0.13  2.13 0.80 0.27  5.20 1.87 0.40  0.33 0.12 0.03  59 57 33  41 43 67  0.48  N-5-51  1 2 3  6.13 1.47 0.40  4.13 0.93 0.27  10.26 2.40 0.67  0.64 0.15 0.04  60 61 60  40 39 40  0.56  1 3  TABLE 12.  (cont.)  Retention Pole number  Zone of Analysis  9  Cu (kg/m )f 3  As (kg/m ) 3  Relative percentage  Total Total (kg/m ) ( l b . / f t . ) 3  3  Mean  1 2  8.06 1.93  0.50 0.12  S t d . Dev.  1 2  2.63 1.01  0.16 0.06  a  1:  Cu  As  6  2: 3:  approximately  The p r e v i o u s r e t e n t i o n s were determined 3 Note:  To convert l b . / f t .  0.16  i n CSA standard  beyond the t r e a t e d zone.  by Ruddick  3 to kg/m  3  0.44  core s e c t i o n from the s u r f a c e o f pole, c u t to the l e n g t h s p e c i f i e d f o r the measurement o f chemical r e t e n t i o n . zone next to the f i r s t s e c t i o n . 1 cm-long s e c t i o n immediately  Retention p r i o r to i n s t a l l a t i o n ^ * (lb./ft. )  , m u l t i p l y by 16.  (1978).  121  As r e p o r t e d by Ruddick  (1978), the m a j o r i t y o f i n i t i a l  r e t e n t i o n s i n t h i s white spruce p o l e study f a i l e d t o achieve the l e v e l e s t a b l i s h e d by the CSA s t a n d a r d . When the r e s u l t s from t h i s study a r e compared w i t h those r e p o r t e d by Ruddick,  t h e r e i s no s i g n i f i c a n t d i f f e r e n c e at  the 90% l e v e l i n the mean r e t e n t i o n f o r the two measurements (Table 13). The mean r e t e n t i o n o f 0.50 l b . / f t . ( 8 . 0 kg/m ) 3  observed  3  f o r zone 1 a f t e r s e v e r a l years o f t e s t i n g , i s s l i g h t 3  l y g r e a t e r than the o r i g i n a l v a l u e o f 0.44 l b . / f t .  3 (7.0 kg/m ) .  T h i s i s a s s o c i a t e d w i t h the f a c t that the samples were removed from the p o l e s at d i f f e r e n t  locations  ( i . e . f o r the present  study, approximately 3 f t . (0.9 m) above the o r i g i n a l zone, which was 10 f t . (3.0 m) from the b u t t o f the p o l e s . it  However,  should be noted that an assay based on a s i n g l e b o r i n g o f  a p o l e can f u r n i s h o n l y an e s t i m a t e o f chemical  retention  i n the zone and a t t h e p o i n t sampled. As shown i n Table 12, i t i s c l e a r that t h e r e i s an abrupt g r a d i e n t i n r e t e n t i o n between the f i r s t and second zones.  The r e s u l t s i n d i c a t e t h a t h a l f o f the t e s t p o l e s 3 3  have r e t a i n e d  l e s s than 0.10 l b . / f t .  As i n the second to  assay zone.  (1.6 kg/m ) o f Cu and  However, i t i s not p o s s i b l e  i n t e r p r e t t h i s poor r e t e n t i o n i n white spruce as b e i n g  s o l e l y due t o a blockage o f the pathways by which the chemical permeates the sapwood.  Rather,  low chemical r e t e n t i o n s i n  TABLE 13.  Present  Student t - t e s t between the mean c u r r e n t and previous ( p r i o r to i n s t a l l a t i o n ) t o t a l s .  Previous  Test statistic  DF  Significance  46  0.2155  Mean  0.50  0.44  t = 1.2559  Variance  0.027  0.026  F = 1.0361  No. o f poles  24  24  Probability  23,23 (1  s t  0.4665  mean) 2 ) = 0.8872 n d  123  the ACA-treated  spruce p o l e s w i t h e x c e l l e n t p e n e t r a t i o n s can  be e x p l a i n e d most p l a u s i b l y i n two ways, such as t h e t r e a t i n g process and the h i g h i n i t i a l moisture content o f wood, thus d i l u t i n g the ACA.  4.1.3  DISTRIBUTION OF CHEMICAL COMPONENTS The e f f e c t i v e n e s s o f a p r e s e r v a t i v e treatment may a l s o  depend on the d i s t r i b u t i o n o f chemical components, p a r t i c u l a r l y i n the waterborne p r e s e r v a t i v e system. of  the s a l t treatments  The good performance  i s p a r t i a l l y a t t r i b u t e d t o the f a c t  that they a r e a b l e t o p e n e t r a t e e a s i l y i n t o the c e l l w a l l of  softwoods and are u n i f o r m l y d i s t r i b u t e d i n the wood. From the r e s u l t s shown i n Table 12, an i n t e r e s t i n g ob-  s e r v a t i o n has been found for  i n the r a t i o o f copper t o a r s e n i c  the r e t e n t i o n s i n the f i r s t  a n a l y t i c a l zone.  r a t i o i s p l o t t e d against the t o t a l retention  When t h i s  ( F i g u r e 11), i t  i s c l e a r l y seen t h a t the r a t i o o f copper t o a r s e n i c i s near u n i t y a t v e r y h i g h t o t a l r e t e n t i o n , but i n c r e a s e s i n the form of  a hyperbolic equation  decreases.  (y = b  Q  retention  the data w e l l a t the 99.9%  judging by the v a l u e o f t h e m u l t i p l e c o e f f i c i e n t o f  determination (b  + b^x"*-) as t o t a l  From the m u l t i p l e r e g r e s s i o n a n a l y s i s shown i n  T a b l e 14, h y p e r b o l i c model f i t s level,  Q  (R ). 2  The estimates o f the model parameters  and b.) a r e a l s o presented i n the same t a b l e , showing  Figure 11. Ratio of copper to arsenic versus total retention.  TABLE 14.  Source  M u l t i p l e r e g r e s s i o n a n a l y s i s o f the r a t i o of copper to a r s e n i c f o r the r e t e n t i o n s i n the f i r s t a n a l y t i c a l zone.  DF  SS  MS  1  1.7406  1.7406  Error  22  1.0899  0.0495  Total  23  2.8305  Regression  Multiple  Variable  R = 0.78418  Partial  Constant 1/ t o t a l  Note:  1c  0.78418  R  2  = 0.61495  F  Signif.  35.135* 0.0000  SE = 0.22258  Coefficient  Std. error  0.8835  0.10565  8.3624* 0.0000  3.9453  0.66561  5.9275* 0.0000  s i g n i f i c a n t a t 0.1% l e v e l .  t  Signif.  126  the p r e d i c t i o n e q u a t i o n o f y = 0.8835 + 3.9453x" total  for  x  the  retention. R e c e n t l y Ruddick e_t a l . (1981) and  reported  the r a t i o o f copper and  woods grown i n Southeast A s i a . portionate  Ruddick (1984) have  a r s e n i c i n ACA-treated hardIn both s t u d i e s , the  uptake o f these chemical components has  c l e a r l y noted.  A c c o r d i n g to Ruddick (1984), a  dispro-  been  dispropor-  t i o n a t e uptake p r e v i o u s l y observed i n those ACA-treated woods can be  explained  o f copper and during  as being due  solutions greater  absorbed than a r s e n i c .  to i n c r e a s e  As  of t h i s disproportionate  a r e s u l t , t h i s would tend  However, s i n c e the  and  and  leached  Ruddick  1984), i t i s necessary to moni-  t o r the t r e a t i n g s o l u t i o n compositions, and required.  arsenic  the t r e a t i n g  i n f r e s h l y t r e a t e d hardwoods by  h i s co-workers (1981  a r s e n i c as  low  been g r a d u a l l y  Where d i s p r o p o r t i o n a l uptake occurs d u r i n g  p r o c e s s , as reported  results  r e t e n t i o n s were observed would a l s o  suggest t h a t the a r s e n i c component has out.  that  uptake were obtained from weathered  i n exposure t e s t s f o r s e v e r a l years,  d i s t r i b u t i o n s where low  that  amount o f copper  the r a t i o o f copper to a r s e n i c compared w i t h  p r e s e n t i n the t r e a t i n g s o l u t i o n .  spruce p o l e s  mainly to the a d a p t a b i l i t y  a r s e n i c to the f i x a t i o n p r o c e s s , s u g g e s t i n g  treatment o f ACA  would be  hard-  add  additional  127  The  importance o f these o b s e r v a t i o n s l i e s i n the f a c t  t h a t the a r s e n i c content i n the wood should not be allowed to f a l l below a s p e c i f i c l e v e l , because a r s e n i c i s needed t o prevent spp.  decay by c o p p e r - t o l e r a n t f u n g i such as P h i a l o p h o r a  Indeed the m i c r o b i o l o g i c a l i n v e s t i g a t i o n s t o f o l l o w  i n d i c a t e t h a t numerous s p e c i e s o f the genus P h i a l o p h o r a have been f r e q u e n t l y i s o l a t e d near the t r e a t e d s u r f a c e o f poles.  4.2  BIOLOGICAL STUDY Wood-inhabiting  f u n g i were i s o l a t e d from the 24 ACA-  t r e a t e d white spruce p o l e s sampled. these f u n g i were i s o l a t e d each c o r e .  As d e s c r i b e d p r e v i o u s l y ,  from the f o u r d i f f e r e n t zones o f  A t o t a l o f 71 f u n g a l i s o l a t e s b e l o n g i n g  t o 17  genera and 4 taxa were i d e n t i f i e d t o genus, w i t h 15 o f these being i d e n t i f i e d as t o s p e c i e s (Table 15). q u e n t l y i s o l a t e d f u n g i were Phoma herbarum  The most  fre-  (24/24, o b t a i n e d  from 24 p o l e s out o f 24 sampled), E x o p h i a l a j e a n s e l m e i Oidiodendron (14/24),  (19/24),  spp. (16/24), Acremonium and P e n i c i l l i u m spp.  P h i a l o p h o r a spp. (13/24),  Sclerophoma p y t h i o p h i l a  (6/24), and V e r t i c i l l i u m spp. (4/24).  B a c t e r i a were a l s o  commonly a s s o c i a t e d w i t h these m i c r o f u n g i i s o l a t e d . no Basidiomycetes,  regarded  However,  as b e i n g t r u e decay f u n g i on the  b a s i s o f clamp c o n n e c t i o n s , were i s o l a t e d from any  ACA-treated  128  TABLE 15.  I d e n t i t y and frequency o f f u n g i i s o l a t e d from 24 white spruce p o l e s a t Westham I s l a n d t e s t f i e l d site.  Fungus  9  Isolation  frequency  ! Poles(24)  Cores(72)  14 1 1 8 1 5  20 1 1 11 2 6  t e n u i s s i m a (Kunze ex Pers.) W i l t s .* 1  1  Acremonium spp. A_. b u t y r i (Van Bevma) W. Gams A. f u s i d i o i d e s (Nicot) W. Gams A. k i l i e n s e Grutz A. s t r i c t u m W. Gams other species Alternaria  Aphanocladium  album (Preuss) W. Gams  2  3  1  2  19  37  1  1  1  1  G i l m a n i e l l a sp.  1  2  G l i o c l a d i u m sp.  1  1  16 10 2 2 1 8  28 15 2 2 1 13  14 1 14  24 1 24  A s p e r q i l l u s sp. Exophiala i e a n s e l m e i (Lanqeron) McGinnis & Padhye #  Fusidtum s p . ' Geomyces pannorum  (Link) S i q l e r & Carmichael  Oidiodendron spp. 0. qriseum Robak cf. 0. rhodoqenum Robak cf. 0. t e n u i s s i m a (Peck) C f . 0 . truncatum Barron other species P e n i c i l l i u m spp. P. canescens Sopp unidentified species  Huqhes  13  TABLE 15.  Fungus  (cont.)  3  I s o l a t i o n frequency ~ Poles(24) Cores(72)  P h i a l o p h o r a spp.* P_. americana cf. P. f a s t i g i a t a cf. P. molorum other species  13 3 6 2 7  28 5 12 2 15  Phoma herbarum  24  72  Sclerophoma p y t h i o p h i l a (Corda) Hohnel.  6  11  S c y t a l i d i u m sp.  1  1  Stemphylium botryosum W a l l r .  1  1  V e r t i c i I l i u m spp. V. n i g r e s c e n s Pethybr. other species  4 2 3  6 2 4  unidentified Taxon 1 Taxon 2 Taxon 3 Taxon 4  a  Westend.  imperfects 1 1 1 1  1 1 1 1  The s p e c i e s marked w i t h * a r e p o t e n t i a l s o f t r o t f u n g i on the b a s i s o f l i t e r a t u r e ( C s e r j e s i , 1984; L e i g h t l e y , 1980 and 1981; N i l s s o n , 1973; Z a b e l e t a l . , 1982).  k The t o t a l numbers o f poles and cores from which f u n g i were i s o l a t e d are p l a c e d i n p a r e n t h e s i s .  130  spruce p o l e s . An  important c o n s i d e r a t i o n i n wood p r o t e c t i o n i s to  determine whether o r not c e r t a i n f u n g i are b e i n g c o n t r o l l e d by a p r e s e r v a t i v e treatment. for  Such knowledge i s e s s e n t i a l  the s e l e c t i o n o f f u n g i to be used i n f u t u r e e x p e r i m e n t a l  t e s t i n g and ments.  a l s o f o r the e v a l u a t i o n o f a p r e s e r v a t i v e t r e a t -  For these reasons, untreated  spruce p o l e s  installed  at Westham I s l a n d were examined f o r the presence o f b a s i d i o carps f r u i t i n g on t h e i r s u r f a c e s .  S e v e r a l wood-destroying  f u n g i which have been a t t a c k i n g spruce c o n t r o l p o l e s listed  i n Table 16.  Both white- and brown-rot f u n g i were  observed, but Gloeophyllum saepiarium r o t was  g e n e r a l l y known that G.  saepiarium  i s a very  and  r e s i s t a n t ( i . e . to d r y i n g and  rot  fungus, which p r i m a r i l y a t t a c k s  (see Table 16)  It is  destructive  high temperatures) brownsapwood but may  As shown i n Table 15,  wood-destroying f u n g i i d e n t i f i e d poles  which causes a brown  the most common among the Baasidiomycetes.  degrade heartwood.  are  later  none o f the  true  from the spruce c o n t r o l  have been i s o l a t e d from the ACA-treated  poles. The  e i g h t major genera o f m i c r o f u n g i  t h e i r p o s i t i o n i n the cores  as to the  were grouped  l o c a t i o n and  time o f o r i g i n o f f u n g a l i n h a b i t a t i o n i n the p o l e s . data are summarized f o r the ACA-treated p o l e s  i  by  possible The  i n Table  17.  131  TABLE 16.  Fungi i d e n t i f i e d from b a s i d i o c a r p s on u n t r e a t e d spruce c o n t r o l p o l e s a t Westham I s l a n d t e s t s i t e ( C s e r j e s i , 1984).  Fungus  Pole number  1980 SP 8  P o r i a sp. Stereum sanquinolentum (Alb. & Schw:Fr.) Pouz, Dacryroyces s t i l l a t u s nees:Fr.  1980 15  Gloeophyllum  1980 26  Leucoqyrophana molluscus  1980 28  Gloeophyllum  1980 31  Crustoderma  1980 32  Gloeophyllum saepiarium Crustoderma dryinum P h l e b i a s u b s e r i a l i s (Bourd. & Galz.) Donk  1980 33  Gloeophyllum  saepiarium (Wolf.:Fr.) K a r s t . (Fr.) Pouzar  saepiarium dryinum  (Berk. & Curt.) Parm.  saepiarium  TABLE 17.  R e l a t i o n s h i p between i s o l a t i o n frequency and core p o s i t i o n f o r the genera o f major f u n g i i s o l a t e d from 24 white spruce p o l e s .  Frequency o f i s o l a t i o n s from a core Core p o s i t i o n  position Total  3  Acremonium  Exophiala  1  8  35  2  3  3 4  Oidiodendron  Fenicillium  Phialophora  Phoma  Sclerophoma  Vertic i l lium  25  16  13  68  5  4  174  1  0  3  6  61  2  0  76  3  0  1  1  6  57  2  0  70  10  2  9  9  11  37  4  2  84  The core p o s i t i o n a r e : 1. the outer zone o f the t r e a t e d wood; 2. the untreated wood immediately adjacent to the outer t r e a t e d s h e l l ; 3. the heartwood r e g i o n (outer heartwood); 4. the inner heartwood i n c l u d i n g p i t h .  133  These data c l e a r l y suggest that most f u n g i were present i n the outer p o r t i o n o f p o l e s .  Since  t h i s was t r e a t e d wood,  the presence o f these f u n g i c o u l d be a t t r i b u t e d t o a h i g h t o l e r a n c e t o one o r a l l o f the chemical components i n the ACA p r e s e r v a t i v e .  I f the t o l e r a n t f u n g i were a b l e t o a t t a c k  c e l l u l o s e o r l i g n i n , then some decay o f the wood c o u l d In p a r t i c u l a r , members o f the genus Phialophora be c o p p e r - t o l e r a n t 1979;  occur.  a r e known t o  ( F r a n c i s and L e i g h t l e y , 1983; L e i g h t l e y ,  L e i g h t l e y and Armstrong, 1980; N i l s s o n and Henningssqn,  1978).  The presence o f f u n g i i n the t r e a t e d wood may a l s o  have been a t t r i b u t e d t o lower chemical r e t e n t i o n than that s p e c i f i e d i n the CSA standard, p o s s i b l y w i t h poor  preserva-  t i v e m a c r o - d i s t r i b u t i o n between wood elements and microdistribution within c e l l walls. c e r t a i n microfungi  Following  frequently isolated  c o l o n i z a t i o n by  from the t r e a t e d wood,  a subsequent stage might then be s u c c e s s i o n by t r u e wooddestroying control  f u n g i such as those i s o l a t e d from t h a untreated  poles.  Fungi occurred  l e s s f r e q u e n t l y i n the zone beyond the  t r e a t e d wood t o the p i t h .  Since  t h i s was untreated  the presence o f f u n g i might be e x p l a i n e d through deep checks p e n e t r a t i o n by pretreatment i n v a s i o n s treatment c y c l e .  wood,  e i t h e r by e n t r y  the o u t e r t r e a t e d s h e l l , o r  that s u r v i v e d  the p r e s e r v a t i v e  Although i t i s known t h a t the i n c r e a s e d  134  decay i n c i d e n c e i s g e n e r a l l y a s s o c i a t e d w i t h check depth i n s e r v i c e , the time o f f u n g a l i n c e p t i o n i n most p o l e s i s unclear.  As shown i n Table 17, the numerical  distribution  o f c e r t a i n f u n g i i n the p o l e s would suggest a t t a c k from the o u t s i d e inwards.  T h i s c o u l d have o c c u r r e d i n the graveyard  test after i n s t a l l a t i o n . that these ACA-treated may  However, i t can a l s o be s p e c u l a t e d  spruce p o l e i n v a s i o n s by those  fungi  have o c c u r r e d i n the t r e e s , as w e l l as i n the p o l e s p r i o r  t o treatment, o r s h o r t l y a f t e r treatment Wood-inhabiting  f u n g i may  and d u r i n g s t o r a g e .  be p r e s e n t i n s t a n d i n g t r e e s and  though some e f f o r t s are made to d i s a l l o w t h e i r presence i n u t i l i t y p o l e s , they can p o t e n t i a l l y be i n c l u d e d i n such a product.  S i n c e the ACA  treatment o f the spruce p o l e s , u s i n g  the Lowry e m p t y - c e l l process v o l v e h i g h temperatures,  ( i . e . 29 to 51°C), d i d not i n -  the presence o f a c e r t a i n f u n g i  as Phoma sp. can be t r a c e d t o the use o f treatment w i t h moderate temperature  regimes.  such  cycles  This species could  remain  a l i v e but dormant through a treatment p r o c e s s , y e t when the wood met  f a v o u r a b l e c o n d i t i o n s ( i . e . re-wetted), dormancy  c o u l d be broken suggested presence  and growth r e - i n i t i a t e d .  Thus i t can be  t h a t i n f e c t i o n w i t h Phoma sp. which show a constant i n almost every p o s i t i o n o f the core had o c c u r r e d i n  the l i v i n g  trees.  I t i s o f i n t e r e s t to note t h a t E x o p h i a l a sp., Oidioderadron  spp.  and  P e n i c i l l i u m spp. were a s s o c i a t e d most  w i t h the t r e a t e d zone (Table  17).  frequently  Supporting evidence f o r  t h i s a s s o c i a t i o n w i t h t r e a t e d wood i s a l s o p r o v i d e d  from  f u n g a l i n f e c t i o n i n the p i t h zone o f k e r f e d p o l e s .  From  the data shown i n Table 18, s p e c i e s was  the presence o f these  almost e x c l u s i v e l y i n the t r e a t e d p i t h area  which r e c e i v e d a c e r t a i n chemical r e t e n t i o n due This observation  can be  i n every i n s t a n c e k e r f i n g had  N i l s s o n and i s one  that  Phoma), the p i t h p o s i t i o n through  the maximum number o f i s o l a t e s among the  three  positions.  Very r e c e n t l y s e v e r a l r e s e a r c h e r s Holt,  to k e r f i n g .  a s c r i b e d p a r t l y to the f a c t  (except  i n t e r n a l , untreated  1984;  three  1983;  N i l s s o n , 1982;  Holt,  1984)  (Drysdale  N i l s s o n and  and  Daniel,  Hedley, 1983;  have suggested t h a t b a c t e r i a l degrade  o f the major types o f decay observed i n untreated  p r e s e r v a t i v e - t r e a t e d wood. degrade was products  They have observed that b a c t e r i a l  usually restricted  (e.g. p i l e s and  severe s o f t r o t .  The  to the s u r f a c e zones o f wood  posts) and  variability  a t t a c k has been s t u d i e d by N i l s s o n observations,  i t can be  and  often associated  i n type and (1984).  with  s e v e r i t y of  Based on h i s  suggested that i n i t i a l b a c t e r i a l  a t t a c k at the s u r f a c e zones o f p o l e s may  have c o n t r i b u t e d  subsequent c o l o n i z a t i o n by c e r t a i n m i c r o f u n g i .  to  Although  b a c t e r i a l degrade has been confirmed i n some wood  products,  TABLE 18.  Frequency o f i s o l a t i o n o f the major f u n g i i n the p i t h zone from both k e r f e d and non-kerfed p o l e s .  Frequency o f i s o l a t i o n s  i n the p i t h zone from a p o l e  Pole c o n d i t i o n Acremonium  Exophiala  2  Oidiodendron  Kerfed  4  5  Non-kerfed  3  0  1  Total  7  2  6  Penicillium  5  Phialophora  Sclerophoma  Phoma  Verticillium  1  9  3  1  1  5  8  1  0  6  6  17  4  1  whether o r not i t o c c u r s i n ACA-treated p o l e s i s u n c e r t a i n . T h i s would be an i n t e r e s t i n g area f o r f u r t h e r study, p a r t i c u l a r l y when inadequate treatment o f d i f f i c u l t - t o - t r e a t ,  non-  durable woods, such as spruce, i s encountered. Although no Basidiomycetes were o b t a i n e d from any ACAt r e a t e d spruce p o l e s , i t should be noted t h a t d e t e c t i o n as conducted  cultural  i n t h i s study i s a c o n s e r v a t i v e e s -  t i m a t o r o f decay due t o the l i m i t e d p o i n t sampling i n h e r e n t i n the increment b o r i n g procedure.  A l s o because  some decay  f u n g i c o u l d be r a p i d l y overrun by b a c t e r i a o r m i c r o f u n g i even w i t h a s e l e c t i v e c u l t u r e medium, they may have f a i l e d to be r e c o g n i z e d i n the i n i t i a l phases o f i s o l a t i o n cores.  from  However, the a s s o c i a t e d c o n d i t i o n o f spruce p o l e  m a t e r i a l w i t h numerous m i c r o f u n g i and some s o f t - r o t  fungi  (e.g. P h i a l o p h o r a spp., A l t e r n a r i a sp., Fusidium sp., and Oidiodendron sp.; see Table 15) c o u l d be judged  generally  to be i n an e a r l y stage o f development i n a l l o f the t e s t p o l e s , based on the frequency o f i s o l a t i o n o f n o n - B a s i d i o myceteous f u n g i o b t a i n e d from the c o r e s o f each p o l e compared w i t h those decay f u n g i i s o l a t e d  from the c o n t r o l p o l e s .  T h i s judgement was a l s o based on the sound v i s u a l  appearance  o f most c o r e s sampled and the r e s u l t s obtained from the Shigometer measurements (see S e c t i o n 4.4). From the r e s u l t s ,  i t can a l s o be suggested t h a t the  138  s o f t r o t and m i c r o f u n g i i s o l a t e d are more t o l e r a n t t o  ACA  p r e s e r v a t i v e than the wood-destroying Basidiomycetes.  Some  Phialophora atives.  s p e c i e s are known t o be most t o l e r a n t t o p r e s e r v -  I t i s recommended t h a t f u r t h e r s t u d i e s should  be  conducted to determine the s o f t r o t c a p a b i l i t y o f the major fungi isolated  4.3  from the ACA-treated  spruce p o l e m a t e r i a l s .  NITROGEN ANALYSIS The  n i t r o g e n a n a l y s i s f o r the ACA-treated  white  spruce  p o l e s a f t e r s e v e r a l years o f exposure i n the graveyard i s presented  i n Table 19.  Tables  20 and  21 are summaries  o f the a n a l y s i s o f v a r i a n c e f o r a s p l i t - p l o t d e s i g n Duncan's m u l t i p l e range t e s t , r e s p e c t i v e l y . three o b s e r v a t i o n s are 1.  and  The f o l l o w i n g  valid:  There i s no s i g n i f i c a n t d i f f e r e n c e between the mean r e s i d u a l n i t r o g e n l e v e l s due  t o treatment ( i . e .  k e r f e d v s . non-kerfed) f o r the f i r s t 2.  test  t h r e e zones.  There i s a s i g n i f i c a n t d i f f e r e n c e between the mean r e s i d u a l n i t r o g e n l e v e l s i n the k e r f e d v s . k e r f e d p o l e s when the l a s t zone i s i n c l u d e d n i f i c a n t at the 99.5% significant  level).  (sig-  There i s a l s o a  i n t e r a c t i o n between treatments  zones ( s i g n i f i c a n t at the 97.5%  non-  level).  and  That i s ,  the mean n i t r o g e n l e v e l f o r the k e r f e d p o l e s i s  TABLE 19.  A n a l y s i s o f n i t r o g e n percentage  i n ACA-treated  Non-kerfed  Kerfed Zone  Pole number  a  white spruce p o l e s .  zone a  3  1  2  3  4  N-3-49 N-4- 2 N-4-10 N-4-23 N-4-29 N-4-41 N-5-11 N-5-16 N-5-23 N-5-29 N-5-50 N-5-51  0. 163 0. 158 0. 185 0. 232 0. 197 0. 275 0. 137 0. 248 0. 224 0. 268 0. 145 0. 272  0.061 0.073 0.098 0.102 0.095 0.129 0.088 0.089 0.086 0.131 0.081 0.161  0.044 0.052 0.089 0.099 0.060 0.070 0.046 0.046 0.054 0.103 0.060 0.119  0. 032 0.094 0.067 0. 104 0. 107 0.097 0.063 0.079 0. 068 0. 100 0. 109 0. 125  K-3-24 K-3-25 K-3-29 K-4- 1 K-4- 5 K-4- 8 K-4-20 K-4-25 K-5-21 K-5-26 K-5-31 K-5-39  Mean S t d . Dev.  0.209 0.051  0.100 0.028  0.070 0.026  0.087 0.026  Mean 0.225 S t d . Dev. 0.038  1) 3)  Note:  t r e a t e d zone heartwood  2) 4)  Pole number  untreated wood immediately pith  0. 210 0. 304 0. 193 0. 277 0. 213 0. 180 0. 205 0. 246 0. 199 0. 191 0. 250 0. 232  0.097 0.147 0.079 0.121 0.094 0.102 0.110 0.139 0.087 0.081 0.181 0.105  0.050 0.092 0.061 0.078 0.077 0.058 0.061 0.080 0.072 0.059 0.102 0.060  0. 093 0. 111 0.078 0. 141 0. 061 0. 159* 0. 178* 0. 215* 0. 171* 0. 136* 0. 149 0. 123  0.112 0.030  0.071 0.016  0.135 0.044  adjacent t o the o u t e r t r e a t e d s h e l l  The values i n the p i t h zone o f k e r f e d p o l e s , marked w i t h *, were measured from sawdust which showed a brown c o l o u r .  140  TABLE 20.  Analysis of variance of residual nitrogen i n the ACA-treated white spruce p o l e s , using s p l i t - p l o t design.  Source  DF  SS  1. 2. 3. 4. 5.  1 22 3 3 66 95  8. 87x 5.98 x 2.87 x 7. 19x 4. 24x 4. 06x  Treatment(T) Pole Zone(Z) Tx Z Error Total  Notes:  *  ** ***  Tested against  MS  10~ IO 10' 10" 10" 10"  3  - 2 1 3 2  8.87x 2. 72x 9. 58x 2.40 x 6. 42x  10-3 10-3 -2 10 -3 10 -4 10  *** ***  3.27 4.23 149.10 3.73 **  2 5 5 5  1  Not s i g n i f i c a n t a t 5% l e v e l , but a t 10% l e v e l S i g n i f i c a n t a t 2.5% l e v e l S i g n i f i c a n t a t 0.1% l e v e l  TABLE 21.  Range t e s t s f o r n i t r o g e n i n f o u r d i f f e r e n t zones.  Zone  Frequency  N i t r o g e n mean  1 2 3 4  24 24 24 24  0.217 0.106 0.070 0.111  Standard  Deviation  0.045 0.029 0.021 0.043  Duncan's m u l t i p l e range t e s t , ranges f o r ©t = 0.05 2.8259 2.9714 3.0668 There a r e 3 homogeneous subsets (subsets o f elements, no p a i r o f which d i f f e r by more than the s h o r t e s t s i g n i f i c a n t range f o r a subset o f that s i z e ) which a r e l i s t e d as follows: 1 4 2 3  141  s i g n i f i c a n t l y h i g h e r than t h a t f o r the non-kerfed p o l e s i n the p i t h  (zone 4) and  between treatments and l a s t zone. 3.  the r e l a t i o n s h i p  zones i s d i f f e r e n t f o r the  T h i s i s apparent from F i g u r e  12.  There i s a s i g n i f i c a n t d i f f e r e n c e between the mean n i t r o g e n l e v e l s across the zones ( s i g n i f i c a n t the 99.9%  level).  The  d i f f e r e n c e i s mostly  by the d i f f e r e n c e between the f i r s t  at  explained  zone and  the  o t h e r three zones. In a d d i t i o n to these o b s e r v a t i o n s , j u s t beyond the outer t r e a t e d s h e l l h i g h e r at the 95%  the n i t r o g e n  (zone 2) i s s i g n i f i c a n t l y  l e v e l than e i t h e r t h a t i n the  heartwood, o r the background n i t r o g e n l e v e l 1979)  untreated  (0.056%; Ruddick,  e s t a b l i s h e d from the a n a l y s i s o f the untreated  borings  removed p r i o r to treatment.  content  sapwood  For the heartwood  (zone  3), the n i t r o g e n l e v e l i s comparable w i t h the background n i t r o g e n l e v e l o f 0.056%, and gen  a l s o w i t h the percentage n i t r o -  r e p o r t e d by Young and Guinn (1966) f o r s e v e r a l c o n i f e r o u s  woods, ranging  from 0.059% to 0.078%.  There are two n i t r o g e n contents (Table 12) samples.  g e n e r a l trends noted when comparing (Table 19) w i t h the chemical  the  retentions  i n the same zone o f a n a l y s i s from the same t e s t F i r s t , l e a s t squares r e g r e s s i o n a n a l y s i s (Table  22)  i n d i c a t e s t h a t the amount o f n i t r o g e n i s d i r e c t l y p r o p o r t i o n a l  142  0.240  < >  0.220  \  \ \  » \  0.200  0.180  HI  0.160  i-  z o o z  111 CD O  0.140  rr  0.120  < 0.100  \\  w w w  \ \  •  •• NO N - K E R F E D  •-  -• K ERFED  w  \\  :\ •\  V  \\  t  t% \ • •• \ • •• \ g  .  \  V  \  \ \\  1 1 1  1 1 1 1 i w 1 1  0.080  0.060  0.040 0.000  2 ZONE  Figure 12. Mean residual nitrogen content versus zone.  v  TABLE 22.  Source  Least squares r e g r e s s i o n a n a l y s i s f o r the n i t r o g e n content and chemical r e t e n t i o n i n the f i r s t a n a l y t i c a l zone.  DF  Regression  1  SS  MS  2.6443"  Error  22  1.9665  Total  23  4.6107"  Multiple  Variable  R = 0.75730  Partial  Constant Retention  Note:  R  2  2  -2  2.6443~  2  8.9385~  4  Signif.  29.584* 0.0000  2  = 0.57350  Coefficient  0.11291 0.75730  F  0.12902"  SE = 0.02990  Std. error  0.20059 1  -1  0.23720"  s i g n i f i c a n t a t 0.1% l e v e l .  2  t  Signif.  5.6287*  0.0000  5.4390*  0.0000  t o t h a t o f the copper and a r s e n i c contained  i n the wood.  T h i s trend c l e a r l y shows t h a t the more chemical the h i g h e r  retention,  the n i t r o g e n percentage ( F i g . 13). Second, as  d e s c r i b e d by Ruddick (1979), i t i s g e n e r a l l y noted t h a t when i n d i v i d u a l cores are examined, both the n i t r o g e n percentage and  the copper and a r s e n i c contents  decrease as the a n a l y t -  i c a l zone moves from the s u r f a c e t o the heartwood where the chemical  r e t e n t i o n i s assumed t o be z e r o .  by the a n a l y t i c a l r e s u l t s f o r a l l cores  The t r e n d i s shown  (Table 19), and i s  i l l u s t r a t e d g r a p h i c a l l y f o r the k e r f e d and non-kerfed using t h e i r mean values  o f the n i t r o g e n percentage  poles  (see F i g .  12) . I t had been g e n e r a l l y assumed t h a t , as mentioned  previ-  o u s l y , the ammonia i s l o s t from the wood during the f i x a t i o n o f ammonia-based wood p r e s e r v a t i v e s , and exposure o f the ACAt r e a t e d wood t o the a c t i o n o f rainwater  markedly reduces the  n i t r o g e n enhancement caused by treatment w i t h the ammonia solution.  The r e s u l t s from t h i s study.confirm  those o f  Ruddick (1979), namely, t h a t a l l the ammonia present  i n ACA  p r e s e r v a t i v e has not been l o s t from the wood during the f i x a t i o n process.  Some may have reacted w i t h the wood t o  i n c r e a s e i t s n i t r o g e n content  i n both the t r e a t e d zone and  those zones beyond the l i m i t o f p e n e t r a t i o n . the r e s u l t s obtained  Compared  by Ruddick (1979), i t can be a l s o  with  145  0.300T  1  1  1  1  1  r —  2.0  4.0  6.0  8.0  10.0  12.0  0.100  °  14.0  CHEMICAL RETENTION (kg/m ) 3  Figure 13. Regression line of nitrogen content over chemical retention in the first analytical zone.  146  concluded from the p r e s e n t study that the enhanced n i t r o g e n l e v e l has not been reduced d u r i n g exposure over prolonged p e r i o d o f s e v e r a l years i n t e s t . R e c e n t l y , King and h i s co-workers  (1980) have r e p o r t e d  t h a t n i t r o g e n compounds migrate t o wood from surrounding soil,  thus i n c r e a s i n g i t s t o t a l n i t r o g e n content d u r i n g  burial.  soil  I f nitrogen transfer i s a function of microbial  t r a n s l o c a t i o n as p o s t u l a t e d by these authors, then the cons i d e r a b l e n i t r o g e n i n c r e a s e s observed i n the t r e a t e d wood would have been a t t r i b u t e d , t o a c e r t a i n e x t e n t , to m i c r o b i a l biomass which suggests a s i g n i f i c a n t c i a l c o l o n i z a t i o n by microorganisms.  involvement o f  sacrifi-  However, i t i s b e l i e v e d  t h a t the n i t r o g e n enhancement i n the t r e a t e d zone has mainly from the ACA  treatment a l o n e .  There i s no q u e s t i o n about of  resulted  the h i g h l y i n c r e a s e d amount  n i t r o g e n observed i n the t r e a t e d zone.  On the o t h e r hand,  two p o s s i b l e suggestions c o u l d be made i n o r d e r t o e x p l a i n s i g n i f i c a n t l y h i g h n i t r o g e n percentage found i n the wood immeidately adjacent t o the o u t e r t r e a t e d s h e l l compared t o that i n the heartwood.  One  i s due t o abnormal  background  l e v e l s o f n i t r o g e n and the o t h e r i s through n i t r o g e n f i x a t i o n by f u n g i and  bacteria.  The p o s s i b i l i t y o f these o b s e r v a t i o n s r e s u l t i n g abnormal background  from  n i t r o g e n l e v e l s can be e l i m i n a t e d on the  b a s i s o f the n i t r o g e n l e v e l sapwood b o r i n g s and  (0.056%) found f o r the  untreated  the range, from 0.059% t o 0.078%, o f n i -  trogen percentage r e p o r t e d by Young and Guinn (1966) f o r s e v e r a l c o n i f e r o u s trunk woods. I t c o u l d be summarized t h a t the n i t r o g e n l e v e l s  adjacent  to the t r e a t e d s h e l l have been enhanced through n i t r o g e n f i x a t i o n by wood-inhabiting sonable  suggestion  bacteria.  T h i s might be a r e a -  s i n c e the r e s u l t s obtained  b i o l o g i c a l assay show a c e r t a i n evidence  of fungal  b a c t e r i a l a t t a c k i n the same a n a l y t i c a l zone. although  from the m i c r o and  However,  the n i t r o g e n enhancement could be p a r t l y a t t r i b u t e d  to the presence o f microorganisms i n h a b i t i n g the wood, i t c o u l d be expected to have o n l y a very s m a l l e f f e c t . survey  of c u l t i v a t e d  f u n g i (Heck, 1929), the percentage o f  t h e i r dry weight a t t r i b u t a b l e to n i t r o g e n was between 2.27%  Thus i t i s concluded  evidence  in Tricho-  t h a t the n i t r o g e n  enhancement r e s u l t s mainly from the ACA Supporting  found t o v a r y  i n Coprinus r a d i c a n s to about 5.13%  derma liqnorum.  treatment  alone.  for t h i s conclusion i s a l s o provided  the a n a l y t i c a l r e s u l t s o b t a i n e d  than t h a t f o r the non-kerfed. v a l u e o f p e n e t r a t i o n , 1.14  by  i n the p i t h zone, wherein  the n i t r o g e n l e v e l f o r the k e r f e d i s s i g n i f i c a n t l y  obtained  In a  higher  Assuming t h a t an average  i n . (2.90  cm;  Table  11),  was  through k e r f i n g i n the p i t h zone, i t would then be  148  obvious that a h i g h e r n i t r o g e n content, found i n the t r e a t e d zone, might r e s u l t .  s i m i l a r to that T h i s i s confirmed  by the l i n e a r r e l a t i o n s h i p between n i t r o g e n content and chemical The  r e t e n t i o n i n the f i r s t  a n a l y t i c a l zone (see F i g . 13).  f o l l o w i n g two s c e n a r i o s have been p o s t u l a t e d by  Ruddick (1979) i n o r d e r t o e x p l a i n how and when the enhancement o f n i t r o g e n l e v e l occurs beyond the t r e a t e d zone: 1.  During  the p r e s s u r e  treatment o f wood w i t h ACA.  2.  During  the f i x a t i o n  process.  When c e r t a i n wood s p e c i e s such as white spruce  and Douglas-  f i r are p r e s s u r e - t r e a t e d w i t h ACA, they darken i n c o l o u r during treatment.  The cause o f t h i s darkening  has not been  v e r i f i e d yet, but i s presumably due t o the use o f ammonium hydroxide  i n the ACA p r e s e r v a t i v e , s i n c e treatment  o t h e r waterborne p r e s e r v a t i v e s  with  (e.g. CCA) which a l s o c o n t a i n  copper and a r s e n i c does not g i v e t h i s c o l o r r e a c t i o n . ACA, as d e s c r i b e d e a r l i e r , w i t h copper arsenate  In  the ammonia i n the s o l v e n t r e a c t s  t o form a s o l u b l e complex.  Although  t h i s ammonia i s s t a b l e i n ammonium hydroxide  solution,  is readily liberated  when the s o l v e n t  i s removed.  from ammonium hydroxide  Thus, i t i s p o s s i b l e t h a t the ammonia  it  penetrates  the wood c e l l s p r i o r t o the p r e s e r v a t i v e s o l u t i o n d u r i n g the p r e s s u r e Rak  treatment o f wood w i t h ACA.  (1977) indeed  explained  Based on t h i s  the enhanced p e r m e a b i l i t y o f  fact,  149  spruce wood t o ACA compared w i t h CCA. to suggest t h a t , during  I t i s a l s o reasonable  the f i x a t i o n p r o c e s s , some o f the  ammonia d i f f u s e s f u r t h e r i n t o the wood S i n c e a l l the t e s t p o l e s  cells.  have been a t the Westham  I s l a n d t e s t f i e l d s i t e f o r s e v e r a l years, that the l e a c h i n g nitrogen this  level.  i s not so.  i t i s possible  a c t i o n o f rainwater may have reduced the From the r e s u l t s shown i n Table 12, however, Supporting evidence i s a l s o provided  the a n a l y t i c a l r e s u l t s reported  by  by Ruddick (1979) f o r ACA-  t r e a t e d spruce p o l e s e c t i o n s , showing t h a t the n i t r o g e n  level  remained enhanced a f t e r two years o f exposure outdoors. Based on these o b s e r v a t i o n s ,  therefore,  i t i s also  possible  to suggest that some o f the ammonia has moved f u r t h e r i n t o wood w i t h m o i s t u r e content above the f i b e r s a t u r a t i o n down a c o n c e n t r a t i o n  gradient  point,  o f ammonia i n the form o f  ammonium hydroxide o r o t h e r ammonium s o l u t i o n s . In summary, although the exact cause o f t h i s enhancement has not been v e r i f i e d yet, the two seem t o best  describe  nitrogen  scenarios  the circumstances p e r m i t t i n g  enhance-  ment o f n i t r o g e n observed i n the ACA-treated wood. I t i s g e n e r a l l y known t h a t i n c r e a s i n g the n i t r o g e n content o f wood f r e q u e n t l y wood-destroying f u n g i . observations  increases  Therefore,  the r a t e o f decay by  the importance o f these  from t h i s study l i e s i n the f a c t that the  a d d i t i o n o f nitrogeneous m a t e r i a l s t o wood may i n c r e a s e i t s s u s c e p t i b i l i t y t o decay.  The h i g h n i t r o g e n l e v e l s at the  s u r f a c e o f the p o l e s a r e u n l i k e l y t o be important,  since  the p r e s e r v a t i v e r e t e n t i o n s a r e a l s o h i g h and would fungal attack.  However, at o t h e r  deter  l o c a t i o n s f a r t h e r from  the s u r f a c e where h i g h e r n i t r o g e n l e v e l s have been observed, the p r e s e r v a t i v e r e t e n t i o n i s very much lower than t h a t r e q u i r e d t o prevent decay.  Thus any damage extending  t h i s zone, e i t h e r by deep checking ing  during  to  subsequent weather-  o r by mechanical damage, could expose wood w i t h a high  n i t r o g e n content  and low o r very  little  preservative retention  Although there i s c o n f l i c t i n g evidence as t o whether decay can be i n c r e a s e d a p p r e c i a b l y by a r t i f i c i a l l y to wood, such s i t u a t i o n s could  adding  nitrogen  lead t o decay o f the exposed  wood, p a r t i c u l a r l y when non-durable spruce wood i s encountered The  r e s u l t s from t h i s study show t h a t the wood t r e a t e d  w i t h ACA has been enhanced i n i t s n i t r o g e n l e v e l . it  i s s t i l l questionable  n i t r o g e n i s present  i n which chemical  However,  form t h i s enhanced  i n the wood, and a l s o whether f u n g i a r e  capable o f m e t a b o l i z i n g  t h i s source o f n i t r o g e n t o promote  t h e i r growth.  little  concerning  To date,  these q u e s t i o n s .  o r no work has been performed  Based on the metabolism o f  n i t r o g e n d e s c r i b e d p r e v i o u s l y , i t may be suggested t h a t  this  n i t r o g e n i s a v a i l a b l e i n a t l e a s t one o f t h r e e p o s s i b l e forms,  151  i . e . n i t r a t e , n i t r i t e o r ammonium  ion.  As d i s c u s s e d e a r l i e r ,  some o f the ammonia which has not been l o s t from the wood e i t h e r d u r i n g the f i x a t i o n process o r a f t e r s e v e r a l years o f exposure  still  remains  i n the form o f ammonium  hydroxide.  The n i t r a t e i o n (NC>3~) may a l s o have been i n c o r p o r a t e d i n t o the wood c e l l s as ammonium n i t r a t e , potassium n i t r a t e o r calcium n i t r a t e  (Cochrane,  1958); i f so, i t then must be  reduced t o the o x i d a t i o n l e v e l o f ammonia b e f o r e the n i t r o g e n can be a s s i m i l a t e d i n t o o r g a n i c compounds.  I f either of  these suggestions a r e c o r r e c t , the enrichment  o f the n i t r o g e n  l e v e l i s l i k e l y t o promote the growth o f some wood-inhabiting microorganisms.  Even w i t h frequent i s o l a t i o n s o f b a c t e r i a  and m i c r o f u n g i i n the t r e a t e d zone, on the o t h e r hand, the a l k a l i e f f e c t due t o ammonium hydroxide i n a s s o c i a t i o n w i t h the h i g h chemical r e t e n t i o n s would almost c e r t a i n l y wood-decaying f u n g i i n t h i s zone. the a l k a l i  exclude  I t has been assumed that  treatment may d e s t r o y thiamine  (Dwivedi and A r n o l d ,  1973), which i s e s s e n t i a l f o r the growth o f many wood-decaying f u n g i , and that the treatment may a l s o i n c r e a s e decay r e s i s t ance i n wood by reducing the a v a i l a b i l i t y o f o t h e r micron u t r i e n t s e s s e n t i a l f o r f u n g a l growth (Baechler, 1959), o r by i n c r e a s i n g the pH o r ammoniacal n i t r o g e n content (Highley, 1973) . F u r t h e r r e s e a r c h i s necessary t o show whether the  enrichment  o f the n i t r o g e n l e v e l i n the ACA-treated  spruce  wood i s favoured p o s i t i v e l y o r n e g a t i v e l y by numerous f u n g i i n h a b i t i n g the wood.  I f found t o be p o s i t i v e , f u r t h e r work  i s a l s o necessary t o c o n f i r m that t h i s o b s e r v a t i o n i s i n d i c a t i v e fo ACA-treated wood i n g e n e r a l , and t o determine i n which chemical form f u n g i are capable o f m e t a b o l i z i n g n i t r o g e n t o promote t h e i r growth. 4.4 4.4.1  EVALUATION OF THE SHIGOMETER MOISTURE MEASUREMENTS As p r e v i o u s l y d e s c r i b e d , moisture measurements were  taken i n each o f the t o t a l 24 spruce p o l e s s e l e c t e d , u s i n g the cores sampled f o r the chemical a n a l y s i s . ments served t o determine p r i o r to Shigometer  i f a d d i t i o n a l moisture was r e q u i r e d  measurements and t o i n d i c a t e the extent  to which the Shigometer than t o decay  These measure-  (Perrin,  i s responding to moisture r a t h e r 1978).  M o i s t u r e measurements determined are shown i n Table 23.  for a l l test poles  The moisture contents o f i n d i v i d u a l  core s e c t i o n s removed from the p o l e s ranged  from 24.5% t o  61.54%, w i t h an o v e r a l l average o f 31,12%.  However, moisture  l e v e l s i n each p o l e were not normally s u b s t a n t i a l l y  different  between the o u t e r t r e a t e d s u r f a c e and p i t h zone, w i t h some exceptions found i n the two k e r f e d p o l e s (K-4-5 and K-5-26) .  TABLE 23.  Moisture Pole number  1  K-3-24 K-3-25 K-3-29 N-3-49 K-4- 1 K-4- 2 K-4- 5 K-4- 8 N-4-10 K-4-20 N-4-23 K-4-25 N-4-29 N-4-41 N-5-11 N-5-16 K-5-21 N-5-23 K-5-26 N-5-29 K-5-31 K-5-39 N-5-50 N-5-51  28.48 29.79 28.28 33.13 32.14 33.33 30.65 31.65 31.78 25.60 33.65 25.93 25.40 29.41 35.65 30.77 28.49 33.87 34.15 32.20 26.95 24.59 33.90 25.71  Mean 30.31 Std.Dew 3.41  a  2  M o i s t u r e contents o f the ACAt r e a t e d spruce t e s t p o l e s .  content  3  3  4  Average  30.74 30.28 30.94 29.71 33.68 30.37 44.54 26.72 34.31 28.97 27.03 29.15 27.59 31.68 30.51 30.11 25.27 31.25 30.10 29.41 28.23 29.00 33.33 29.90  32.61 28.15 32.00 32.41 32.38 30.91 61.54 28 57 30.77 28.46 27.93 25.10 30.39 28.79 29.25 27.18 32.71 30.84 32.65 30.15 27.66 30.11 31.25 31.63  31.21 30.33 33.83 28.83 33.65 29.25 58.54 28.83 30.16 31.71 27.96 28.07 32.14 29.30 29.63 28.83 29.00 29.41 51.58 29.70 29.31 31.78 28.36 31.40  30.81 29.64 31.26 31.02 32.96 30.97 48.82 28.94 31.81 28.69 29.64 27.06 28.88 29.80 31.26 29.22 28.87 31.34 37.12 30.37 28.04 28.87 31.71 29.66  30.54 3.66  31.40 6.73  32.20 7.30  31.12 4.26  Weather condition when sampled  A B A B A A A B B B C A A B B A A E D E A E A A  Each sampled c o r e was c u t i n t o f o u r equal s e c t i o n s and numbered from the s u r f a c e t o the p i t h .  k A) sunny B) r a i n e d the day b e f o r e C) r a i n e d the morning D) "C" and a g a i n d u r i n g sampling E) cloudy  till  154  The Shigometer f u n c t i o n s o n l y above the f i b e r s a t u r a t i o n p o i n t o f wood t i s s u e , which averages tent  (Shigo et_ a l . ,  1977) .  about 27% moisture  con-  I t has u s u a l l y been found t h a t ,  at g r o u n d l i n e , the moisture content o f p o l e s i n the ground i s above the f i b e r s a t u r a t i o n p o i n t , and t h a t when m i c r o organisms a r e a c t i v e i n wood, the moisture content i s above the f i b e r s a t u r a t i o n p o i n t w i t h a few r a r e e x c e p t i o n s . A l though there i s some o p i n i o n that moisture contents between 25% and 35% a r e below the c r i t i c a l (Brudermann, 1977), based  limit  on instrument  f o r the Shigometer specifications  (Osmose Wood P r e s e r v i n g Co., 1980) and the r e s u l t s from the measurements o f moisture content drilled  (see Table 23), the holes  f o r the Shigometer measurements were not a d d i t i o n a l l y  s a t u r a t e d w i t h d e i o n i z e d water.  Support  for this  decision  was a l s o gained from the o b s e r v a t i o n t h a t an abrupt drop i n e l e c t r i c a l r e s i s t a n c e readings may be simply due t o h i g h moisture content above f i b e r s a t u r a t i o n .  Very  recently,  M o r r i s and h i s co-workers (1984) have r e p o r t e d t h a t t h e r e i s a l a r g e d i f f e r e n c e between readings o f wood below 38% and above 45% moisture content, suggesting t h a t moisture content alone c o u l d r e s u l t i n a marked lowering o f r e s i s t a n c e . As shown i n Table 23, i t i s i n t e r e s t i n g t o note t h a t f o r p o l e s K-4-5 and K-5-26, r e l a t i v e l y h i g h moisture were observed  p a r t i c u l a r l y i n the i n n e r zones.  contents  Since both  p o l e s were k e r f e d , abnormally h i g h moisture content c o u l d be due t o the e f f e c t o f the k e r f through which ground c o u l d move i n t o the i n n e r p a r t s o f the p o l e s .  As  a l r e a d y , moisture content would be w e l l above the s a t u r a t i o n p o i n t i f microorganisms  water  mentioned fiber  were a c t i v e i n wood.  Thus, these high moisture contents may  mean that t h e r e has  been e x t e n s i v e decay o r d e g r a d a t i o n by o t h e r non-decay microorganisms  i n s i d e the p o l e s .  However, i t should be  noted that moisture d e t e c t i o n alone would not normally serve to d e t e c t decay i n a f i e l d  s i t u a t i o n where d i f f e r e n t p a r t s  o f a p o l e would be s u b j e c t t o d i f f e r e n t environmental ditions.  T h e r e f o r e , a high degree o f s i g n i f i c a n c e  con-  cannot  be attached t o these measurements a t t h i s time, as f a r as decay by a c t i v e microorganisms  i s concerned.  F o r the purposes o f t h i s study, knowledge of the a b s o l u t e wood moisture content i s not e s s e n t i a l . to take measurements w i t h the Shigometer,  In o r d e r  i t i s important  to know t h a t the wood moisture content i s above f i b e r u r a t i o n so t h a t the Shigometer  can s u c c e s s f u l l y  sat-  function.  Thus m o i s t u r e measurements were not taken i n the same h o l e as Shigometer  measurements.  On the o t h e r hand, at the  h i g h e r m o i s t u r e contents observed, i t would be  desirable  t o see whether the m o i s t u r e content causes the  Shigometer  to respond t o moisture r a t h e r than t o decay.  In t h i s  way,  r e l a t i v e changes i n Shigometer readings would be compared w i t h some v a l i d i t y t o r e l a t i v e changes i n m o i s t u r e .  The  e f f e c t o f moisture content on e l e c t r i c a l r e s i s t a n c e w i l l  be  d i s c u s s e d i n d e t a i l i n S e c t i o n 4.4.3.  4.4.2  SHIGOMETER MEASUREMENTS Although  to  the l i t e r a t u r e c o n t a i n s c o n f l i c t i n g views as  the e f f e c t i v e n e s s o f the Shigometer f o r d e t e c t i n g i n t e r n a l  wood c o n d i t i o n , t h i s instrument has been used,  to a c e r t a i n  extent, t o d e t e c t d i s c o l o u r e d and decayed wood i n u t i l i t y poles.  Decayed wood i s d e t e c t e d not on the b a s i s o f a b s o l u t e  r e s i s t a n c e measurements, but on the change o f the r e s i s t a n c e measurements between sound and decayed Shigometer readings are presented d e f l e c t i o n percentage  zones. i n Table 24,  c a l c u l a t e d as the d i f f e r e n c e between  the lowest and the h i g h e s t v a l u e f o r a c o r e . co-workers (1977 of  and  with  1978)  Shigo and h i s  have emphasized t h a t the p a t t e r n  readings at i n t e r v a l s along one h o l e and not  individual  r e a d i n g s , should be taken t o i n d i c a t e the wood c o n d i t i o n . Decay i s i n d i c a t e d w i t h a d e f l e c t i o n o f 75% o r more i n the readings.  The  Co.,  also states this c r i t e r i o n for predicting  1980)  Shigometer manual (Osmose Wood P r e s e r v i n g decay.  Thus the core p o s i t i o n s where the d e f l e c t i o n percentage 75% o r g r e a t e r were i n i t i a l l y  was  regarded t o s u f f e r from decay.  TABLE  24.  Electrical  resistance  readings  (ka)  with  the Shigometer  Depth  i n ACA-treated  i n pole  spruce  (cm)  SequenPole  t i a l  Deflec-  number1*  Pole  radius  number  tionc(%)  0.3  1  2  3  4  5  6  7  8  9  10  K-3-24(l) K-3-25(l) K-3-29(3)  11.9 12.4 12.8  A B  45 28  275 360  360  465  c  220  +  195  + +  + +  + +  + +  + +  + +  + +  + +  50  160  +  320  320  300  310  310  275  250  260  N-3-49(l)  13.2  D  59  215  205  260  220 385  K-4-  1(1)  11.9  E  12  2(1)  F  0 78  430  460  H  440  460  I J  31 46  345  12.4  405  + 365 370  + + + + +  + + + + + + + + + +  + + + + + + + + + +  + + + + + + + + + +  + + +  G  + + + + + + + + + +  + + +  5(1)  + + +  + + +  K-4-  12.1 11.5 12.0  + +  455  N-4-  + +  K-4- 8(3) 19-4-10(1)  120  110  120  + + + + + +  + + + + + +  + + + +  K  36  320 320  28  360  490  12.2  L M  440  N  25 64  375  11.9  +  +  210  180  180  185  200  190  N-5-ll(l)  10.7  36  210 320  200 440  285  K-5-2l(2)  10.2 11.6  0 P  64  N-5-16(3)  + + +  + + +  + + +  + + +  N-5-23(2) K-5-26(l)  10.9 11.4  340  350  500  460  + + + 500  470  220  400  440  480  430  +  500  +  +  +  460 440  K-4-20(3)  11.9  N-4-23(2) K-4-25(2)  11.6 11.8  N-4-29(3) N-4-41(3)  36  + + + + + + + •+ +  + +  36  320  +  64  180  220  S  79  100  150  320 200  T  88  180  240  340  Q R  -  195 180  + +  480  +  11  12  460  395  + +  +  250  + 440  +  +  100 +  440  330 +  270 370  + 460 +  200  185  180  205  420  375  + + +  + +  +  420  180  100  (right  60  260  (left)  poles.  TABLE 24.  (cont.)  Depth i n pole (cm) Pole number**  SequenDeflecPole tial radius number t i o n (%) 0.3 0  N-5-29(1) K-5-31(2) K-5-39(l)  10.9 11.4 11.4  N-5-50(3) N-5-51(3)  11.1 10.7  a  b  U V W X Y Z  27 0 62 60 34 36  1  2  + 365 + + + + + 430 480 200 350 400 330 400 + + 320 +  3  4  5  + + + + + +  + + + + + +  + + + + + +  6  7  8  9  10  11  12  + + + + + + + + + + + + 425 205 190 190 200 230 (right) + 330 220 250 350 360 (below) + + + 480 + + + + + 475  "+" sign indicates resistance reading over 500 ksj. Numbers i n parentheses represent the positions where Shigometer measurements were made. (1) : right of the f i r s t core p o s i t i o n made f o r b i o l o g i c a l i n v e s t i g a t i o n ; (2) and (3)t r i g h t o f the second and t h i r d cores, r e s p e c t i v e l y .  c Maximum e l e c t r i c a l resistance - minimum e l e c t r i c a l  resistance  100: Maximum e l e c t r i c a l resistance To c a l c u l a t e d e f l e c t i o n percentage, readings over 500 k a were taken as 500 ka. x  Note:  For two poles (K-5-26 and K-5-39), readings were taken at two d i f f e r e n t p o s i t i o n s .  P r i o r t o f u r t h e r a n a l y s i s , the f o l l o w i n g t h r e e b a s i c p a t t e r n s o f e l e c t r i c a l r e s i s t a n c e were observed  i n the  total  o f 24 p o l e s where no v o i d s were d e t e c t e d by p h y s i c a l d r i l l ing and  probing:  1.  A l l readings < 500 ksi  2.  A l l readings > 500  3.  Mixed  In two p o l e s  ka  readings  (N-4-2 and K-5-31), a l l r e s i s t a n c e readings  were above 500 k a the e n t i r e l e n g t h o f the h o l e and f o r e beyond the s c a l e o f the meter.  In two p o l e s  and K-5-26) , a l l readings were below 500 k s .  there-  (K-3-29  i n the o t h e r  twenty p o l e s , some readings were below 500 k a and  some above  500 ksa. In numerous s t u d i e s o f a pulsed e l e c t r i c a l c u r r e n t to d e t e c t i n t e r n a l decay i n u t i l i t y poles Shigo ejt a l . , 1977; 1982;  (Brudermann,  S h o r t l e et a l . , 1978;  Wilkes  and  1977; Heather,  Wilson e_t a l . , 1982) , a v i s u a l assessment of the s t a t e  o f decay was  a l s o made on the p o l e c r o s s s e c t i o n at the same  l o c a t i o n s where Shigometer readings had been taken. the Shigometer readings were subsequently r e s u l t s o f the corresponding  r e l a t e d t o the  v i s u a l assessments i n o r d e r t o  be a b l e to e v a l u a t e the accuracy and instrument  Thus  s u i t a b i l i t y o f the  f o r d e t e c t i o n o f decay and s t a i n .  In t h i s  study,  however, such v i s u a l assessments c o u l d not be made s i n c e the  160  p o l e s must remain i n t e s t f o r f u r t h e r s t u d i e s .  Consequently,  the Shigometer readings were compared i n s t e a d t o the r e s u l t s obtained  from f u n g a l i s o l a t i o n s t u d i e s .  From the r e s u l t s o f the m i c r o b i o l o g i c a l study and a l s o observations during d r i l l i n g , t r a t i o n o f the d r i l l ,  i . e . the d i f f i c u l t y o f pene-  none o f the 24 spruce p o l e s seemed  t o have decay.  However, based on the Shigometer  readings  alone, symptoms  o f decay were p r e d i c t e d i n a few p o l e s  having  the f o l l o w i n g readings o f e l e c t r i c a l r e s i s t a n c e (Table 25): 1.  Some > 500 ka, some < 125 k a (G and T i n Table 24);  2.  A l l < 500 ka, lowest  l e s s than 75% o f h i g h e s t ( S ) .  According  t o the Shigometer manual, no symptoms  indicated  i n wood o f most p o l e s having  o f decay are  the f o l l o w i n g readings  o f r e s i s t a n c e (Table 25): 1.  A l l > 500 k a (F and V i n Table 24) ;  2.  Some > 500 ka, none  3.  A l l < 500 ka, but lowest not l e s s than 75% o f  250 ka. (A,B, E,H-M, P,Q,U, Y,Z) ;  highest (C); 4.  Some > 500 ka, some < 250 ka, but none < 125  (D,  N,0,R,W,X). V a r i o u s r e s u l t s from o t h e r s t u d i e s o f a p u l s e d  electric  c u r r e n t t o d e t e c t i n t e r n a l decay i n wood g e n e r a l l y have i n d i cated t h a t the p a t t e r n s o f readings which show abrupt c r e a s e s r e p r e s e n t decay.  de-  The q u e s t i o n i s , however, how much  TABLE 25.  E l e c t r i c a l r e s i s t a n c e readings o f p o l e s c l a s s i f i e d t o i n d e n t i f y those g r e a t e s t d e f l e c t i o n readings ( i n d i c a t i v e o f deca  No. o f p o l e s  Electrical r e s i s t a n c e readings (kft)  All  Low o r deflection moderate  > 500  Some>500, none > 250 All  High deflection  > 500, but lowest not l e s s 75% o f h i g h e s t  14 than  Some > 500, some > 250, but none > 125  5(1)  KD  Some > 500, some > 125 All  >500, lowest l e s s than 75% o f highest  Total  22(1)  T h i s c l a s s i f i c a t i o n was made on the b a s i s o f that o f S h o r t l e e t a l . (1978). Number i n b r a c k e t s i n d i c a t e s those p o l e s (K-5-26 and (K-5-39) where two d r i l l h o l e s were measured.  2(1)  162  o f a drop i n the r e a d i n g i s necessary t o i n d i c a t e decay i n p o l e s t h a t a r e made from a v a r i e t y o f t r e e s p e c i e s and p r e served w i t h a v a r i e t y o f p r e s e r v a t i v e s .  Data from numerous  s t u d i e s g i v e some answers but d e f i n i t e l y not a l l . The  Shigometer manual, as mentioned p r e v i o u s l y , o n l y  s t a t e s t h a t a decrease o f 75% o r more i n d i c a t e s decay. addition to this c r i t e r i o n ,  Shortle et a l . ( 1 9 7 8 )  In  also stated  t h a t where the h i g h e s t reading was over 5 0 0 k a , a reading o f l e s s than 2 5 0 k a would i n d i c a t e the c o n d i t i o n o f i n t e r n a l decay.  I t has been shown i n t h e i r study t h a t wood i n p o l e s  having some readings a b o v e ' 5 0 0 ,  some below 2 5 0 , and none  l e s s than 1 2 5 k a was sometimes decayed.  Although  some o f  the suspect p o l e s d i d not appear t o have decay, they  decided  t h a t i f e r r o r s were to be made i n u s i n g these c r i t e r i a , e r r o r s should be made i n f a v o r o f c a l l i n g r a t h e r than a decayed p o l e sound.  such  a sound p o l e decayed  F o r t h i s reason,  they have  claimed t h a t a l l such p o l e s must be c o n s i d e r e d decay c a n d i dates.  In t h i s p r e s e n t study, however, those spruce  poles  (having some readings > 5 0 0 , some < 2 5 0 , but none < 1 2 5 k a ) not appear t o have decay.  did  T h i s was based on the i n f o r m a t i o n  from c u l t u r e s o b t a i n e d from b o r i n g s taken adjacent t o the Shigometer measurements, and the l a c k o f ease o f p e n e t r a t i o n o f the d r i l l .  Thus those f i v e suspect p o l e s a r e c a t e g o r i z e d  i n t o the group without  Shigometer symptoms o f wood decay  163  (Table 25).  Prom T a b l e 26, which shows t h r e e t e s t measure-  ments o b t a i n e d from suspect spruce p o l e s , a c l o s e o f the zones w i t h low r e s i s t a n c e r e v e a l s t h a t  examination  relatively  more f u n g i were i s o l a t e d from approximately matched but none were Basidiomycetes. pect p o l e s are not decayed  zones,  T h e r e f o r e , w h i l e those s u s -  (or v e r y l i t t l e decayed  due  to  the presence o f s o f t r o t t e r s such as P h i a l o p h o r a spp.), they might have been a l t e r e d o r degraded o t h e r types o f microorganisms  by the presence  of  (e.g. b a c t e r i a and m i c r o f u n g i ) ,  r e s u l t i n g i n r e l a t i v e l y low readings o f e l e c t r i c a l  resistance.  In a very recent study o f the e f f e c t o f moisture content on the e l e c t r i c a l r e s i s t a n c e o f timber, M o r r i s et concluded that the abrupt drop i n Shigometer 38% and 45% moisture content may  al.(1984)  readings between  be due t o the f o r m a t i o n o f  a continuous water f i l m between the two e l e c t r o d e s p e r m i t t i n g e a s i e r i o n movement.  Thus low r e s i s t a n c e r e a d i n g s i n the  suspect p o l e s (Table 26) may  be a t t r i b u t e d j u s t as l i k e l y to  v a r i a t i o n i n moisture content r a t h e r than decay.  The e f f e c t  o f moisture content on e l e c t r i c a l r e s i s t a n c e w i l l be d i s c u s s e d i n the f o l l o w i n g  further  section.  From the r e s u l t s shown i n T a b l e 24,  relatively  low  readings o f e l e c t r i c a l r e s i s t a n c e at the s u r f a c e s o f most p o l e s were observed.  Since these s u r f a c e zones have h i g h  p r e s e r v a t i v e r e t e n t i o n s w i t h s i g n i f i c a n t l y l a r g e amounts o f  '  TABLE  26.  Examples  of  test  measurements  obtained  seven  Depth  Pole Category  from  number  suspect  in pole  spruce  poles.  (cm)  Test 10  0.3  N-3-49  N-4-41  M o i s t u r e 1 (%) Shigometer(k ) No. o f fungi isolated2  33.13 215  Moisture Shigometer  29.41  No.  Some some but  500, 250,  none  125k  N-5-11  K-5-39  fungi  Moisture Shigometer No.  N-5-23  of  of  fungi  + 35.65 210  24.59  + 200  fungi  210  2(1)  2 9 . 71 385 2(1)  31.68 180  3 2 . ' 41  +  +  +  180  185  28.79 200  200  285  30.51 +  31.25 320 340  480 400  29.00 + + 1  +  +  190  195  29.30 200  185  180  +  +  180  29.63 205  420  375 2  200 350  230 360 1  3  350  30.84 500  1  430 350  +  1  29.25  +  2  220  +  +  27. 41 500 470  460  + +  30.11 425  205 330  + 3  + 2(1)  2(1)  + +  12  28.83  + 1  1  4  Moisture  of  +  4(1)  33.87 180 2  No.  260  2(1)  Moisture Shigometer No. o f fungi  Shigometer^  205  11  170 220  31.78 190 250  +  TABLE  26.  (cont.)  Depth  Pole number  Category  in  pole  (cm)  Test 10  0.3  Lowest than  of  K-4-  5  poles  i n i t i a l l y as  decay.  Number zones The  in for  contents bracket  of  determined  in  indicates  that  m i c r o b i o l o g i c a l assay  Shigometer  measurements  +  2(1)  150  200  220  180  240  340  + 2  400  • +  the  zones  produced  by  at  least  one  rotting  soft  at  two  different  440  480  430  460  180  100  +  +  +  440  60  260  1  cutting  core  fungus  work.  obtained  120  110  100  51.68  32.65  100 3  58.34 120  +  6(1)  30.10  34.15  fungi  61.54  44.54 +  +  460  4  fungi  Shigometer No.  Moisture  of  Moisture K-5-26  regarded  430  Shigometer No.  highest, i . e .  30.65  Moisture  less  75%  11  sites.  3  equally was  into  isolated  four in  pieces.  four  different  12  166  nitrogen,,it  i s expected t h a t the presence o f ACA  t i v e s a l t s and/or o t h e r  ionized materials  s u b s t a n t i a l l y a f f e c t r e s i s t a n c e readings  preserva-  (e.g. NH.4 ) c o u l d +  i n the same manner  as i n c r e a s i n g ash content o f decaying wood appears t o a f f e c t the r e a d i n g s . t h i s regard,  Although very  l i t t l e work has been done i n  i t i s b e l i e v e d that the e f f e c t i v e n e s s o f the  Shigometer f o r t r e a t e d wood i n s e r v i c e i s compromised by the p o s s i b l e e f f e c t o f i o n i z e d m a t e r i a l s i s supported from the o b s e r v a t i o n  i n the wood.  by James (1965) t h a t water-  s o l u b l e , s a l t - t y p e wood p r e s e r v a t i v e s  had a s u b s t a n t i a l e f f e c t  on the accuracyyof e l e c t r i c moisture meters. and  Shigo (19 74)  have reported  This  Indeed, Shigo  t h a t the Shigometer seems t o  be more e f f e c t i v e i n d e t e c t i n g decay i n c r e o s o t e - t r e a t e d poles  than i n wood t r e a t e d w i t h f i r e r e t a r d a n t s  borne p r e s e r v a t i v e The  o r water-  salts.  m i c r o b i o l o g i c a l study showed that a r e l a t i v e l y  l a r g e number o f i s o l a t e s o f f u n g i were present  i n the ACA-  t r e a t e d zone t o depths o f s e v e r a l m i l l i m e t e r s r a d i a l l y the s u r f a c e o f p o l e s .  According  the d e g r a d a t i o n o f wood s u r f a c e s  t o Banks and Evans  from  (1984),  i s due p a r t l y t o water-  created physico-chemical processes.  Coupled w i t h the  assumption d e s c r i b e d by Carey (1982), that i n c r e a s e d  mois-  t u r e c o n t e n t s a l s o encourage c o l o n i z a t i o n by microorganisms, i t can be suggested t h a t b i o l o g i c a l and p h y s i c a l d e g r a d a t i o n  a l s o c o n t r i b u t e t o r e l a t i v e l y low readings  of e l e c t r i c a l  r e s i s t a n c e , p a r t i c u l a r l y near the s u r f a c e s o f most p o l e s . The  Shigometer was o r i g i n a l l y designed f o r decay  detec-  t i o n i n l i v i n g t r e e s , where the wood moisture i s w e l l above the f i b e r s a t u r a t i o n p o i n t and where there i s most always some sound sapwood p r e s e n t . are a l l r e l a t i v e v a l u e s ,  likely  Since the meter  readings  they have t o be r e l a t e d t o wood o f  the same sample that i s s u b s t a n t i a l l y devoid  o f fungal  deter  i o r a t i o n and t h a t can be t h e r e f o r e be taken as a r e f e r e n c e . T h i s would be p o s s i b l e i n a l i v i n g t r e e but i n timber i n s e r v i c e , i t i s not p o s s i b l e t o d i f f e r e n t i a t e c l e a r l y between apparently  sound wood and wood c o n t a i n i n g s t a i n o r any i n c i p  i e n t decay.  In t h i s study, two f a c t o r s have been  identified  which made e v a l u a t i o n o f the e f f e c t i v e n e s s o f the Shigometer more d i f f i c u l t .  First,  s i n c e t h e r e was no v i s u a l assessment  n e i t h e r any p o s s i b l e decay nor other (e.g. voids)  c o u l d be d e t e c t e d .  l a t i o n s provided conditions.  internal  conditions  The r e s u l t s o f f u n g a l  iso-  o n l y l i m i t e d i n f o r m a t i o n on i n t e r n a l wood  Second, as d e s c r i b e d  i n the study reported by  S h o r t l e est a l . (1978) , the meter measures r e s i s t a n c e o n l y t o 500  kft, y e t many readings  exceed t h i s v a l u e .  t r u e r e s i s t a n c e corresponding  t o readings  Because the  beyond 500 kn. was  not known, the percentage d e f l e c t i o n owing t o the lower readings  c o u l d not be a c c u r a t e l y c a l c u l a t e d .  Thus, i f p o l e s  168  w i t h these c h a r a c t e r i s t i c s poles  to be i n s p e c t e d ,  make up a l a r g e percentage  of  f u r t h e r refinements o f the method  o r the meter need to be d e v e l o p e d . 4.4.3  EFFECT OF MOISTURE CONTENT ON THE SHIGOMETER MEASUREMENTS The q u e s t i o n o f whether such r e d u c t i o n s i n e l e c t r i c a l  r e s i s t a n c e as measured i n the suspect spruce p o l e s were due to the presence o f decay o r simply the v a r i a t i o n i n moisture content can be addressed K-5-26) readings  to the two k e r f e d p o l e s  (K-4-5 and  which showed the g r e a t e s t d e f l e c t i o n i n r e s i s t a n c e (Table 24).  It  i s g e n e r a l l y known that changes  in  moisture content are g r a d u a l i n the v e r t i c a l d i r e c t i o n , but abrupt changes  do occur i n p o l e s p a r t i c u l a r l y i n r e l a t i o n  to the presence o f c h e c k s .  In k e r f e d p o l e s ,  the k e r f  to  the p i t h o f a p o l e normally f u n c t i o n s as a major check below g r o u n d l i n e , p e r m i t t i n g l o c a l i z e d upward movement o f moisture along a continuous c a p i l l a r y above the ground.  If  the S h i g o -  meter probe encounters such a column o f wetter wood, the i n t e r p r e t a t i o n o f the Shigometer readings l a r l y ambiguous.  c o u l d be p a r t i c u -  Moving the Shigometer probe from wood  near the f i b e r s a t u r a t i o n p o i n t to wood at  significantly  h i g h e r moisture contents would have caused a drop i n r e s i s t ance r e a d i n g .  F o r example. T a b l e 26 shows that as the probe  passed through moisture g r a d i e n t s ,  the Shigometer  readings  ranged  from above 500 t o 120 kft f o r the p o l e K-4-5, and  from 440 t o 60 kfl. (or 460 t o 100 k«) f o r the p o l e K-5-26. T h i s i s more than a 75% drop even when t a k i n g the maximum as 500 ksi as recommended by Shigo e t a l . (1977) .  With the  p r e v i o u s l y observed moisture content d i s t r i b u t i o n s poles,  i n spruce  i t i s concluded t h a t the abrupt drops i n Shigometer  readings i n the suspect p o l e s are due t o the e f f e c t o f variation point.  i n moisture content above the f i b e r s a t u r a t i o n  170  5.0  CONCLUSIONS  5.1  CHEMICAL STUDY F o r t h e ACA-treated  spruce p o l e s a f t e r seven years i n  t e s t , the p e n e t r a t i o n conformed t o , but the r e t e n t i o n was i n s u f f i c i e n t t o conform t o , t h e l e v e l s e s t a b l i s h e d by t h e CSA  standard.  S a t i s f a c t o r y penetration values i n r e f r a c t o r y  spruce wood a r e a t t r i b u t e d  t o the combination o f i n c i s i n g  and ACA treatment, w h i l e low chemical r e t e n t i o n s i n the ACAt r e a t e d spruce p o l e s can be a s c r i b e d most p l a u s i b l y t o the use o f an e m p t y - c e l l process and the impregnation o f p o l e s which had been i n s u f f i c i e n t l y  dried.  The d i s p r o p o r t i o n a t e uptake o f the a c t i v e ACA c h e m i c a l components a t low r e t e n t i o n s , p r e v i o u s l y d e s c r i b e d by o t h e r r e s e a r c h e r s , has been confirmed.  S i n c e the o r i g i n a l  formu-  l a t i o n o f ACA c o n t a i n e d e q u a l amounts o f c u p r i c and a r s e n i c o x i d e s , t h e d i s p r o p o r t i o n a t e r e t e n t i o n o f copper t o a r s e n i c can be e x p l a i n e d as b e i n g due mainly t o the d i f f e r i n g  adapt-  a b i l i t y o f those components t o t h e f i x a t i o n p r o c e s s , and p a r t l y to p o s s i b l e leaching o f arsenic during s e r v i c e . 5.2  BIOLOGICAL STUDY M i c r o b i o l o g i c a l i n v e s t i g a t i o n s i n d i c a t e d that numerous  m i c r o f u n g i were commonly a s s o c i a t e d w i t h the 24 ACA-treated spruce p o l e s used  i n t h i s study.  The most f r e q u e n t l y i s o l a t e d  171  m i c r o f u n g i were: 24 p o l e s sampled), spp.  Phoma herbarum (24 i s o l a t e s o b t a i n e d from E x o p h i a l a j e a n s e l m e i (19/24), Oidiodendron  (16/24), Acremonium and P e n i c i l l i u m spp.  phora spp.  (13/24), Sclerophoma p y t h i o p h i l a  V e r t i c i l l i u m spp.  (4/24).  (14/24),  Phialo-  (6/24), and  B a c t e r i a were a l s o commonly found  a s s o c i a t e d w i t h these m i c r o f u n g i . However, i n c o n t r a s t t o the u n t r e a t e d spruce c o n t r o l p o l e s , no t r u e wood-decaying fungi, Basidiomycetes, isolated  from the ACA-treated p o l e s .  were  I t can be concluded  that the m i c r o f u n g i i s o l a t e d are more t o l e r a n t t o ACA s e r v a t i v e s than are the wood-destroying  5.3  pre-  Basidiomycetes.  NITROGEN STUDY The r e s u l t s from the n i t r o g e n a n a l y s i s e v i d e n t l y  that the treatment o f spruce wood w i t h ACA  prove  significantly  i n c r e a s e s the n i t r o g e n content i n the t r e a t e d zone and  also  p r o v i d e s a s i g n i f i c a n t enhancement o f n i t r o g e n l e v e l beyond the p e n e t r a t i o n l i m i t .  A l i n e a r r e l a t i o n s h i p e x i s t s between  n i t r o g e n content and chemical r e t e n t i o n i n the f i r s t ical  analyt-  zone. I t i s not c l e a r l y understood whether the enrichment  n i t r o g e n l e v e l due t o ACA  treatment i n spruce wood i s c o r r e -  l a t e d w i t h i t s s u s c e p t i b i l i t y t o f u n g a l and b a c t e r i a l nization.  of  colo-  172  5.4  SHIGOMETER STUDY P r e v i o u s l y r e p o r t e d e f f e c t s o f moisture content  variation  w i t h i n the range 38 t o 45% on the Shigometer readings have been confirmed. it  S i n c e no evidence o f decayed wood was  found,  i s not p o s s i b l e to assess t h e accuracy o f the Shigometer  f o r d e t e c t i o n o f i n t e r n a l decay. observed  However, r e s i s t a n c e v a l u e s  f o r two o f the p o l e s show changes due t o moisture  content f l u c t u a t i o n which are s i m i l a r t o those reported by p r e v i o u s workers.  Hence the p r a c t i c a l a p p l i c a t i o n o f the  Shigometer f o r d e t e c t i o n o f i n t e r n a l decay may be l i m i t e d due t o the known v a r i a t i o n i n moisture content o f the groundl i n e region o f poles.  5.5  GENERAL Untreated spruce c o n t r o l p o l e s i n the graveyard  test  had a l r e a d y decayed s e v e r e l y a t g r o u n d l i n e c o n t a c t a f t e r seven years o f s e r v i c e s i m u l a t i o n .  Although the ACA-treated  spruce p o l e s were i n f e c t e d moderately  w i t h numerous m i c r o -  f u n g i and some s o f t - r o t f u n g i , the complete absence o f B a s i diomycetes  and t h e good p h y s i c a l c o n d i t i o n o f the t r e a t e d  p o l e s i s encouraging  enough t o warrant  native f o r t r a d i t i o n a l pole species.  promise as an a l t e r With the a v a i l a b i l i t y  o f white spruce i n l a r g e q u a n t i t i e s , there should be c o n s i d e r a b l e i n t e r e s t i n the p o t e n t i a l o f t h i s s p e c i e s f o r s a t i s -  f y i n g some o f the f u t u r e demand i n Canada and making p o l e supply more f l e x i b l e . It in  i s , however, recommended t h a t p e r i o d i c i n v e s t i g a t i o n  field  t e s t be performed to v e r i f y the u t i l i t y o f  t r e a t e d spruce as p o l e m a t e r i a l .  ACA-  Since the poor r e t e n t i o n  i n spruce i s a fundamental, f i r s t o r d e r problem to overcome, the g r e a t e s t step to be taken i n p r e s e r v a t i v e treatment i s to improve the t r e a t a b i l i t y o f r e f r a c t o r y spruce wood, by c a r e f u l d r y i n g , improved i n c i s i n g and cesses.  From the r e s u l t s to date,  t h a t the CSA they c a l l ments.  i t might be  s p e c i f i c a t i o n s are too c o n s e r v a t i v e  However, f u r t h e r work would be this.  Further  p o l e s , and  i n that require-  r e q u i r e d to prove  s t u d i e s are a l s o r e q u i r e d  an i n d i c a t i o n o f the extent  pro-  speculated  f o r a more r e t e n t i o n than a c t u a l f i e l d  or disprove provide  optimal pressure  o f checking  the a b i l i t y o f k e r f i n g to prevent the  o f deep checks i n ACA-treated spruce p o l e s .  to  in treated formation  REFERENCES  Adolph, F.P. 1976. 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PREPARATIONS  A c i d i f i e d M a l t Agar Malt extract Agar Malic acid* D i s t i l l e d water  (AMA) 20 20 5 1000  g (2%) g (2%) g (0.5%) ml  * A c i d s o l u t i o n was a u t o c l a v e d s e p a r a t e l y and added to 1 l i t r e o f the s t e r i l e media a f t e r autoclaving. 2.  Benomyl T e t r a c y c l i n e M a l t Agar Malt extract Agar Benomyl Tetracycline D i s t i l l e d water  20 20 15 10 1000  (BTMA) g (2%) g (2%) ml (7.5 ml (100 ml  ppm) ppm)  * 0.1 g o f 50% a c t i v e i n g r e d i e n t powder i n 100 ml d i s t i l l e d H 2 O was used to y i e l d 0.5/10 f o r 7.5 ppm. 3  0.5 g powder to 50 ml d i s t i l l e d H 2 O y i e l d e d 10 mg/ml; 10 ml o f 10 mg/10 ml t e t r a c y c l i n e s t o c k s o l u t i o n kept i n a r e f r i g e r a t o r were added s e p a r a t e l y to 1 l i t r e o f the s t e r i l e media t o y i e l d 100 ppm. Note:  A l l these media were autoclaved f o r 20 minutes at the temperature o f 121°C w i t h the p r e s s u r e o f 100 kPa.  

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