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Relative susceptibility of interior spruce (Picea glauca x engelmannii engelm.) and lodgepole pine (Pinus… Schulting, Peter John 1987

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RELATIVE SUSCEPTIBILITY OF INTERIOR SPRUCE (PICEA GLAUCA X ENGELMANNII ENGELM.) AND LODGEPOLE PINE (PINUS CONTORTA DOUGL. VAR. LATIFOLIA ENGELM.) TO INONOTUS TOMENTOSUS (FR.) TENG IN CENTRAL BRITISH COLUMBIA by PETER J . SCHULTING A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE s in THE FACULTY OF GRADUATE STUDIES Department of F o r e s t r y We accept t h i s t h e s i s as conforming to the requi red standard THE UNIVERSITY OF BRITISH COLUMBIA 6 October 1987 © Peter J . S c h u l t i n g , 1987 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of •^ o^ e.sVcc^  The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date QA. 1 , \<\H1 ABSTRACT Twenty sample p l o t s l o c a t e d i n Inonotus tomentosus (F r . ) Teng c e n t e r s i n mixed l o d g e p o l e p i n e (Pinus c o n t o r t a Dougl. v a r . l a t i f o l i a Engelm.) and i n t e r i o r spruce ( P i c e a  g l a u c a x engelmannii Engelm.) stands i n c e n t r a l B r i t i s h Columbia were s t u d i e d t o i n v e s t i g a t e the behaviour o f , and v a r i a t i o n i n host s p e c i e s a t t a c k e d by the pathogen. The e f f e c t of i n f e c t i o n on the r a d i a l increment of spruce and p i n e was s t u d i e d by measuring increment b o r e s . C h a r a c t e r i s t i c s of the fungus i n c u l t u r e were s t u d i e d u s i n g i s o l a t e s o b t a i n e d from each of the study p l o t s . In some c a s e s , the fungus was found to behave d i f f e r e n t l y on spruce and p i n e . In p i n e , advanced n e c r o s i s of the cambium and phloem of the r o o t s caused crown t h i n n i n g and e v e n t u a l s t a n d i n g m o r t a l i t y . In spruce, decay of the heartwood and i n n e r xylem of the r o o t s caused w i n d f a l l of the t r e e , o f t e n b e f o r e e x p r e s s i o n of n o t i c a b l e crown symptoms. In both host s p e c i e s s t u d i e d , spread was commonly observed from i n f e c t e d t o h e a l t h y , c o n t a c t i n g r o o t s . P o s s i b l e c a s e s of spore i n o c u l a t i o n through r o o t wounds were a l s o found. In a l l p l o t s , p i n e showed a h i g h e r i n f e c t i o n l e v e l than s p r u c e . S u b a l p i n e f i r (Abies l a s i o c a r p a (Hook.) Nutt.) and D o u g l a s - f i r (Pseudotsuqa m e n z i e s i i (Mirb.) i i Franco) pres e n t w i t h i n the p l o t s were not found t o be i n f e c t e d . I n f e c t i o n by tomentosus was not found to reduce s i g n i f i c a n t l y the b a s a l area increment i n p i n e or spruce. The fungus i n c u l t u r e demonstrated a l a r g e amount of v a r i a t i o n i n growth r a t e , mycelium c o l o r and mat c o l o r and t e x t u r e . Such v a r i a t i o n o c c u r r e d both w i t h i n and among i s o l a t e s , and c o u l d not be r e l a t e d t o the host s p e c i e s from which the i s o l a t e was o b t a i n e d . i i i Table of Contents Abstract i i L i s t of Tables v i L i s t of F igures v i i i Acknowledgement ix A. In t roduct ion 1 B. Review of the L i t e r a t u r e 2 1 . Taxonomy 2 2. D i s t r i b u t i o n and Host Species 6 3. Methods of Spread 16 4. Ecology 20 5. Damage 22 a . Windthrow . 22 b. Standing M o r t a l i t y 24 c . Butt C u l l . . .25 d . Increment Reduction 26 e. Ind i rec t Losses 27 6. V a r i a b i l i t y of Inonotus tomentosus 29 C. Methods 31 1. S e l e c t i o n of S i t e s and Plot Locat ion 31 2. Data C o l l e c t i o n 35 3. Host Species S u s c e p t i b i l i t y 36 4. E f f e c t of I n fec t ion on Increment 38 5. I d e n t i f i c a t i o n and D e s c r i p t i o n in Cul ture 39 D. Resul ts and D i s c u s s i o n 40 1. E t i o l o g y 40 iv 2. Spread 54 3. Host S p e c i e s S u s c e p t i b i l i t y 54 4. E f f e c t of I n f e c t i o n on Increment 73 a. Lodgepole pine 73 b. I n t e r i o r Spruce 76 5. C u l t u r a l C h a r a c t e r i s t i c s .....79 E. C o n c l u s i o n s 89 L i t e r a t u r e C i t e d 92 Appendices 97 1. Appendix A ...97 2. Appendix B 118 3. Appendix C 119 v L i s t of T a b l e s 1. H i s t o r i c a l nomenclature of tomentosus 5 2. Host species of tomentosus 8 3. Frequency of i s o l a t i o n of tomentosus as a percent of a l l fungal i s o l a t e s in Canadian decay studies 11 4. Incidence l e v e l s of tomentosus on i n t e r i o r spruce in Canada 13 5. Stand age, region and e c o l o g i c a l c l a s s i f i c a t i o n of sample s i t e s 34 6. Proportions of pine and spruce i n f e c t e d and the d i f f e r e n c e in proportion of pine and spruce i n f e c t e d by s i t e 56 7. Paired-sample T-test on the proportion of pine i n f e c t e d and the proportion of spruce i n f e c t e d 58 8. w i l c o x i n Matched-Pairs Signed-Ranked t e s t , proportion of pine i n f e c t e d with proportion of spruce i n f e c t e d 59 9. C o r r e l a t i o n of the proportion of lodgepole pine i n f e c t e d with the proportion of spruce i n f e c t e d 60 10. T-test on the slope of the c o r r e l a t i o n of the proportion of pine i n f e c t e d with the proportion of spruce i n f e c t e d 62 11. Summary of the proportions of pine and spruce infected and the d i f f e r e n c e between the proportions of pine and spruce i n f e c t e d 66 12. T-test on the d i f f e r e n c e in proportions i n f e c t e d by geographic region 67 v i L i s t of Tables (con ' t ) 13. Groupings of e c o l o g i c a l a s s o c i a t i o n s by moisture and nut r ient status 6B 14. A n a l y s i s of var iance of the d i f f e rence in the propor t ion of pine and spruce in fec ted by e c o l o g i c a l grouping 70 15. Mean i n i t i a l basal area and basal area increment of healthy and diseased pine and spruce 75 16. A n a l y s i s of var iance in r a d i a l increment of pine 77 17. Summary of mean stand ages and tree basal areas by subzone 78 18. A n a l y s i s of var iance in r a d i a l increment of spruce 81 19. Common mycelium types found in cu l tu re ,87 v i i L i s t o f F i g u r e s 1. Exposed root b a l l of an i n t e r i o r spruce in an I.  tomentosus i n f e c t i o n center 23 2. Locat ion of study s i t e s in the Pr ince George Forest Region 32 3. Locat ion of study s i t e s in the Pr ince Rupert Forest Region 33 4. L ight Red Sta in in root i n f e c t e d with tomentosus 41 5. Reddish-brown s t a i n i n g and ea r ly p i t t e d decay in I.  tomentosus i n f e c t e d roots . . . 4 2 6. Advanced tomentosus decay 43 7. Above ground symptoms of an i n f e c t e d pine 47 8. Red s t a i n i n g extending from an o l d root wound 53 9. C o r r e l a t i o n of the propor t ion of pine i n f e c t e d with the propor t ion of spruce i n f e c t e d 61 10. Quant i ta t i ve d i f f e r e n t i a l v a r i a t i o n in host spec ies s u s c e p t i b i l i t y 64 11. Q u a l i t a t i v e d i f f e r e n t i a l v a r i a t i o n in host spec ies s u s c e p t i b i l i t y 64 12a. tomentosus in c u l t u r e - Type 1 85 12b. tomentosus in c u l t u r e - Type 2 85 12c. tomentosus in c u l t u r e - Type 3 86 13. Rudimentary tomentosus f r u i t i n g bodies 88 v i i i Acknowledgement I wish to thank my wi fe , Maureen, in a l l th ings my i n s p i r a t i o n . ix I. INTRODUCTION Inonotus (Polyporus) tomentosus (Fr.) Teng i s a basidiomycetous fungus which a t t a c k s the l i v i n g r o o t s of c o n i f e r o u s t r e e s i n North America and abroad. While a t t a c k s are b e l i e v e d to o r i g i n a t e i n the r o o t s , i n f e c t i o n o f t e n extends i n t o the butt as w e l l . I n f e c t i o n leads t o n e c r o s i s of t r e e t i s s u e . Subsequent d i g e s t i o n of host t i s s u e r e s u l t s i n a p i t t e d r o t . Since l i v i n g t i s s u e s are a t t a c k e d , I .  tomentosus q u a l i f i e s as a root and butt r o t t i n g pathogenic s p e c i e s . Other root r o t s p e c i e s such as A r m i l l a r i a obscura (Pers.) Herink and P h e l l i n u s w e i r i i (Murr.) G i l b e r t s o n have been e x t e n s i v e l y s t u d i e d and are considered t o be the important root r o t s i n B r i t i s h Columbia. The i n c i d e n c e and importance of K. tomentosus i n B r i t i s h Columbia has yet t o be determined. E a r l y estimates of i t ' s i n c i d e n c e , i t ' s u b i q u i t o u s nature i n sub-boreal and b o r e a l f o r e s t s , and i t ' s wide geographic range suggest I ^ tomentosus may be the most important root r o t i n Canada i n terms of timber volume l o s t . C l e a r l y , as northern i n t e r i o r f o r e s t s become more i n t e n s i v e l y managed, the r o l e played by 1^ tomentosus must be c l a r i f i e d . The i n c i d e n c e , d i s t r i b u t i o n and t r e e species a f f e c t e d must be determined before l o s s e s t o the disease and p o s s i b l e c o n t r o l methods can be considered i n timber management p l a n s . 1 2 The purposes of t h i s study were: 1. To d e s c r i b e the symptoms produced i n I .  tomentosus i n f e c t e d i n t e r i o r spruce ( P i c e a g l a u c a x engelmanni i Engelm.) and l o d g e p o l e p i n e (Pinus c o n t o r t a v a r . l a t i f o l i a D o u g l . ) . 2. To determine the r e l a t i v e s u s c e p t i b i l i t i e s of n o r t h e r n c o n i f e r s t o t h i s pathogen. 3. To determine whether host s p e c i f i c i t y i s p r e s e n t i n the pathogen. 4. To d e s c r i b e the e f f e c t of i n f e c t i o n on b a s a l area increment. 5. To d e s c r i b e c h a r a c t e r i s t i c s of the fungus i n c u l t u r e and attempt to r e l a t e these to the host s p e c i e s or geographic r e g i o n from which they were o b t a i n e d . A. REVIEW OF THE LITERATURE 1. TAXONOMY The taxonomic h i s t o r y of 1^ tomentosus was reviewed i n some d e t a i l by Haddow (1941) and G o s s e l i n (1944). Inonotus  ( P o l y p o r u s ) tomentosus was f i r s t d e s c r i b e d by F r i e s i n Sweden i n 1821 i n h i s "Systema mycologicum" as P o l y p o r u s  tomentosus. F r i e s a l s o d e s c r i b e d Trametes c i r c i n a t u s which he l a t e r (1863) r e v i s e d to P o l y p o r u s c i r c i n a t u s . The 3 d i s t i n c t i o n between these two fungi was made on the basis of gross morphological features of the sporophore; e s s e n t i a l l y the context s t ruc ture (supposedly homogenous in P.  tomentosus and duplex in E\ c i r c i n a t u s ) , and the r e l a t i v e depth of the pore layer (greater in P_j_ c i r c i n a t u s ) . H i s t o r i c a l l y , there has e x i s t e d a great deal of confus ion regarding the proper taxonomic s ta tus of t h i s fungus. In Europe the fungus was r e c l a s s i f i e d severa l t imes. The genus was changed to P o l y s t i c t u s by Cooke ( 1886) and Saccardo (1888). Karsten (1889) p laced the species into the genus Onnia. Two s p e c i e s , tomentosus and c i r c i n a t u s were recognized by most authors . In North America, a s i m i l a r cond i t ion ex is ted with severa l authors r e c l a s s i f y i n g the fungus. E l l i s and Everhart (1889) p laced i t i n to the genus Mucronoporus, M u r r i l l (1908) in to C o l t r i c i a and L loyd (1908) in to P o l y s t i c t u s . In f a c t , some authors be l i eved that Polyporus tomentosus d i d not occur in North America at a l l . Instead, c l o s e l y r e l a t e d s p e c i e s , P_j_ d u a l i s Peck, and P. c i r c i n a t u s were descr ibed (Peck 1878). In a c t u a l i t y , few authors gave P_j_ d u a l i s species s t a t u s . Instead they re legated i t to v a r i e t y s tatus or be l ieved i t to be synonymous with P. tomentosus or P_j_ c i r c i n a t u s . Even tua l l y , Peck himself came to regard i t as a v a r i e t y of P o l y s t i c t u s  c i r c i n a t u s (Haddow 1941). Table 1 provides an overview of 4 the n o m e n c l a t u r a l changes under gone between 1849 and 1944. Haddow a t t r i b u t e d most of t h i s c o n f u s i o n t o a la c k of proper type specimens and to a g r e a t d e a l of v a r i a t i o n i n sporophore s i z e and h a b i t , s t r a t i f i c a t i o n of the con t e x t and depth of the pore l a y e r . Through an examination of a g r e a t number of specimens used by the a u t h o r s l i s t e d i n T a b l e 1 Haddow d i s c o v e r e d t h a t the c o n t e x t was, i n a l l c a s e s duplex. C o n f u s i o n i n e a r l y d e s c r i p t i o n s a r o s e due t o v a r i a t i o n i n the r e l a t i v e t h i c k n e s s of the two c o n t e x t l a y e r s . The setae were found t o be the o n l y d i a g n o s t i c f e a t u r e , w i t h s t r a i g h t s e t a e p r e s e n t i n P_;_ tomentosus v a r . tomentosus and cur v e d s e t a e i n tomentosus v a r . c i r c i n a t u s . Haddow r e c l a s s i f i e d tomentosus, c i r c i n a t u s and d u a l i s as a s i n g l e s p e c i e s : P o l y p o r u s tomentosus wi t h i t ' s v a r i e t y c i r c i n a t u s . P. d u a l i s was deemed synonymous t o P_j_ tomentosus v a r . c i r c i n a t u s . G i l b e r t s o n (1974) t r a n s f e r r e d the fungus i n t o the genus Inonotus w i t h two s p e c i e s ; c i r c i n a t u s and tomentosus. While the s h i f t t o the genus Inonotus has g e n e r a l l y been a c c e p t e d , some prominent a u t h o r s c o n t i n u e t o c l a s s i f y I_j_ c i r c i n a t u s as a v a r i e t y of I_j_ tomentosus. Jahn ( 1978) proposed t r a n s f e r of the fungus i n t o the genus Onnia but t h i s p r o p o s a l has not yet been adopted. T A B L E 1 H i s t o r i c a l Nomenclature of Inonotus tomentosus. 5 F r i e s 1821 F r i e s 1849 Peck 1878 Cooke 1886 Saccardo 1888 Karsten 1869 E l l i s and Ever hart 1689 Hennings 1898 P a t o u l i l a r d 1900 M u r r i l l 1904 Haddow (1908) Lloyd 1908 and 1912 Ames 1913 Neuman 1914 Bresadola 1920 Polyporus tomentosus  Polyporus tomentosus  Polyporus tomentosus  P o l y s t I c t u s tomentosus  P o l y s t l c t u s tomentosus  Onnla tomentosa Mucroporus tomentosus  P o l y s t l c t u s tomentosus  Xanthochrous c i r c i n a t u s Co11r1cia tomentosa  Polyporus tomentosus  P. c i r c i n a t u s  P o l y s t i c t u s tomentosus S a r t o r y and Maire 1922 Konrad and Maublanc 1926 tomentosus Bourdot and G a l z i n 1927 Ki l l e r m a n 1928 P o l y s t l c t u s tomentosus Shope 1931 Overholts 1933 Lowe 1934 Jor s t a d + Juul 1938 Haddow 1941 G i l b e r t s o n 1974 Polyporus d u a l i s Polyporus c i r c i n a t u s P. c i r c i n a t u s  P. tomentosus  P. tomentosus var. amerlcanus Polyporus tomentosus  Inonotus tomentosus P_: c i r c i n a t u s P. c i r c i n a t u s P. d u a l i s P. c i r c i n a t u s P. c i r c i n a t u s O. c i r c i n a t u s M. c i r c i n a t u s P. c i r c i n a t u s I. tomentosa  P. d u a l l s P o l y s t l c t u s  c i r c i n a t u s  P. d u a l i s  Polyporus  d u a l l s P_. t r l q u e t e r JL* tomentosus var c i r c i n a t u s F o m e s (xarthochrous ) c i r c i n a t u s Polyporus  c i r c i n a t u s  P o l y s t l c t u s  c i r c i n a t u s var. t r i q u e t e r P. c i r c i n a t u s  5ualIs  P. d u a l i s i P . d u a l i s P.tomentosus var. c i r c i n a t u s I. c i r c i n a t u s 6 2. DISTRIBUTION AND HOST SPECIES Inonotus tomentosus i s an ubiqui tous fungus. It has been found in North America, Europe and A s i a . In North America, tomentosus root rot occurs as far north as Northern B r i t i s h Columbia, Northern Saskatchewan and Alaska (Shaw 1985). Inonotus tomentosus or I_j_ c i r c i n a t u s have been reported south to Georgia and the F l o r i d a peninsula (Kossuth and Barnard 1983, Ross 1966). Reports from the most southern States re fe r e x c l u s i v e l y to I^  c i r c i n a t u s (Barnard et a l 1985, Kossuth and Barnard 1983, Boyce 1963). Most repor ts from Wisconsin , the P a c i f i c Northwest and northwards are of JN_ tomentosus (Hobbs and Par t r idge 1979, Davidson and Redmond 1957, Whitney and Van Groenewoud 1964). Th is may portend a large sca le geographical t rend in d isease d i s t r i b u t i o n . Some southern l i m i t of I^  tomentosus may e x i s t in the southern U . S . beyond which only c i r c i n a t u s o c c u r s . However, Northern occurrences of JN c i r c i n a t u s have been reported above t h i s l i n e (Van Groenewoud 1956). Thus the ranges of JN c i r c i n a t u s and I_j_ tomentosus are not mutual ly e x c l u s i v e . The ranges of the two species may become c l e a r e r in future i f c l a s s i f i c a t i o n to species (or v a r i e t y ) in surveys and s tud ies becomes more common. 7 Reported incidences in Europe include Sweden (F r i es 1863, L loyd 1908 and M u r r i l l 1908), A u s t r i a (Lloyd 1920) and Germany ( M u r r i l l 1904). Bakshi (1971) found I. tomentosus to be damaging in Northern Ind ia . L loyd (1920), reported I.  tomentosus in A f r i c a . Teng (1932) and S h i r a i (1927) reported I. tomentosus in China and Japan r e s p e c t i v e l y . G o s s e l i n (1944) observed that the 36th p a r a l l e l appeared to be the southern l i m i t of the s p e c i e s . However, he a l s o p r e d i c t e d more southern occurrences at high a l t i t u d e s . Tomentosus root rot a t tacks a great many t ree species over i t ' s wide geographic range (Table 2 ) . Whitney (1977) repor ts that a l l nat ive Canadian spruce spec ies and most nat ive p ines are a t tacked . The d isease has not been reported a t tack ing any hardwood s p e c i e s . However, s u c c e s s f u l i n o c u l a t i o n s have been made on white b i r c h (Betula  p a p y r i f e r a Marsh.) and t rembl ing aspen (Populus tremuloides Michx. ) (Whitney 1964b, Whitney and Van Groenewoud 1964). As wel l Whitney (1964) found that a wide range of hardwoods could be used as inoculum c a r r i e r s . Th is p a r a l l e l s the f i n d i n g s of W a l l i s and Reynolds (1962) with P h e l l i n u s w e i r i i on D o u g l a s - f i r (Pseudotsuga menz ies i i (Mirb. ) F r a n c o ) . In ne i ther case does the v i a b i l i t y of hardwoods as inoculum c a r r i e r s ind ica te an a b i l i t y by the fungus to at tack l i v i n g or c o l o n i z e dead hardwoods in natura l c o n d i t i o n s . TABLE 2 C o n i f e r Hosts of I. tomentosus 8 a) In Canada: Abies amabi 1ls (Dougl.) Forb. Abies balsamea (L.) M i l l . Abies l a s i o c a r p a (Hook.) Nutt. L a r i x l a r i c i n a (Du Roi) K. Koch L a r i x o c c i d e n t a l i s N u t t . P l c e a a b i e s K a r s t P i c e a engelmanni i P a r r y P i c e a g l a u c a (Moench) Voss P i c e a g l a u c a (Moench) Voss v a r . A l b e r t i a n a (S.Brown) Sarg. P l c e a marlana ( M i l l . ) B.S.P. P i c e a rubens Sarg. P l c e a s l t c h e n s l s (Bong.) c a r r . Plnus bankslana Lamb. Plnus c o n t o r t a Dougl. Pinus c o n t o r t a Dougl. v a r . l a t i f o l i a Engelm. Pinus m o n t i c o l a Dougl. Pinus ponderosa Laws. Pinus r e s i n o s a A i t . Pinus s t r o b u s L. PseHdotsuqa m e n z e i s i i (Mirb.) Franco Thuja p l i c a t a Donn ex D. Don Tsuga c a n a d e n s l s (L.) C a r r . Tsuga h e t e r o p h y l l a (Raf.) Sarg. b) Host s p e c i e s abroad (other than those l i s t e d above): Abies p r o c e r a Rehd. Cedrus deodora Roxb. P i c e a a b i e s K a r s t . P i c e a pungens Engelm. P i c e a rubens Sarg. P i c e a smythiana B o i s s . Plnus e l l i o t i l Engelm. Pinus n i g r a A r n o l d Pinus r a d i a t a D.Don. Plnus r l g l d a M i l l . P i n u s s v l v e s t r l s L. Pinus taeda L. Pinus c l a u s a v a r . immuginata From Whitney 1977 and Whitney 1978. 9 While these s p e c i e s are a t t a c k e d , not a l l are impacted e q u a l l y . I n o c u l a t i o n experiments on s e e d l i n g s and o l d e r t r e e s have y i e l d e d an e s t i m a t e of the r e l a t i v e s u s c e p t i b i l i t y of a s m a l l number of s p e c i e s {Whitney and Bohaychuk 1976, Whitney and Bohaychuk 1977, Whitney 1964b). From these s t u d i e s , spruce and tamarack ( L a r i x sp. ) are c o n s i d e r e d h i g h l y s u s c e p t i b l e and p i n e s somewhat l e s s s u s c e p t i b l e (Whitney 1977, Whitney 1962). A s i d e from these few i n o c u l a t i o n experiments, s u s c e p t i b i l i t y of ho s t s p e c i e s has g e n e r a l l y been e x t r a p o l a t e d from i n c i d e n c e s u r v e y s . While h i g h i n c i d e n c e l e v e l s are v a l i d i n d i c a t o r s of a s p e c i e s ' p o t e n t i a l s u s c e p t i b i l i t y , i t i s d i f f i c u l t or i m p o s s i b l e t o use such data t o e x t r a p o l a t e i n f e c t i o n hazard to the s p e c i e s on ot h e r s i t e s . At any r a t e , low l e v e l s of i n f e c t i o n c e r t a i n l y do not a c c u r a t e l y r e f l e c t the a b s o l u t e s u s c e p t i b i l i t y of a s p e c i e s . Such low i n f e c t i o n l e v e l s may be due t o h a b i t a t e f f e c t s on the fungus or t o an i n t e r a c t i o n between s i t e f e a t u r e s on the host and root d i s e a s e s p e c i e s . I t may be t h a t the predominance of l o d g e p o l e p i n e , jack p i n e (P. banksiana Lamb.), white spruce (F\ gl a u c a (Moench) Voss) and b l a c k spruce (P^ mariana ( M i l l . ) B.S.P.) as host s p e c i e s i s due t o a c o i n c i d e n c e of t h e i r ranges w i t h the range of I. tomentosus where i t i s most v i r u l e n t . Some idea of the r e l a t i v e importance of tomentosus 10. to the d i f f e r e n t c o n i f e r species can be der ived from the proport ion of t h e i r decay a t t r i b u t a b l e to the d i s e a s e . In Canada, tomentosus is a major pathogen in white spruce and lodgepole pine (Table 3) . Basham and Morowski (1964) found tomentosus to be the second most important i d e n t i f i e d decay causing fungus in white and black spruce, t h i r d in jack pine and f i r s t in a l i m i t e d red pine (P.  res inosa A i t . ) study. Whitney (1978) obtained s i m i l a r r e s u l t s for white and black spruce in northern O n t a r i o . The low propor t ion of I^  tomentosus decay on the other species l i s t e d in Table 3 may r e f l e c t t h e i r l e s s e r s u s c e p t i b i l i t y due to some r e s i s t a n c e mechanism. It may a l s o , for some species r e f l e c t l i m i t e d over lap of the h o s t ' s and pathogen's geographic ranges. Inonotus tomentosus i s c h a r a c t e r i z e d as a disease of sub-borea l and borea l f o r e s t s . Th is may r e f l e c t the range of the most s u s c e p t i b l e host spec ies or i t may r e f l e c t the optimal growing c o n d i t i o n s , ( c l i m a t i c , a b i o t i c and b i o t i c ) of the fungus. If the l a t t e r i s t r u e , then the tree species most heav i l y at tacked are just a r t i f a c t s of where they are growing. Th is idea i s supported by the l i m i t e d occurrence of I^  tomentosus in Northern Idaho. Hobbs and Par t r idge (1979), found the disease to be l i m i t e d to higher e leva t ions (above 1500 M). In B r i t i s h Columbia, the disease i s not known in low e l e v a t i o n southern i n t e r i o r lodgepole pine or c o a s t a l shore pine f o r e s t s . However, at TABLE 3 1 1 Frequency of i s o l a t i o n of tomentosus as a percent of a l l fungal i s o l a t e s i n Canadian decay s t u d i e s . SPECIES LOCATION % OF TOTAL INFECTIONS AUTHOR Abies amabl1ls (Dougl.) Forb. Abies balsamea (L.) M i l l . P l c e a glauca (Moench) voss Picea mariana ( M i l l . ) B.S.P. Pinus c o n t o r t a Dougl. var l a t i f o l i a Engelm. Pinus strobus L. Pseudotsuqa m e n z i e s i i (Mirb) Franco Tsuga h e t e r o p h y l l a (Raf) Sarg. B r i t i s h Columbia E a s t e r n Canada Ontar io A l b e r t a O n t a r i o O n t a r i o A l b e r t a Ontario B r i t i s h Columbia B r i t i s h Columbia 1.0% Buckland et a l 1949 1.5% Basham et a l 1953 1.7% Whitney 1978 Denyer and R i l e y 85.0% 1953 16.2% Whitney 1978 17.9% Whitney 1978 Denyer and R i l e y 14.0% 1953 1.3% White 1953 Thomas and Thomas 0.3% 1954 1.4% Buckland et a l 1949 0.8% F o s t e r and Foster 1951 From M e r l e r , 1984 1 2 higher e l e v a t i o n s , the author has found i t a t tack ing Douglas-f i r , spruce and p i n e . Th is information says nothing of the average l e v e l s of the disease in stands of these tree s p e c i e s , nor does i t i nd ica te whether damaging incidence l e v e l s occur and i f so , how f r e q u e n t l y . In f a c t , incidence l e v e l data i s f a i r l y scarce for most host s p e c i e s . However, a number of surveys have been performed on spruce stands in North America. In spruce , s tud ies ind ica te that inc idence l e v e l s of 20% or more in a f f e c t e d stands may not be uncommon. Whitney (1962), reported 19.7% of a l l spruce t rees examined were i n f e c t e d with tomentosus. More r e c e n t l y , Merler (1984) reported i n f e c t i o n l e v e l s of 28.4 % in spruce in stands in the c e n t r a l i n t e r i o r of B r i t i s h Columbia and Whitney (1986) reported i n f e c t i o n l e v e l s of up to 27% in eastern Canadian spruce f o r e s t s . Table 4 summarizes incidence l e v e l s found in Canadian spruce stands. It should be noted, however, that many of these inc idence s tud ies inc lude an element of i n t r i n s i c b i a s . Some were, in f a c t , s tud ies of the disease i t s e l f . A c c o r d i n g l y , stands known to be i n f e c t e d were s e l e c t e d , s tud ied and surveyed. This p r i o r knowledge of i n f e c t i o n assures bias which d i s q u a l i f i e s these inc idence l e v e l s as i n d i c a t o r s of Table 4 13 I n c i d e n c e L e v e l s of I ^ tomentosus on I n t e r i o r Spruce i n Canada S p e c i e s L o c a t i o n P e r c e n t Author I n f e c t e d W. Spruce Pr.Rupert 14% Kondo T a y l o r , 1965 Spruce Sask . 19.7% Whitney, 1962 Spruce P r . Georqe 28.4% * M e r l e r , 1964 Spruce P r . Rupert 5% Unger, 1984 W. Spruce Ontar i o 27% Whitney, 1986 Spruce BC/Yukon 35% * Wood, Van S i c k l e Yukon 33% and Shore, 1984 McLeod, B.C. 55% B. spruce N. O n t a r i o 18% * Whitney 1978 w. spruce N. O n t a r i o 14%* Whitney 1978 * Represents averaqe i n f e c t i o n l e v e l s c a l c u l a t e d t o r stands of v a r i o u s aaes. 1 4 average i n f e c t i o n l e v e l s for stands in t h e i r respect ive reg ions . As w e l l , severe ly in fec ted stands are more l i k e l y to catch the a t ten t ion of those performing the study. At any ra te , a c e r t a i n amount of d isease i s required to make disease behaviour s tud ies e f f i c i e n t . Thus these f igures are i n d i c a t i o n s of the l e v e l s which can be found in stands, but they say nothing of the average inc idence . They a l s o give no idea of the propor t ion of stands i n f e c t e d . Without an average i n f e c t i o n l e v e l for a l l s tands, or the propor t ion of stands i n f e c t e d , the importance of tomentosus cannot accura te ly be assessed . Kondo and Taylor (1985) and Van S i c k l e (1984) are repor ts of the Canadian Forest Serv ice Forest Insect and Disease Survey. As such they report inc idences but say nothing of the stand s e l e c t i o n p r o c e s s . They a l s o f a i l to report how many stands ( i f any) were surveyed and found to be free of the d i s e a s e . Without t h i s in format ion , again no statements regarding average i n f e c t i o n l e v e l s can be made. More severe problems e x i s t for pine surveys s ince inc idence s tud ies in pines are more r a r e . Most o f t e n , i t seems pine spec ies are included i f they occur with spruce in the stands s t u d i e d . The except ions to t h i s would for the most part be s tud ies on I^  c i r c i n a t u s on hard pines in the southern Uni ted S t a t e s . Unger and .Stewart ( 1986) surveyed 15 lodgepole pine stands in the c e n t r a l i n t e r i o r of B r i t i s h Columbia for tomentosus root r o t . However, the extremely high i n f e c t i o n l e v e l s reported (averaging 87% in pure pine stands and 90% in mixed pine and spruce s tands ) , coupled with very low assoc ia ted mor ta l i t y rates lead the author to quest ion the survey methods used and the i n f e c t i o n status assessment and pathogen i d e n t i f i c a t i o n techniques u t i l i z e d . D e t a i l s of these methods were not suppl ied in the r e p o r t . Fur ther quest ion of these r e s u l t s i s introduced by the fact that the e t i o l o g y for the pathogen appears to resemble P h e l l i n u s p i n i (ThorerFr . ) P i l . more than i t does tomentosus. The o v e r a l l e f f e c t of t ree vigour on host s u s c e p t i b i l i t y to tomentosus i s not c l e a r l y understood. It has been shown that low tree vigour r e s u l t s in heightened s u s c e p t i b i l i t y to root d isease (Whitney 1977). However, G o s s e l i n (1944), found f a s t e r growing t rees to have higher i n f e c t i o n rates than t h e i r slower growing c o u n t e r p a r t s . A ""posi t ive c o r r e l a t i o n between i n f e c t i o n rate and host growth rate may be due to more extensive root systems in fas te r growing (and thus l a rger ) t r e e s . Larger root systems have a greater p r o b a b i l i t y of contac t ing an inoculum source . Evidence regarding p r e d i s p o s i t i o n through s t r e s s to I.  tomentosus may be confused by the d i r e c t e f f e c t s of the 16 s t ress inducing agent on i n f e c t i o n p r o b a b i l i t y . The root c o l l a r w e e v i l , Hylobius warreni Wood i s a good example of t h i s . While s tudies have shown a c o r r e l a t i o n between incidence of tomentosus and at tack by H_;_ warreni at the root c o l l a r ( K r e b i l l 1962, Whitney 1961), i t i s not c lea r whether t h i s c o r r e l a t i o n i s due to weakening of the tree or to the p r o v i s i o n of i n f e c t i o n cour ts for b a s i d i o s p o r e s . The c o r r e l a t i o n i s fur ther confounded by the quest ion of which pest a r r i v e d on the scene f i r s t . E i t h e r pest cou ld be p red ispos ing (through s t ress ) the host for more s u c c e s s f u l at tack by the o ther . 3 . METHODS OF SPREAD The p r i n c i p a l method of d isease spread occurs v i a root contacts between healthy roots and i n f e c t e d roots or stumps (Whitney 1977). Th is spread mechanism a l s o a l lows t r a n s f e r of i n f e c t i o n into the next r o t a t i o n . Such t r a n s f e r occurs r e a d i l y where fungal mycelium i s present on or in the bark of the i n f e c t e d root (Myren and Patton 1970). In a r t i f i c i a l i n o c u l a t i o n s , root wounds were necessary for s u c c e s s f u l t rans fe r of mycelium (Whitney 1962, 1963, 1964). Th is does not appear to be the case in na tura l c o n d i t i o n s . The necess i ty of wounds in a r t i f i c i a l cond i t ions 17 may be due to the i n f e r i o r inoculum p o t e n t i a l of the pathogen i n these experiments (Myren and P a t t o n 1970). Although not s t r i c t l y n e c e s s a r y , r o o t wounds a r e b e l i e v e d t o promote i n f e c t i o n i n n a t u r a l c o n d i t i o n s by p r o v i d i n g l o c a l i z e d a r e a s of d e c l i n i n g t i s s u e which are s u s c e p t i b l e t o i n f e c t i o n ( K r e b i l l 1962, Whitney 1961). T h i s may be at l e a s t p a r t of the reason why t i g h t l y appressed r o o t c o n t a c t s are the s i t e of most s u c c e s s f u l inoculum t r a n s f e r s . Where two r o o t s a r e t i g h t l y a ppressed a compression wound can r e s u l t i n the a r e a of c o n t a c t , thus f u r t h e r f a c i l i t a t i n g spread of mycelium between them (Redmond 1957, Whitney 1961). Given s u f f i c i e n t p r e c i p i t a t i o n i n the l a t e summer to e a r l y f a l l , s porophores and b a s i d i o s p o r e s are produced i n abundance. Sporophores can be s t i p i t a t e or s e s s i l e . There i s e v i d e n c e t o suggest t h a t sporophore h a b i t may d i f f e r between I . tomentosus and c i r c i n a t u s . Inonotus c i r c i n a t u s tends to produce s e s s i l e sporophores w h i l e tomentosus produces mainly s t i p i t a t e sporophores (Whitney 1977). I n f e c t i o n by s p o r e s i n nature has not been demonstrated. The chances of o b s e r v i n g such an event, however, are very s l i m g i v e n the s m a l l number of new spore induced i n f e c t i o n s l i k e l y t o occur over a year i n a g i v e n s t a n d . The c o n t i n u e d p r o d u c t i o n of sporophores, the u b i q u i t o u s nature of t h i s 18 fungus and the presence of new i n f e c t i o n centers bearing no apparent h i s t o r i c a l i n f e c t i o n sources , suggest that some i n f e c t i o n centers must be i n i t i a t i e d by b a s i d i o s p o r e s . However, the frequency (and thus the importance) of t h i s event i s often quest ioned. There i s some i n d i r e c t evidence which suggests spread by spores may be a common event . Inonotus tomentosus has been reported in a number of p l a n t a t i o n s in Wisconsin a l l of which were loca ted on o l d c u l t i v a t e d f i e l d s (Barnard et a l 1985). The l e v e l s of i n f e c t i o n and the number of i n d i v i d u a l i n f e c t i o n centers reported in t h i s study, in the absence of i n f e c t e d stumps or roots from a previous r o t a t i o n , s t r o n g l y suggest that bas id iopores play an important and frequent ro le in spread of t h i s fungus. The avenue of i n f e c t i o n by bas id iospores i s a l s o in q u e s t i o n . Cut stumps have not been shown to be i n f e c t i o n cour ts (Barnard e_t al_ 1985, Whitney 1966). In a r t i f i c i a l i n o c u l a t i o n s t u d i e s , wounding of roots to the cambium or deeper was found necessary for s u c c e s s f u l i n o c u l a t i o n with bas id iospores (Whitney 1963, Whitney 1966). If e x t r a p o l a t i o n of these r e s u l t s to na tura l c o n d i t i o n s i s v a l i d , a source of wounding would be requi red for bas id iospore i n f e c t i o n . Animal t rampl ing , compression wounds, excessive mois ture , root feeding organisms, basal cankers of Cronartium 19 fusiforme (Cumm.) Hedge, and Hunt and root deformation due to improper p lan t ing procedures have been suggested as s u i t a b l e wound causing agents (Redmond 1957, K r e b i l l 1962, Whitney 1961, Boyce 1963). In fec t ion of in jured subterranean roots requ i res spores to be washed or otherwise c a r r i e d through the s o i l . Spore c a r r i e r s could include root feeding insec ts ( e s p e c i a l l y Hylobius warren i ) , s q u i r r e l s , vo les or just ra in water. The capac i ty of these bas id iospores for s u r v i v a l dur ing t ransport into the s o i l i s c l e a r l y ev iden t . Bas id iospores of Heterobasidion annosum (Fr . ) B r e f . can surv ive and remain v i a b l e in the s o i l (Kuhlman 1969). Whitney (1966), reported that spores of I_j_ tomentosus remained v i a b l e a f t e r storage at -18 deg. C and a f te r severa l c y c l e s of f r e e z i n g and thawing. Resistance to c o l d temperatures would al low for germination and i n f e c t i o n in the spr ing fo l lowing spore d i s p e r s a l in the f a l l and overwinter ing in the s o i l . The r o l e of wounding in e i t h e r spread mechanism would seem to be a combination of two f a c t o r s : f i r s t ; the p r o v i s i o n of a p h y s i c a l avenue in to the t r e e ' s t i s s u e and second; the c rea t ion of low v igour host t i s s u e in the v i c i n i t y of the wound. K r e b i l l (1962) and Whitney (1960 and 1961), suggest that the ro le of wounds in p rov id ing avenues 20 of i n f e c t i o n seems t o l i e i n the l a t t e r f a c t o r r a t h e r t h a t the former. 4. ECOLOGY Data r e g a r d i n g the a u t e c o l o g y of I_j_ tomentosus comes from o b s e r v a t i o n s of the fungus i n c u l t u r e and i n c i d e n c e s t u d i e s i n the f i e l d . Both s o u r c e s p r o v i d e i n d i r e c t evidence which must be e x t r a p o l a t e d t o f u n g a l e c o l o g y i n n a t u r e . Important f a c t o r s a f f e c t i n g mycelium growth i n c u l t u r e are pH and temperature. In c u l t u r e , tomentosus and I .  c i r c i n a t u s have been found t o grow best on a c i d i c media (Whitney 1962b). Whitney and Bohaychuk (1977), found t h a t a temperature of a p p r o x i m a t e l y 20 degrees C. was best f o r m y c e l i a l growth. F i e l d s t u d i e s have l i n k e d a number of s i t e f e a t u r e s to hi g h i n c i d e n c e s of I_j_ tomentosus ro o t d i s e a s e . G e n e r a l l y , s h a l l o w , sandy s o i l s which have a t h i c k humus l a y e r (mor humus form), low pH, are e x c e s s i v e l y d r a i n e d and are s u b j e c t to p e r i o d i c drought are h i g h r i s k a r e a s (Whitney 1962). T h i c k , moist (mor) humus forms favour b e e t l e s of the H y l o b i u s complex (Warren 1956). Thus, a mor humus might 21 therefore a f f e c t tomentosus incidence through i t s e f f e c t s on the number of avenues of i n f e c t i o n . A l t e r n a t i v e l y , mor humus forms are often i n d i c a t i v e of slow nu t r i en t turnover and consequently poor s o i l nu t r ien t c o n d i t i o n s . Such cond i t ions could cause tree s t r e s s which may predispose them to i n f e c t i o n . In f a c t , at tack by warreni could a l s o s t r e s s the t ree and cause p r e d i s p o s i t i o n . Thus the mechanism behind t h i s a s s o c i a t i o n i s u n c l e a r . Fac tors such as humus type and water d e f i c i e n t s o i l s may re la te more to t ree s t r e s s p r e d i s p o s i t i o n than to fungal eco logy . S i m i l a r l y , s o i l shal lowness probably has i t s main e f f e c t through p rov id ing a higher propor t ion of root contacts and wounds ( e s p e c i a l l y compression wounds) and thus f a c i l i t a t i n g spread of the fungus (Myren and Patton 1971). The f i n d i n g s regarding pH agree with s tud ies of the fungus in c u l t u r e . Stands with low s o i l pH (down to 4.5) were most heav i l y a f f l i c t e d while those with a s o i l pH of 7 or higher showed no s i g n i f i c a n t damage (Van Groenewoud 1956). Whitney (1962), found that I^  tomentosus had a compet i t ive advantage at temperatures below 20 degrees C. Th is a b i l i t y to t h r i v e at lower temperatures has been postu la ted as an important fac tor in determining the fungus' geographic and e l e v a t i o n a l d i s t r i b u t i o n (Hobbs and Par t r idge 1979). The mechanisms behind the e f f e c t s of s o i l texture have not been c l e a r l y demonstrated. While sandy s o i l s represent high hazard the 22 reason f o r t h i s i s u n c l e a r . I t c o u l d be r e l a t e d t o drainage or a v a i l a b i l i t y of a i r or other pore s i z e e f f e c t s i n c l u d i n g the a s s o c i a t e d n u t r i e n t l e v e l . Such f a c t o r s c o u l d e x e r t t h e i r i n f l u e n c e d i r e c t l y on f u n g a l v i t a l i t y or i n d i r e c t l y through t r e e s t r e s s or m i c r o b i a l c o m p e t i t i o n e f f e c t s . 5. D A M A G E D i r e c t damage by I ^ tomentosus can take four forms: l i v e windthrow, s t a n d i n g m o r t a l i t y , increment r e d u c t i o n and b u t t c u l l . a. WINDTHROW L i v e windthrow i s the predominant i n d i c a t o r of the presence, of tomentosus i n the f i e l d . Windthrow due to r o o t d i s e a s e r e s u l t s from the decay of major s u p p o r t i n g r o o t s . Rotten r o o t s o f f e r l i t t l e s t r u c t u r a l s u p p o r t . The r e s u l t i n g i n s t a b i l i t y of the t r e e r e s u l t s i n i t s t o p p l i n g i n v e r y l i t t l e wind. T h i s e v e n t u a l l y r e s u l t s i n areas of windthrows which have f a l l e n i n a l l d i r e c t i o n s . T h i s m u l t i - d i r e c t i o n a l f a l l i n g , a l o n g w i t h the s m a l l amount of root mass exposed, ( F i g u r e 1) d i s t i n g u i s h e s r o o t d i s e a s e induced windthrow from g a l e winds. In spruce, windthrow can occur w i t h l i t t l e apparent THE QUALITY OF THIS MICROFICHE IS HEAVILY DEPENDENT UPON THE QUALITY OF THE THESIS SUBMITTED FOR MICROFILMING. LA QUALITE DE CETTE MICROFICHE DEPEND GRANDEMENT DE LA QUALITE DE LA THESES SOUMISE AU MICROFILMAGE. UNFORTUNATELY THE COLOURED ILLUSTRATIONS OF THIS THESIS CAN ONLY YIELD DIFFERENT TONES OF GREY. MALHEUREUSEMENT, LES DIFFERENTES ILLUSTRATIONS EN COULEURS DE CETTE THESES NE PEUVENT DONNER QUE DES TEINTES DE GRIS. 23 Figure 1 Exposed root b a l l of an i n t e r i o r spruce in an I_. tomentosus i n f e c t i o n c e n t e r . 24 r e d u c t i o n i n crown v i g o r . T r e e s are o f t e n green and a p p a r e n t l y q u i t e h e a l t h y when they f a l l . T h i s i s due i n a l a r g e p a r t t o the p a t t e r n of decay i n l a r g e spruce r o o t s . Q u i t e o f t e n , e x t e n s i v e l y decayed r o o t s w i l l s t i l l have a t h i n s h e l l of l i v i n g t i s s u e s u r r o u d i n g the decayed xylem ( M e r l e r 1984). In a d d i t i o n , a d v e n t i t i o u s r o o t s may be produced to r e p l a c e those k i l l e d ( M e r l e r 1984). Assessment of the impact of windthrow on the merchantable volume of a stand i s d i f f i c u l t . M e r l e r (1984) e s t i m a t e d 1% annual l o s s t o tomentosus induced windthrow i n s i x stands i n the i n t e r i o r of B.C. T h i s e s t i m a t e was a d m i t t e d l y crude as i t was made from one y e a r ' s o b s e r v a t i o n s and t h e r e f o r e an a c c u r a t e p i c t u r e of the r a t e of windthrow over time c o u l d not be o b t a i n e d . Whitney (1978), r e p o r t e d annual I_j_ tomentosus induced m o r t a l i t y and windthrow at 2.7% f o r 75 year o l d b l a c k spruce and 1.1% f o r 64 yea r o l d white s p r u c e . P r o l o n g e d l o s s e s of t h i s magnitude c o u l d prevent such stands from ever p r o d u c i n g a merchantable y i e l d . b. STANDING MORTALITY St a n d i n g m o r t a l i t y o c c u r s when the r o o t system of the t r e e has been k i l l e d t o an ext e n t which p r e v e n t s i t from meeting the m o i s t u r e and n u t r i e n t a b s o r p t i o n r e q u i r e m e n t s of the t r e e . Such m o r t a l i t y w i l l o b v i o u s l y be hastened on droughty 25 s i t e s or i f the tree i s otherwise s t ressed by b i o t i c or a b i o t i c agents. Whitney (1978) l i s t s shal low, a c i d , sandy s o i l s with deep humus that are subject to high moisture d e f i c i t s as being most conducive to standing m o r t a l i t y . However, these s o i l f ac to rs are probably promoting mor ta l i ty in d i f f e r e n t ways. Shallow s o i l s have been postu la ted to promote i n f e c t i o n due to increased root wounding. Ac id c o n d i t i o n s ( s o i l ) are conducive to tomentosus growth (Whitney 1960). These fac to rs l i k e l y exert t h e i r e f f e c t s on out r ight m o r t a l i t y through promotion of i n f e c t i o n and pathogen spread. Sandy s o i l s may a c t u a l l y ind ica te a low s o i l nu t r i en t content and excessive dra inage. These fac tors may be i n f l u e n c i n g the rate of mor ta l i t y through s t r e s s e f f e c t s on the t r e e . Attack by bark beet les or other insect pests could a lso be expected to hasten t ree m o r t a l i t y . Such mor ta l i t y may, in some instances be a t t r i b u t e d s o l e l y to the more obvious (above ground) p e s t . Such an assessment could r e s u l t in underest imation of the impact of tomentosus. c . BUTT CULL Inonotus tomentosus decay often extends in to the butt and the bole of severe ly in fec ted t r e e s . Decay commonly extends one to two meters in to the bole and can extend as high as four meters (Whitney 1978). Losses due to decay can be s u b s t a n t i a l . Whitney (1978), found that about 4.4% and 3.2% 26 of the gross merchantable volume were l o s t to tomentosus butt c u l l in northern Ontar io black and white spruce stands r e s p e c t i v e l y . Losses of t h i s type in jack pine and eastern white pine (P_j_ strobus L.) were found to be much lower (0.3%). While butt and stem decay are accounted for in y i e l d p r e d i c t i o n s , the propor t ion due to tomentosus i s unc lea r . Th is i s important s ince tomentosus as a root rot w i l l requ i re d i f f e r e n t management than decays and heart r o t s . As w e l l , while decay and heart rot losses may be expected to decrease sharply with short second growth r o t a t i o n s , t h i s may not be true for tomentosus. d . INCREMENT REDUCTION As p r e v i o u s l y s t a t e d , K. tomentosus d i s r u p t s and k i l l s root bark and cambium and induces decay of the xylem. Defense r e a c t i o n s to i n f e c t i o n and the product ion of advent i t ious roots u t i l i z e energy which might otherwise be put in to incremental growth. As w e l l , a l o s s of conduct ive t i s s u e can impair water and nut r ien t uptake of the t r e e . Such s t r e s s would l o g i c a l l y be expected to r e s u l t in a decreased growth r a t e . Thus, as more and more of the root system i s a t tacked , a gradual reduct ion (over 15-20 years) in t ree growth occurs (Whitney 1962b). Merler (1984), reported a reduct ion of 20% in the 27 l a t e s t f i v e year increment of d iseased white spruce t rees aged 30 to 65 years . On a per stand b a s i s , Whitney (1978), reported annual increment reduct ions of 0.11% in white spruce stands sampled and 0.52% in black spruce s tands. While these annual reduct ions appear i n s i g n i f i c a n t , such losses are cumulative and thus represent s u b s t a n t i a l losses over a r o t a t i o n . The type of m o r t a l i t y which occurs w i l l , to some extent depend on the inoculum p o t e n t i a l of the fungus. Where growing cond i t ions for the fungus are optimum, more r a p i d death may be expected and thus more standing m o r t a l i t y , and a shorter per iod of increment reduct ion p r i o r to m o r t a l i t y . The age of the in fec ted tree could a l s o be expected to a f f e c t i t ' s symptom development (and thus the type of l o s s i n c u r r e d ) . Younger, smal ler t rees may be expected to show above ground symptoms sooner due to younger, smal ler root systems. Th is would l i k e l y r e s u l t in swi f te r mor ta l i t y and hence more standing m o r t a l i t y and a r e l a t i v e l y short per iod of increment r e d u c t i o n . e. INDIRECT LOSSES There are a lso i n d i r e c t sources of damage assoc ia ted with I.  tomentosus. Dendroctonus r u f i p e n n i s Ki rby (spruce bark b e e t l e ) , uses w i n d f a l l t rees to b u i l d up i t s popula t ions 28 before l i v i n g t rees are at tacked (Dyer and Tay lor 1971). Such t rees are suppl ied in abundance by tomentosus in many areas of B . C . As w e l l , spread to l i v i n g t rees may be f a c i l i t a t e d by the presence of tomentosus s t ressed trees in the immediate v i c i n i t y . Thus tomentosus can be seen as an accomplice in spruce bark beet le a t t a c k . A l e s s d i s t i n c t r e l a t i o n s h i p e x i s t s between I.  tomentosus and Hylobius warreni (Warren's c o l l a r w e e v i l ) . Strong c o r r e l a t i o n s between the inc idences of these two pests have been reported ( K r e b i l l 1962, Whitney 1961). However, the nature of the r e l a t i o n s h i p between the two has not been c l e a r l y demonstrated. Warren's c o l l a r weevi ls tunnel in to the root c o l l a r causing bark mor ta l i t y and can eventua l ly g i r d l e (and thus k i l l ) the t r e e . Ser ious weevi l a t tack undoubtedly weakens the t ree perhaps depr iv ing i t of any r e s i s t a n c e mechanisms to i n f e c t i o n by tomentosus. A l t e r n a t i v e l y , advanced i n f e c t i o n by 1^ tomentosus weakens the host t ree and can cause r e s i n o s i s . Exudations from such t rees may" a t t r a c t Warren's c o l l a r w e e v i l s . Once a t t r a c t e d , the weakened state of the t ree may i n h i b i t p i t c h i n g out and thus c l e a r the way for insect a t t a c k . 6. VARIABILITY OF INONOTUS TOMENTOSUS 29 Inonotus tomentosus has long been r e c o g n i z e d as a h i g h l y v a r i a b l e fungus. So much so t h a t a number of s t r a i n s or v a r i e t i e s have been proposed t o e x p l a i n i t s d i v e r s i t y ( G o s s e l i n 1944, Haddow 1941). Haddow (1941) s t a t e s : " c u l t u r a l experiments have shown t h a t each form (P.  tomentosus and P_j_ tomentosus v a r . c i r c i n a t u s ) c o m prises s e v e r a l s t r a i n s which d i f f e r c o n s p i c u o u s l y among themselves i n c u l t u r a l c h a r a c t e r i s t i c s " . However, f u r t h e r e l a b o r a t i o n on these s t u d i e s i s l a c k i n g and no p u b l i c a t i o n s of these data were c i t e d . Haddow may i n f a c t have been r e f e r r i n g t o work done by S a r t o r y and M a i r e (1922), i n which s e v e r a l v a r i e t i e s of P_j_ tomentosus were proposed. More r e c e n t l y , Whitney and Bohaychuk (1977), s t u d i e d the v a r i a t i o n of I .  tomentosus i n c u l t u r a l c h a r a c t e r i s t i c s and p a t h o g e n i c i t y on c o n i f e r s e e d l i n g s . C l u s t e r a n a l y s i s r e s u l t e d i n mat c o l o r , chlamydospore p r o d u c t i o n , p a t h o g e n i c i t y and growth r a t e s h a r i n g s i g n i f i c a n t v a r i a t i o n among i s o l a t e s . T h i s v a r i a b i l i t y may s i g n i f y a number of s t r a i n s w i t h i n one or both of the r e c o g n i z e d s p e c i e s . Such s t r a i n s would be of g r e a t s i l v i c u l t u r a l importance i f s i g n i f i c a n t d i f f e r e n c e s i n p a t h o g e n i c i t y e x i s t s between them. I t i s g e n e r a l l y a c c e p t e d t h a t c i r c i n a t u s i s l e s s p a t h e n o g e n i c . I f so, 30 c o n t r o l of l o s s e s i n second growth stands c o u l d be achieved by i d e n t i f y i n g the s p e c i e s or s t r a i n present and p l a n t i n g species o u t s i d e of the fungus' host range. M e r l e r (1984) hypothesized that tomentosus may comprise a number of s t r a i n s , each s p e c i f i c to one or a very few s p e c i e s w i t h i n the o v e r a l l host range. T h i s p o s t u l a t i o n was prompted by the absence of tomentosus i n f e c t i o n on pines and subalpine f i r (Abies l a s i o c a r p a (Hook.) N u t t . ) , on h i s study s i t e s d e s p i t e these species being r e p o r t e d as hosts elsewhere i n Canada. S t r a i n s of H e t e r o b a s i d i o n annosum have been documented. More i m p o r t a n t l y , these s t r a i n s have s i g n i f i c a n t l y d i f f e r e n t p a t h o g e n i c i t y and host s p e c i e s ranges (Korhonen 1978). As w e l l , A r m i l l a r i a mellea sensu l a t o has r e c e n t l y been shown to be a number of d i f f e r e n t s p e c i e s , each w i t h d i f f e r e n t host ranges and p a t h o g e n i c i t i e s (Morrison et a l 1985). Thus, i t can be seen that the precedent has a l r e a d y been set and that the v a r i a b i l i t y of IN tomentosus may be e x p l a i n e d by the e x i s t e n c e of s t r a i n s or v a r i e t i e s . V a r i a t i o n i n tomentosus root r o t behaviour has been o f f i c i a l l y recognized w i t h the v a r i e t y c i r c i n a t u s (now a separate s p e c i e s ) . Aside from the d i f f e r e n c e i n setae shape, 1^ c i r c i n a t u s has a l s o been shown t o be somewhat l e s s pathogenic on s e e d l i n g s and f a s t e r growing i n c u l t u r e (Whitney and Bohaychuk 1977). 31 B. METHODS 1. SELECTION OF SITES AND PLOT LOCATION Twenty p l o t s were sampled i n the Sub-boreal Spruce b i o g e o c l i m a t i c zone (SBS), of n o r t h c e n t r a l B r i t i s h Columbia ( F i g u r e s 2 and 3, T a b l e 5 ) . Candidate stands were s e l e c t e d from f o r e s t cover maps of the P r i n c e George E a s t and West D i s t r i c t s of the P r i n c e George F o r e s t Region and the M o r i c e , Lakes and B u l k l e y D i s t r i c t s of the P r i n c e Rupert F o r e s t Region. Inonotus tomentosus i n f e c t e d mixed l o d g e p o l e p i n e and i n t e r i o r spruce stands between 50 and 100 y e a r s were d e s i r e d . S i n c e f o r e s t cover maps do not show i n f e c t i o n s t a t u s , c a n d i d a t e stands were surveyed f o r the presence of I. tomentosus roo t r o t p r i o r t o b e i n g s e l e c t e d f o r sampling. P l o t s were c i r c u l a r and were p o s i t i o n e d t o encompass an I .  tomentosus i n f e c t i o n c e n t e r . In each p l o t , a t l e a s t ten c h a l l e n g e d t r e e s of both spruce and p i n e were r e q u i r e d . A c h a l l e n g e d t r e e was d e f i n e d as a t r e e which o c c u r r e d w i t h i n t h r e e meters of an i n f e c t e d t r e e or which was found (upon e x c a v a t i o n ) t o have r o o t c o n t a c t w i t h an i n f e c t e d r o o t . The s i z e of the i n f e c t i o n c e n t e r was t e n t a t i v e l y e s t i m a t e d u s i n g above ground symptoms (where expressed) and c u r s o r y r o o t e x a m i n a t i o n s . P l o t s were l o c a t e d w i t h i n c e n t e r s t o ensure t h a t a l l t r e e s w i t h i n the p l o t had a r e a s o n a b l y h i g h chance F i g u r e 2. L o c a t i o n of Study S i t e s l n the P r i n c e George F o r e s t Region. S c a l e = 1:300,000 Figure 3 . Locat ion res t Region of study s i t e s In the Pr ince Rupert Table 5 Stand Age, Region and Biogeoclimatic Classification of Sample Sites Site no. Stand age Region Subzone Association * or Variant 1 105 PG ** SBSK3 04.1 2 88 PG SBSK3 04.1 3 103 PG SBSK3 01 4 75 PG SBSK3 04.1 5 50 PG SBSe2 01 6 54 PG SBSe2 01 7 110 PG SBSe2 04 8 104 PG SBSe2 01 9 45 PG SBSe2 04 10 52 PG SBSe2 01 11 50 PG SBSe2 01 12 86 PR SBSel 04 13 87 PR SBSel 01 14 90 PR SBSel 04 15 80 PR SBSel 01 16 73 PR SBSd 08 17 74 PR SBSel 04 18 54 PR SBSd 07 19 54 PR SBSd 07 20 87 PR SBSel 01 * described in Appendix B ** PG = Prince George PR = Prince Rupert 35 of contact ing inoculum (and thus becoming i n f e c t e d ) . Plot s i z e was 0.049 ha (12.5 m radius) or 50 t rees (spruce and p i n e ) , whichever was l e s s . 2. DATA COLLECTION Each main canopy tree in each p lo t was marked with a number. A c e n t r a l t r e e , approximating the center of the i n f e c t e d area was des ignated . The center t ree was taken to be the tree which showed most advanced symptoms of I.  tomentosus root r o t . Th is c e n t r a l t ree served as a reference point from which the other t rees in the p lo t were mapped. Th is was accomplished using d is tances and compass readings from the c e n t r a l t r e e . On each t r e e , three major roots were sampled within 30 cm of the b o l e . Sampling involved d r i l l i n g a 3/8 inch diameter hole in each root using an Atom D r i l l attachment for a chainsaw. Inonotus tomentosus i n f e c t i o n was i n d i c a t e d by red s ta ined wood ch ips or white p i t t e d , rot ted wood. Root excavat ions were performed and samples taken for c u l t u r i n g where any doubt regarding the i n f e c t i o n status of a t ree e x i s t e d . Trees designated as healthy upon d r i l l sampling were not excavated. A number of samples were c o l l e c t e d from s ta ined and r o t t e d roots in each p l o t for i s o l a t i o n and study of c h a r a c t e r i s t i c s in c u l t u r e . 36 Each p l o t map was examined to r e d e f i n e the c e n t e r w i t h i n . Trees suspected of being o u t s i d e the i n f e c t i o n c e n t e r were re-examined. Suspect t r e e s were those which were more t h a t t h r e e meters away from any a d j a c e n t , i n f e c t e d t r e e s and which had no i n f e c t e d t r e e s f u r t h e r away from the c e n t e r than themselves. Such t r e e s were noted and were checked f o r r o o t c o n t a c t s w i t h an I ^ tomentosus i n f e c t i o n source when the p l o t s were r e - e n t e r e d . Where no c o n t a c t with a d i s e a s e d t r e e was found, the t r e e was removed from the p l o t . For each p l o t the v e g e t a t i o n was c l a s s i f i e d t o e c o l g i c a l a s s o c i a t i o n u s i n g the b i o g e o c l i m a t i c e c o l o g i c a l c l a s s i f i c a t i o n system ( K r a j i n a 1965). S i t e f e a t u r e s of the a r e a were r e c o r d e d . A s o i l p i t was excavated and depth and t e x t u r e were r e c o r d e d by h o r i z o n i n the f i e l d . S o i l samples were c o l l e c t e d f o r d e t e r m i n a t i o n of pH. Measurements of the h e i g h t and age of the main canopy were taken u s i n g a c l i n o m e t e r and increment b o r e r . In 10 p l o t s , up t o 20 t r e e s were s e l e c t e d a t random and diameter measurements and increment bores were taken from them. 3. HOST SPECIES SUSCEPTIBILITY For each s p e c i e s w i t h i n each p l o t , the number of i n f e c t e d t r e e s was t o t a l l e d and d i v i d e d by the t o t a l number of c h a l l e n g e d t r e e s ( h e a l t h y and i n f e c t e d ) , of t h a t s p e c i e s , 37 wi th in the p l o t . Th is propor t ion represented the i n f e c t i o n rate for the spec ies in that p l o t . Root excavat ions were performed on se lec ted t rees to determine whether root contac ts or g r a f t s e x i s t e d and to study the growth and spread behaviour of the d i s e a s e . Observat ions of the e t i o l o g y and induced symptomology of t h i s pathogen were made and any v a r i a b i l i t y in behaviour with t ree spec ies or geographica l l o c a t i o n was noted. A t - t e s t and an a n a l y s i s of var iance were performed to determine i f geographica l l o c a t i o n or e c o l o g i c a l c l a s s i f i c a t i o n a f f e c t e d the d i f f e r e n c e s between i n f e c t i o n ra tes of pine and spruce on each s i t e . I n f e c t i o n ra tes (within centers) were compared for the two spec ies using a pa i red sample t - t e s t (with each p l o t being one p a i r ) . As i t was b e l i e v e d that the i n f e c t i o n ra tes of the two spec ies wi th in each p lo t were not independent, a non-parametr ic test was performed to compare i n f e c t i o n ra tes by spec ies and by s i t e . A Wi lcox in matched p a i r s tes t was performed to determine i f i n f e c t i o n ra tes wi th in centers ( s i t e s ) were equal for pine and spruce . These analyses were performed using the MIDAS (Fox and Guire 1976) and SPSS.X (Lai 1983) s t a t i s t i c a l packages on the UBC MTS mainframe computer. 4. EFFECT OF INFECTION ON INCREMENT 38 One hundred and e l e v e n 1/4 i n c h increment bores were taken at b r e a s t h e i g h t from h e a l t h y and d i s e a s e d spruce and pine t r e e s i n the P r i n c e George and P r i n c e Rupert F o r e s t Regions. A l l bores were taken from the n o r t h s i d e of the t r e e . Where o b s t r u c t i o n s e x i s t e d , the sample was taken as c l o s e t o the n o r t h s i d e as p o s s i b l e . Each bore was s t o r e d i n a p l a s t i c straw u n t i l measurements c o u l d be made. The diameter a t b r e a s t h e i g h t and the i n f e c t i o n s t a t u s of each t r e e were noted. The age was determined and the l a s t f i v e y e a r s increment was measured u s i n g an Addo-X measurer. Only the l a s t f i v e y e a r s were used as t h i s was the maximum p e r i o d over which the i n f e c t i o n s t a t u s of the t r e e c o u l d be assumed to have been c o n s t a n t . Where bo l e decay o c c u r r e d at b r e a s t h e i g h t , the increment sample was d i s c a r d e d s i n c e the t r e e ' s age c o u l d not be determined. The b a s a l area increment over the l a s t f i v e y e a r s was c a l c u l a t e d from the r a d i a l increment. A t w o - f a c t o r a n a l y s i s of v a r i a n c e was performed f o r each s p e c i e s . B i o g e o c l i m a t i c subzone and i n f e c t i o n s t a t u s were used as f a c t o r s . Tree age and t r e e diameter were t e s t e d f o r p o s s i b l e i n c l u s i o n as c o v a r i a t e s . B a s a l a r e a increment was the independant v a r i a b l e . The a n a l y s e s of v a r i a n c e were performed u s i n g the 39 GENLIN s t a t i s t i c a l package (Greig and B j e r r i n g 1980) on the UBC MTS mainframe. 5. CULTURAL IDENTIFICATION AND DESCRIPTION Rotted and/or s ta ined wood was c o l l e c t e d from each host spec ies on each s i t e for i s o l a t i o n and i d e n t i f i c a t i o n in c u l t u r e . Samples from each s i t e were subsequently stored at 1 degree C e l s i u s for 3 months. The samples were then removed from c o l d storage and c u l t u r e s of I_j_ tomentosus on 3% malt agar in d isposable 100 X 15 mm p e t r i p la tes were obtained from each. I d e n t i f i c a t i o n s of I_j_ tomentosus were made using Nobles I d e n t i f i c a t i o n of Cu l tu res of Wood Rot t ing Fungi (1948). Each cu l tu re was stored in the dark for ten days at room temperature at which time the growth margin was de l im i ted on the bottom of the p e t r i d i s h with an i n d e l i b l e marker. The growth margin was again de l im i ted at 20 and 30 days . The average of the two r a d i a l increments was then used to c a l c u l a t e the growth rate ( in mm per day) for each i s o l a t e . Mat co lo r and changes there in were recorded concurrent ly with growth margin d e l i n e a t i o n . Mat c o l o r and growth c h a r a c t e r i s t i c s of each i s o l a t e were then compared to those of other i s o l a t e s . C . RESULTS AND DISCUSSION 4 0 1. ETIOLOGY D i f f e r e n c e s were noted i n the behaviour and appearance of tomentosus between the two h o s t s s t u d i e d . On the spruce s t u d i e d the presence of the d i s e a s e was f i r s t d e t e c t a b l e as a l i g h t r e d s t a i n a t or near the c e n t e r of the r o o t s ( F i g u r e 4 ) . T h i s red s t a i n i n g i n the i n n e r xylem t i s s u e became p r o g r e s s i v e l y d a r k e r as the o r i g i n of i n f e c t i o n was approached. Such s t a i n p r o g r e s s e d t o a r u s t y brown c o l o r i n which white and then y e l l o w i s h p i t t i n g was c l e a r l y e v i d e n t ( F i g u r e 5 ) . Advanced r o t had l a r g e p i t s with white mycelium ( F i g u r e 6 ) . O f t e n e a r l y t o advanced r o t was p r e s e n t throughout the r o o t system even though the o u t e r c o n d u c t i v e t i s s u e was a l i v e . Such r o o t s p r o v i d e d l i t t l e s t r u c t u r a l support to the t r e e . They appeared, however, to p r o v i d e the t r e e w i t h s u f f i c i e n t water and n u t r i e n t s to m a i n t a i n an a p p a r e n t l y h e a l t h y crown. In c a s e s where severe decay o c c u r r e d , a d v e n t i t i o u s r o o t s were o f t e n abundant at the r o o t c o l l a r . In some ca s e s , mycelium p r o g r e s s e d a l o n g and i n the r o o t cambium. T h i s caused d i s r u p t i o n of the cambium and r e s u l t e d i n n e c r o s i s of phloem t i s s u e . Mycelium o c c u r r e d i n patches of v a r i o u s s i z e s or a c o n t i n u o u s mat. The mycelium was creamy white and f l a k e - l i k e . In p l a c e s 41 F i g u r e 4 L i g h t r e d s t a i n i n i n f e c t e d p i n e w i t h l_. tomentosus. 42 43 44 mycelium adhered to or grew i n t o the s o i l c a u s i n g hardened clumps of s o i l on the r o o t s u r f a c e . T h i s h a b i t of a d h e r i n g t o the s o i l tended to mask the presence of the mycelium. In the l a t e r s t a g e s of decay, the mycelium formed sheets between the bark and xylem s h i c h were e a s i l y s e p a r a t e d from the wood. The presence of mycelium d i d not n e c e s s a r i l y precede or f o l l o w severe s t a i n i n g and r o t t i n g of the i n n e r xylem. In some c a s e s , e x t e n s i v e s t a i n i n g and p i t t i n g was p r e s e n t without any s u r f a c e mycelium. C o n v e r s e l y , many r o o t s had e x t e n s i v e m y c e l i a l growth i n and on the r o o t bark and l i g h t or no apparent r o o t s t a i n i n g . The type of m y c e l i a l development appeared t o be r e l a t e d t o r o o t diameter. I t appeared ( a l t h o u g h no q u a n t i t a t i v e data was recorded) t h a t medium s i z e d and s m a l l r o o t s ( a p p r o x i m a t e l y 12 cm diameter and l e s s ) sometimes e x p e r i e n c e d c o n c u r r e n t i n t e r n a l and c a m b i a l f u n g a l p r o g r e s s i o n w h i l e l a r g e r r o o t e x p e r i e n c e d i n t e r n a l a t t a c k o n l y and had l i v i n g cambium. T h i s was o n l y an observed t r e n d . E x c e p t i o n s were p r e s e n t and the c u t o f f diameter (12 cm) between c l a s s e s i s a d m i t t e d l y v e r y approximate. M e r l e r (1984) a l s o found c o r r e l a t i o n s between r o o t diameter and d i s e a s e b e h a v i o u r . The fungus was found t o be unable t o p e n e t r a t e the t h i c k bark of l a r g e r o o t s . I n s t e a d p r o g r e s s i o n from a column of decay i n the stump t o a h e a l t h y 45 root o c c u r r e d i n the xylem and cambium u n t i l a t a diameter of a p p r o x i m a t e l y f i v e cm the fungus was a b l e to p e n e t r a t e the bark and grow al o n g the s u r f a c e . The r e v e r s e o r d e r was observed p r o x i m a l l y as the fungus approached the b u t t . These b e h a v i o u r a l t r e n d s , a l o n g with those d i s c o v e r e d i n t h i s study, suggest t h a t i n f e c t i o n through s m a l l e r diameter r o o t s p r o g r e s s e s i n t e r n a l l y ( i n the xylem and cambium) and s u r f i c i a l l y . Beyond a c e r t a i n r o o t diameter e x t e r n a l p r o g r e s s i o n c e a s e s . Near the r o o t c o l l a r , the d i s e a s e i s no l o n g e r a b l e t o c o l o n i z e the cambium of the l a r g e diameter r o o t s . The fungus appears on or near the s u r f a c e of a l a r g e r o o t o n l y a f t e r the c e n t e r of the r o o t i s i n advanced stages of c o l o n i z a t i o n ( d a r k l y s t a i n e d or r o t t e d ) . In many of the study p l o t s the d i s e a s e m a n i f e s t e d i s e l f d i f f e r e n t l y i n p i n e . Both below ground behaviour and above ground symptomology d i f f e r e d . While a l i g h t s t a i n i n g of the xylem was a g a i n p r e s e n t , as one p r o g r e s s e d toward the o r i g i n of i n f e c t i o n only a medium s t a i n i n g o c c u r r e d b e f o r e the o u t e r sapwood and cambium were k i l l e d . T h i s was o f t e n a s s o c i a t e d w i t h r e s i n s o a k ing of the r o o t t i s s u e s . Such r o o t s were c h a r a c t e r i s t i c a l l y q u i t e b r i t t l e . T h i s c o p i o u s p r o d u c t i o n of r e s i n d i d not appear t o be e f f e c t i v e i n s t o p p i n g the p r o g r e s s i o n of the fungus. Inonotus tomentosus was commonly i s o l a t e d from w i t h i n r e s i n soaked wood and 46 p r o g r e s s i o n of the fungus was apparent. L i t t l e or no decay was observed i n these r o o t s . I t i s p o s s i b l e , however, t h a t decay o c c u r r e d i n s m a l l l a t e r a l r o o t s ( l e s s than 1 cm d i a m e t e r ) , which were l e f t i n the s o i l or ot h e r w i s e obscured d u r i n g the e x c a v a t i o n . A lthough l i t t l e or no s i g n of mycelium was noted at the time of e x c a v a t i o n , mycelium and what appeared t o be rudimentary f r u i t i n g b o d i e s appeared on and i n many of the r o o t s a f t e r two months s t o r a g e a t 1 degree C e l s i u s . T h i s form of a t t a c k i n pin e r e s u l t e d i n obvious above ground symptoms i n d i s e a s e d t r e e s . I n f e c t e d p i n e s showed pronounced crown t h i n n i n g and e v e n t u a l m o r t a l i t y ( F i g u r e 7 ) . Trees k i l l e d i n t h i s manner u s u a l l y d i e d s t a n d i n g , presumably due to the f a c t t h a t decay of the main s u p p o r t i v e r o o t s had not o c c u r r e d . A f t e r death of the h o s t , d r y i n g and i n v a s i o n of t r e e t i s s u e s by saprophytes appeared t o prevent u t i l i z a t i o n of the t i s s u e by I_;_ tomentosus. Thus the c h a r a c t e r i s t i c p i t t e d r o t and p r o d u c t i o n of f r u i t i n g b o d ies d i d not o c c u r . In t h r e e s i t e s i n the P r i n c e George r e g i o n and i n many of the P r i n c e Rupert s i t e s , pine d i s p l a y e d symptoms (above and below ground) s i m i l a r t o those d e s c r i b e d f o r sp r u c e . L i v i n g t r e e s showed e x t e n s i v e r o o t and butt r o t and green 47 F i g u r e 7 Above ground symptoms i n an i n f e c t e d p i n e . 48 w i n d f a l l o c c u r r e d . Such behaviour was a l s o observed i n stands i n the C a r i b o o Region. G e n e r a l l y , where spruce-type symptoms o c c u r r e d , p i n e s were s t i l l prone t o pronounced cambial n e c r o s i s and r e s i n s o a k i n g i n r o o t s l e s s than f i v e cm dia m e t e r . The cause of t h i s v a r i a t i o n i n the development of the d i s e a s e i n p i n e i s u n c l e a r . I t may a r i s e from p h y s i o l o g i c a l or m o r p h o l o g i c a l d i f f e r e n c e s between pine and spruce or i t c o u l d be due to d i f f e r e n t s t r a i n s of the pathogen being p r e s e n t . The f a i l u r e of decay t o d e v e l o p i n i n f e c t e d p i n e s on some s i t e s may have an e f f e c t on the t r a n s m i s s i b i l i t y of the d i s e a s e from the c u r r e n t s t a n d t o the s u c c e e d i n g one. I f decay f a i l s t o d e v e l o p b e f o r e the t r e e i s k i l l e d , i t w i l l l i k e l y not d e v e l o p a t a l l . F a s t e r growing, s a p r o p h y t i c decay f u n g i w i l l l i k e l y c o l o n i z e the r o o t s and stump. Without the l a r g e inoculum r e s e r v e s p r o v i d e d by d e c a y i n g stumps and l a r g e r o o t s , tomentosus may not be a b l e t o s u r v i v e on the s i t e u n t i l r e g e n e r a t i o n i s o l d enough t o s u p p l y a new food s o u r c e . I f t h i s i s the case, then p i n e i n f e c t i o n s may i n some c a s e s be n o n - t r a n s m i s s i b l e . However, where d i s e a s e p r o g r e s s i o n i n p i n e s was s i m i l a r t o t h a t i n spruce, these t r e e s would c l e a r l y r e p r e s e n t p o s s i b l e inoculum r e s e r v e s f o r i n f e c t i o n i n the next r o t a t i o n . 49 Observat ions of in fec ted pines (both in and outside of sample p l o t s ) suggested that the d i s t i n c t i o n between symptomology types may be age r e l a t e d . Older pine t rees and stands seemed to show the more c l a s s i c , spruce- type symptoms. Whereas younger pines d i d not . It i s a l s o poss ib le that symptom expression i s re la ted to tree v i g o u r , fungal inoculum p o t e n t i a l or even to races or v a r i e t i e s of the d i s e a s e . None of these f a c t o r s could be c l e a r l y impl ica ted from t h i s study. However, Whitney (1985), reported that p ines in Ontar io are genera l ly i n f e c t e d with c i r c i n a t u s , even when in c lose quar ters with spruce i n f e c t e d with I.  tomentosus. While t h i s study found pines to be in fec ted at l eas t as often as spruce , the determinat ion of the s p e c i e s , I. tomentosus or c i r c i n a t u s cou ld not be made. Thus i t i s qu i te p o s s i b l e that the spec ies of Inonotus present i s causing the v a r i a b i l i t y in symptom e x p r e s s i o n . The absence of advanced decay in pine a l s o has i m p l i c a t i o n s in surveys for the d i s e a s e . I d e n t i f i c a t i o n of the d isease in the f i e l d r e l i e s heav i l y on green w i n d f a l l s and the presence of p i t t e d rot and dark red s t a i n . Thus, surveys for the d isease in pine could be g r o s s l y inaccurate in areas where these symptoms are not r e l i a b l y produced. Th is s i t u a t i o n may be p a r t i a l l y respons ib le for the r a r i t y of reported inc idences of the d isease on pine in B r i t i s h 50 Columbia. Although u n d e r s t o r y p i n e and spruce t r e e s were found to be i n f e c t e d i n some of the study p l o t s , these t r e e s were g e n e r a l l y f a i r l y o l d and sup p r e s s e d . Thus o b s e r v a t i o n s on the symptomology e x p r e s s d by these t r e e s can not n e c e s s a r i l y be e x t r a p o l a t e d t o young p l a n t a t i o n t r e e s . O b s e r v a t i o n s of the d i s e a s e were, however, made i n p l a n t a t i o n s of spruce . I n f e c t e d p l a n t a t i o n p i n e s were not observed. I n f e c t e d spruce 15 y e a r s o l d or l e s s showed b l u e i n g of n e e d l e s , reduced needle l e n g t h , reduced l e a d e r growth l e a d i n g t o crown rounding, t h i n n i n g of the crown and e v e n t u a l l y d eath. I n f e c t i o n was o f t e n found i n a s s o c i a t i o n w i t h what appeared t o be compression wounds. Wounds due t o H y l o b i u s  warreni and animal t r a m p l i n g were a l s o observed. The compression wounds noted were a s s o c i a t e d w i t h t i g h t l y a ppressed r o o t c o n t a c t s . I n f e c t i o n o f t e n o c c u r r e d as a r e s u l t of t h i s c o n t a c t between h e a l t h y and i n f e c t e d r o o t s . However, no i n c i d e n c e s of i n f e c t i o n o r i g i n a t i n g a t a roo t c o n t a c t without one p r e v i o u s l y i n f e c t e d r o o t p r e s e n t were noted, thus no spore i n f e c t i o n i n these a r e a s was i n e v i d e n c e . Spread v i a r o o t c o n t a c t s appeared t o occur i n some cases without t i g h t a p p r e s s i o n , e s p e c i a l l y where a l a r g e i n o c u l a t i o n source was p r e s e n t (advanced d e c a y ) . T h i s would 51 seem to- i n d i c a t e t h a t compression wounds are conducive t o , but not necessary f o r i n f e c t i o n . H y l o b i u s warreni wounds were common i n many of the study p l o t s . Feeding by t h i s w e e v i l r e s u l t e d i n r e s i n o u s t u n n e l s at and around the r o o t c o l l a r . N e c r o s i s of the c o r t e x o c c u r r e d and was e x t e n s i v e i n some c a s e s . Weevil t u n n e l s may have p r o v i d e d avenues of i n f e c t i o n i n t o the xylem. Red s t a i n i n g i n the xylem i n c l o s e a s s o c i a t i o n with w e e v i l t u n n e l s was observed i n t h r e e t r e e s . Attempts to i s o l a t e from t h i s s t a i n e d wood f a i l e d t o y i e l d I .  tomentosus. However, i n two of these i n s t a n c e s , the samples were s e v e r e l y d i s t u r b e d and s u b s e q u e n t l y contaminated. I n f e c t i o n would i n v o l v e b a s i d i o s p o r e s c a r r i e d on the w e e v i l s themselves or c a r r i e d by wind and water. As such t u n n e l s q u i c k l y become plugged w i t h r e s i n , t h e r e i s o n l y a s h o r t p e r i o d d u r i n g which spor e s c o u l d be washed or blown i n . I f s p o r e s or m y c e l i a are c a r r i e d i n on the i n s e c t i t s e l f , the p r o d u c t i o n of r e s i n i s l i k e l y t o have l i t t l e e f f e c t as a d e t e r r e n t to i n f e c t i o n . Whitney and Denyer (1969) r e p o r t e d t h a t i n f e c t i o n by 1^ tomentosus was not d e t e r r e d by r e s i n s o a k i n g of i n o c u l a t e d r o o t wounds. Thus, a l t h o u g h H_j_ warreni t u n n e l s were t y p i c a l l y found t o be r e s i n f i l l e d , t h e r e i s at l e a s t a s h o r t time p e r i o d d u r i n g which spores c o u l d wash or be c a r r i e d i n . H_j_ w a r r e n i has a f o u r year l i f e c y c l e w i t h 52 stages of development which are not t i e d to s p e c i f i c seasons. Thus at any given time in the year , a l l of the stages of development are l i k e l y to be present . The weevil i s there fore l i k e l y to be a c t i v e dur ing the per iod of spore r e l e a s e . Whitney (1963, 1966) reported s t a i n i n g in root wounds of white spruce inocula ted with tomentosus b a s i d i o s p o r e s . Such s t a i n i n g d id not occur in roots which had been wounded but not i n o c u l a t e d . Chr is tensen (1940) reported that I. tomentosus hyphae were sparse in l i g h t l y d i s c o l o r e d wood. Since tomentosus could not be i s o l a t e d from many of the red s ta ined specimens i t i s p o s s i b l e that the s t a i n i n g may have been p a r t i a l l y a reac t ion by the tree to i n f e c t i o n . Trampling was e s p e c i a l l y evident in Pr ince George s i t e s one and two where c a t t l e graz ing had occur red . Wounding at the root c o l l a r was e v i d e n t . S t a i n i n g on one sample was observed extending to or from what appeared to be an o ld root wound (Figure 8) . Inonotus tomentosus was i s o l a t e d from beneath the bark at the o l d wound. As the extent of s t a i n i n g was very l i m i t e d and no other avenue of i n f e c t i o n was apparent , t h i s would s t rong ly impl ica te t h i s root wound as the avenue of i n f e c t i o n in t h i s c a s e . Since no source of inoculum was in ev idence, i t appeared that i n o c u l a t i o n must 53 Red s t a i n F i g u r e 8. extending from an o l d root wound. 54 have o c c u r r e d by a means other than root c o n t a c t . 2. SPREAD Spread by r o o t c o n t a c t was f r e q u e n t l y i n e v i d e n c e . T h i s o c c u r r e d where r o o t s were t i g h t l y , or i n some c a s e s , l o o s e l y a p p r e s s e d . In the l a t t e r case, e c t o t r o p h i c mycelium was r e q u i r e d . Root c o n t a c t spread was observed i n t e r - and i n t r a - s p e c i f i c a l l y i n pin e and s p r u c e . Roots of v a r i o u s s i z e s (2 cm. t o 12 cm.) were i n v o l v e d . Spread between g r a f t e d r o o t s was a l s o o b served. Such spread was observed i n e a r l y and l a t e stages of i n f e c t i o n . T r a n s f e r between xylem was app a r e n t . However, i n many c a s e s , the r o o t s were decayed t o an e x t e n t which p r e v e n t e d d e t e r m i n a t i o n of the r o o t t i s s u e through which spread had o c c u r r e d . Where roo t g r a f t s i n v o l v e d one r o o t w i t h dark s t a i n i n g or r o t t i n g , t r a n s f e r of inoculum t o the p r e v i o u s l y h e a l t h y r o o t r e g u l a r l y o c c u r r e d . There were no i n d i c a t i o n s of spread through the s o i l . * 3. HOST SPECIES SUSCEPTIBILITY F i g u r e s 2 and 3 show the l o c a t i o n s of sample p l o t s i n the P r i n c e George and P r i n c e Rupert f o r e s t r e g i o n s r e s p e c t i v e l y . Table 5 l i s t s the age, region and biogeoclimatic c l a s s i f i c a t i o n of a l l s i t e s sampled. Region r e f e r s not to the B r i t i s h Columbia Ministry of Forests and Lands administrative region but to the general location of the plo t within B r i t i s h Columbia. The plots were d i s t r i b u t e d in two widely separated c l u s t e r s . One c l u s t e r was located around Prince George and the other was located around Houston. The stands ranged in age from 45 to 110 years. The following Sub-Boreal Spruce subzones were represented; the Spruce Subzone (SBSd), the Subalpine f i r Subzone, Western Variant (SBSel), the Fraser Basin Moist Cool Central Sub-Boreal Spruce Subzone (SBSe2) and the Nechako River Warm Dry Southern Sub-Boreal Spruce Subzone (SBSk3). Appendix A contains a map of the challenge trees in each sample p l o t . Challenge trees were those trees ( l i v i n g , dead, inf e c t e d or healthy) which occurred within three meters of an i n f e c t e d tree or which were found (upon excavation) to have root contact with an i n f e c t e d root. As can be seen in Table 6, the proportion of challenged lodgepole pine i n f e c t e d (PPIN) was in a l l cases greater than the proportion of challenged i n t e r i o r spruce i n f e c t e d (PSIN). The proportion of lodgepole pine i n f e c t e d ranged from 0.429 to 1.00 with a mean of 0.830. The proportion of i n t e r i o r spruce in f e c t e d ranged from 0.125 to 0.897 with a mean of 0.563. Table 6 Proportions of Pine and Spruce Infected and the Difference in Proportion of Pine and Spruce Infected by Site Site Spruce Pine No. H. I. PSIN H. I. PPIN DIFF *1 *2 *3 1 10 12 0.55 3 14 0.82 0.26 2 8 10 0.56 5 7 0.58 0.03 3 3 20 0.26 5 6 0.55 0. 29 4 4 12 0. 43 6 15 0.71 0.29 5 14 2 0.13 3 14 0.62 0.70 6 12 7 0.37 1 12 0.92 0.55 7 13 7 0.35 3 16 0.64 0.49 8 15 7 0.32 2 10 0.83 0.52 9 7 4 0.36 4 3 0.43 0.07 10 9 10 0.53 2 13 0.87 0.34 11 10 6 0.44 2 10 0.63 0.39 12 11 14 0.56 3 14 0.82 0.26 13 3 16 0.84 2 19 0.91 0.06 14 6 18 0.75 0 19 1.00 0.25 15 6 13 0.68 0 11 1.00 0.32 16 3 26 0.90 1 11 0.92 0.02 17 5 26 0.84 1 9 0.90 0.06 18 4 14 0. 78 1 20 0.95 0.18 19 3 12 0.60 0 23 1.00 0.20 20 2 10 0.83 3 23 0.69 0.05 *1 Sites 1-11 located ln the Prince George Forest Region Sites 12-20 located i n the Prince Rupert Forest Region *2 The number of healthy trees in the p l o t . *3 The number of infected trees i n the p l o t . PSIN= proportion of i n t e r i o r spruce in f e c t e d PPIN= proportion of lodgepole pine i n f e c t e d DIFF = PPIN - PSIN 57 The d i f f e r e n c e between the propor t ion of lodgepole pine i n f e c t e d and the propor t ion of i n t e r i o r spruce in fec ted (PPIN - PSIN) was represented by the d i f f e r e n c e in propor t ion i n f e c t e d (DIFF). The d i f f e r e n c e in propor t ion i n f e c t e d ranged from 0.020 to 0.699 with a mean of 0.267. These r e s u l t s c l e a r l y i n d i c a t e d that both c o n i f e r species were at tacked on a l l s i t e s s t u d i e d . A p a i r e d sample • t - test on the p ropor t ions of lodgepole pine and i n t e r i o r spruce i n f e c t e d , with each s i t e represent ing a p a i r , showed that the d i f f e r e n c e between the two p r o p o r t i o n s was s i g n i f i c a n t at the 0.01 l e v e l (Table 7) . The Wilcoxon pa i red sample tes t performed on the propor t ions of each spec ies i n f e c t e d was found to be s i g n i f i c a n t at the 0.05 l e v e l (Table 8 ) . Thus the i n f e c t i o n l e v e l s in lodgepole pine were s i g n i f i c a n t l y higher than those of i n t e r i o r spruce . C o r r e l a t i o n of the propor t ion of lodgepole pine i n f e c t e d with the propor t ion of i n t e r i o r spruce i n f e c t e d y i e l d e d a s i g n i f i c a n t c o r r e l a t i o n (P=0.012 ) with an R-square of 0.30. The slope of t h i s c o r r e l a t i o n was p o s i t i v e (0.369) (Table 9, F igure 9) . A t - t e s t performed on t h i s c o r r e l a t i o n showed s i g n i f i c a n t d e v i a t i o n from a s lope of one at the 0.01 l e v e l (Table 10). The p o s i t i v e s lope of t h i s c o r r e l a t i o n and the s i g n i f i c a n t d e v i a t i o n from a slope of one i n d i c a t e that the v a r i a t i o n in host spec ies Table 7 P a i r e d T-Test on the P r o p o r t i o n of Pine I n f e c t e d and the P r o p o r t i o n of Spruce I n f e c t e d 58 v a r i a b l e No. of Cases Mean Standard Standard D e v i a t i o n E r r o r P r o p o r t i o n 0.563 0.228 0.051 of spruce i n f . 20 P r o p o r t i o n 0.830 0.154 0.034 of pine i n f . D i f f e r e n c e s t a n d a r d Standard Mean D e v i a t i o n E r r o r -0.267 0.193 0.043 2 - t a i l e d T-value Degrees of 2 - t a i l Prob. Freedom Prob. 0.012 -6.18 19 0.000 Table 8 59 w i l c o x i n Matched-Pairs signed-Ranked Te s t on the P r o p o r t i o n of Pine I n f e c t e d with P r o p o r t i o n of Spruce I n f e c t e d Mean Rank cases 00 - Ranks ( P r o p o r t i o n of pine i n f e c t e d l e s s than P r o p o r t i o n of spruce i n f e c t e d ) 10.50 20 + Ranks ( P r o p o r t i o n of pine i n f e c t e d g r e a t e r than P r o p o r t i o n of pine i n f e c t e d ) .00 T i e s ( P r o p o r t i o n of pine i n f e c t e d e q u a l t o the p r o p o r t i o n of spruce i n f e c t e d ) 20 T o t a l Z=3.920 2 - t a i l e d P=0.0001 Table 9 C o r r e l a t i o n of the P r o p o r t i o n of Lodgepole pine I n f e c t e d on the P r o p o r t i o n of Spruce I n f e c t e d . 60 N = 20 Source Df Sum of Squares Mean Square F - S t a t S i g n i f . C o r r e l a t i o n 1 E r r o r 18 T o t a l 19 0.135 0.314 0.449 0.135 0.017 7.755 0.012 Mult. R. = 0.549 R-Square = 0.301 SE = 0.132 V a r i a b l e P a r t i a l C o e f f . S t d . E r r o r T - S t a t S i g n i f . Constant P r o p o r t i o n of Spruce I n f e c t e d 0.549 0.622 0.369 0.080 0.133 7.738 2.785 0.000 0.012 61 F i g u r e 9 C o r r e l a t i o n of the p r o p o r t i o n of p i n e i n f e c t e d on the p r o p o r t i o n of spruce i n f e c t e d Table 1 0 T-Test of the slope of the C o r r e l a t i o n of the P r o p o r t i o n of Pine I n f e c t e d on the P r o p o r t i o n of Spruce I n f e c t e d Ho: Regression has a slope equal to 1 . Ha: Regression has a slope not equal to 1 . Slope of R e s i d u a l SS R e s i d u a l T-Value Prob. Regression f o r Regression Df 0 . 3 6 9 0 . 1 3 3 1 8 - 4 . 7 4 < 0 . 0 0 1 63 s u s c e p t i b i l i t y was p o s i t i v e , d i f f e r e n t i a l and q u a n t i t a t i v e . That i s the i n f e c t i o n r a t e s of both s p e c i e s v a r i e d i n the same d i r e c t i o n (hence p o s i t i v e ) , but to d i f f e r e n t e x t e n t s (hence d i f f e r e n t i a l ) . S i n c e the i n f e c t i o n r a t e s v a r i e d along a continuum from h i g h t o low, the v a r i a t i o n was q u a n t i t a t i v e . I f n e g a t i v e d i f f e r e n t i a l v a r i a t i o n i n host s p e c i e s s u s c e p t i b i l i t y e x i s t e d the c o r r e l a t i o n would have been n e g a t i v e ( F i g u r e 1 0 ) . In t h i s case the s u s c e p t i b i l i t y of one s p e c i e s would i n c r e a s e as the oth e r s p e c i e s s u s c e p t i b i l i t y d e c r e a s e d . Q u a l i t a t i v e d i f f e r e n t i a l v a r i a t i o n was a l s o p o s s i b l e . Q u a l i t a t i v e v a r i a t i o n i n host s p e c i e s s u s c e p t i b i l i t y o c c u r s where s p e c i e s s u s c e p t i b i l i t y forms d i s c r e t e c a s e s r e p r e s e n t i n g r e l a t i v e i n f e c t i o n l e v e l s , r a t h e r than v a r y i n g a l o n g a continuum. N e g a t i v e q u a l i t a t i v e v a r i a t i o n e x i s t s where, on a g i v e n s i t e the s u s c e p t i b i l i t y of one s p e c i e s i s h i g h when t h a t of the o t h e r s p e c i e s i s low (and v i c e v e r s a ) . P o s i t i v e q u a l i t a t i v e v a r i a t i o n e x i s t s where, on a given s i t e , the s u s c e p t i b i l i t i e s of the two s p e c i e s a re the same ( e i t h e r r e l a t i v e l y h i g h or l o w ) . P o s i t i v e q u a l i t a t i v e v a r i a t i o n would be expected i f one were comparing i n f e c t i o n r a t e s w i t h i n l_y_ tomentosus i n f e c t i o n c e n t e r s w i t h i n f e c t i o n r a t e s w i t h i n I_j_ c i r c i n a t u s i n f e c t i o n c e n t e r s . As I_;_ c i r c i n a t u s i s c o n s i d e r e d t o be l e s s p a t h o g e n i c , one would expect the i n f e c t i o n r a t e s of both host s p e c i e s t o be lower i n I ^ c i r c i n a t u s c e n t e r s 1 . 0 64 P r o p o r t i o n of Spruce I n f e c t e d 1.0 F i g u r e 1 0 Q u a n t i t a t i v e D i f f e r e n t i a l V a r i a t i o n i n Host S p e c i e s S u s c e p t i b i l i t y 1.0 P r o p o r t i on of P i n e I n f e c t e d » * * % X x x * * x X X X X N e g a t i ve Posi t i ve • # P r o p o r t i o n of Spruce I n f e c t e d 1.0 F i g u r e 1 1 Q u a l i t a t i v e D i f f e r e n t i a l V a r i a t i o n i n Host S p e c i e s S u s c e p t i b i l i t y 65 than in tomentosus c e n t e r s . D i f f e r e n t i a l q u a l i t a t i v e v a r i a t i o n would have r e s u l t e d in a c l u s t e r e d d i s t r i b u t i o n s i m i l a r to those shown in F igure 11. Table 11 summarizes PSIN, PPIN and DIFF by r e g i o n . A - t - test on the d i f f e r e n c e in- the p ropor t ions of pine and spruce i n f e c t e d by region ind ica ted s i g n i f i c a n t d i f f e r e n c e in DIFF due to region (Table 12). B iogeoc l imat ic a s s o c i a t i o n was not tes ted as a f ac to r as such a t e s t would be very unbalanced and would lack r e p l i c a t e s for three a s s o c i a t i o n s . Ins tead , a s s o c i a t i o n s were grouped together for the a n a l y s i s . They were grouped on the b a s i s of s i m i l a r i t y in moisture and nu t r i en t regime. It was f e l t that such groups were more homogenous for these f a c t o r s than were a s s o c i a t i o n s wi th in i n d i v i d u a l subzones. Thus these groupings were used ins tead of subzones in the a n a l y s i s . The three a s s o c i a t i o n groups der ived are l i s t e d in Table 13. Group 1 inc luded the mesic a s s o c i a t i o n s ; SBSe 01: Mesic Bunchberry - Moss, SBSe2 01: Bunchberry - Moss and SBSk3 01: P r i c k l y Rose - Queen's Cup. Group 2 inc luded the submesic a s s o c i a t i o n s ; SBSel 01: Submesic Bunchberry - Moss, SBSe2 01: D o u g l a s - f i r - Subalpine f i r and SBSk3 04.1: Wi ld Table 11 66 Summary of the P r o p o r t i o n of Pine and Spruce I n f e c t e d and D i f f e r e n c e between P r o p o r t i o n s of Pine and Spruce I n f e c t e d V a r i a b l e Region N Minimum Maximum Mean standard *1 *2 D e v i a t i o n PSIN 1 11 0.125 0.560 0.389 0.130 PSIN 2 9 0.560 0.897 0.775 0.102 PPIN 1 11 0.429 0.923 0.747 0.158 PPIN 2 9 0.824 1.000 0.931 0.061 DIFF 1 11 0.028 0.699 0.358 0.203 DIFF 2 9 0.020 0.316 0.156 0.109 *1 PPIN = P r o p o r t i o n of Pine I n f e c t e d PSIN = P r o p o r t i o n of Spruce I n f e c t e d DIFF = D i f f e r e n c e i n P r o p o r t i o n s of Pine and Spruce I n f e c t e d *2 1= P r i n c e George F o r e s t Region 2- P r i n c e Rupert F o r e s t Region Table 12 67 Two Sample T - t e s t on the d i f f e r e n c e in p ropor t ions i n f e c t e d by geographic r e g i o n . Region N Mean DIFF Var iance Pr ince George 1 1 0.358 0.041 Pr ince Rupert 9 0.1 56 0.012 T e s t Df S i g n i f i c a n c e T=2.680 18 0.015 T a b l e 13 68 Grouping of E c o l o g i c a l A s s o c i a t i o n s by M o i s t u r e and N u t r i e n t S t a t u s Group E c o l o g i c a l A s s o c i a t i o n s I n c l u d e d PR N * PG Group 1 : SBSk3 01 : P r i c k l y Rose - Queen's Cup SBSel 01 : Mesic Bunchberry - Moss SBSe2 01 : Bunchberry - Moss 3 1 5 Group 2 : SBSk3 04.1 : Wild S a r s a p a r i l l a - P r i n c e ' s Pine SBSel 04 : Submesic Bunchberry -Moss SBSe2 04 : Douglas f i r - S u b a l p i n e f i r 3 3 2 Group 3 : SBSd 07 : Submesic Bunchberry - Moss SBSd 08 : M o i s t Shrub - Forb 2 1 * PG = PR = P r i n c e George F o r e s t Region P r i n c e Rupert F o r e s t Region 9 1 1 69 Sarsaparilla - Prince's Pine. The third group included the Spruce Subzone (SBSd) associations which did not f i t in with Group 1 or 2 due to differences in moisture or nutrient regimes. These were: SBSd 07: Submesic Bunchberry - Moss and SBSd 08: Moist Shrub - Forb. The effect of these groups on the difference in pine and spruce infected DIFF was not significant at the 0.05 level (Table 14). The infection rates for both species were higher in the Prince Rupert Forest Region than in the Prince George Forest Region (Table 11). This may be due to the fact that the Prince Rupert stands were older. Older stands would allow for greater intensification of infection centers. Such intensification would l i k e l y result in higher infection rates within infection centers and the expression of more advanced symptoms (rot etc.). Plots in the Prince Rupert region had more developed symptoms (as well as having higher infection rates). While PSIN and PPIN were both higher in Prince Rupert, the difference between them, DIFF was less. This was due to a greater average difference in PSIN than PPIN between regions (0.386 as compared to 0.184). A regression of DIFF on s o i l pH resulted in no significant regression being found. Table 14 70 A n a l y s i s of v a r i a n c e of the D i f f e r e n c e l n the P r o p o r t i o n of Pine and Spruce I n f e c t e d by Groupings of E c o l o g i c a l A s s o c i a t i o n s . Model: D i f f e r e n c e i n the P r o p o r t i o n of Pine and Spruce i n f e c t e d = Groupings of E c o l o g i c a l A s s o c i a t i o n s Source Df Between 2 Wi t h i n 17 T o t a l 19 Sum of Mean Squares Square 0.149 0.075 0.559 0.033 0.708 F - s t a t S i g n i f . 2.270 0.134 71 The d r i v i n g f a c t o r behind the v a r i a t i o n i n DIFF with r e g i o n c o u l d not be determined i n t h i s study. As p r e v i o u s l y s t a t e d , s t a n d age or the age of the i n f e c t i o n c e n t e r c o u l d be r e s p o n s i b l e . As w e l l , t h e r e c o u l d be d i f f e r e n t i a l e f f e c t s on the r o o t i n g p a t t e r n s of the two t r e e s p e c i e s . D i f f e r e n c e s i n r o o t i n g c o u l d a f f e c t the number of roo t c o n t a c t s and root g r a f t s between h e a l t h y and i n f e c t e d r o o t s . I t i s p o s s i b l e t h a t b i o t i c and a b i o t i c f a c t o r s a f f e c t i n g r o o t i n g of the two s p e c i e s c o u l d d i f f e r e n t i a l l y a f f e c t s u s c e p t i b i l i t y . D i f f e r e n t i a l e f f e c t s of the s i t e on t r e e v i g o u r (thus a f f e c t i n g r e s i s t a n c e mechanisms) and d i f f e r e n t i a l e f f e c t s on f u n g a l v i g o u r (inoculum p o t e n t i a l ) are a l s o p o s s i b l e . I f l o d g e p o l e p i n e and i n t e r i o r spruce have d i f f e r e n t t h r e s h o l d s of inoculum p o t e n t i a l f o r s u c c e s s f u l i n f e c t i o n , then s i t e e f f e c t s on inoculum p o t e n t i a l c o u l d a f f e c t the i n f e c t i o n l e v e l s of the two s p e c i e s d i f f e r e n t i a l l y . None of the 25 main canopy s u b a l p i n e f i r l o c a t e d w i t h i n study p l o t s were found t o be i n f e c t e d w i t h I ^ tomentosus. A l l were c o n s i d e r e d t o be c h a l l e n g e d . T h i s would i n d i c a t e a low s u s c e p t i b i l i t y t o t h i s d i s e a s e . At a 5% c o n f i d e n c e l e v e l the p r o b a b i l i t y (P) of i n f e c t i o n would have t o be such t h a t ((1-P)**25=0.05). Thus the p r o b a b i l i t y of i n f e c t i o n i n s u b a l p i n e f i r would have to be 0.11 or l e s s w i t h i n i n f e c t i o n c e n t e r s . T h i s would c l e a r l y r e p r e s e n t a much lower i n f e c t i o n 72 r a t e than on spruce or pine i n these s t a n d s . However, the symptomology of i n f e c t e d s u b a l p i n e f i r i s not w e l l documented. T h e r e f o r e , i t i s u n c e r t a i n whether i n f e c t i o n s would have been d e t e c t e d u s i n g the methods i n v o l v e d w i t h t h i s study. In f a c t , subsequent o b s e r v a t i o n s made on i n f e c t e d s u b a l p i n e f i r not l o c a t e d w i t h i n study p l o t s i n d i c a t e d t h a t t h i s may w e l l have been the ca s e . Symptoms were g e n e r a l l y p o o r l y developed or absent i n c l o s e p r o x i m i t y t o the root c o l l a r ( w i t h i n 0.6 m e t e r s ) . Brown s t a i n i n g and the c h a r a c t e r i s t i c p i t t e d r o t were u s u a l l y p r e s e n t i n more d i s t a l p o r t i o n s of i n f e c t e d r o o t s . Cambial n e c r o s i s (from which I_j_ tomentosus was l a t e r i s o l a t e d ) was a l s o observed i n these d i s t a l r o o t p o r t i o n s . G e n e r a l l y , s t a i n i n g of the xylem extended o n l y a s h o r t d i s t a n c e from an area of advanced decay. S u b a l p i n e f i r i s c u r r e n t l y c o n s i d e r e d by many i n the f o r e s t i n d u s t r y t o be an u n d e s i r a b l e c r o p s p e c i e s . The s p e c i e s ' r e p u t e d p r o p e n s i t y f o r decay i s one reason f o r t h i s a t t i t u d e . However, many of the p e r c e i v e d p a t h o l o g i c a l problems a s s o c i a t e d w i t h t h i s t r e e s p e c i e s a re based on decadent stands of 200 y e a r s or o l d e r . T h e r e f o r e , f u r t h e r study of t h i s s p e c i e s i s r e q u i r e d b e f o r e i t can be recommended or d i s m i s s e d as an a l t e r n a t e r e g e n e r a t i o n s p e c i e s f o r tomentosus roo t r o t i n f e s t e d s t a n d s . 73 Due t o the dark s t a i n i n g of D o u g l a s - f i r r o o t heartwood, i d e n t i f i c a t i o n of tomentosus caused s t a i n i n g u s i n g the methods l i s t e d above was not p o s s i b l e . D e t e r m i n a t i o n of the l e v e l of i n f e c t i o n was t h e r e f o r e a l s o i m p o s s i b l e . However, I . tomentosus was not o b t a i n e d i n c u l t u r e from t e n D o u g l a s - f i r samples. As w e l l , none of the D o u g l a s - f i r w i t h i n sample p l o t s were decayed or d e c l i n i n g and t h e r e were no s i g n s of abnormal r o o t n e c r o s i s . The evidence would seem to agree w i t h r e p o r t s of low s u s c e p t i b i l i t y of t h i s s p e c i e s (Thomas and Thomas 1 9 5 4 ) . Where D o u g l a s - f i r o c c u r r e d i n sample p l o t s , i t appeared t o be growing w e l l . On many of these s i t e s D o u g l a s - f i r f a r out grew p i n e and spruce of s i m i l a r age. T h i s v i g o u r a l o n g w i t h the s p e c i e s ' a p p a r e n t l y low s u s c e p t i b i l i t y t o tomentosus suggest t h a t i t may be a s u i t a b l e r e g e n e r a t i o n s p e c i e s on such s i t e s where h i g h l e v e l s of the pathogen were p r e s e n t i n the p r e v i o u s s t a n d . 4. EFFECT OF INFECTION ON RADIAL INCREMENT a. LODGEPOLE PINE The r a d i a l increment a t b r e a s t h e i g h t f o r the l a s t f i v e y e a r s was measured f o r 5 7 p i n e t r e e s i n v a r i o u s s t a g e s of I .  tomentosus i n f e c t i o n , and was c o n v e r t e d t o b a s a l area 74 increment over the l a s t f i v e years (BAI). The diameter and basal area increment are descr ibed by i n f e c t i o n c l a s s in Table 15. As can be seen, healthy t rees were on average la rger than diseased t rees (370.01 s q . cm. basal area as compared to 300.66 s q . cm. ) . Th is d i f f e r e n c e was found not to be s i g n i f i c a n t using a T - t e s t («*=0.05) (Appendix C ) . Diseased t rees showed a 24% reduct ion in basa l area increment in the 1979-1984 per iod (16.51 s q . cm. as compared to 12.55 s q . cm. ) . The basal area increment was used as the v a r i a b l e in a two- factor ANOVA where subzone and i n f e c t i o n c l a s s were the f a c t o r s . Basal area increment was found to c o r r e l a t e s i g n i f i c a n t l y (*=0.05) with the basal area at the beginning of the f i v e year per iod (Appendix C ) . Thus basa l area at the beginning of the f i v e year per iod was inc luded in the a n a l y s i s of var iance as a c o v a r i a t e . Age was not found to s i g n i f i c a n t l y a f f e c t basal area increment and was therefore not inc luded in the a n a l y s i s . Transformations of the i n i t i a l basa l area d i d not improve the l i n e a r i t y of the regress ion with basal area increment. The i n i t i a l basa l area was therefore inc luded in the a n a l y s i s of var iance as a covar ia te without t rans format ion . A strong l i n e a r r e l a t i o n s h i p between the v a r i a t e and the c o v a r i a t e was requi red for the GENLIN a n a l y s i s . The e f f e c t of i n f e c t i o n T a b l e 15 Mean I n i t i a l B a s a l Area and Change i n B a s a l Area of H e a l t h y and D i s e a s e d Pine and Spruce 75 S p e c i e s N I n f e c t i o n Mean B a s a l Stand. S t a t u s Area cm-2 Dev. Mean Stand Change Dev. i n B a s a l Area cm-2 PINE 24 h e a l t h y 370.01 33 d i s e a s e d 300.66 296.98 237.94 13.12 9.03 10.53 6.04 SPRUCE 21 h e a l t h y 245.93 17 d i s e a s e d 248.69 152.79 136.12 13 .05 12.54 8 . 54 12.23 * a t b e g i n n i n g of f i v e year p e r i o d . s t a t u s was not found to be s i g n i f i c a n t (P = 0.32) (Table 16). Thus i n f e c t i o n by tomentosus d i d not cause a s i g n i f i c a n t r e d u c t i o n i n b a s a l area increment i n p i n e . The e f f e c t of subzone on b a s a l area increment was a l s o not s i g n i f i c a n t (Table 16). T h i s would i n d i c a t e t h a t there was no s i g n i f i c a n t v a r i a t i o n i n p r o d u c t i v i t y between the subzones. The b a s a l area (at the time of the study) and the mean age f o r each subzone are summarized i n T a b l e 17. From t h i s summary i t i s apparent t h a t d i f f e r e n c e s i n p r o d u c t i v i t y d i d e x i s t . The l a r g e amount of v a r i a t i o n shown i n T a b l e 15 i n d i c a t e d t h a t a l a r g e r sample s i z e would l i k e l y be n e c e s s a r y to d e t e c t d i f f e r e n c e s i n b a s a l a r e a increment due to the two f a c t o r s . b. INTERIOR SPRUCE T h i r t y - s e v e n spruce t r e e s were bored and t h e i r increments r e c o r d e d . A summary of the increment data f o r the spruce t r e e s sampled i s p r e s e n t e d i n T a b l e 15. A T-Test demonstrated the i n i t i a l b a s a l area of h e a l t h y t r e e s t o be s i g n i f i c a n t l y lower than f o r d i s e a s e d t r e e s (Appendix C ) . R e g r e s s i o n of b a s a l a r e a increment w i t h age and i n i t i a l b a s a l area showed i n i t i a l b a s a l a r e a t o be s i g n i f i c a n t . I n i t i a l b a s a l area was t h e r e f o r e i n c l u d e d i n the t w o - f a c t o r a n a l y s i s of v a r i a n c e as a c o v a r i a t e . Age was not found to .Table 16 77 A n a l y s i s of v a r i a n c e i n R a d i a l Increment of Pine Model: (1 ) TDBA «= INF + SUB + INF*SUB + BAl Sour ce Sum of Df Mean F - r a t l o P r o b a b i l i t y (1) Squares Square 1. INF 9.02 1 . 9.02 1 .28 0.26 2. SUB 9.27 2. 4.63 0.66 0.52 3 . INF*SUB 27.07 2. .13.53 1 .92 0.15 4 .BA1 180.05 1 . 180.05 25.64 0.00 5.Residual 351.03 50. 7.02 T o t a l 692.14 56 O v e r a l l mean Overal1 standard D e v i a t i o n TDBA 12.52 3.51 BA1 32986 .0 26506. -(1) INF = I n f e c t i o n Status (hea l thy or d iseased) SUB = B i o g e o c l i m a t i c Subzone BAl = I n i t i a l Basal Area ( c o v a r i a t e ) TDBA = Transformed change in Basa l Area (DBA * * .37105) T a b l e 17 sumrnar y of Mean Stand Ages by subz one or v a r i a n t Subzone N Min i mum Max imum Mean Standard or V a r i a n t D e v i a t i on SBSk3 23 8u . 0 104 . 0 93 . 1 7 . 0 SBSel 5 80. 0 104 . 0 87. 4 9.6 SBSe2 9 73 . 0 151. 0 101 . 3 21. 3 SBSd 20 75. 0 113 . 0 101. 0 10 . 3 Summary of Mean Tree B a s a l Areas cm 2 by i Subzone or V a r i a n t Subzone N Min imum Maximum Mean Standard or V a r i a n t Dev i a t i on SBSk3 23 95 .03 564 .10 225 .07 115. 84 SBSel 5 206 .12 1281 .97 546 .66 437.30 SBSe2 9 96 . 77 844 .96 212 . 58 238.91 SBSd 20 93 . 31 1158 .10 4 79 . 59 284.51 79 have a s i g n i f i c a n t e f f e c t and was therefore excluded. Again the e f f e c t of i n f e c t i o n status on basal area increment was not found to be s i g n i f i c a n t (Table 18). The e f f e c t s of subzone and of fac tor i n t e r a c t i o n s were not s i g n i f i c a n t at the 0.05 l e v e l (Table 18). These r e s u l t s do not concur with the f i n d i n g s of Merler (1984). Merler reported a 20% reduct ion in increment of I.  tomentosus in fec ted spruce . Merler a l s o found that in fec ted spruce were of smal ler average diameter than heal thy ones. The discrepancy between M e r l e r ' s r e s u l t s and those descr ibed in t h i s study may be the r e s u l t of i n s u f f i c i e n t sample s i z e s in t h i s study. They may a l s o be due to d i f f e r e n c e s in the stand ages. Merler sampled t rees aged 30 to 65 y e a r s . The t rees involved in t h i s study were 70 to 120 years o l d . As w e l l , M e r l e r ' s study invo lved stands with higher s tocking d e n s i t i e s (1450 stems per hectare as compared to 800 stems per h e c t a r e ) . The high s tock ing l e v e l in M e r l e r ' s study may have ampl i f i ed the e f f e c t of i n f e c t i o n due to dens i ty re la ted s t r e s s e f f e c t s . 5 . CULTURAL CHARACTERISTICS Attempts to c u l t u r e I^  tomentosus from c o l l e c t e d samples were not always s u c c e s s f u l . V i a b l e c u l t u r e s from T a b l e 18 A n a l y s i s of Var iance in Radia l Increment of spruce Mode 1: (1) TDBA = INF 4 SUB • lNF*SUB + BAl Source Sum of Df Mean F- r a t i o P r o b a b i l i t y (1) Squares Square l . INF 0.0015 1 . 0.0015 2 . 15 0.152 2. SUB 0.0028 2 . 0.0014 1 .92 0. 1G3 3 . INF*SUB 0.0045 2 . 0.0023 3 . 15 0.056 4 .BAl 0.0087 1 . 0.0087 12 . 12 0.001 5.Residual 0. 0222 31 . 0.0007 T o t a l 0.0415 37 . O v e r a l l mean O v e r a l l s tandard D e v i a t i o n TDBA 0.654 0.033 BAl 24716. 14365. (1) INF = I n f e c t i o n Status (hea l thy or d iseased) SUB * B i o g e o c l i m a t l c Subzone BAl = I n i t i a l Basal Area ( c o v a r i a t e ) TDBA = Transformed change i n Basa l Area (DBA * * .37105) l i g h t l y t o medium s t a i n e d xylem were p a r t i c u l a r l y d i f f i c u l t . In many c a s e s the presence of the fungus was c o n f i r m e d by c u l t u r a l i s o l a t i o n from p o r t i o n s ,of the r o o t which showed more advanced symptoms. C h r i s t e n s e n (1940) and Whitney (1963, 1966) p r e s e n t e d e v i d e n c e t o suggest t h a t hyphae are sometimes r a r e or perhaps absent i n s t a i n e d wood. The s t a i n i n g i n e a r l y stages may r e p r e s e n t a p h y s i o l o g i c a l r e a c t i o n by the host t o i n f e c t i o n . U n s a n i t a r y c o n d i t i o n s l e d t o a l a r g e amount of c o n t a m i n a t i o n i n f i e l d i s o l a t i o n attempts. As I ^ tomentosus i s a slow growing fungus ( a p p r o x i m a t e l y 1.5 mm per day), i t ' s p r esence was e a s i l y masked as i t was o f t e n overgrown by ( f a s t e r growing) contaminants. C u l t u r e i s o l a t i o n was more s u c c e s s f u l when c a r r i e d out on a laminar a i r flow bench. At l e a s t two samples from i n f e c t e d spruce and p i n e were c o l l e c t e d from each s i t e . In each case (105 samples), I .  tomentosus was i s o l a t e d and i d e n t i f i e d u s i n g c u l t u r a l c h a r a c t e r i s t i c s as o u t l i n e d i n Nobles key t o i d e n t i f i c a t i o n of c u l t u r e s of wood r o t t i n g f u n g i (1948). Over an e i g h t month p e r i o d , i s o l a t e s were c u l t u r e d from samples s t o r e d at a p p r o x i m a t e l y 1 degree C. A h i g h success r a t e i n i s o l a t i n g I_j_ tomentosus was a c h i e v e d throughout the 82 s t o r a g e p e r i o d f o r most samples. However, c o n t a m i n a t i o n by other f u n g i made i s o l a t i o n from samples from two of the s i t e s i m p o s s i b l e a f t e r a p p r o x i m a t e l y five'months. Fungal c h a r a c t e r i s t i c s i n c u l t u r e , i n c l u d i n g : hyphal c o l o r , mat c o l o r and t e x t u r e , advancing zone c h a r a c t e r i s t i c s and growth r a t e were observed f o r a subset of 50 i s o l a t e s m a i n t a i n e d over a two month p e r i o d . A gr e a t d e a l of v a r i a t i o n was found t o occur i n a l l of the observed c h a r a c t e r i s t i c s both among and w i t h i n i s o l a t e s . The advancing zones of the c u l t u r e s s t u d i e d were found t o be even, f o r the most p a r t . However, f a n - l i k e e x t e n s i o n s of more r a p i d l y growing mycelium were found w i t h r e g u l a r i t y i n the P r i n c e Rupert s i t e two spruce and on o c c a s i o n i n othe r i s o l a t e s . The c o l o r of the submerged mycelium was h y a l i n e t o golden brown t o dark brown w i t h the l a t t e r being most common. Oft e n the submerged mycelium would darken w i t h age. E s t a b l i s h e d mycelium was o f t e n much d a r k e r than the advancing zone. Some i s o l a t e s had h y a l i n e a d v a n c i n g zones but dark brown e s t a b l i s h e d mycelium. V a r i a t i o n i n c h a r a c t e r i s t i c s was a l s o observed w i t h i n i s o l a t e s . In one case, h y a l i n e mycelium from the advancing zone of an i s o l a t e w i t h golden brown e s t a b l i s h e d mycelium was s u b c u l t u r e d to produce an i s o l a t e w i t h h y a l i n e s u b s u r f a c e mycelium which 83 remained such with age. The complete range of mat c o l o r s as d e s c r i b e d by other a u t h o r s (Whitney 1977, Whitney and Bohaychuk 1977) was not e x p r e s s e d by the i s o l a t e s s t u d i e d . However, c o n s i d e r a b l e v a r i a t i o n d i d o c c u r . The mat c o l o r s expressed were cream, ta n , c h e s t n u t brown and dark brown. In some c a s e s , more than one mat c o l o r was e x p r e s s e d by a s i n g l e i s o l a t e . T y p i c a l l y , changes i n mat c o l o r c o r r e s p o n d e d t o i n c r e a s i n g age of the c u l t u r e . The m y c e l i a l mats ( a e r i a l mycelium) were appressed to downy t o c o t t o n y i n t e x t u r e . In some c a s e s , a e r i a l mycelium was p r e s e n t i n one c o n t i n u o u s sheet which c o v e r e d most of the i n h a b i t e d agar. In o t h e r s , s p e c i f i c a l l y those w i t h downy mats, the a e r i a l hyphae were s c a t t e r e d and s p a r s e . In one i s o l a t e , s p a r s e clumps of downy mycelium o c c u r r e d . There was l e s s v a r i a t i o n i n mat c o l o r and t e x t u r e w i t h i n i s o l a t e s (they remained q u i t e c o n s t a n t ) of s i m i l a r age. However, o l d e r c u l t u r e s , s u b c u l t u r e d from p r e v i o u s agar i s o l a t e s tended t o produce more a e r i a l mycelium than young c u l t u r e s i s o l a t e d d i r e c t l y from samples. Some c h a r a c t e r i s t i c combinations of mat c o l o r and t e x t u r e and s u b s u r f a c e m y c e l i a l c o l o r e x i s t e d . Three such 84 combinations were d e t e c t e d and were denoted f o r the purposes of t h i s study as 'mycelium t y p e s ' . Type one mycelium had c h e s t n u t c o l o r e d a e r i a l and s u b s u r f a c e mycelium and a mat which was t y p i c a l l y c o t t o n y i n t e x t u r e ( F i g u r e 12a). Type two mycelium had dark brown a e r i a l and s u b s u r f a c e mycelium and the mat t e x t u r e was v e l v e t y ( F i g u r e 12b). Type t h r e e mycelium had dark brown a e r i a l and s u b s u r f a c e mycelium. The mat t e x t u r e was sparse down ( F i g u r e 12c). These t h r e e mycelium types are summarized i n T a b l e 19. No d i s t i n c t i o n c o u l d be made between p i n e and spruce i s o l a t e s u s i n g the c u l t u r a l c h a r a c t e r i s t i c s s t u d i e d . The h i g h degree of v a r i a b i l i t y both among and w i t h i n i s o l a t e s would l i k e l y have masked any v a r i a t i o n between i s o l a t e s due to host s p e c i e s ( i f such v a r i a t i o n d i d e x i s t ) . I t c o u l d not be c o n c l u d e d from the r e s u l t s of t h i s study t h a t t h e r e e x i s t e d e i t h e r more or l e s s v a r i a t i o n w i t h i n p l o t s than between p l o t s . As w e l l , v a r i a t i o n i n c u l t u r a l c h a r a c t e r i s t i c s d i d not appear t o be r e l a t e d t o v a r i a t i o n i n e t i o l o g y on the h o s t s from which the i s o l a t e s were d e r i v e d . In s e v e r a l i s o l a t e s rudimentary f r u i t i n g b o d i e s were produced ( F i g u r e 13). No s p e c i a l c o n d i t i o n s were nec e s s a r y to produce these s t r u c t u r e s . However, o n l y o l d e r c u l t u r e s ( g r e a t e r than f o u r months s i n c e i s o l a t i o n ) , produced t h e s e . F i g u r e 1 2 b I. tomentosus i n c u l t u r e - Type 2 . 86 F i g u r e 12c I . tomentosus i n c u l t u r e - Type 3. T a b l e 19 Common Mycelium Types Found i n C u l t u r e Subsur face C o l o r A e r i a l c o l o r Mat t e x t u r e Type 1. Chestnut Chestnut Cottony Type 2. Dark brown Dark brown V e l v e t y Type 3. Brown b l a c k Dark brown Sparse down Figure 13 Rudimentary fruiting body of I_. tomentosus. 89 Growth r a t e s f o r i n d i v i d u a l c u l t u r e s ranged from 0.79 t o 1.72 mm. per day. Average growth r a t e s ( f o r a s i n g l e host sp e c i e s or s i t e ) ranged from 0.89 t o 1.53 mm. per day. D. CONCLUSIONS The r e s u l t s c l e a r l y show t h a t s t r o n g d i f f e r e n t i a l v a r i a t i o n i n host s p e c i e s s u s c e p t i b i l i t y to I ^ tomentosus does not e x i s t between lodgepole pine and i n t e r i o r spruce i n the areas s t u d i e d . I t was found t h a t the s u s c e p t i b i l i t y of the two sp e c i e s v a r i e d i n a p o s i t i v e , d i f f e r e n t i a l , q u a n t i t a t i v e manner. Such v a r i a t i o n was l i k e l y due t o a d i f f e r e n t i a l e f f e c t of a b i o t i c or a b i o t i c f a c t o r on the s u s c e p t i b i l i t y of the host s p e c i e s , r a t h e r than t o the presence of host s p e c i f i c races of the pathogen. The l a t t e r c o n d i t i o n would more l i k e l y have r e s u l t e d i n n e g a t i v e , d i f f e r e n t i a l q u a l i t a t i v e v a r i a t i o n . D i f f e r e n c e s were noted i n the behavior of I_j_ tomentosus on pine and spruce and i n the above ground symptoms expressed by these two s p e c i e s . The pathogen o f t e n caused pronounced n e c r o s i s of root phloem i n pines without causing decay of the heartwood. I n f e c t e d pine r o o t s were o f t e n very r e s i n o u s but t h i s r e a c t i o n d i d not appear to stop the advance of the fungus. In spruce the root xylem was of t e n 90 e x t e n s i v e l y decayed while the outer c o n d u c t i v e t i s s u e s were s t i l l a l i v e . I n f e c t e d p i n e s d i s p l a y e d obvious t h i n n i n g of the crown and o f t e n d i e d s t a n d i n g . I n f e c t e d spruce commonly showed no crown symptoms and o f t e n were windthrown while s t i l l green. A l t h o u g h I_j_ tomentosus i s g e n e r a l l y c o n s i d e r e d t o be a d i s e a s e of spruce i n B r i t i s h Columbia, l o d g e p o l e p i n e was a l s o found t o be a t t a c k e d . In f a c t , p i n e s showed h i g h e r i n f e c t i o n r a t e s ( w i t h i n i n f e c t i o n c e n t e r s ) than d i d spruce on a l l study s i t e s . The i n f e c t i o n r a t e w i t h i n i n f e c t i o n c e n t e r s v a r i e d between the two f o r e s t r e g i o n s s t u d i e d , w i t h the h i g h e r i n f e c t i o n r a t e i n the P r i n c e Rupert r e g i o n r e s u l t i n g i n more d i s t i n c t i n f e c t i o n c e n t e r s b e i n g formed t h e r e . However, t h i s does not n e c e s s a r i l l y e x t r a p o l a t e to i n c i d e n c e l e v e l s on the two s p e c i e s i n the f i e l d . The data i n d i c a t e t h a t v a r i a t i o n i n the s u s c e p t i b i l i t y of spruce and p i n e t o tomentosus i n the a r e a s s t u d i e d would not a l l o w f o r e f f e c t i v e r e d u c t i o n of l o s s e s t o the d i s e a s e by t h e i r use as a l t e r n a t e r e g e n e r a t i o n s p e c i e s . Inonotus tomentosus was not d e t e c t e d on D o u g l a s - f i r or s u b a l p i n e f i r w i t h i n any of the sample p l o t s . These s p e c i e s are t h e r e f o r e p o s s i b l e a l t e r n a t e s p e c i e s f o r r e g e n e r a t i n g s i t e s w i t h severe I.  tomentosus i n f e s t a t i o n s . D o u g l a s - f i r would be a p p r o p r i a t e f o r many s i t e s i n the P r i n c e George r e g i o n . S u b a l p i n e f i r i s 91 c u r r e n t l y not used as a r e g e n e r a t i o n s p e c i e s . However, i n t e r e s t i n the s p e c i e s i s growing and i t may become widely used i n the near f u t u r e . For both p i n e and spruce, i n f e c t i o n by tomentosus was not found to have a s i g n i f i c a n t e f f e c t on b a s a l area increment. In f a c t , i n spruce the b a s a l area increment was found to be h i g h e r i n i n f e c t e d t r e e s . Inonotus tomentosus i n c u l t u r e showed a g r e a t d e a l of v a r i a t i o n i n hyphal c o l o r , mat c o l o r and mat t e x t u r e . 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BC-X-246 32 pp. APPENDIX A Maps of Study P l o t s 98 20 PG 1 19 - 0 ie- 4 v 17 -16-15- $ • + 14-13-v + 0 + i H • A S c a l e = I t 200 10 H * + 9 - + + A 7 - 0 A v + 6- A 4 -2 1 Q-\—i—|—|—l—I—I—I—I—I I I I 1 r 2 4 & 6 10 12 14 1t> tt 0 Healthy spruce 0 Healthy pine A Infected spruce + Infected pine PG 2 99 20 ieH 17-1& • 15-14-13-12-11 10 e 7 & 5 4 3 2 1 0 S c a l e - 1:200 X A V + A O D v -j 1 1 1 1—I 1 1 1—I 1 I I " 1 1 1 r 0 2 4 l> e 10 12 14 15 ie 0 Healthy spruce O Healthy p i n e X Subalpine f i r 1 Infected spruce -f Infected p i n e y Douglas f i r 100 PG 3 10 19 -16 -17 -1& -15 -14 -13 -12 -11 -10 --6 -7 -5 -5 -4 -3 -2 -1 -0 0 + 0 S c a l e - 1:200 X ^ 0 0. A M. A X * A D v + • A X . 0 + 0 + + 0 A A 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 T 2 4 & 6 10 12 14 1& 16 2> v Healthy spruce Q Healthy pine X Subalpine f i r A I n f e c t e d spruce -f I n fected p i n e y Douglas f i r 101 PG 4 20-19-ie-17-15-1$ 14 i y 12 11 10 9 6 7 & 5 4 3 2 1 0 S c a l e » 1x200 A v v i 3 A +0 + A V + A ++ A - i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i r~ 0 2 4 & 6 10 12 14 1& 16 20 v Healthy spruce • Healthy p i n e X Subalpine f i r A I n f e c t e d spruce -j- I n f e c t e d p i n * jf Douglas f i r 102 PG 5 20 19 -ie-17-1&-15-14-13-12-11 -10-9 -e-7 a 5 4 3H 2 1 H 0 0 4- + 4 + 0 S c a l e « 1:200 A 0 + + + + + V 0 + + + 0 - i—i—i—i—i—i—i—i—i—i—i—i—i—i—i i i i r 0 2 4 & e 10 12 14 to 16 20 0 Healthy spruce D Healthy pine A I n f e c t e d spruce + Infected pine 103 PG 6 S c a l e " H200 20 19 H • 1ft-17- + 14-+ n- A + 15- • v + + + A v + « 1 • * . A + A + 0 11 -10-9- + v ft -7 H . * + v • &H 5 -4-3 -2-1 -0 - | — i — i — l — I — l — l — l — l — I — l — I 1 1 1 1 1 1 1 r 2 4 & $ 10 12 14 15 1* v Healthy spruce 0 Healthy pine A Infected spruce + Infected pine 104 20 PG 7 19 -17-it>-15-14-13-12-11 -10-9 -e -7 -5 -5 -4 -3 -2 -1 -0 -0 A 0 + 0 + V S c a l e « 1x200 + + + A + v D + + A "1 | 1 1 1 1 1 1 1 1 1 1 1 1 1 I I T 2 4 5 S 10 12 14 It 16 2} ^ Healthy spruce Q Healthy pine A Infected spruce •f Infected pine 1 0 5 9 -ft- v Scale = 1:200 PG 8 20 n -17-15-15-1 4 " . A + 13- * • • 12- A + 11 -0 A 10 H +. + A + A 0 A + v 7 i + * 5 5 H ++ 3-2-1 OH—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i r 0 2 4 5 f t 10 12 14 15 1ft 20 0 Healthy spruce D Healthy pine A Infected spruce -{- Infected pine 106 PG 9 20 19-16-17 It 15 14 13 12 11 10 9 e 7 & 5 4 3 2 1 0 S c a l e = Ii200 X • X X X A X X + A n—i—i—i—i—i—i—r 12 14 1t 16 2} n—i—i—i—i—i—i—i—i—r 0 2 4 t 6 10 0 Healthy spruce fl Healthy pine X Douglas f i r A Infected spruce + Infected p i n e 107 PG 10 20 - i 19 - A S c a l e •> l i 2 0 0 • A 14-17- +• 1&- + A A A + + A A 15- V + 14- + + A 13- v 12- + + A 11 - A 10-9 -0 4-7- 0 5 - + 5-4 - + V 3-2-1 -Si 1 1 1 1 1 I 1 i I I 1 ! 1 1 1 1 l l l 0 2 4 5 4 10 12 14 15 14 20 Vs Healthy spruce • Healthy pine A Infected spruce •+• Infected pine PG 11 108 20-19 -S c a l e • 1:200 16-17-0 A • 0 + + 16- + 15-14- A 13- V 12- V A A A Aa + 11 - • + + 10- + 9 - + e-7- + A V 6 -5 - A + A 4-3- V 2-1 -A 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 2 4 & 6 10 12 14 1& 16 2> 0 Healthy spruce • I n f e c t e d spruce O Healthy pine + Infected pine 109 PR 1 S c a l e «= 1:200 + + + A A A + v A + A ° * 4 A 20 19 -ie-17-i&-15-14 13 H 12 1 H 10 :i 7 & 5 4 3 2 -1 -01—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—r +• + A + + A A ^ A A + + + A $ 10 12 14 15 W 20 v* Healthy spruce A I n f e c t e d spruce D Healthy pine + Infected pine 110 PR 2 £ Healthy spruce rj Healthy pine A I n f e c t e d spruce + Infected pine I l l PR 3 20 19 H 14 17-15-15-14-13-S c a l e «= 1:200 A A + + 12-1 A • . + « H +++ + * + A * 10 H « A A 9 H ft 7 H 1 A * 5 - A v ^ 4- + 3-2-1 -O i — i — i — i — r — i — r ~ ~ — i — i — i — i — i — I — T — i — i — i — i — r 2 4 & 4 10 12 14 15 14 2> 0 Healthy p i n e ^ Healthy spruce T Subalpine f i r + Infected pine A Infected spruce 20-r 19-16-17-16 -15-14-13-12-11 -10-9 -e-7-6 -5-4-3-2-1 -A A + PR 4 + 112 Sca l e * 1:200 A A D A 0 1 +1 Jr A A A A A + + ~i i i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — r ~ 0 2 4 I A 10 12 14 n 16 2£> D Healthy pine ^ Healthy spruce "t" I n f ected pine A I n f e c t e d spruce 113 0 Healthy pine ^ Healthy spruce 4 Infected pine £ Infected spruce 114 PR 6 20-r 19 -ie-17-15-15-14-13-12-11 -10-9-6-7-6-5-4-3-2-1 -0-+ Scale » H200 + -+ + n—i—i—r H ia 20 i — i — i — i — i — i — i — i — i — i — i — i — i — r 2 4 6 e 10 12 14 0 Healthy p i n e v* Healthy spruce X Subalpine f i r + Infected pine A Infected spruce 115 PR 7 20 ie-17-K' + + A 15- + v 14- A A X t 15- 1 4 A 12 11 -9 -+ + + en A + + o A 7-1 + A + 0 + S c a l e = 1:200 10H * + i + + A 6 -5-4-5-j +++ 2 1 -0 1 — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — r 2 4 t $ 10 12 14 16 16 20 • Healthy p i n e 0 Healthy spruce % Subalpine f i r +• Infected pine A Infected spruce PR 8 116 ^ 1 + • Scale - 1«200 19 H + I H + 17 „ I H * 1 + + 1 H D « + 14 H A i H + + + + k + I H I H + * » -»- » + D + 7- + + 6-5 -4-J -2 -1 -o H — i — i — i — i — i — I I I — i — i — i — i — i — i — i — i — i — i — r 4 A 2 4 5 6 10 12 14 15 16 2> D Healthy p i n * 4 Infected pine ^ Healthy spruce A Infected spruce PR ^ S c a l e - 1:200 + + + 0 x • • + A v X 4 A + A 4 A + 20 19 -1ft-17-15 15-14-13-12-11 " 10-9 -ft-7 5 5 4 3 2-1 -01—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—r + + 4 4 0 <• + + f A * 0 A 0 A 0 2 4 & ft 10 12 14 15 1ft 2> • Healthy pine 4 Healthy spruce X Subalpine f i r 4- Infected pine A Infected spruce Appendix B 118 The e c o l o g i c a l associations included i n t h i s study are l i s t e d below: symbol E c o l o g i c a l Association Moisture Nutrient Regime Regime SBSd 07 Submesic Bunchberry - Moss SBSd 08 Moist Shrub - Forb SBSel 01 Mesic Bunchberry - Moss SBSel 04 Submesic Bunchberry - Moss SBSe2 01 Bunchberry - Moss SBSe2 04 Douglas f i r - Subalpine f i r Mesic to Submesic Mesic to Subhygric Mesic Submesic Mesic subxeric to Submesic SBSk3 01 P r i c k l y Rose - Queen's Cup Mesic SBSk3 04.1 Wild S a r s a p a r l l l a -Prince's Pine Submesic Oligo to Mesotrophic Submeso to Subeutrophic Mesotrophic Oligo to Mesotrophic Submeso to Permesotroph Submeso to Mesotrophic Submeso to Permesotroph Submeso to Mesotrophic APPENDIX C S t a t i s t i c a l Te Two Sample T-Test on the I n i t i a l Basal Area of Healthy and Infected Pine. V a r i a b l e N Mean I n i t i a l Basal Area (cm sq) Standard D e v i a t i o n (cm sq) Healthy 24 370.01 945.46 Infe c t e d 33 300.66 752.42 Test Df S i g n i f i c a n c e T=0.97483 F=1.5789 55 23, 32 0.334 0.115 121 Regression of the Change i n Basal Area with I n i t i a l Basal Area Source Sum of Squares Df Mean Square F - r a t l o P r o b a b i l i t y Regression 0.183E+8 Error 0.212E+8 1 0.183E+8 55 0.386E+6 47.363 .000 To t a l 0.395E+8 Mult R = 0.680 R-Square = 0 .463 SE - 612.08 Vari a b l e P a r t i a l Coeff Std.Error T-Stat S i g n i f . Constant I n i t i a l BA .680 364.26 .022 132.04 .003 2.759 .008 6.882 .000 Two sample T-Test on the i n i t i a l Basal Area of Healthy and Infected Spruce V a r i a b l e N Mean basal area cm-sg Standard D e v i a t i o n Healthy 21 245.93 152.79 Infected 17 246.69 136.12 Test S t a t . Df S i g n i f i c a n c e T= -.058 36 .953 F= 1.259 20, 16 .322 The p r o b a b i l i t y of healthy t r e e s being l a r g e r than i n f e c t e d t r e e s i s 0.52 

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