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Field evaluations of herbicides for the control of Centaurea diffusa lam. and C. maculosa lam. Douglas, Brian John 1983

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FIELD EVALUATIONS OF HERBICIDES FOR THE CONTROL OF C E N T A U R E A DIFFUSA L A M . A N D C . MACULOSA L A M . by BRIAN JOHN DOUGLAS B.Sc. (Agr.), The University of British Columbia, 1979 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department of Plant Science) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September 1983 (c)Brian 3ohn Douglas, 1983 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study. I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the head o f my department o r by h i s o r her r e p r e s e n t a t i v e s . I t i s understood t h a t copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n p e r m i s s i o n . Department of • P l a n t S c i e n c e The U n i v e r s i t y of B r i t i s h Columbia 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5 November 18 , 1983 DE-6 (2/79) ABSTRACT Diffuse knapweed (Centaurea diffusa) and spotted knapweed (C. maculosa) are widespread in the southern interior of British Columbia and are rapidly spreading to colonize new areas. The use of herbicides for control of these knapweeds has been restricted because of the high cost of and environmental impact resulting from applications of picloram. Phytotoxic residues of picloram have caused damage to cultivated plants in B.C. and at present the only effective alternate herbicide is 2,4-D. Field studies were conducted in the Thompson Valley to evaluate picloram, triclopyr, 3,6-dichloropicolinic acid and chlorsulfuron for control of diffuse and spotted knapweeds. Triclopyr and chlorsulfuron provided control of both species only for the season of treatment. Picloram and 3,6-dichloropicolinic acid controlled spotted knapweed for at least 300 days and diffuse knapweed for at least 420 days. Both herbicides also provided residual control of knapweed seedlings. The addition of Citowett Plus (50% alkyl aryl polyethylene glycol) at 0.1% (v/v) to solutions of chlorsulfuron did not improve control of diffuse knapweed with chlorsulfuron. Chlorsulfuron had some soil residual activity against diffuse knapweed seedlings. The experimental sulfonyl urea, DPX-T6376 applied at 20 to 160 grams/ha controlled existing diffuse knapweed plants and emerging seedlings in the season of treatment. A minimum effective rate of 3,6-dichloropicolinic acid for control of existing diffuse knapweed plants and residual control of seedlings for the season of treatment was 150 g/ha. Rates of 3,6-dichloropicolinic acid below this provided poor control of emerging seedlings and many diffuse knapweed plants were able to recover from the treatment. The effects of picloram, triclopyr, 3,6-dichloropicolinic acid and chlorsulfuron on seed germination, radicle elongation and seedling growth of diffuse knapweed, spotted knapweed, bluebunch wheatgrass and crested wheatgrass were evaluated in Petri plates. Chlorsulfuron reduced the radicle elongation and seedling growth of diffuse and spotted knapweeds. The effects of the pyridine herbicides varied with concentration and herbicide. iv TABLE OF CONTENTS Page Abstract ii List of Tables vii List of Figures ix Acknowledgement xi I. Introduction 1 II. Limitations to the use of picloram for knapweed control 4 III. Review of herbicides 10 IV. Descriptions of field sites 22 V. Evaluation of herbicides for residual control of knapweed 39 VI. Chlorsulfuron plus surfactant field trial 53 VII. DPX-T6376 57 VIII. 3,6-dichloropicolinic acid minimum rate trial 60 IX. Effect of herbicides on seed germination 63 X . Discussion 80 XI. Summary 85 XII. Bibliography 87 XIII. Appendices A . Ashcroft and Walhachin sites - pretreatment yields of knapweed and grass and analyses of variance. 94 V T A B L E O F C O N T E N T S (continued) Page B. Ashcroft site - post treatment yields of diffuse knapweed and grass (30 days), analyses of variance and multiple comparisons. 105 C. Walhachin site - post treatment yields of spotted knapweed and grass (30 days), analyses of variance and multiple comparisons. 112 D. Ashcroft site - post treatment yields of diffuse knapweed and grass (300 days), analyses of variance and multiple comparisons. 119 E. Walhachin site - post treatment yields of spotted knapweed and grass (300 days), analyses of variance and multiple comparisons. 138 F. Ashcroft site - post treatment yields of diffuse knapweed and grass (420 days), analyses of variance and multiple comparisons. 159 G. Chlorsulfuron plus surfactant field trial - post treatment yields of diffuse knapweed (52 days), analyses of variance and multiple comparisons. H. DPX-T6376 field trial - post treatment yields of diffuse knapweed (48 days), analyses of variance and multiple comparisons. 187 TABLE OF CONTENTS (continued) I. 3 ,6-d ich loropico l in ic ac id m i n i m u m rate t r i a l - post t r e a t m e n t yields of d i f fuse knapweed (45 days), analyses of var iance and mul t ip le compar isons . 3. Seed germinat ion exper iments - number o f g e r m i n a t e d seeds, rad i c le lengths/seed and to ta l seed l ing length/ seed, analyses of va r i ance and mul t ip le compar i sons . vii LIST OF TABLES Table Page I. Physical and chemical properties of soil at the Ashcroft site 26 II. Plant species collected at the Ashcroft site 27 III. Physical and chemical properties of soil at the Walhachin site 31 IV. Plant species collected at the Walhachin site 32 V. Physical and chemical properties of soil at the Cache Creek site 36 VI. Plant species collected at the Cache Creek site 38 VII. Herbicides applied June 1981 at Walhachin and Ashcroft sites 41 VIII. Ashcroft site 30 days post treatment - main plot yields 43 IX. Walhachin site 30 days post treatment - main plot yields 44 X. Walhachin site 300 days post treatment - main plot yields and plant numbers 46 XI. Ashcroft site 300 days post treatment - main plot yields and plant numbers 48 XII. Ashcroft site 420 days post treatment - main plot yields and plant numbers 51 viii LIST OF TABLES (continued) Table Page XIII. Chlorsulfuron plus surfactant field trial - post treatment yields and plant numbers (52 days) 55 XIV. DPX-T6376 field trial - post treatment yields and plant numbers (48 days) 58 XV. 3,6-dichloropicolinic acid minimum rate trial - post treat-ment yields and plant numbers 61 i x LIST OF FIGURES Figure Page 1. Picloram 11 2. Triclopyr 12 3. 3,6-dichloropicolinic acid 15 4. Chlorsulfuron 18 5. DPX-T6376 20 6. Map showing location of field sites 23 7. Topographic map showing location of Ashcroft site 24 8. Topographic map showing location of Walhachin site 29 9. Topographic map showing location of Cache Creek site 35 10. Effect of herbicides on germination of diffuse knapweed 68 11. Effect of herbicides on radicle length of diffuse knapweed seedlings 69 12. Effect of herbicides on total length of diffuse knapweed seedlings 70 13. Effect of herbicides on germination of spotted knapweed 71 14. Effect of herbicides on radicle length of spotted knapweed seedlings 72 X LIST OF FIGURES (continued) F i g u r e Page 15. Effect of herbicides on total length of spotted knapweed seedlings 73 16. Effect of herbicides on germination of bluebunch wheatgrass 74 17. Effect of herbicides on radicle length of bluebunch wheatgrass seedlings 75 18. Effect of herbicides on total length of bluebunch wheatgrass seedlings 76 19. Effect of herbicides on germination of crested wheatgrass 77 20. Effect of herbicides on radicle length of crested wheatgrass seedlings 78 21. Effect of herbicides on total length of crested wheatgrass seedlings 79 A C K N O W L E D G E M E N T The author expresses sincere thanks to committee members Dr. B.G. Todd for initiating the project and acting as initial supervisor; Dr. M.D. Pitt for taking over as my supervisor and for his advice; and Dr. V.C. Runeckles for his advice and assistance. Cooperation of the following individuals is greatly appreciated; Mr. W.R. Eld, Mr. T. Rolphe, Mr. J. Regier (Chataway Ranch), Mr. R. Willis (Merryfield Feeders Ltd.) and Mr. R.E. Blackshaw (DuPont Canada Inc.). Financial support for this project was provided by DuPont Canada Inc. and the Bostock Fund. The author is grateful to the Dow Chemical Co. and DuPont Canada Inc. for supplying the herbicides for this project. The guidance and assistance of Dr. G.W. Eaton with data analysis is greatly appreciated. I. Introduction Diffuse knapweed (Centaurea diffusa Lam.) was introduced into British Columbia prior to 1930 (Renney 1959) and was first collected in B.C. at Oyama in 1936 (Watson and Renney 1974). Spotted knapweed (Centaurea maculosa Lam.) was first collected in B.C. at Victoria in 1893 (Groh 1944). Willis (1951) estimated that there were 250 acres (101.21 ha) of diffuse knapweed and 300 acres (121.45 ha) of spotted knapweed in the Thompson and Nicola River drainage systems in 1951. By 1968 diffuse knapweed had spread to occupy 19,495 ha and spotted knapweed was found on 1,484 ha (Renney and Hughes 1969). Watson and Renney (1974) estimated that diffuse knapweed had infested 25,952 ha and spotted knapweed occuppied 3,460 ha in the southern interior of B.C. by 1974. The potential spread of these knapweeds was identified in the early 1950's (Willis 1951; Hanna 1952) and their detrimental effects are now well documented (Watson and Renney 1974; Maddox 1979; Strang et al. 1979). It has been suggested that if these species were to spread to their ecological limits, they could occupy 1.1 million ha of rangeland in B.C. (Select Standing Committee on Agriculture 1978) and 8.4 to 10.7 million ha of uncultivated drylands in western Canada (Harris and Cranston 1979). Both diffuse and spotted knapweed can be controlled by cultural methods (Popova 1960; Watson and Renney 1974), by chemical methods (Renney and Hughes 1969) and perhaps with biological control agents (Harris and Cranston 1979). Experimental evaluations of herbicides for knapweed control were first conducted in 1950 by F. Carmichael, District Agriculturist, Grand Forks, B.C. (Anonymous 1977). Carmichael found that an ester formulation of 2,4-D (2,4-dichlorophenoxy acetic acid) at 1.68 to 2.24 kilograms of active ingredient per hectare (kg/ha) gave variable control of diffuse knapweed seedlings. Willis (1951) reported that 2,4-D at 2.24 kg/ha killed the foliage of diffuse knapweed but did not prevent regrowth in subsequent years. In 1952, field trials with herbicides were conducted by the University of B.C. and the Canada Department of Agriculture Research Station at Kamloops, B.C. Results of these trials led to a recommendation of 2,4-D ester at 2.24 to 4.48 kg/ha for diffuse knapweed control. This treatment was effective against knapweed seedlings but only partially effective on established plants (Anonymous 1977). These 2,4-D treatments did not prevent seed germination or recruitment from the seed bank. In 1964, Dr. A.J. Renney evaluated 2,4-D, MCPA (2-methyl-4-chloro phenoxy-acetic acid), silvex (2-(2,4,5-trichlorophenoxy) propionic acid) and picloram (4-amino-3,5,6-trichloropicolinic acid) for diffuse knapweed control. The only rate of picloram used was 1.61 kg/ha. Picloram provided residual control for the season of treatment and for the next three seasons (Renney 1967). Further trials with picloram and other herbicides were conducted in 1965 and 1966, at Keremeos by the B.C. Department of Agriculture and the University of B.C. The optimum rate of picloram for diffuse knapweed control was found to be in the range of 0.42 to 0.56 kg/ha when weed control and grass injury were both considered. Combinations of sodium borate/2,3,6-TBA (2,3,6-trichlorobenzoic acid) and sodium borate/bromacil (5-bromo-3-sec-butyl-6-methyluracil) gave excellent control of diffuse knapweed plants, but associated grass species were also killed. The rate of picloram necessary for control of diffuse knapweed was found to be site-dependent. Picloram applied at 0.28 to 0.42 kg/ha was found to be effective for diffuse knapweed control in some seasons and locations (Anonymous 1977; Hubbard 1975). Picloram provided excellent control of knapweed regardless of time of application; but applications in the early flowering stage were most effective (Renney and Hughes 1969). Picloram at rates between 0.42 and 0.56 kg/ha is recommended for the control of diffuse and spotted knapweed in B.C. (B.C. Department of Agriculture 1971). II. Limitations to the use of picloram for knapweed control The use of picloram for control of diffuse and spotted knapweed has been restricted because of the high cost of chemical treatment and the persistence and broad spectrum of activity of the herbicide (Watson and Renney 1974). Picloram is an extremely stable compound (National Research Council 1974; Naik et al. 1972) and injury to susceptible crops can result even four years after the time of application (Fryer et al. 1979). Residues of picloram are a danger to cultivated crops even after passing through the digestive tracts of animals (Maddox 1979); adequate buffer zones must be maintained from desirable vegetation such as trees, alfalfa (Medicago sativa L.) and vegetables (Anonymous 1977) and contamination of irrigation water may occur (Bovey and Scrifes 1971). Picloram can inhibit the activity of Nitrosomonas bacteria and decrease the conversion of ammonia to nitrite (Debona and Audus 1970). Legumes cannot be established for up to four years following the application of picloram for knapweed control; thus long term management plans must be considered. Reseeding of areas treated with picloram must be delayed for 6 to 12 months after treatment because picloram is detrimental to root growth in grass seedlings (Harris and Cranston 1979). The application of picloram to grassland ecosystems can have both short term effects and long term effects. With most herbicides (except picloram), the direct toxicity of the herbicide is limited to the year of application. As picloram is very persistent, the long term effects can be of two types; direct phytotoxicity to both target and non-target species and modification of the succession of the plant c o m m u n i t y ( N e w t o n and N o r r i s 1976). The most i m p o r t a n t c h a r a c t e r i s t i c of p i c l o r a m f r o m an e c o l o g i c a l po int o f v i e w is i t s pe rs i s ten t p h y t o t o x i c i t y (Moore 1967; P i m e n t e l and E d w a r d s 1982). The w ide p h y t o t o x i c range of p i c l o r a m a lso r e d u c e s the d i v e r s i t y of p l a n t spec ies in the c o m m u n i t y f o r s e v e r a l y e a r s . T h i s p roduces less s t a b l e sys tems du r ing t i m e s of d rought or o the r s t resses ( N a t i o n a l R e s e a r c h C o u n c i l 1974). The a b i l i t y o f a p lant c o m m u n i t y t o w i t h s t a n d drought is p a r t i c u l a r l y i m p o r t a n t in w e s t e r n C a n a d i a n range lands w h e r e f r e q u e n t ser ies of dry y e a r s r e d u c e the abundance and c o v e r of h igher y i e l d i n g grasses ( C a m p b e l l e t a l . 1962). D r o u g h t c a n a lso be an i m p o r t a n t means o f t r i g g e r i n g nox ious p lant i nvas ion on range p r e v i o u s l y w e a k e n e d by g r a z i n g or o t h e r f a c t o r s ( V a l l e n t i n e 1971). In years o f l o w p r e c i p i t a t i o n , these knapweeds c o u l d i nvade range land a reas p rev ious l y t r e a t e d w i t h p i c l o r a m . P i c l o r a m a t r a t e s used fo r k n a p w e e d c o n t r o l w i l l r e m o v e a l m o s t a l l b r o a d l e a v e d herbs and some woody shrubs . A n abundance of n o n - g r a s s y herbs p rov ides good g r a z i n g f o r sheep and some spec ies of w i l d l i f e (Weaver and C l e m e n t s 1938). A p p l i c a t i o n s o f 2 , 4 - D to a sagebrush ( A r t e m i s i a  t r i d e n t a t a N u t t . ) range r e d u c e d f o r b popu la t ions f o r t h r e e to f i v e yea rs ( H e d r i c k 1967). A s p i c l o r a m is m o r e p e r s i s t e n t than 2 , 4 - D , a p p l i c a t i o n s o f th is h e r b i c i d e fo r k n a p w e e d c o n t r o l on ranges in the s e m i - a r i d a reas of B . C . c o u l d r e d u c e f o r b popu la t ions fo r a t l eas t f i v e y e a r s . On n a t i v e range lands , both l i v e s t o c k and w i l d l i f e f e e d e x t e n s i v e l y on b r o w s e and fo rbs , as w e l l as g rasses . D i v e r s i t y of these range p lan t c o m m u n i t i e s p rov ides a v a r i e t y o f p lants fo r the chang ing seasona l needs of g r a z i n g a n i m a l s ( V a l l e n t i n e 1971). The a p p l i c a t i o n of p i c l o r a m c a n r e d u c e the d i v e r s i t y o f p lan t c o m m u n i t i e s and the r e t u r n of these c o m m u n i t i e s to t h e i r o r i g i n a l s t a t e may be d e t e r m i n e d by t h e i r s tage of success ion at t i m e of t r e a t m e n t . C o m m u n i t i e s a t a l o w e r s u c c e s s i o n a l s tage (more sera i ) r e c o v e r to t h e i r o r i g i n a l s t a t e more q u i c k l y f r o m p i c l o r a m a p p l i c a t i o n s than c o m m u n i t i e s c l o s e r to c l i m a x a t the t i m e of t r e a t m e n t ( T o m k i n s and G r a n t 1977). P i c l o r a m w i l l not on ly r e m o v e b r o a d l e a v e d h e r b s , but dec iduous and c o n i f e r o u s t r e e s and some grass spec ies c a n a lso be i n j u r e d . P i c l o r a m a t 50 and 100 p a r t s per m i l l i o n (ppm) caused a b n o r m a l d e v e l o p m e n t o f red p ine (P inus res inosa A i t . ) seed l ings and i n h i b i t e d root g r o w t h at 0.01 ppm ( K o z l o w s k i and S a s a k i 1968; Wu e t a l . 1971). H a r r i s and C r a n s t o n (1979) suggested t h a t k n a p w e e d s c o u l d i nvade the D a r k B r o w n and B r o w n s o i l zones of w e s t e r n C a n a d a in a reas o f u n c u l t i v a t e d l a n d . If p i c l o r a m w e r e used fo r k n a p w e e d c o n t r o l in these shor tg rass and m i x e d p r a i r i e s , i t c o u l d r e t a r d the g r o w t h and r e p r o d u c t i o n of some n a t i v e grass s p e c i e s . B lue g r a m a (Bou te loua g r a c i l i s ( H . B . K . ) L a g . ex Steud. ) is an i m p o r t a n t c o m p o n e n t of the m i x e d p r a i r i e in w e s t e r n C a n a d a , e s p e c i a l l y in d r i e r p a r t s of t he B r o w n so i l zone (Smol iak et a l . 1976). B l u e g r a m a is found in the S t i p a - B o u t e l o u a t y p e , the B o u t e l o u a - A g r o p y r o n t y p e and in l i g h t to heavy t e x t u r e d s o l o n e t z i c so i ls in the B r o w n s o i l z o n e . P i c l o r a m app l i ed a t 0.84 k g / h a and above p r e v e n t e d the g e r m i n a t i o n of seeds of b lue g r a m a , s ideoats g r a m a ( B o u t e l o u a c u r t i p e n d u l a ( M i c h x . ) To r r . ) , b ig b l u e s t e m (Andropogon g e r a r d i i V i t m a n . ) and s w i t c h g r a s s ( P a n i c u m v i r g a t u m L. ) . P i c l o r a m app l i ed at 1.68 k g / h a and above also d e c r e a s e d the y i e l d of a l l these grasses e x c e p t b ig b l u e s t e m when t r e a t m e n t was at the t w o - l e a f s tage ( A r n o l d and S a n t e l m a n n 1966). A t the four l e a f s t a g e , most of these grasses w e r e r e s i s t a n t to p i c l o r a m at r a t e s less than 3.36 k g / h a . R o o t p r o d u c t i o n of s w i t c h g r a s s and s ideoats g r a m a was d e c r e a s e d w i t h on ly one or t w o ppm p i c l o r a m in the s u r f a c e i n c h of s o i l ( Se r i f es and H a l i f a x 1972a). P i c l o r a m app l i ed at 1.12 k g / h a fo r the c o n t r o l of R u s s i a n k n a p w e e d ( C e n t a u r e a repens L.) c a u s e d p r o s t r a t e g r o w t h of grass s p e c i e s (Wyoming A g r i c u l t u r a l E x p e r i m e n t S t a t i o n 1979). G e r m i n a t i o n of c a r y o p s e s of b u f f a l o g r a s s (Buch loe d a c t y l o i d e s (Nut t . ) E n g e l m . ) , s i deoats g r a m a and s w i t c h g r a s s was not a f f e c t e d by 1,000 p a r t s per b i l l i o n (ppb) p i c l o r a m , bu t r a d i c l e e l o n g a t i o n was r e d u c e d by 125 ppb (Ser i fes and H a l i f a x 1972b). The p r o b a b i l i t y of s i g n i f i c a n t q u a n t i t i e s o f p i c l o r a m in runo f f w a t e r under n o r m a l usage fo r range m a n a g e m e n t is l o w (Ser i fes 1977). T h e r e i s , h o w e v e r , c o n c e r n a b o u t the s a f e t y of p i c l o r a m use (Reuber 1981; Johnson 1971) and the p o s s i b i l i t y o f m o v e m e n t f r o m the s i t e of a p p l i c a t i o n (Bovey and S c r i f e s 1971). U n d e r f i e l d c o n d i t i o n s , the p e r s i s t e n c e and m o v e m e n t o f p i c l o r a m a r e d e t e r m i n e d by c l i m a t o l o g i -c a l and edaph ic f a c t o r s . The loss o f p i c l o r a m f r o m g rass land wate rsheds is d i r e c t l y r e l a t e d to the t i m e b e t w e e n t r e a t m e n t and the f i r s t major r a i n f a l l (Haas e t a l . 1971; Bovey et a l . 1974). P l a n t w a s h o f f by r a i n f a l l is the m a i n sou rce of h e r b i c i d e in s u r f a c e runof f w a t e r ( S c r i f e s e t a l . 1971 a ,b ; 3ohnsen 1980). The c o n c e n t r a t i o n of p i c l o r a m in both s u r f a c e and s u b s u r f a c e d ra inage is a f f e c t e d by so i l t e x t u r e , p r e c i p i t a t i o n , s o i l o r g a n i c m a t t e r and d e n s i t y of v e g e t a t i o n (Bovey and S c r i f e s 1971). L a t e r a l m o v e m e n t and l e a c h i n g of p i c l o r a m is g r e a t e s t in sandy l o a m so i ls (Her r e t a l . 1966; L u t z et a l . 1973), l ow in o r g a n i c m a t t e r ( G r o v e r 1973; G o r i n g and H a m a k e r 1971) w i t h s l i g h t l y a c i d i c or a l k a l i n e p H (Dav is and Ingebo 1973). In so i ls w i t h these c h a r a c t e r i s t i c s , l e a c h i n g by r a i n f a l l c o u l d l ead to c o n t a m i n a t i o n o f g roundwate r s o u r c e s . L e a c h i n g by r a i n f a l l is one of the m o s t i m p o r t a n t means of p i c l o r a m d i s a p p e a r a n c e f r o m so i l s (Bovey et a l . 1969). P i c l o r a m a p p l i e d to a sandy s o i l a t 0.56 k g / h a or less d id not m o v e deeper than 30 c e n t i m e t e r s (cm) (Bovey and S e r i f e s 1971). The loss o f p i c l o r a m in s u r f a c e runof f w a t e r a f t e r a p p l i c a t i o n to a range land w a t e r s h e d suppo r t i ng stands of honey m e s q u i t e (P rosop is  j u l i f l o r a (Swartz ) D . C . v a r . g landu losa (Torr . ) C o c k e r e l ) , c o m m o n b r o o m w e e d ( X a n t h o c e p h a l u m d r a c u n c u l o i d e s (D .C . ) B lake ) and need legrasses (S t ipa spec ies ) was s i m i l a r whethe r the p i c l o r a m was a p p l i e d as an aqueous spray or as p e l l e t s (Bovey et a l . 1978). D e c o m p o s i t i o n o f p i c l o r a m is d e t e r m i n e d p r i m a r i l y by t e m p e r a t u r e and m o i s t u r e c o n d i t i o n s and less by o r g a n i c m a t t e r c o n t e n t of the s o i l ( H a m a k e r et a l . 1967). The s o i l c o n c e n t r a t i o n o f p i c l o r a m a p p l i e d to a s i l t l o a m s o i l i n B . C . a t 0.5 k g / h a dec reased f r o m 0.28 ppm a t a p p l i c a t i o n t i m e to 0.02 ppm a f t e r 1.5 yea rs (Hogue e t a l . unpubl ished) . P i c l o r a m at l e v e l s e x c e e d i n g 290 ppb is d e t r i m e n t a l to the g r o w t h o f c u t t h r o a t t r o u t f r y (Sa lmo c l a r k i R i c h a r d s o n ) . W o o d w a r d (1979) suggested t h a t p i c l o r a m not be a p p l i e d on s t r e a m and l akeshore s lopes and t h a t the p e r s i s t e n c e and m o b i l i t y of p i c l o r a m in the e n v i r o n m e n t and the r e s u l t i n g h a z a r d to a q u a t i c h a b i t a t s are c o n s i d e r e d b e f o r e any a p p l i c a t i o n s to range lands . P i c l o r a m res idues are h a r m f u l to the g e r m i n a t i o n of some f o r a g e grasses used to reseed d e p l e t e d range lands and seed ing must be d e l a y e d a f t e r p i c l o r a m t r e a t m e n t (Ha r r i s and C r a n s t o n 1979). When reseed ing range lands , d i f f u s e and s p o t t e d k n a p w e e d c a n q u i c k l y c o l o n i z e these d i s tu rbed areas and e f f e c t i v e l y c o m p e t e w i t h p e r e n n i a l grass seedlings. Once annual species have dominated a site, control of herbaceous weeds is necessary for successful establishment of seeded grasses. Broadleaf weeds, such as the knapweeds, can form a serai community which guarantees their domination of disturbed areas (Evans et al. 1969). The control of these broadleaf species is necessary for the successful establishment of perennial wheatgrasses (Robocker et al. 1965). Picloram is excluded from use in these situations because of its detrimental effects on grass seedlings (Harris and Cranston 1979; McCarty 1979). Control of broadleaved weeds helped to maintain seedbed conditions within germination and growth requirements of intermediate wheatgrass, (Agropyron intermedium (Host) Beauv.) by eliminating established weeds and their competitive effects (Evans et al. 1970). A lack of effective alternate herbicides to picloram (Fryer 1976; Anonymous 1980a, 1980b) and concern over its safety (Lynn 1965), persistence, mobility and wide phytotoxic range provided the stimulus for this study. A ban on the use of picloram in the Central Okanagan Regional District in 1980 emphasized the need for effective alternate herbicides. III. Review of herbicides P i c l o r a m P i c l o r a m (F igure 1) (Dow C h e m i c a l Co . ) is a s u b s t i t u t e d p i c o l i n i c a c i d p h y t o t o x i c to a w ide range o f d i c o t y l e d e n o u s p lan ts . It c a n pe rs i s t in a p h y t o t o x i c f o r m f o r one to f i v e yea rs depend ing on e n v i r o n m e n t a l c o n d i t i o n s . D e g r a d a t i o n of p i c l o r a m in s o i l is most rap id under a e r o b i c c o n d i t i o n s , a t h igh t e m p e r a t u r e s w i t h adequate s o i l m o i s t u r e ( N a t i o n a l R e s e a r c h C o u n c i l 1974). P i c l o r a m is w i d e l y used for the c o n t r o l o f weeds r e s i s t a n t to phenoxy h e r b i c i d e s , brush c o n t r o l and p e r e n n i a l w e e d c o n t r o l in n o n - c r o p l a n d . In C a n a d a , i t is used on r i g h t s - o f - w a y i n c l u d i n g u t i l i t y l i n e s , p i p e l i n e s , h ighways and r a i l w a y s . It is a lso used as a spot t r e a t m e n t f o r the c o n t r o l o f p e r e n n i a l and b i e n n i a l weeds in p e r m a n e n t grass pasture and r a n g e l a n d . T r i c l o p y r T r i c l o p y r ( ( ( 3 , 5 , 6 - t r i c h l o r o - 2 - p y r i d i n y l ) - o x y ) a c e t i c ac id ) ( F igu re 2) (Dow C h e m -i c a l Co . ) is a s u b s t i t u t e d o x y a c e t i c a c i d c o n t a i n i n g a p y r i d i n e r i n g . It is a ve ry e f f e c t i v e h e r b i c i d e for the c o n t r o l o f many woody p lants and b r o a d l e a f weeds ( L i c h y 1980). E s t a b l i s h e d grasses n o r m a l l y are not i n ju red by ra tes of t r i c l o p y r needed for weed and brush c o n t r o l . It has been e x t e n s i v e l y e v a l u a t e d fo r the c o n t r o l of woody p l a n t s , p a r t i c u l a r l y on e l e c t r i c t r a n s m i s s i o n l i ne r i g h t s - o f - w a y ( H a a g s m a 1975b; crNvrx:—OH • » o F i g u r e 1. Picloram , (4-amino-3,5,6 t r i c h l o r o p i c o l i n i c acid.) Cl Cl 0 - C H 2 - C o OH F i g u r e 2 . T r i c l o p y r , ( ( 3 , 5 , 6 - t r i c h l o r o - 2 - p y r i d i n y l ) oxy ) a c e t i c a c i d F e a r s and D i c k e n s 1978). L o b l o l l y p ine (P inus t a e d a L. ) and w h i t e p ine (P inus s t robus L.) c a n be c o n t r o l l e d by a p p l i c a t i o n s o f 6.72 k g / h a , but red p ine is not a f f e c t e d at r a t e s up to 10.08 k g / h a (By rd and C o l b y 1978). S a l a l ( G a u l t h e r i a s h a l l o n Pursh) and h e m l o c k (Tsuga h e t e r o p h y l l a (Ra f . ) Sarg.) w i l l t o l e r a t e up to 3.36 k g / h a (Byrd e t a l . 1975). P o n d e r o s a p ine (Pinus ponderosa Dougl . ) is s u s c e p t i b l e a t r a t e s o f 2.24 k g a c i d e q u i v a l e n t (a .e . ) /ha but D o u g l a s - f i r (Pseudotsuga m e n z i e s i i ( M i r b e l ) F r a n c o ) c a n t o l e r a t e 6.72 k g a . e . / h a . Y e l l o w s t a r t h i s t l e ( C e n t a u r e a s o l s t i t i a l i s L.) c a n be c o n t r o l l e d w i t h 0.43 k g / h a and squar rose k n a p w e e d ( C e n t a u r e a s q u a r r o s a W i l l d . ) c a n be c o n t r o l l e d w i t h 1.12 k g / h a ( G e r o n i m o 1978). S m o o t h b r o m e (Bromus i n e r m i s L e y s . ) and i n t e r m e d i a t e wheatg rass a re not in ju red by a p p l i c a t i o n s o f t r i c l o p y r a t r a t e s up to 1.68 k g / h a ( M c C a r t y 1979). T r i c l o p y r is r e a d i l y absorbed by b o t h l e a v e s and roots and is t r a n s l o c a t e d th roughout the p lan t ( K i n g and R a d o s e v i c h 1979; R a d o s e v i c h and B a y e r 1979). It is m o r e e f f e c t i v e than p i c l o r a m on most e v e r g r e e n s p e c i e s , but p i c l o r a m is a p p r o x i -m a t e l y t h r e e t i m e s as t o x i c to dec iduous brush as t r i c l o p y r ( G r a t k o w s k i e t a l . 1978). T r i c l o p y r degrades under f i e l d c o n d i t i o n s m o r e s l o w l y t h a n 2 ,4 ,5 -T ( 2 , 4 , 5 - t r i c h l o r o -p h e n o x y a c e t i c ac id ) , but f a s t e r than p i c l o r a m . S o i l res idues of t r i c l o p y r should not be p h y t o t o x i c a f t e r one y e a r , a t the e x p e c t e d a p p l i c a t i o n r a t e s to be used on range lands and u t i l i t y r i g h t s - o f - w a y (0.56 to 10.08 k g / h a ) ( L i c h y 1980). The degree of s o i l adso rp t i on of t r i c l o p y r depends on the o r g a n i c m a t t e r c o n t e n t and p H of the s o i l . Some l e a c h i n g of the h e r b i c i d e may o c c u r in l i ght so i ls under h igh r a i n f a l l c o n d i t i o n s (Weed S c i e n c e S o c i e t y of A m e r i c a 1980). In f o res t so i l s h igh in organic matter, there is little movement of triclopyr from the 0 to 10 cm depth (Perala 1980). The butoxyethyl ester formulation is highly toxic to fish (Dow Chemical Co.). 3,6-dichloropicolinic acid 3,6-dichloropicolinic acid (Figure 3) (Dow Chemical Co.) is a substituted picolinic acid with a phytotoxicity range similar to picloram but it is a less persistent herbicide (Naik et al. 1972). It controls many weeds tolerant to the phenoxy herbicides in the Polygonaceae and Compositae families and many legumes (Haagsma 1975a). At rates normally used for herbaceous weed control, most plants in the Gramineae and Cruciferae families are resistant to 3,6-dichloropicolinic acid. Canada thistle (Cirsium arvense Scop.) can be controlled with 140 g/ha (Whitesides and Appleby 1978) and 70 and 105 g/ha are satisfactory for control of wild buckwheat (Polygonum  convulvulus L.) and Russian thistle (Salsola pestifer Nels.), respectively (Keys 1975). Applications of 3,6-dichloropicolinic acid at 1.12 to 2.80 kg/ha give 100% control of Russian knapweed during the season of treatment and for two subsequent years (Wyoming Agricultural Experiment Station 1977, 1978, 1979). Yellow starthistle can be controlled at 430 g/ha and squarrose knapweed can be controlled at 560 g/ha (Geronimo 1978). This herbicide is absorbed by both roots and shoots and is readily translocated throughout the plant. X O 0 = 0 At-T3 •H O rt o •H d •H rH O CJ •H P i O H O rH ^ O •H TJ I v£> t o CO u CJO -H 0 4 Wheat (Triticum aestivum L.), oat (Avena sativa L.) and barley (Hordeum vulgare L.) have excellent tolerance to 3,6-dichloropicolinic acid at rates up to 560 g/ha when applied prior to the flowering and filling stage. Applications to wheat at 560 and 1120 g/ha at flowering, reduce grain yields (Keys 1975). Smooth brome and intermediate wheatgrass are not injured by 3,6-dichloropicolinic acid at rates up to 1.68 kg/ha (McCarty 1979). This herbicide is less persistent than picloram; at rates of 70 to 280 g/ha there should be little or no problem with phytotoxic residues in most soils one year after application (Haagsma 1975a). The half-life in a soil with 3.2% organic matter held at 29°C and field capacity for water was 27 days (Dow Chemical Co. 1974). Climatic conditions appear to have a greater influence on disappearance rate than differences in soil types (Pik et al. 1977). This compound leached rapidly in a Brown Chernozem and an Ortho Eutric Brunisol, thus it may be effective for the control of deep rooted species in these soil types. Adsorption to soil organic matter can occur in drier areas and this could prevent microbial degradation of the herbicide, especially over the winter (Pik et al. 1977). Degradation of this compound is slower after a winter in the soil than in the season of application. Under dry conditions and relatively low average yearly temperatures, 3,6-dichloropicolinic acid persisted for up to 14 months after an application of 0.95 kg/ha (Pik et al. 1977; Rahman et al. 1981). A clay loam soil with 13.4% organic matter had no detectable residues of 3,6-dichloropicolinic acid three months after treatment at 280 or 560 g/ha. When applied at 1120 g/ha, approximately 5% of the amount applied still remained after three months (Vanden Born and Schraa 1975). C h l o r s u l f u r o n C h l o r s u l f u r o n ( 2 - c h l o r o - N - ( ( 4 - m e t h o x y - 6 - m e t h y l - l , 3 , 5 - t r i a z i n - 2 - y l ) a m i n o c a r -bony l ) b e n z e n e s u l f o n a m i d e ) ( F igu re 4) (E.I . d u P o n t de N e m o u r s <5c C o . Inc.) is a new s u l f o n y l u r e a h e r b i c i d e . C h l o r s u l f u r o n c o n t r o l s most b r o a d l e a v e d weeds a t 10-25 g / h a and has shown e x c e l l e n t c r o p s e l e c t i v i t y in w h e a t , b a r l e y , o a t s and r y e (Seca le c e r e a l e L . ) ( P a l m e t a l . 1980; L e v i t t e t a l . 1981; C o r n w e l l and L a n e 1981). S e v e r a l weed s p e c i e s t o l e r a n t to phenoxy and b e n z o i c a c i d h e r b i c i d e s a r e c o n t r o l l e d a t these ra tes o f c h l o r s u l f u r o n . C o r n f l o w e r ( C e n t a u r e a c y a n u s L.) c a n be e f f e c t i v e l y c o n t r o l l e d w i t h 7 to 17 g / h a and y e l l o w s t a r t h i s t l e c a n be c o n t r o l l e d w i t h 39 -79 g / h a (E.I . D u P o n t de N e M o u r s & C o . Inc. 1981). E x c e l l e n t c o n t r o l o f C a n a d a t h i s t l e c a n be o b t a i n e d w i t h 20 -30 g / h a . T o l e r a n c e of w h e a t , b a r l e y and many grasses t o c h l o r s u l f u r o n is due t o p l a n t d e g r a d a t i o n of the h e r b i c i d e to i n a c t i v e ( n o n - p h y t o t o x i c ) p r o d u c t s . Wheatg rasses ( A g r o p y r o n spec ies ) , f e s c u e s ( F e s t u c a spec ies ) and b u f f a l o g r a s s c a n t o l e r a t e 25 t o 75 g / h a w i t h o u t p h y t o t o x i c e f f e c t s . E s t a b l i s h e d K e n t u c k y b luegrass s tands (Poa  p ra tens is L.) c a n t o l e r a t e up to 50 g / h a . C h l o r s u l f u r o n is r e a d i l y absorbed by bo th r o o t s and shoots , but d e a t h of p lan ts is s l o w . C h l o r o s i s , n e c r o s i s , t e r m i n a l bud death and v e i n d i s c o l o r a t i o n deve lop (Sut t le and S c h r e i n e r 1982). Th is h e r b i c i d e i n t e r f e r e s w i t h c e l l d i v i s i o n in p lants at c o n c e n t r a t i o n s as low as one par t per m i l l i o n (Ray 1980). It has no e f f e c t on seed g e r m i n a t i o n , but the so i l r e s i d u a l e f f e c t s of a p o s t e m e r g e n c e a p p l i c a t i o n , Chlorsulfuron , ( 2-chlorc-N- ( ( 4-methoxy-6-roethyl-1,3, t r i a z i n - 2 - y l ) aminocarbonyl ) benzene sulfonamide ) w h e n a c t i v a t e d by r a i n f a l l , w i l l usua l ly c o n t r o l seed l ings w h i c h e m e r g e a f t e r t r e a t -m e n t ( P a l m e t a l . 1980). T h e h a l f - l i f e o f c h l o r s u l f u r o n in C a n a d i a n p r a i r i e so i l s in the B r o w n and D a r k B r o w n s o i l zones is 1 t o 2 months . The ra te o f b r e a k d o w n is i n f l u e n c e d by s o i l t e m p e r a t u r e , s o i l m o i s t u r e and s o i l p H . D e g r a d a t i o n of t he h e r b i c i d e is f a s t e s t w i t h low s o i l p H ; over p H 8.0 b r e a k d o w n is s l o w e d . A d s o r p t i o n of c h l o r s u l f u r o n to c l a y is l o w , but o r g a n i c m a t t e r r e t a i n s some of the c h e m i c a l . T r e a t m e n t s a p p l i e d to g r a v e l l y -sandy so i l s w i t h less t h a n 1% o r g a n i c m a t t e r have had the g r e a t e s t a c t i v i t y ( P a l m e t a l . 1980). D P X - T 6 3 7 6 D P X - T 6 3 7 6 ( m e t h y l 2 - ( ( ( ( 4 - m e t h o x y - 6 - m e t h y l - l , 3 , 5 - t r i a z i n - 2 - y l ) a m i n o c a r b o n -y l ) am ino ) su l fony l ) benzoa te ) ( F i gu re 5) (E.I . d u P o n t de N e m o u r s & C o . Inc.) is an e x p e r i m e n t a l s u l f o n y l u r e a h e r b i c i d e s i m i l a r in s t r u c t u r e to c h l o r s u l f u r o n . It p rov ides c o n t r o l of a l a r g e number o f b r o a d l e a v e d weeds when a p p l i e d a t r a t e s o f 70 to 280 g / h a (E.I . d u P o n t de N e m o u r s <5c C o . Inc.). D P X - T 6 3 7 6 a t 250 to 1000 g / h a c o n t r o l s pop la r and aspen (Populus spec ies ) , w i l l o w (Sa l ix spec ies ) and C a n a d a t h i s t l e . A t 280 to 560 g / h a , i t causes severe d e f o l i a t i o n of many woody shrubs and t r e e s . Th is h e r b i c i d e has a lso shown some short Figure 5. DPX-T6376 , ( methyl 2 - ( ( ( ( 4-methoxy-6-methyl-1,3,5 t r i a z i n - 2 - y l ) amino carbonyl ) amino ) sulfonyl ) benzoate ) o t e r m p r e - e m e r g e n c e a c t i v i t y on many b road lea f weeds and some grasses . It is r e a d i l y abso rbed by both roots and shoots and t r a n s l o c a t e d th roughout the p lant to g r o w i n g t i p s w h e r e i t i n h i b i t s c e l l d i v i s i o n . D P X - T 6 3 7 6 is less p e r s i s t e n t t h a n c h l o r s u l f u r o n and i t s b r e a k d o w n is less s e n s i t i v e to s o i l p H . Its h a l f - l i f e in the B r o w n and D a r k B r o w n s o i l zones of t he C a n a d i a n p r a i r i e s is a p p r o x i m a t e l y t h r e e w e e k s ( R . E . B l a c k s h a w pers . c o m m . 1982). IV. Descriptions of field sites During the summers of 1981 and 1982, field trials with herbicides were conducted near Ashcroft, Walhachin and Cache Creek, B.C. (Figure 6). All three field sites are located in the Thompson Valley and occur in the Ponderosa pine - bunchgrass (PPBG) biogeoclimatic zone (Valentine et al. 1978). The elevational range of this zone varies with aspect, but generally occurs between 270 and 750 meters (Valentine et al. 1978). This area has hot dry summers, with summer moisture deficits of up to 400 mm in southern valleys. The season of moisture deficit is approximately from April to October. The 30 year average for precipitation at Ashcroft is 23.5 cm, with June being the wettest summer month. The May to September precipitation averages 10.82 cm (B.C. Department of Agriculture 1974). Ashcroft site Location: This site is located on a bench on the south shore of Barnes Lake at an elevation of approximately 700 meters. The exposure is northwest. The location is approxi-mately 121°15' west longitude and 50°43' north latitude (Figure 7). Soils: The soil at this site is a Dark Brown Chernozem, less than 1 meter deep with a surface capping of fine, silty wind blown material. The lower horizons of this soil are F i g u r e 6 . Map showing l o c a t i o n o f f i e l d s i t e s . F i g u r e 7. Topographic map showing l o c a t i o n A s h c r o f t site.H v e r y s tony and basa l t is p resent th roughout the s i t e . N e a r K a m l o o p s , D a r k B r o w n C h e r n o z e m s at th i s e l e v a t i o n have d e v e l o p e d on g l a c i a l t i l l o f the h igher v a l l e y and l o w e r p l a t e a u s lopes . The v e g e t a t i o n is p r i m a r i l y grass c o v e r d o m i n a t e d by n e e d l e -a n d - t h r e a d (S t ipa c o m a t a T r i n . & Rupr . ) and Sandberg's b luegrass ( P o a sandbe rg i i Vasey ) ( V a l e n t i n e e t a l . 1978). T h e c h e m i c a l and p h y s i c a l c h a r a c t e r i s t i c s of s o i l a t t h i s s i t e a r e p resen ted in T a b l e I. V e g e t a t i o n : P l a n t s p e c i e s c o l l e c t e d at th i s s i t e a re l i s t e d i n T a b l e II. T h i s s i t e o c c u r s in the A g r o p y r o n - A r t e m i s i a zone (T isda le 1947) or t he l o w e r g rass land zone ( R y s w y k , van e t a l . 1966; M c L e a n and M a r c h a n d 1968). E d a p h i c c o m m u n i t i e s d o m i n a t e d by n e e d l e - a n d - t h r e a d and sand dropseed (Sporobolus  c r y p t a n d r u s (Torr . ) A . G r a y ) o c c u r in the A g r o p y r o n - A r t e m i s i a zone on l o a m y sand , sands and g r a v e l l y l o a m s (T isda le 1947; Pa rsons e t a l . 1971). The d o m i n a n t grass on th i s s i t e is n e e d l e - a n d - t h r e a d , w i t h Sandberg 's b luegrass and sand d ropseed as a s s o c i a t e s . T h e use of a t e x t u r a l t r i a n g l e i d e n t i f i e d s o i l a t t h i s s i t e as a l o a m ( C a n a d a D e p a r t m e n t of A g r i c u l t u r e 1976). S o i l t e x t u r e has been found to be one of the most i m p o r t a n t c h a r a c t e r i s t i c s a f f e c t i n g the d i s t r i b u t i o n o f grass s p e c i e s i n th i s zone (Parsons e t a l . 1971). The sand c o n t e n t in so i l s under n e e d l e - a n d - t h r e a d was found to be c o n s i s t e n t l y h igher t h a n i n so i ls suppo r t i ng b luebunch w h e a t g r a s s . T h e p e r c e n t a g e o f g r a v e l s and c o b b l e s a lso i n c r e a s e d w i t h dep th on n e e d l e - a n d - t h r e a d s i t e s and added to the coa rseness of l o w e r s o i l h o r i z o n s . Thus n e e d l e - a n d - t h r e a d s i t e s a re m o r e sub jec t to d rought than b luebunch w h e a t g r a s s s i t e s because of a r e d u c e d w a t e r ho ld ing c a p a c i t y . 26 Table I: Physical and chemical properties of soil at the Ashcroft site. P h y s i c a l c h a r a c t e r i s t i c s (by we ight ) 47 .6 % sand (2 m m to 50 fj) 43.5 % s i l t (50 u to 2 ^ ) 8.9 % c l a y ( less than 2 fd C h e m i c a l ana lyses p e r c e n t o r g a n i c m a t t e r p H s a l t ( c o n d u c t i v i t y ) n i t r a t e s (NO^) phosphorus p o t a s s i u m c a l c i u m m a g n e s i u m g r e a t e r than g r e a t e r than 3 . 7 6 . 9 0 . 3 2 ( m e g a m h o s / c m ) 13 p p m w 56 p p m w 500 p p m w 2620 p p m w 500 p p m w 27 Table II: Plant species collected at Ashcroft site. F o r b s and shrubs C e n t a u r e a d i f f u s a L a m . A r t e m i s i a t r i d e n t a t a N u t t . O p u n t i a f r a g i l i s (Nut t . ) H a w . O p u n t i a p o l y a c a n t h a H a w . A r t e m i s i a f r i g i d a W i l l d . E r i g e r o n c o m p o s i t u s Pu rsh A r a b i s h o l b o e l l i i H o r n e m . P h a c e l i a l i n e a r i s (Pursh) H o l z . T ragopogon dubius S c o p . d i f f u s e k n a p w e e d b i g sagebrush b r i t t l e p r i c k l y pear m a n y - s p i n e d p r i c k l y pear pas tu re sage d w a r f m o u n t a i n f l e a b o n e r o c k c r e s s n a r r o w l e a v e d p h a c e l i a w e s t e r n goat 's beard G rasses S t i p a c o m a t a T r i n . and R u p r . P o a s a n d b e r g i i Vasey Sporobo lus c r y p t a n d r u s (Torr . ) A . G r a y F e s t u c a o c t o f l o r a W a l t . P o a p ra tens i s L . B r o m u s t e c t o r u m L . K o e l e r i a c r i s t a t a (L. ) P e r s . n e e d l e - a n d - t h r e a d Sandberg 's b luegrass sand d ropseed s i x - w e e k s f e s c u e K e n t u c k y b luegrass downy b r o m e Junegrass Needle-and-thread is more drought tolerant than bluebunch wheatgrass and often forms a climax with big sagebrush on some coarse textured soils (McLean 1979). A relict area of this type studied by Tisdale (1947) consisted of needle-and-thread and sand dropseed as dominant species with pasture sage and brittle prickly pear also common species. Heavy grazing on these types of sites will reduce needle-and-thread, while sand dropseed and big sagebrush will increase. Prolonged overgrazing will lead to an increase in the abundance of annuals, shrubs and certain perennial forbs (Tisdale 1947). This site is dominated by diffuse knapweed with densities averaging 158 plants per square meter. The area has previously been heavily grazed and diffuse knapweed has been present on the site since at least 1965 (T. Rolphe pers. comm. 1981). Festuca octoflora Walt* is present in moister areas of the site and is considered to be an invader on heavily used range (McLean and Tisdale 1972). Erigeron compositus Pursh is the most abundant forb on the site. The presence of this species indicates past disturbance or overgrazing and often occurs on gravelly soils (McLean 1979). Walhachin site Location: This site is located near Walhachin on the north side of the Thompson River at approximately 121°2' west longitude and 50°46' north latitude (Figure 8). The site is at an elevation of approximately 400 meters with a southern exposure. F i g u r e 8. Topographic map showing l o c a t i o n of Walhachin 40\/ BRITISH C O L U M B I A WEST OF SIXTH MERIDIAN SCALE 1:50,000 1.25 inches to 1 mile approximately 9 2 I/14E I—• u-l i 1 1000 500 2000 1000 Metres 1000 500 3000 I l-l ri i - i i - i r-i~ C O N T O U R INTERVAL 100 F E E T Elevations in Feet above Mean Sea Level North American Datum 1927 Universal Transverse Mercator Protect ion 38 39 R22 40 ro M A G N E H CU A" Annuji S o i l s : The s o i l a t th is s i te is an O r t h i c B r o w n C h e r n o z e m o f the S e m l i n se r ies (Sprout and K e l l e y 1963). These so i ls have f o r m e d on a l l u v i a l - c o l l u v i a l depos i ts and c o n t a i n a m e d i u m to h igh degree of g rave l s and c o b b l e s . T h e topography has an o v e r a l l d o w n w a r d s lope f r o m the apex t o w a r d the v a l l e y c e n t e r w i t h most s lopes b e t w e e n 3 and 1 5 % . The s u r f a c e 15 to 30 c m may be f i n e r t e x t u r e d than the subso i l due to the a d d i t i o n o f e o l i a n s e d i m e n t s . Where these w ind depos i ts o c c u r , the c o n t e n t o f g r a v e l s and stones is l i g h t to n o n - e x i s t e n t , but o t h e r w i s e s u r f a c e s ton iness is m o d e r a t e to h e a v y . These so i ls a r e w e l l d ra ined and have d e v e l o p e d under bunchgrasses . T h e p r o f i l e of these so i l s is c h a r a c t e r i z e d by a b r o w n i s h A h h o r i z o n and a s t r u c t u r e d B m ( c o m p l e t e r e m o v a l o f ca rbonates ) h o r i z o n . A l i g h t e r c o l o u r e d h o r i z o n of c a r b o n a t e a c c u m u l a t i o n is found at depths of 30 to 60 c m . The s o i l a t th is s i t e was c l a s s i f i e d as a sandy l o a m . The s u r f a c e r e a c t i o n s of t he S e m l i n so i ls range f r o m n e u t r a l to s l i g h t l y a l k a l i n e ; the p H va lues be ing f r o m 7.0 to 7.7 (Sprout and K e l l e y 1963). C h a r a c t e r i s t i c s of s o i l c o l l e c t e d at th is s i t e a re p r e s e n t e d in T a b l e III. V e g e t a t i o n : P l a n t s p e c i e s c o l l e c t e d at th is s i t e a re l i s t e d in T a b l e IV. Th is s i te is in the A g r o p y r o n - A r t e m i s i a zone of T i s d a l e (1947). The a r e a has been used for f a l l g r a z i n g fo r c a t t l e and horses (W.R . E l d pers . c o m m . 1981) and is d o m i n a t e d by b ig sagebrush , downy b r o m e and spo t ted k n a p w e e d . D o w n y b r o m e is a 31 Table III: Physical and chemical properties of soil at the Walhachin site. P h y s i c a l c h a r a c t e r i s t i c s (by weight ) 56.0 % sand 34.6 % s i l t 9.4 % c l a y C h e m i c a l ana lyses p e r c e n t o r g a n i c m a t t e r p H s a l t ( c o n d u c t i v i t y ) n i t r a t e s ( N 0 3 ) phosphorus p o t a s s i u m c a l c i u m m a g n e s i u m g r e a t e r than g r e a t e r than 2 . 7 6 . 5 0 . 1 6 ( m e g a m h o s / c m ) 3 . 0 p p m w 3 7 . 5 p p m w 500 p p m w 2157 p p m w 500 p p m w Table IV: Plant species collected at the Walhachin site. F o r b s and shrubs C e n t a u r e a m a c u l o s a L a m . O p u n t i a f r a g i l i s (Nut t . ) H a w . O p u n t i a p o l y a c a n t h a H a w . A r t e m i s i a t r i d e n t a t a N u t t . A r t e m i s i a f r i g i d a W i l l d . L o m a t i u m m a c r o c a r p u m (Nut t . ) C o u l t . & R o s e S a l s o l a p e s t i f e r N e l s . A r a b i s h o l b o e l l i i H o r n e m . G rasses B r o m u s t e c t o r u m L . Sporobo lus c r y p t a n d r u s (Torr . ) A . G r a y P o a s a n d b e r g i i Vasey A g r o p y r o n s p i c a t u m (Pursh) S c r i b n . & S m i t h s p o t t e d k n a p w e e d b r i t t l e p r i c k l y pear m a n y - s p i n e d p r i c k l y pear b ig sagebrush pas tu re sage l a r g e f r u i t e d l o m a t i u m R u s s i a n t h i s t l e r o c k c r e s s downy b r o m e sand d ropseed Sandberg's b luegrass b luebunch w h e a t g r a s s c o m m o n invader on o v e r g r a z e d ranges in th i s z o n e , e s p e c i a l l y on B r o w n C h e r n o z e m i c so i l s ( M c L e a n 1979). A c l o s e l y g r a z e d a r e a in th is zone was found to be d o m i n a t e d by sagebrush , b r i t t l e p r i c k l y pear and annua l s p e c i e s such as downy b r o m e and D e s c u r a i n i a s p e c i e s (T isda le 1947). S p o t t e d knapweed dens i t i es at th is s i t e a v e r a g e 53 p lan ts per square m e t e r (seedl ings , r o s e t t e s and m a t u r e p lants ) . R o s e t t e s and seed l ings a r e mos t abundant under b ig sagebrush and under and around e x i s t i n g s p o t t e d k n a p w e e d p l a n t s . D o w n y b r o m e o c c u p i e s a reas b e t w e e n the l a rge r p l a n t s , w i t h d e c r e a s e d d e n s i t i e s a round b i g sagebrush , spo t ted knapweed and b luebunch w h e a t g r a s s p l a n t s . L i t t e r on the s o i l s u r f a c e cons is ts m a i n l y of lea f l i t t e r f r o m b ig sagebrush and d r i e d s t e m s of s p o t t e d knapweed and Russ ian t h i s t l e . It appears t h a t R u s s i a n t h i s t l e was a d o m i n a n t p lan t on th is s i te in the past , but has now been r e p l a c e d by downy b r o m e ( P i e m e i s e l 1951). The c o n c e n t r a t i o n o f k n a p w e e d seed l ings a round e s t a b l i s h e d p lan ts suggests t h a t in some w a y the m i c r o c l i m a t e is be ing m o d i f i e d , a l l o w i n g an i n c r e a s e in s e e d l i n g s u r v i v a l c o m p a r e d to bare a reas b e t w e e n p lants (Evans and Y o u n g 1972). T h e m o d i f y i n g e f f e c t of l i t t e r may c r e a t e a d d i t i o n a l " s a f e " m i c r o s i t e s ( H a r p e r 1977) f o r the e s t a b l i s h m e n t o f knapweed seed l ings . P l a n t l i t t e r c o v e r i n g the s o i l s u r f a c e a c t s as a l a y e r o f i n s u l a t i o n m o d e r a t i n g t e m p e r a t u r e and m o i s t u r e and c r e a t i n g f a v o u r a b l e s i t e s f o r g e r m i n a t i o n and the e s t a b l i s h m e n t of annua l weed s p e c i e s in r ange land c o m m u n i t i e s (Evans and Y o u n g 1970). Where downy b rome is d o m i n a n t , a l i t t e r c o v e r may be r e q u i r e d f r o m year to year for g e r m i n a t i o n and s e e d l i n g s u r v i v a l a d e q u a t e to rep len i sh the popu la t i on of th is s p e c i e s . 34 Bluebunch wheatgrass is present as small isolated plants. There were no bluebunch wheatgrass seedlings found at any time at this site. Sand dropseed is general throughout the site and most often is associated with one of the cacti. Cache Creek site Location: This site is located east of Cache Creek adjacent to the Trans-Canada Highway between the Pass Valley road and the highway. The location is approximately 121°77' west longitude and 50°48' north latitude (Figure 9). The site is located on level terrain at an elevation of 400 meters. Soils: The soil at this site belongs to the Anglesey series of Rego-Brown soils (Sprout and Kelley 1963). These soils occur in the area at 305 to 610 meters elevation and the topography is usually undulating to level. These soils have developed on gravelly glacio-fluvial deposits. The parent material is composed of gravelly and stony deposits in the form of glacial outwash terraces. These coarse textural glacial deposits are covered with 15 to 30 cm of finer textured materials. This capping, which ranges from loamy sand to silt loam, was deposited by water and wind. The soil at this site is a loamy sand. The Ah horizon of the Anglesey series is brownish, alkaline and has an accumulation of organic matter. At 15 to 35 cm below the surface, there is a strongly calcareous Ck horizon. The pH values of these soils range from 7.4 to 8.4. These soils support a native cover of big sagebrush, Opuntia species, downy brome and various weeds (Sprout and Kelley 1963). Properties of soil collected at this site are listed in Table V. gure 9- Topographic map showing l o c a t i o n Cache Creek s i t e . H MAGNETIC DECLINATI l ' ' 36 Table V: Physical and chemical properties of soil at the Cache Creek site. P h y s i c a l c h a r a c t e r i s t i c s (by we igh t ) 77.8 % sand 17.4 % s i l t 4.8 % c l a y C h e m i c a l ana lyses p e r c e n t o r g a n i c m a t t e r 8 . 0 s a l t ( c o n d u c t i v i t y ) 0 . 1 6 ( m e g a m h o s / c m ) n i t r a t e s (NO-.) 3 . 0 p p m w phosphorus 35 p p m w p o t a s s i u m g r e a t e r than 500 p p m w c a l c i u m g r e a t e r than 500 p p m w V e g e t a t i o n : P l a n t spec ies c o l l e c t e d at th is s i t e a re l i s t e d in T a b l e VI . T h e s i te has been s u b j e c t e d to d i s t u r b a n c e in the pas t . D i f f u s e k n a p w e e d is the d o m i n a n t p lant on th is s i t e and o c c u r r e d in m o n o c u l t u r e s in some a r e a s . K n a p w e e d d e n s i t i e s ( roset tes and m a t u r e p lants ) a v e r a g e 253 p l a n t s per square m e t e r . P l a n t l i t t e r on th is s i t e is c o m p o s e d m a i n l y of dead d i f f u s e k n a p w e e d p lants f r o m prev ious yea rs and ranges f r o m 0 t o 25 c m d e e p . B i g sagebrush is p resent as i s o l a t e d p l a n t s , but is not abundant . Iso lated p a t c h e s of downy b r o m e and sand dropseed a re the on ly grasses on the s i t e . Table VI: Plant species collected at the Cache Creek site. F o r b s and shrubs C e n t a u r e a d i f f u s a L a m . K o c h i a s c o p a r i a (L.) S c h r a d e r A r t e m i s i a t r i d e n t a t a N u t t . M e d i c a g o s a t i v a L . L e p i d i u m d e n s i f l o r u m S c h r a d . C e n t a u r e a m a c u l o s a L a m . G rasses d i f f u s e k n a p w e e d kochia b ig sagebrush a l f a l f a c o m m o n peppergrass s p o t t e d k n a p w e e d B r o m u s t e c t o r u m L . A g r o p y r o n c r i s t a t u m (L.) G a e r t n . Sporobo lus c r y p t a n d r u s (Torr . ) A . G r a y downy b r o m e c r e s t e d w h e a t g r a s s sand dropseed V. Evaluation of herbicides for residual control of knapweed M a y - June 1981 In M a y 1981 f a c t o r i a l e x p e r i m e n t s us ing a s p l i t - p l o t d e s i g n , w i t h the m a i n p lo ts a r r a n g e d in a r a n d o m i z e d c o m p l e t e b l o c k des ign , w e r e e s t a b l i s h e d a t the A s h c r o f t and W a l h a c h i n s i t e s . E a c h e x p e r i m e n t c o n t a i n e d f i v e t r e a t m e n t s ( u n t r e a t e d , p i c l o r a m , t r i c l o p y r , 3 , 6 - d i c h l o r o p i c o l i n i c a c i d , c h l o r s u l f u r o n ) and was r e p l i c a t e d fou r t i m e s . T h e t r e a t m e n t s w e r e ass igned to the m a i n p lo ts and the r a t e s o f h e r b i c i d e s to the subp lo ts . The subp lot s i z e was f i v e m e t e r s by t w o m e t e r s . B o t h s i t e s w e r e f e n c e d to a he ight of f i v e f e e t to e x c l u d e l a r g e g r a z i n g a n i m a l s . A survey of the l i t e r a t u r e on the use of ana lys i s o f c o v a r i a n c e suggested t h a t fo r p e r e n n i a l c rops or areas w h e r e the p lots have the s a m e p lan ts f r o m yea r to y e a r , the use o f p r e - t r e a t m e n t y i e l d s and ana l ys i s o f c o v a r i a n c e m a y r e d u c e e x p e r i m e n t a l e r r o r ( L o v e 1936). P r e - t r e a t m e n t y i e lds o f f o l i a g e o f grasses and k n a p w e e d w e r e s a m p l e d by 2 c l i p p i n g , a t ground l e v e l , a random 0.25 m a r e a f r o m e a c h subp lo t . The v e g e t a t i o n was d r i e d in an oven a t 65°C fo r f i v e days and then w e i g h e d . D r y w e i g h t s o f samp les f r o m the A s h c r o f t s i t e and the W a l h a c h i n s i t e a re p r e s e n t e d in A p p e n d i x A . The p lo ts at the A s h c r o f t s i te w e r e c l i p p e d f r o m June 5th to 10th, 1981. Many d i f f u s e k n a p w e e d p lants were f u l l y b o l t e d by th is t i m e . G r a s s y i e l d was not s e p a r a t e d out by s p e c i e s but c o n s i s t e d m a i n l y o f n e e d l e - a n d - t h r e a d and sand d r o p s e e d . The p lo ts a t the W a l h a c h i n s i te were c l i p p e d June 12th to 18th, 1981. G rass y i e l d s a t th is t i m e w e r e m a i n l y f r o m downy b r o m e , b luebunch wheatg rass and sand d r o p s e e d . To d e t e r m i n e w h e t h e r or not c o v a r i a n c e a n a l y s i s was n e c e s s a r y , ana lyses o f v a r i a n c e w e r e c o n d u c t e d using the p r e - t r e a t m e n t y i e l d s of grass and k n a p w e e d fo r e a c h s i t e (Append ix A ) . These ana lyses showed t h a t t h e r e w e r e no s i g n i f i c a n t (p <.Q1) d i f f e r e n c e s a m o n g the p lo ts for grass or k n a p w e e d y i e l d p r i o r to t r e a t m e n t . In s tud ies on the c o n t r o l o f A r t e m i s i a spec ies in O r e g o n , H e d r i c k e t a l . (1966) d e t e r m i n e d p r e -t r e a t m e n t y i e l d s o v e r a t h r e e year pe r i od by c l i p p i n g 9.6 square f o o t p lo ts a t ground l e v e l . They found t h a t p r e - t r e a t m e n t y ie lds w e r e e q u a l a m o n g p lo ts and s i n c e the d i f f e r e n c e s in s p e c i e s c o m p o s i t i o n w e r e s m a l l , t h e y c o n c l u d e d t h a t p o s t - t r e a t m e n t c o m p a r i s o n s w e r e v a l i d w i t h o u t the use o f c o v a r i a n c e a n a l y s i s . In g rass land c o m m u n i t i e s , y i e l d is d e t e r m i n e d by s tand but is a lso i n f l u e n c e d by the c u r r e n t year ' s p r e c i p i t a t i o n . The use o f p r e - t r e a t m e n t y i e l d s f r o m on ly one yea r as a c o v a r i a t e c o u l d r e s u l t in a b iased c o n c l u s i o n b e c a u s e of a d i f f e r e n t i a l response of s p e c i e s to p r e c i p i t a t i o n (Stoddar t e t a l . 1975). A s p r e - t r e a t m e n t y i e l d s w e r e not s i g n i f i c a n t l y d i f f e r e n t (p ^ .01) p o s t - t r e a t m e n t y i e l d s c a n be c o m p a r e d w i t h o u t the use o f c o v a r i a n c e a n a l y s i s . The A s h c r o f t and W a l h a c h i n s i t e s w e r e t r e a t e d w i t h h e r b i c i d e s on June 26th and 25th r e s p e c t i v e l y , w i t h the r a t e s l i s t e d in T a b l e VII. A l l h e r b i c i d e s w e r e a p p l i e d w i t h a C 0 2 ~ p o w e r e d sprayer a t 276 K P a w i t h a s o l u t i o n v o l u m e of 500 L / h a . The spray boom was equ ipped w i t h four T e e - J e t 8004 n o z z l e s . The w e a t h e r was hot (30°C) and dry a t the t i m e o f a p p l i c a t i o n . Table VII: Herbicides applied June 1981 at Walhachin and Ashcroft sites. herbicide formulation rate (grams/ha) chlorsulfuron 75% dry flowable (GLEAN) 20 40 80 160 triclopyr triethyiamine salt (GARLON 3A) 250 500 750 1000 3,6-dichloropicolinic acid monoethanolamine salt (M-3972) 250 500 750 1000 picloram potassium salt (TORDON 22K) 250 500 750 1000 A u g u s t 1981 Y i e l d s f r o m bo th s i tes were d e t e r m i n e d at 30 days p o s t - t r e a t m e n t by c l i p p i n g 2 r andom 0.25 m samples f r o m e a c h subp lot . P l o t s a t t he A s h c r o f t s i t e w e r e c l i p p e d f r o m J u l y 29th to A u g u s t 6 t h , 1981. V i s u a l o b s e r v a t i o n s a t t he d i f f u s e k n a p w e e d s i t e i n d i c a t e d tha t a l l r a t e s o f p i c l o r a m and 3 , 6 - d i c h l o r o p i c o l i n i c a c i d t e s t e d c o m p l e t e l y k i l l e d the k n a p w e e d . T r i c l o p y r at 1000 g / h a caused s l i g h t e p i n a s t y i n some d i f f u s e k n a p w e e d p lants but many w e r e ab le to f l o w e r . R a t e s of t r i c l o p y r b e l o w 1000 g / h a w e r e not obv ious ly p h y t o t o x i c to d i f f u s e k n a p w e e d . C h l o r s u l f u r o n at r a t e s of 80 and 160 g / h a k i l l e d m a t u r e d i f f u s e k n a p w e e d p lants and r o s e t t e s . T h e r e w e r e no a p p a r e n t p h y t o t o x i c e f f e c t s on grasses due to any o f the h e r b i c i d e t r e a t m e n t s . D ry we igh ts o f grass and d i f f u s e k n a p w e e d c o l l e c t e d f r o m th is s i t e a f t e r 30 days w e r e ob ta ined and ana lyses o f v a r i a n c e c o n d u c t e d ( A p p e n d i x B ) . T h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s i n weed y i e l d fo r d i f f e r e n t r a t e s a p p l i e d w i t h i n a g i v e n h e r b i c i d e ( i .e . a l l r a t e s w e r e equa l l y e f f e c t i v e in r e d u c i n g k n a p w e e d dry w e i g h t s ) . A l l h e r b i c i d e t r e a t m e n t s s i g n i f i c a n t l y r e d u c e d k n a p w e e d y i e l d r e l a t i v e to the u n t r e a t e d p lo ts (Tab le VIII). D i f f u s e knapweed y i e l d was r e d u c e d f r o m 711 k g / h a (un t rea ted p lots ) to 308 k g / h a (average of t r e a t e d p lo ts ) . A t th is s a m p l i n g t i m e t h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s in weed y i e l d among the v a r i o u s h e r b i c i d e t r e a t m e n t s . Y i e l d of grasses was not a f f e c t e d by any of the t r e a t m e n t s . The a v e r a g e y i e l d o f grasses f r o m a l l p lo ts was 76 k g / h a . P l o t s at the W a l h a c h i n s i te w e r e s a m p l e d for grass and k n a p w e e d y i e l d f r o m A u g u s t 8th to 13th, 1981. A l l ra tes of p i c l o r a m and 3 , 6 - d i c h l o r o p i c o l i n i c a c i d 43 Table VIII: Ashcroft site 30 days post treatment - main plot yields.* d i f f u s e k n a p w e e d grass . T r e a t m e n t ( g /m ) ( g / m ) c o n t r o l 71.41 a 9.20 a c h l o r s u l f u r o n 36.64 b 8.49 a t r i c l o p y r 33.38 b 5.29 a 3 , 6 - d i c h l o r o p i c o l i n i c a c i d 2 7 . 2 1 b 9.03 a p i c l o r a m 23.80 b 7.50 a * means w i t h i n a c o l u m n f o l l o w e d by the s a m e l e t t e r a re not s i g n i f i c a n t l y d i f f e r e n t (F isher 's p r o t e c t e d L S D p <.Q1). e v a l u a t e d gave c o m p l e t e k i l l o f a l l spo t ted k n a p w e e d p lan ts (Tab le IX ) . T r i c l o p y r a t 1000 g / h a caused some e p i n a s t y in knapweed p lan ts but was not p h y t o t o x i c at l o w e r r a t e s . C h l o r s u l f u r o n p rov ided c o n t r o l of s p o t t e d k n a p w e e d on ly a t 160 g / h a . The s p o t t e d knapweed p lants appeared to be a f f e c t e d less than the d i f f u s e k n a p w e e d p lan ts a t A s h c r o f t when e q u i v a l e n t r a t e s o f c h l o r s u l f u r o n or t r i c l o p y r w e r e a p p l i e d . V i s u a l o b s e r v a t i o n s at th is s i t e suggest t h a t s p o t t e d k n a p w e e d may have to be t r e a t e d a t an e a r l i e r g r o w t h s tage than d i f f u s e k n a p w e e d fo r e f f e c t i v e c o n t r o l w i t h c h l o r s u l f u r o n a t r a t e s l ower than 160 g / h a . A n a l y s i s of v a r i a n c e of y i e l d d a t a f r o m th i s s i t e (Append ix C ) showed a s i g n i f i c a n t d i f f e r e n c e in s p o t t e d k n a p w e e d y i e l d b e t w e e n t r e a t e d and u n t r e a t e d m a i n p lo ts but no s i g n i f i c a n t d i f f e r e n c e s in grass y i e l d . H e r b i c i d e , t r e a t m e n t s r e d u c e d s p o t t e d k n a p w e e d y i e l d f r o m 950 k g / h a ( u n t r e a t e d p lots ) to 411 k g / h a ( t rea ted p lots ) . The a v e r a g e grass y i e l d fo r a l l p lo ts was 81 k g / h a . T h e r e w e r e no s i g n f i c a n t d i f f e r e n c e s a m o n g the h e r b i c i d e t r e a t m e n t or a m o n g r a t e s w i t h i n a g i v e n h e r b i c i d e . M a y 1982 P l o t s at the W a l h a c h i n s i te w e r e e v a l u a t e d fo r w e e d c o n t r o l and grass t o l e r a n c e by c l i p p i n g a s a m p l e (0.25 m ) f r o m e a c h p lot f r o m M a y 3rd t o 7 t h , 1982. The numbers o f s p o t t e d k n a p w e e d seed l ings (up to 2 t rue leaves) and r o s e t t e s (more than 2 t r u e leaves) w e r e a lso c o u n t e d fo r e a c h p lot (Append ix E) . A l l r a t e s of p i c l o r a m and 3 , 6 - d i c h l o r o p i c o l i n i c a c i d t e s t e d p r o v i d e d c o m p l e t e c o n t r o l of spo t ted k n a p w e e d 300 days a f t e r t r e a t m e n t (Tab le X ) . T h e r e were no k n a p w e e d seed l ings in these p lo ts and t h e r e was no r e g r o w t h f r o m s p o t t e d k n a p w e e d 45 Table IX: Walhachin site 30 days post treatment - main plot yields.* spotted knapweed gras^ Treatment (g/m ) (g/m ) control 95.01 a 8.37 a chlorsulfuron 44.65 b 6.21 a triclopyr 40.54 b 10.38 a 3,6-dichloropicolinic acid 31.26 b 7.47 a picloram 45.08 b 8.45 a means within a column followed by the same letter are not significantly different (Fisher's protected LSD p_jf.05). 46 Table X: Walhachin site 300 days post treatment - main plot yields and plant numbers.* spotted Treatment knapweed grass rosettes seedlings (g/m2) (g/m2) (no./m2) (no./m2) control chlorsulfuron triclopyr 3,6-dichloropicolinic acid picloram 13.84 a 1.03 a 5.50 b 3.40 a 9.14 ab 2.71 a 0 c 8.68 b 0 c 3.84 a 1.69 a 13.88 a 1.00 a 2.63 be 1.38 a 7.38 b 0 b 0 c 0 b 0 c means within a column followed by the same letter are not significantly different (Fisher's protected LSD p_< .05). p lan ts t r e a t e d i n 1981. B o t h 3 , 6 - d i c h l o r o p i c o l i n i c a c i d and p i c l o r a m w e r e m o r e e f f e c t i v e than t r i c l o p y r in reduc ing k n a p w e e d y i e l d , the number o f k n a p w e e d seed l ings and the number of r o s e t t e s . The a v e r a g e s p o t t e d k n a p w e e d y i e l d s w e r e 138 k g / h a (unt reated) , 91.4 k g / h a ( t r i c l o p y r - t r e a t e d ) and 55 k g / h a ( c h l o r s u l f u r o n - t r e a t e d ) . 3 , 6 -d i c h l o r o p i c o l i n i c a c i d was super ior t o a l l o t h e r h e r b i c i d e s in i n c r e a s i n g grass y i e l d . F o r r a t e s w i t h i n a p a r t i c u l a r h e r b i c i d e t h e r e were no s i g n i f i c a n t d i f f e r e n c e s in t r i c l o p y r and p i c l o r a m . C h l o r s u l f u r o n at 160 g / h a was super io r to a l l o t h e r r a t e s o f c h l o r s u l f u r o n a p p l i e d . N e i t h e r t r i c l o p y r nor c h l o r s u l f u r o n p r o v i d e d r e s i d u a l c o n t r o l of m a t u r e s p o t t e d k n a p w e e d . p l a n t s . C h l o r s u l f u r o n r e d u c e d the number o f k n a p w e e d seed l ings r e l a t i v e t o the u n t r e a t e d p l o t s , but s p o t t e d knapweed y i e l d in c h l o r s u l f u r o n - t r e a t e d p lo ts was m a i n l y due to r e g r o w t h o f p lants w h i c h m a t u r e d i n 1981. C h l o r s u l f u r o n a t the r a t e s e v a l u a t e d here appears to p rov ide good c o n t r o l of t o p g r o w t h , but does not c o m p l e t e l y k i l l the p lant w i t h on ly one season's t r e a t m e n t . The A s h c r o f t s i t e was samp led fo r d i f f u s e k n a p w e e d and grass y i e l d s f r o m M a y 2 8th to 13th, 1982 by c l i p p i n g a 0.25 m a r e a f r o m e a c h p l o t . P i c l o r a m and 3 ,6 -d i c h l o r o p i c o l i n i c a c i d p rov ided c o m p l e t e c o n t r o l of d i f f u s e k n a p w e e d at th is s i t e a t a l l ra tes e v a l u a t e d (Append ix D) . B o t h of these h e r b i c i d e s w e r e e q u a l l y m o r e e f f e c t i v e than t r i c l o p y r in r e d u c i n g weed y i e l d and i n c r e a s i n g grass y i e l d (Tab le XI) . T r i c l o p y r d id not p rov ide r e s i d u a l c o n t r o l of d i f f u s e k n a p w e e d at th i s s i t e . D i f f u s e k n a p w e e d y i e l d f r o m t r i c l o p y r t r e a t e d p lots was 49 k g / h a . 48 Table XI: Ashcroft site 300 days post treatment - main plot yields and plant numbers.* diffuse Treatment knapweed grass rosettes seedlings (g/m2) (g/m2) (no./m2) (no./m2) control 6. 90 a 3 .76 a 8. 25 ab 25. .81 a chlorsulfuron 5. 77 a 3 .93 a 8. 31 ab 23. .38 ab triclopyr 4. 92 a 3 .23 a 4. 25 be 12. .50 be 3,6-dichloropicolinic acid 0 b 9 .55 b 0 c 0 c picloram 0 b 8 .96 b 0 b 0 c * means within a column followed by the same letter are not significantly different (Fisher's protected LSD pjf.05). Many k n a p w e e d p lants in p lo ts t r e a t e d w i t h c h l o r s u l f u r o n i n 1981 w e r e ab le to r e g r o w f r o m the c r o w n . Th is r e g r o w t h c o n t r i b u t e d the mos t to w e e d y i e l d in these p lo ts i n 1982. C h l o r s u l f u r o n d id not p rov ide any r e s i d u a l c o n t r o l o f d i f f u s e k n a p w e e d . D i f f u s e knapweed y i e l d f r o m c h l o r s u l f u r o n - t r e a t e d p lo ts was 57 k g / h a . C o m p a r e d to the u n t r e a t e d p l o t , c h l o r s u l f u r o n d id not a f f e c t w e e d or grass y i e l d . D i f f u s e k n a p w e e d y i e l d f r o m u n t r e a t e d p lots was 69 k g / h a . A l l r a t e s of c h l o r s u l f u r o n e v a l u a t e d w e r e equa l l y i n e f f e c t i v e . Sandberg's b luegrass and n e e d l e - a n d - t h r e a d w e r e the major s p e c i e s c o n t r i b u t i n g to grass y i e l d a t th is s a m p l i n g d a t e . N e i t h e r s p e c i e s showed obv ious p h y t o t o x i c e f f e c t s f r o m h e r b i c i d e res idues . A u g u s t 1982 F i n a l samp les at the A s h c r o f t s i t e w e r e made f r o m J u l y 29 to A u g u s t 5, 1982 (420 days p o s t - t r e a t m e n t ) . Y i e l d d a t a and ana lyses of v a r i a n c e a r e p resen ted in A p p e n d i x F . P l o t s t r e a t e d w i t h p i c l o r a m and 3 , 6 - d i c h l o r o p i c o l i n i c a c i d in J u n e 1981 c o n t a i n e d no d i f f u s e k n a p w e e d p lants and grass r e l e a s e was e x c e l l e n t . G rass y i e l d (ma in l y n e e d l e - a n d - t h r e a d and sand dropseed) was six to e i g h t t i m e s h igher in these p lo ts than in the u n t r e a t e d p l o t s . G rass y i e l d f r o m p i c l o r a m - t r e a t e d p lo ts was 287 k g / h a and f r o m 3 , 6 - d i c h l o r o p i c o l i n i c a c i d t r e a t e d p lots y i e l d was 254 k g / h a . These h e r b i c i d e s were equa l l y super ior to t r i c l o p y r in d e c r e a s i n g d i f f u s e k n a p w e e d y i e l d and i n c r e a s i n g 50 grass y i e l d (Table XII) . F o r a g i ven h e r b i c i d e t h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s in w e e d or grass y i e l d w i t h d i f f e r e n t h e r b i c i d e r a t e s . C h l o r s u l f u r o n and t r i c l o p y r d id not p rov ide r e s i d u a l c o n t r o l o f d i f f u s e k n a p w e e d nor d id t h e y s i g n i f i c a n t l y i n c r e a s e grass y i e l d above the y ie lds of the u n t r e a t e d p l o t . D i f f u s e k n a p w e e d y i e l d s w e r e 387 k g / h a f r o m u n t r e a t e d p lo ts , 320 k g / h a f r o m c h l o r s u l f u r o n - t r e a t e d p lo ts and 342 k g / h a f r o m t r i c l o p y r - t r e a t e d p lo ts . G rass y i e l d s w e r e 39 k g / h a f r o m u n t r e a t e d p lo ts , 75 k g / h a f r o m c h l o r s u l f u r o n - t r e a t e d p lo ts and 60 k g / h a f r o m t r i c l o p y r - t r e a t e d p l o t s . B o t h t r i c l o p y r and c h l o r s u l f u r o n r e d u c e d the number o f k n a p w e e d seed l ings and r o s e t t e s c o m p a r e d to the u n t r e a t e d p l o t s . D i s c u s s i o n P i c l o r a m or 3 , 6 - d i c h l o r o p i c o I i n i c a c i d a p p l i e d a t 250 -1000 g / h a w i l l c o m p l e t e l y c o n t r o l spo t ted k n a p w e e d fo r a t l e a s t 300 days and d i f f u s e k n a p w e e d f o r a t l eas t 420 days under the e n v i r o n m e n t a l c o n d i t i o n s o f th is s tudy . T r e a t m e n t o f k n a p w e e d - i n f e s t e d range w i t h these h e r b i c i d e s r e s u l t e d in an i n c r e a s e in grass p r o d u c t i o n f r o m 39 k g / h a fo r u n t r e a t e d p lots to 287 and 254 k g / h a fo r p i c l o r a m - a n d 3 , 6 - d i c h l o r o p i c o l i n i c a c i d -t r e a t e d p l o t s , r e s p e c t i v e l y . P i c l o r a m is w i d e l y used for the c o n t r o l of d i f f u s e and s p o t t e d k n a p w e e d and resu l ts of p rev ious work a re c o n f i r m e d h e r e . Some s tud ies have noted stand r e d u c t i o n and p r o s t r a t e g r o w t h of grasses caused by p i c l o r a m t r e a t m e n t , but no such e f f e c t s w e r e observed over the d u r a t i o n of these e x p e r i m e n t s (Wyoming A g r i c u l t u r a l E x p e r i -ment S t a t i o n 1979). 51 Table XII: Ashcroft site k20 days post treatment - main plot yields and plant numbers.* Treatment diffuse knapweed (g/m2) grass (g/m2) rosettes (no./m2) seedlings (no./m2) bolted plants 2 (no./m ) control 38.71 a 3.90 a 64.00 a 29.25 a 21.25 a chlorsulfuron 32.14 a 7.46 a 46.25 a 21.25 b 32.50 a triclopyr . 34.20 a 6.05 a 45.75 b 8.75 b 19.50 a 3,6-dichloro- 0 b 25.36 b 0 b 0 b 0 b picolinic acid picloram 0 b 28.67 b 0 b 0 b 0 b means within a column followed by the same letter are not significantly different (Fisher's protected LSD p_f .05). 3 , 6 - d i c h l o r o p i c o l i n i c a c i d is less p e r s i s t e n t than p i c l o r a m (Na ik e t a l . 1972) and should not l eave p h y t o t o x i c res idues one yea r a f t e r a p p l i c a t i o n . C l i m a t i c c o n d i t i o n s s t r o n g l y i n f l u e n c e the p e r s i s t e n c e of th is c o m p o u n d (P ik e t a l . 1977) and in the s e m i -a r i d Thompson V a l l e y i t c o u l d pers is t in a p h y t o t o x i c f o r m fo r more than one yea r and thus p rov ide r e s i d u a l c o n t r o l of the k n a p w e e d s p e c i e s . R e l a t i v e to the C a c h e C r e e k s i t e , knapweed seed l i ng l e v e l s w e r e qu i te l o w a t b o t h the A s h c r o f t and W a l h a c h i n s i t e s . The ave rage number of s e e d l i n g s / m f o r u n t r e a t e d p lo ts was 2,902 fo r t he C a c h e C r e e k s i t e , 29 fo r the A s h c r o f t s i t e and 14 f o r the W a l h a c h i n s i t e . Th is c o u l d be due to l o w e r weed d e n s i t i e s a t b o t h these s i t e s . Thus , t he h e r b i c i d e c o u l d be p r o v i d i n g res idua l c o n t r o l and p r e v e n t i n g s e e d l i n g g r o w t h , or so i l seed bank l e v e l s c o u l d be so l o w tha t no g e r m i n a t i o n o c c u r r e d a n d / o r e n v i r o n m e n t a l c o n d i t i o n s w e r e not s u i t a b l e fo r g e r m i n a t i o n . A t a l l s a m p l i n g da tes where seed l ings w e r e c o u n t e d , t he re w e r e no k n a p w e e d seed l ings in any p l o t s t r e a t e d w i t h 3 , 6 - d i c h l o r o p i c o l i n i c a c i d . C h l o r s u l f u r o n and t r i c l o p y r c a n p rov ide e f f e c t i v e c o n t r o l of d i f f u s e and s p o t t e d k n a p w e e d on ly fo r the season of a p p l i c a t i o n . A n a l y s e s of y i e l d d a t a i n d i c a t e d t h a t a l l r a t e s o f c h l o r s u l f u r o n and t r i c l o p y r w e r e equa l l y e f f e c t i v e fo r k n a p w e e d c o n t r o l , but v i s u a l obse rva t ions suggested tha t a m i n i m u m e f f e c t i v e r a t e fo r c h l o r s u l f u r o n is 80 g / h a and fo r t r i c l o p y r 1000 g / h a . S ince the h a l f - l i f e of c h l o r s u l f u r o n is on ly 1 to 2 months in these c l i m a t e s , i t is u n l i k e l y to p rov ide any k n a p w e e d c o n t r o l in the yea r a f t e r a p p l i c a t i o n . It does, h o w e v e r , have some short t e r m a c t i v i t y aga ins t e m e r g i n g seed l ings ( P a l m et a l . 1980). 53 VI. Chlorsulfuron plus surfactant field trial The herbicidal activity of chlorsulfuron on some plant species has been improved by the use of a surfactant in the spray solution (Chow and Taylor 1980). Retention of sprays containing chlorsulfuron can be enhanced by the addition of a non-ionic agricultural surfactant at 0.1 to 0.5% v/v. The addition of a surfactant is most beneficial to herbicidal activity if the relative humidity is low and the weather is dry before and after treatment. It has been suggested that the leaves of diffuse knapweed are pubescent enough to influence the retention and penetration of herbicidal sprays (Ormrod and Renney 1968). A factorial experiment with four replicates in a split-plot design was established in May 1982 at the Cache Creek site to evaluate the addition of Citowett Plus (BASF Canada) to chlorsulfuron for diffuse knapweed control. Chlorsulfuron was evaluated at 0, 20, 40, 80 and 160 g/ha with and without the addition of Citowett Plus (50% alkyl aryl polyethylene glycol) at 0.1% v/v. Control of common chickweed (Stellaria media (L.) Vill.) with chlorsulfuron has been improved by the addition of Citowett Plus (Chow and Taylor 1980). The herbicide treatments were applied June 5, 1982 using the CC"2 powered sprayer at 276 KPa and a solution volume of 500 L/ha. Herbicide efficacy was evaluated from July 27th to 29th, 1982 by visual observations and by clipping 2 diffuse knapweed yield from a 0.25 m area. The number of diffuse knapweed seedlings, rosettes and bolted plants was also recorded for each plot (Appendix G). The diffuse knapweed vegetation was dried and weighed and yields and plant numbers were analyzed by analysis of variance. A l l r a t e s o f c h l o r s u l f u r o n e v a l u a t e d e f f e c t i v e l y reduced the dry w e i g h t of d i f f u s e k n a p w e e d c o m p a r e d to the u n t r e a t e d p lo ts (Tab le XIII). D i f f u s e knapweed y i e l d s w e r e 1170 k g / h a f r o m u n t r e a t e d p lots and 328 k g / h a f r o m c h l o r s u l f u r o n t r e a t e d p l o t s . The a d d i t i o n of C i t o w e t t P l u s at 0 . 1 % v / v d id not enhance the p h y t o t o x i c i t y of c h l o r s u l f u r o n on d i f f u s e k n a p w e e d . H e r b i c i d e a p p l i c a t i o n s d id not r e d u c e the numbers o f b o l t e d p lan ts , but d id reduce the numbers o f r o s e t t e s and seed l ings . The numbers of d i f f u s e knapweed r o s e t t e s / m w e r e 155 f r o m u n t r e a t e d p lo ts and 74 f r o m c h l o r -s u l f u r o n t r e a t e d p l o t s . The a d d i t i o n o f C i t o w e t t P lus r e s u l t e d in a g r e a t e r r e d u c t i o n in r o s e t t e numbers than d id c h l o r s u l f u r o n a l o n e . A l l r a t e s of c h l o r s u l f u r o n a p p l i e d w e r e e q u a l l y e f f e c t i v e in r e d u c i n g d i f f u s e k n a p w e e d dry w e i g h t per square m e t e r . A t r a t e s o f c h l o r s u l f u r o n b e l o w 80 g / h a , many d i f f u s e k n a p w e e d p lants w e r e ab le to f l o w e r ; the a b i l i t y o f these p lants to p roduce v i a b l e seed was not e v a l u a t e d . S u b l e t h a l e f f e c t s of c h l o r s u l f u r o n i nc luded a n t h o c y a n e s c e n c e (Sut t le and S c h r e i n e r 1982) and a c l u m p i n g o f buds e s p e c i a l l y a t the b ranch e x t r e m i t i e s . A t these l o w e r r a t e s , many k n a p w e e d r o s e t t e s w e r e ab le to o v e r c o m e the p h y t o t o x i c e f f e c t s of c h l o r s u l f u r o n and w e r e r e c o v e r i n g f r o m the h e r b i c i d e t r e a t m e n t a t the t i m e o f h a r v e s t . H e a v y ra ins dur ing the end o f June and the beg inn ing o f J u l y 1982 s t i m u l a t e d the g e r m i n a t i o n of d i f f u s e k n a p w e e d seed in the s o i l . A l l u n t r e a t e d p lo ts c o n t a i n e d h igh 2 numbers o f k n a p w e e d seed l ings (2 ,977 /m ) (Append ix G ) , but the re w e r e no seed l ings in any of the c h l o r s u l f u r o n - t r e a t e d p l o t s . C h l o r s u l f u r o n does not p reven t k n a p w e e d seed g e r m i n a t i o n (see S e c t i o n IX) , but i t is known to have some shor t t e r m r e s i d u a l a c t i v i t y aga ins t e m e r g i n g b r o a d l e a v e d seed l ings ( P a l m et a l . 1980). It is apparent f r o m th is e x p e r i m e n t tha t in a d d i t i o n to c o n t r o l l i n g e x i s t i n g p l a n t s , c h l o r s u l f u r o n at r a t e s as low as 20 g / h a , c a n c o n t r o l d i f f u s e k n a p w e e d seed l ings fo r a t l eas t t w o months . 55 Table XIII: Chlorsulfuron plus surfactant field trial - post treatment  yields and plant numbers (52 days)* Treatment diffuse bolted (g/ha knapweed plants rosettes seedlings chlorsulfuron) (g/m2 !) (no./i m2) (no./m2) (no./m2 0 155.55 a 32 a 126 a 2586 a 20 50.56 b 23 a 78 ac 0 b 40 44.71 b 27 a 81 ac 0 b 80 41.69 b 36 a 38 be 0 b 160 16.71 b 15 a 72 ac 0 b 0 + 0.1% Citowett 78.30 a 26 a 183 a 3367 a 20 + 0.1% Citowett 32.51 b 15 a 99 b 0 b 40 + 0.1% Citowett 29.54 b 17 a 73 b 0 b 80 + 0.1% Citowett 27.40 b 11 a 106 b 0 b 160 + 0.1% Citowett 19.28 b 13 a 49 b 0 b * means within a treatment followed by the same letter are not significantly different (Fisher's protected LSD p-<: .01). Stud ies in Wash ington S t a t e have d e t e r m i n e d tha t f l o w e r i n g of d i f f u s e and s p o t t e d k n a p w e e d p lants is d i r e c t l y r e l a t e d to t h e i r t i m e of e m e r g e n c e (Sch i rman 1981). Seed l ings w h i c h e m e r g e in M a r c h or A p r i l p roduced f l o w e r i n g s t e m s in 7 0 - 9 5 % o f p lants dur ing the f o l l o w i n g y e a r . Seed l ings w h i c h e m e r g e d in J u n e or J u l y d id not p roduce f l o w e r i n g s t e m s in the subsequent y e a r . E a r l y spr ing t r e a t m e n t w i t h a h e r b i c i d e l i k e c h l o r s u l f u r o n wou ld c o n t r o l r o s e t t e s and b o l t e d p lan ts and p rov ide r e s i d u a l c o n t r o l o f k n a p w e e d seed l ings u n t i l m i d - s u m m e r . If e m e r g e n c e of seed l ings c a n be e f f e c t i v e l y c o n t r o l l e d w i t h h e r b i c i d e s u n t i l J u n e , ve ry l i t t l e f l o w e r i n g and subsequent seed p r o d u c t i o n is l i k e l y t o o c c u r in the f o l l o w i n g y e a r ( S c h i r m a n 1981). Thus , one season's t r e a t m e n t w i t h c h l o r s u l f u r o n c o u l d t h e o r e t i c a l l y p rov ide a c c e p t a b l e c o n t r o l o f d i f f u s e and s p o t t e d k n a p w e e d f o r t w o y e a r s . VII. DPX-T6376 T h i s e x p e r i m e n t a l h e r b i c i d e is s t r u c t u r a l l y s i m i l a r to c h l o r s u l f u r o n but is less pe rs i s ten t and more a c t i v e at e q u i v a l e n t r a t e s . D P X - T 6 3 7 6 is e f f e c t i v e at l ow r a t e s on a w ide v a r i e t y of b r o a d l e a v e d p l a n t s . A s ing le f a c t o r e x p e r i m e n t in a r a n d o m i z e d c o m p l e t e b l o c k des ign w i t h fou r r e p l i c a t e s was e s t a b l i s h e d a t t he C a c h e C r e e k s i t e to e v a l u a t e D P X - T 6 3 7 6 fo r d i f f u s e knapweed c o n t r o l . D P X - T 6 3 7 6 was a p p l i e d at 0, 20, 40 , 80 and 160 g / h a us ing a CC> 2 p o w e r e d sprayer at 276 K P a w i t h a s o l u t i o n v o l u m e of 500 L / h a . C i t o w e t t P l u s a t 0 . 1 % v / v was added to a l l spray s o l u t i o n s . T h e h e r b i c i d e t r e a t m e n t s w e r e a p p l i e d 3une 5 t h , 1982. The w e a t h e r at t h i s t i m e was o v e r c a s t and c o o l . These p lots w e r e e v a l u a t e d 3u ly 23 rd , 1982 (48 days p o s t - t r e a t m e n t ) by c l i p p i n g 2 0.25 m samp les f r o m e a c h p lo t and by c o u n t i n g the numbers of b o l t e d k n a p w e e d p l a n t s , r o s e t t e s and seed l ings f r o m the s a m p l e . A l l r a t e s of D P X - T 6 3 7 6 e v a l u a t e d w e r e equa l l y e f f e c t i v e in r e d u c i n g d i f f u s e k n a p w e e d dry w e i g h t per square m e t e r (Append ix H) . The h e r b i c i d e t r e a t m e n t s had no e f f e c t on the number of b o l t e d d i f f u s e knapweed p lan ts or the number of k n a p w e e d r o s e t t e s per square m e t e r . A s in t h e c h l o r s u l f u r o n e x p e r i m e n t at th is s i t e , u n t r e a t e d p lo ts c o n t a i n e d h igh numbers of d i f f u s e k n a p w e e d seed l ings . T h e r e w e r e no d i f f u s e k n a p w e e d seed l ings in any o f the p lo ts t r e a t e d w i t h D P X - T 6 3 7 6 (Tab le X I V ) . A l t h o u g h D P X - T 6 3 7 6 has a s h o r t e r h a l f -l i f e than c h l o r s u l f u r o n in the s o i l , i t r e m a i n e d in a p h y t o t o x i c f o r m fo r at l eas t 48 days and was ab le to p rov ide c o m p l e t e r e s i d u a l c o n t r o l o f d i f f u s e k n a p w e e d at r a t e s as low as 20 g / h a . 58 Table XIV: DPX-T6376 field trial - post treatment  yields and plant numbers (48 days)* Treatment diffuse bolted (g/ha knapweed plants rosettes seedlings DPX-T6376) (g/m2) (no./m2) (no./m2) (no./m2) 0 147.09 a 11.25 a 29.25 a 2580 a 20 + 0.1% Citowett 44.27 b 6.25 a 17.00 a 0 b 40 + 0.1% Citowett 25.64 b 4.25 a 12.75 a 0 b 80 + 0.1% Citowett 36.21 b 6.25 a 13.25 a 0 b 160 + 0.1% Citowett 30.44 b 3.75 a 7.00 a 0 b means within a column followed by the same letter are not significantly different (Fisher's protected LSD pj<.05). A t r a t e s b e l o w 80 g / h a D P X - T 6 3 7 6 was super io r to c h l o r s u l f u r o n in c o n t r o l l i n g d i f f u s e k n a p w e e d . A l l b o l t e d p lants and r o s e t t e s w e r e c o m p l e t e l y k i l l e d and t h e r e was no e v i d e n c e of r e c o v e r y f r o m the h e r b i c i d e t r e a t m e n t s . B o t h c h l o r s u l f u r o n and D P X -T6376 a r e e x c e l l e n t h e r b i c i d e s fo r k n a p w e e d c o n t r o l w h e r e short t e r m (up to fou r months) n o n - r e s i d u a l c o n t r o l is d e s i r a b l e . B o t h c h l o r s u l f u r o n and D P X - T 6 3 7 6 a r e r a p i d l y degraded ( c o m p a r e d to p i c l o r a m ) and s o i l res idues should not be p h y t o t o x i c to most c u l t i v a t e d c rops one yea r a f t e r a p p l i c a t i o n . VIII. 3,6-dichloropicolinic acid minimum rate trial E x p e r i m e n t a l e v a l u a t i o n s o f 3 , 6 - d i c h l o r o p i c o l i n i c a c i d in 1981 i n d i c a t e d t h a t the l o w e s t r a t e of a p p l i c a t i o n t e s t e d (250 g /ha) gave c o m p l e t e c o n t r o l o f both d i f f u s e and s p o t t e d k n a p w e e d . Th is h e r b i c i d e is e f f e c t i v e on some b r o a d l e a v e d weeds at ra tes as l o w as 70 g / h a ( K e y s 1975). A n e x p e r i m e n t was set up in the s u m m e r of 1982 at t he C a c h e C r e e k s i t e to d e t e r m i n e a m i n i m u m r a t e of 3 , 6 - d i c h l o r o p i c o l i n i c a c i d f o r d i f f u s e k n a p w e e d c o n t r o l . A n e x p e r i m e n t in a r a n d o m i z e d c o m p l e t e b l o c k des ign w i t h f o u r r e p l i c a t e s was es tab l i shed in J u n e 1982. The h e r b i c i d e was a p p l i e d a t 0, 50, 100, 150 and 250 g / h a . P i c l o r a m at 100 g / h a has been e v a l u a t e d fo r d i f f u s e k n a p w e e d c o n t r o l and was found to p rov ide t h r e e yea rs of c o n t r o l . A p i c l o r a m t r e a t m e n t of 100 g / h a was i n c l u d e d i n th i s e x p e r i m e n t . A l l h e r b i c i d e s w e r e a p p l i e d June 5 th , 1982 us ing a C O ^ p o w e r e d sp raye r w i t h pressure r e g u l a t e d at 276 K P a and a s o l u t i o n v o l u m e o f 500 L / h a . Weed c o n t r o l was e v a l u a t e d J u l y 20th to 23rd , 1982 by v i s u a l o b s e r v a t i o n and by c l i p p i n g d i f f u s e 2 k n a p w e e d v e g e t a t i o n at g round l e v e l f r o m a 0.25 m a r e a in e a c h p l o t . The n u m b e r s o f b o l t e d (mature) p lan ts , r o s e t t e s and seed l ings in e a c h p lo t w e r e a lso r e c o r d e d (Append ix I). A n a l y s i s of v a r i a n c e of these d a t a showed a s i g n i f i c a n t d i f f e r e n c e in weed y i e l d and the number o f seed l ings fo r the d i f f e r e n t t r e a t m e n t s a p p l i e d (Tab le X V ) . T h e r e w e r e no s i g n i f i c a n t d i f f e r e n c e s in the numbers o f b o l t e d p lan ts and r o s e t t e s . 61 Table XV: 3,6-dichloropicolinic acid minimum rate trial - post treatment  yields and plant numbers days)* diffuse bolted Treatment knapweed plants rosettes seedlings (g/ha) (g/m2) (no./m2) (no./m2) (no./m2) 3,6-dichloropicolinic acid 0 113.21 a 42 a 202 a 3078 a 50 83.94 ab 27 a 113 a 1041 b 100 36.42 c 21 a 93 a 620 b 150 56.72 be 40 a 60 a 39 c 250 31.59 c 28 a 59 a 0 c picloram 100 47.68 be 23 a 67 a 0 c * means within a column followed by the same letter are not significantly different (Fisher's protected LSD p <s.Q5). R e l a t i v e to the u n t r e a t e d p l o t s , a l l r a t e s o f 3 , 6 - d i c h l o r o p i c o l i n i c a c i d a b o v e 50 g / h a and p i c l o r a m a t 100 g / h a r e d u c e d d i f f u s e knapweed dry w e i g h t y i e l d . M a n y d i f f u s e knapweed r o s e t t e s w e r e ab le to r e c o v e r f r o m the a p p l i c a t i o n of 3 , 6 - d i c h l o r o -p i c o l i n i c a c i d a t 50 g / h a and many b o l t e d p lants w e r e ab le to f l o w e r . U n t r e a t e d p lo ts at th is s i t e c o n t a i n e d h igh numbers of d i f f u s e k n a p w e e d seed l ings . A l l h e r b i c i d e t r e a t m e n t s s i g n i f i c a n t l y r e d u c e d the number o f s u r v i v i n g d i f f u s e k n a p w e e d seed l i ngs . R a t e s o f 3 , 6 - d i c h l o r o p i c o l i n i c a c i d b e l o w 150 g / h a d id not c o m p l e t e l y k i l l r o s e t t e s and gave poor c o n t r o l o f k n a p w e e d seed l i ngs . P i c l o r a m a t 100 g / h a c o n t r o l l e d b o l t e d p l a n t s , r o s e t t e s and seed l ings f o r the d u r a t i o n o f t he e x p e r i -m e n t . F r o m th i s e x p e r i m e n t , a m i n i m u m a c c e p t a b l e r a t e o f 3 , 6 - d i c h l o r o p i c o l i n i c a c i d f o r d i f f u s e k n a p w e e d c o n t r o l w o u l d be 150 g / h a . Th is w o u l d ensure c o n t r o l o f c u r r e n t season g r o w t h as w e l l as r e s i d u a l c o n t r o l o f any e m e r g i n g seed l i ngs . P i c l o r a m a t 100 g / h a was as e f f e c t i v e i n d i f f u s e k n a p w e e d c o n t r o l as 3 , 6 - d i c h l o r o p i c o l i n i c a c i d a t 150 and 250 g / h a . IX. Effect of herbicides on seed germination One of the d e s i r a b l e a t t r i b u t e s o f a h e r b i c i d e to be used f o r k n a p w e e d c o n t r o l is t h a t i t be ab le t o c o n t r o l e m e r g i n g k n a p w e e d seed l ings fo r some t i m e a f t e r t r e a t m e n t . S i n c e p i c l o r a m is p e r s i s t e n t i n a p h y t o t o x i c f o r m , i t is v e r y e f f e c t i v e f o r the r e s i d u a l c o n t r o l o f k n a p w e e d and th is is p r i m a r i l y why i t is f a v o u r e d over o t h e r h e r b i c i d e s (Renney and Hughes 1969). P i c l o r a m is a lso t o x i c to seed l ings o f many n a t i v e and c u l t i v a t e d grasses and c a n n o t be used w h e r e p h y t o t o x i c res idues a re a p r o b l e m ( S c r i f e s and H a l i f a x 1972b). S e v e r a l e x p e r i m e n t s w e r e c o n d u c t e d in g r o w t h c a b i n e t s to d e t e r m i n e the e f f e c t s o f h e r b i c i d e s used in the f i e l d s tud ies on seed g e r m i n a t i o n and s e e d l i n g g r o w t h of d i f f u s e k n a p w e e d , s p o t t e d k n a p w e e d , b luebunch w h e a t g r a s s and c r e s t e d w h e a t g r a s s ( A g r o p y r o n d e s e r t o r u m (F isch . ) S c h u l t . c v . No rdan ) . P i c l o r a m , 3 , 6 - d i c h l o r o p i c o l i n i c a c i d , t r i c l o p y r and c h l o r s u l f u r o n w e r e e v a l u a t e d f o r e a c h s p e c i e s . T w e n t y - f i v e seeds o f one s p e c i e s w e r e added to a 10 c m p l a s t i c P e t r i - p l a t e c o n t a i n i n g t w o W h a t m a n N o . 1 f i l t e r papers and 5 m l of a h e r b i c i d e s o l u t i o n . The e x p e r i m e n t s w e r e c o n d u c t e d in a da rk g r o w t h c h a m b e r m a i n t a i n e d at a p p r o x i m a t e l y 25°C. The seeds w e r e a l l o w e d to g e r m i n a t e and g r o w f o r seven days . A t the end o f t h i s p e r i o d the number o f g e r m i n a t e d seeds was c o u n t e d and r a d i c l e and t o t a l seed l i ng l ength w e r e m e a s u r e d . The d a t a and ana lyses a r e p resen ted in A p p e n d i x 3. R e s u l t s of these g e r m i n a t i o n e x p e r i m e n t s a re s u m m a r i z e d in F i g u r e s 10 -21 . G e r m i n a t i o n o f d i f f u s e k n a p w e e d seed was r e d u c e d by c h l o r s u l f u r o n a t 0.01 p p m . Spotted knapweed germination was reduced by chlorsulfuron at 0.01 and 1.0 ppm. Chlorsulfuron did not reduce the germination of crested wheatgrass and bluebunch wheatgrass seed. It does not affect seed germination at concentrations up to 10 ppm (Ray 1980) but radicle and shoot elongation are suppressed. Chlorsulfuron is known to be a potent inhibitor of cell division at concentrations as low as 1 ppb (Ray 1980). Chlorsulfuron at 0.5-4.0 ppb reduces the radicle length of corn (Zea mays L.) seedlings (E.I. duPont de Nemours & Co. Inc., unpublished data). Chlorsulfuron at 10 and 100 ppm reduced the radicle length of diffuse knapweed and bluebunch wheatgrass seedlings. The effects on crested wheatgrass were variable. The radicle length of seedlings was reduced at 100 ppm but increased at 0.01 and 0.1 ppm. The radicle length of spotted knapweed seedlings was reduced only at 100 ppm. Chlorsulfuron decreased the total length of spotted knapweed seedlings at 1.0-100 ppm and diffuse knapweed seedlings at 0.1-100 ppm. The total length of crested wheatgrass seedlings was increased at 0.1 ppm and decreased at 100 ppm. The total length of bluebunch wheatgrass seedlings was reduced at 100 ppm. Soil residues of chlorsulfuron prevented the emergence of diffuse knapweed seedlings at the Cache Creek site (see Section VI). Germination of diffuse knapweed seed was reduced by triclopyr and 3,6-dichloro-picolinic acid at 100 and 1000 ppm and by picloram at 0.1-1000 ppm. Triclopyr reduced the germination of spotted knapweed seed at 10-1000 ppm but germination was increased at 0.1 ppm. Germination was reduced by 3,6-dichloropicolinic acid at 10-1000 ppm and picloram at 1.0-1000 ppm. B l u e b u n c h wheatg rass seed g e r m i n a t i o n was r e d u c e d by t r i c l o p y r a t 0 . 1 - 1 0 0 0 p p m , 3 , 6 - d i c h l o r o p i c o l i n i c a c i d at 0 .1 , 1.0, 100 and 1000 ppm and p i c l o r a m at 1 .0 -1000 p p m . The r a d i c l e l eng th of d i f f u s e k n a p w e e d seed l ings was r e d u c e d by t r i c l o p y r a t 1 0 - 1 0 0 0 ppm and 3 , 6 - d i c h l o r o p i c o l i n i c a c i d and p i c l o r a m a t 1 .0 -1000 p p m . R a d i c l e l e n g t h of s p o t t e d k n a p w e e d seed l ings was r e d u c e d by t r i c l o p y r , 3 , 6 - d i c h l o r o p i c o l i n i c a c i d and p i c l o r a m a t 0 . 1 - 1 0 0 0 p p m . The r a d i c l e l eng th o f c r e s t e d w h e a t g r a s s seed l ings was s i g n i f i c a n t l y r e d u c e d by t r i c l o p y r at 10 -1000 ppm and 3 , 6 - d i c h l o r o p i c o l i n i c a c i d and p i c l o r a m a t 1 .0 -1000 p p m . R a d i c l e l e n g t h o f b luebunch w h e a t g r a s s seed l ings was r e d u c e d by t r i c l o p y r a t 10 -1000 p p m , 3 , 6 - d i c h l o r o p i c o l i n i c a c i d at 0 . 1 - 1 0 0 0 ppm and p i c l o r a m a t 10 -1000 p p m . The t o t a l l e n g t h of d i f f u s e k n a p w e e d seed l ings was r e d u c e d by t r i c l o p y r a t 10 -1000 p p m , 3 , 6 - d i c h l o r o p i c o l i n i c a c i d a t 1 .0 -1000 ppm and p i c l o r a m a t 1 .0 -1000 p p m . T o t a l l e n g t h o f s p o t t e d k n a p w e e d seed l ings was r e d u c e d by a l l t h r e e p y r i d i n e h e r b i c i d e s a t 0 . 1 - 1 0 0 0 p p m . T o t a l l e n g t h of c r e s t e d wheatg rass seed l ings was r e d u c e d by t r i c l o p y r and p i c l o r a m a t 10 -1000 p p m . 3 , 6 - d i c h l o r o p i c o l i n i c a c i d was less t o x i c to c r e s t e d w h e a t g r a s s seed l i ngs ; s i g n i f i c a n t l e n g t h r e d u c t i o n s o c c u r r e d on ly a t 1000 p p m . T r i c l o p y r and p i c l o r a m a t 100 and 1000 ppm r e d u c e d the t o t a l l e n g t h of b luebunch wheatg rass seed l ings . 3 , 6 - d i c h l o r o p i c o l i n i c a c i d r e d u c e d t o t a l s e e d l i n g l e n g t h a t 0 .1 , 10 and 1000 ppm but not a t 1.0 and 100 p p m . S o i l res idues o f p i c l o r a m c a n e f f e c t i v e l y c o n t r o l e m e r g i n g k n a p w e e d seed l ings f o r 3 - 5 yea rs a f t e r t r e a t m e n t but seed ing of the a r e a w i t h grasses must be d e l a y e d f o r 6 - 1 2 months ( H a r r i s and C r a n s t o n 1979). O b s e r v a t i o n s o f d i f f u s e and s p o t t e d k n a p w e e d seed in P e t r i p l a tes c o n t a i n i n g p i c l o r a m so lu t i ons i n d i c a t e t h a t th i s h e r b i c i d e does not p r e v e n t g e r m i n a t i o n ( e x c e p t a t 1000 ppm) but r a d i c l e g r o w t h is dep ressed . D e c r e a s e s in r a d i c l e l e n g t h due to p i c l o r a m are a c c o m p a n i e d by an i n c r e a s e in t h i c k n e s s ( S c r i f e s and H a l i f a x 1972b). P i c l o r a m reduces the r a d i c l e l e n g t h o f b u f f a l o g r a s s , s ideoats g r a m a and s w i t c h g r a s s seed l ings a t 125 ppb but does not a f f e c t g e r m i n a t i o n a t 3 2 - 1 0 0 0 ppb ( S c r i f e s and H a l i f a x 1972b). Shoot g r o w t h o f b u f f a l o g r a s s was s t i m u l a t e d a t 125 ppb. A r n o l d and S a n t e l m a n n (1966) r e p o r t e d t h a t p i c l o r a m r e d u c e d g e r m i n a t i o n of s i deoa ts g r a m a , b i g b l u e s t e m , s w i t c h g r a s s and b lue g r a m a but the c o n c e n t r a t i o n of p i c l o r a m in s o i l r e s u l t i n g f r o m f i e l d a p p l i c a t i o n s shou ld not be d e t r i m e n t a l t o b u f f a l o g r a s s or s ideoats g r a m a seed l ings ( S c i f e s and H a l i f a x 1972b). F i e l d a p p l i c a t i o n r a t e s of p i c l o r a m w i l l v a r y depend ing on the s i t e and thus s o i l c o n c e n t r a t i o n s a f t e r a p p l i c a t i o n w i l l be d i f f e r e n t . Hogue e t a l . (unpubl ished) found p i c l o r a m s o i l l e v e l s of 280 ppb f o l l o w i n g an a p p l i c a t i o n o f 0.5 k g / h a to a s i l t -l o a m s o i l i n B . C . T r i c l o p y r has been e v a l u a t e d p r i m a r i l y f o r the c o n t r o l o f woody s p e c i e s and t h e r e have not been any pub l ished s tud ies of t he e f f e c t of t h i s h e r b i c i d e on seed g e r m i n a t i o n , r a d i c l e g r o w t h or seed l i ng g r o w t h . R e s u l t s of the g e r m i n a t i o n e x p e r i -m e n t s show t h a t t r i c l o p y r w a s , in g e n e r a l , m o r e t o x i c t o g e r m i n a t i o n and e a r l y s e e d l i n g g r o w t h o f the k n a p w e e d t h a n to the g rasses . In f i e l d p lo ts t r i c l o p y r d i d not c o n t r o l e m e r g i n g k n a p w e e d seed l ings o v e r the d u r a t i o n of the e x p e r i m e n t . T h e p h y t o t o x i c range of 3 , 6 - d i c h l o r p i c o l i n i c a c i d is s i m i l a r t o p i c l o r a m and t h i s h e r b i c i d e has a s i m i l a r e f f e c t on g e r m i n a t i o n and seed l i ng g r o w t h o f the k n a p w e e d s . 3 , 6 - d i c h l o r o p i c o l i n i c a c i d was less d e t r i m e n t a l than p i c l o r a m to g r o w t h of c r e s t e d w h e a t g r a s s seed l i ngs . In f i e l d p lo ts e m e r g i n g d i f f u s e k n a p w e e d seed l ings w e r e c o n t r o l l e d f o r 420 days by 3 , 6 - d i c h l o r o p i c o l i n i c a c i d a t 2 5 0 - 1 0 0 0 g / h a . The resu l ts of these e x p e r i m e n t s i n d i c a t e t h a t s o i l l e v e l s o f c h l o r s u l f u r o n and 3 , 6 - d i c h l o r o p i c o l i n i c a c i d should be m o n i t o r e d f o l l o w i n g an a p p l i c a t i o n f o r k n a p w e e d c o n t r o l . Diffuse Knapweed CO "O CD CD CO CD •4—• 03 C 0 • chlorsulfuron B t r i c l o p y r 0 3.6-dichloropipolinic acid A picloram LSD 1{P = . 0 5 ) 0 1 2 3 4 5 6 Herbicide Concentration (log ppb) F i g u r e 1 0 , E f f e c t o f h e r b i c i d e s on g e r m i n a t i o n o f d i f f u s e knapweed* 03 E 0 0 CO C 0 0 O • mmm C O DC Diffuse Knapweed • c h l o r s u l f u r o n B t r i c l o p y r O 3.6 -d ich loropico l in ic acid 0 p i c lo ram L S D ( P = . 0 5 ) 1 2 3 4 5 6 Herbicide Concentration (log ppb) F i g u r e 11• E f f e c t o f h e r b i c i d e s on r a d i c l e l e n g t h of d i f f u s e knapweed s e e d l i n g s . CO E Diffuse Knapweed E Q c h l o r s u l f u r o n Herbicide Concentration (log ppb) F i g u r e 12 . E f f e c t of h e r b i c i d e s on t o t a l l e n g t h o f d i f f u s e knapweed s e e d l i n g s . o E £15.0, "S12.51 Spotted Knapweed • c hlorsulfuron • tr ic lopy r O 3 .6-dichloropicolinic acid 0 piclora m L S D 1 P = . 0 5 ) 1 2 3 4 5 6 Herbicide Concentration (log ppb) F i g u r e 14. E f f e c t o f h e r b i c i d e s on r a d i c l e l e n g t h o f s p o t t e d knapweed s e e d l i n g s . E E Spotted Knapweed Herbicide Concentration (log ppb) F i g u r e 1 5 . E f f e c t of h e r b i c i d e s on t o t a l l e n g t h of s p o t t e d knapweed s e e d l i n g s . Bluebunch Wheatgrass C O T J 0 0 CO "D 0 C 0 r j chlorsulfuron • triclopyr O 3»6-dichloropicolinic acid # picloram LSD (P=.05 ) 1 2 3 4 5 6 Herbicide Concentration (log ppb) F i g u r e 16. E f f e c t o f h e r b i c i d e s on g e r m i n a t i o n o f b l u e b u n c h w h e a t g r a s s . Bluebunch Wheatgrass Herbicide Concentration (log ppb) F i g u r e 17. E f f e c t o f h e r b i c i d e s on r a d i c l e l e n g t h of b l u e b u n c h w h e a t g r a s s s e e d l i n g s . E E H 80] CD o) 6 0 \ u CD CD CO -4—• o Bluebunch Wheatgrass 4a • chlorsulfuron • triclopyr O 3.6-d ich loropicol i nic acid # picloram L S D ( P = . 0 5 } 1 2 3 4 5 6 Herbicide Concentration (log ppb) F i g u r e 18. E f f e c t of h e r b i c i d e s on t o t a l l e n g t h o f b l u e b u n c h w h e a t g r a s s s e e d l i n g s . Crested Wheatgrass (0 "O CD 0 CO "O 0 0 o D chlorsulfuron I tri clopyr O 3 .6-d ich loropicol i nic acid # picloram L S D (P=.05) 1 2 3 4 5 6 Herbicide Concentration (log ppb) F i g u r e 19» E f f e c t of h e r b i c i d e s on g e r m i n a t i o n o f c r e s t e d wheatgrass« E E •o 0 <D CO O) c 0 - J 0 O • M M CO tr Crested Wheatgrass • chlorsulfuron • triclopyr O 3 >6-dichloropicol in ic acid # picloram L S D ( P = . 0 5 ) 1 2 3 4 5 6 Herbicide Concentration (log ppb) Figure 20. E f f e c t o f herbicides on r a d i c l e l e n g t h o f c r e s t e d w h e a t g r a s s s e e d l i n g s . 09 E Crested Wheatgrass E Herbicide Concentration (log ppb) F i g u r e 2 1 . E f f e c t of h e r b i c i d e s on t o t a l l e n g t h o f c r e s t e d w h e a t g r a s s s e e d l i n g s . co X. Discussion The use o f h e r b i c i d e s f o r t he c o n t r o l of d i f f u s e and s p o t t e d k n a p w e e d in B . C . is c u r r e n t l y a i m e d a t c o n t r o l l i n g the spread o f these spec ies w i t h i n the p r o v i n c e r a t h e r t h a n w i d e s p r e a d e r a d i c a t i o n (Anonymous 1977). The use o f p i c l o r a m f o r k n a p w e e d c o n t r o l on i n f e s t e d range lands in B . C . is e c o n o m i c a l l y j u s t i f i a b l e w h e n on ly y i e l d s o f n a t i v e f o r a g e a r e c o n s i d e r e d (Ha r r i s and C r a n s t o n 1979) but as p i c l o r a m w i l l r e d u c e f o r b popu la t ions in r ange land ( A r n o l d and S a n t e l m a n n 1966) the t r e a t m e n t of l a r g e a reas c o u l d have a d e t r i m e n t a l e f f e c t on w i l d l i f e . The r e s u l t s f r o m p i c l o r a m t r e a t e d p lo ts c o n f i r m t h a t at 4 2 0 - 5 6 0 g / h a i t e f f e c t i v e l y c o n t r o l s bo th knapweeds fo r t w o seasons (Renney and Hughes 1969). A t t he A s h c r o f t s i t e r e m o v a l of d i f f u s e k n a p w e e d r e s u l t e d in an i n c r e a s e in grass y i e l d . A t 300 days post t r e a t m e n t grass y i e l d s (S t i pa c o m a t a and P o a sandberg i i ) w e r e 96 k g / h a ( 3 , 6 - d i c h l o r o p i c o l i n i c a c i d t r e a t e d ) , 90 k g / h a ( p i c l o r a m t r e a t e d ) and 38 k g / h a (unt reated ) . The y i e l d o f S. c o m a t a a t 420 days post t r e a t m e n t on 3 , 6 - d i c h l o r o p i c o l i n i c a c i d and p i c l o r a m t r e a t e d p lo ts was 247 and 276 k g / h a r e s p e c t i v e l y , c o m p a r e d to 46 k g / h a on u n t r e a t e d p l o t s . S. c o m a t a i n c r e a s e s i n c o v e r f o l l o w i n g a p i c l o r a m a p p l i c a t i o n f o r k n a p w e e d r e m o v a l (Renney and Hughes 1969). G rass y i e l d s a t the W a l h a c h i n s i t e a t 300 days post t r e a t m e n t w e r e 81 k g / h a ( 3 , 6 - d i c h l o r o p i c o l i n i c a c i d t r e a t e d ) , 38 k g / h a ( p i c l o r a m t r e a t e d ) and 10 k g / h a (un -t r e a t e d ) . K n a p w e e d i n f e s t e d range m a y p roduce as l i t t l e as 20 k g / h a o f f o r a g e (Renney and Watson 1974). 3 , 6 - d i c h l o r o p i c o l i n i c a c i d p rov ided c o m p l e t e c o n t r o l o f d i f f u s e k n a p w e e d fo r 14 months at the A s h c r o f t s i t e . In l o a m so i l s under l o w p r e c i p i t a t i o n i t c a n p e r s i s t f o r more than 14 months (P ik e t a l . 1977). It is a c t i v e on C e n t a u r e a spp. a t 4 3 0 - 5 6 0 g / h a ( G e r o n i m o 1978) and w i l l p rov ide c o n t r o l fo r s ix months a t th is r a t e . R e s u l t s o f the f i e l d e x p e r i m e n t s i n d i c a t e t h a t 2 5 0 - 1 0 0 0 g / h a w i l l c o n t r o l d i f f u s e k n a p w e e d fo r t w o seasons and t h a t 150 g / h a is a m i n i m u m ra te for c u r r e n t season c o n t r o l . T r i c l o p y r was not e f f e c t i v e fo r c o n t r o l o f d i f f u s e or s p o t t e d k n a p w e e d e v e n a t 1000 g / h a . It r e d u c e d the d ry we igh t o f bo th s p e c i e s but d id not p r e v e n t r e g r o w t h f r o m the c r o w n in the subsequent y e a r . T h e r e w e r e no s i g n i f i c a n t i n c r e a s e s in grass y i e l d on t r i c l o p y r t r e a t e d p l o t s . It is less a c t i v e than 3 , 6 - d i c l o r o p i c o l i n i c a c i d on p lants of t he C o m p o s i t a e f a m i l y ( G e r o n i m o 1978). T r i c l o p y r c a n c o n t r o l C . s o l s t i t i a l i s and C . squar rosa fo r s ix months a t 430 and 1120 g / h a , r e s p e c t i v e l y ( G e r o n i m o 1978). T r e a t m e n t o f d i f f u s e and spo t ted k n a p w e e d b e f o r e b o l t i n g m a y i m p r o v e c o n t r o l w i t h t r i c l o p y r . C h l o r s u l f u r o n at 2 0 - 1 6 0 g / h a r e d u c e d the dry w e i g h t o f bo th k n a p w e e d s in the season of t r e a t m e n t but d id not p reven t r e g r o w t h in the second season . It p r e v e n t e d e m e r g e n c e of d i f f u s e k n a p w e e d seed l ings fo r 52 days f o l l o w i n g a p p l i c a t i o n s a t these ra tes . D e g r a d a t i o n o f c h l o r s u l f u r o n in the s o i l is i n f l u e n c e d by s o i l m o i s t u r e and s o i l p H (E.I. d u P o n t de N e m o u r s & C o . Inc. 1981). A t l o w s o i l m o i s t u r e and h igh p H (over 8.0) d e g r a d a t i o n is s l o w e d . S o i l p H is 6.9 at the A s h c r o f t s i te and 6.5 at the W a l h a c h i n s i t e . C h l o r s u l f u r o n was not pe rs i s ten t enough to p rov ide r e s i d u a l k n a p w e e d c o n t r o l a t e i t h e r s i t e . The p e r s i s t e n c e and a c t i v i t y of c h l o r s u l f u r o n and subsequent k n a p w e e d c o n t r o l w i l l v a r y depend ing on y e a r l y w e a t h e r p a t t e r n s . C h l o r s u l f u r o n c a n c o n t r o l C e n t a u r e a spp. a t r a t e s as l o w as 7 g / h a (E.I . duPont de N e m o u r s & C o . Inc. 1981). The a d d i t i o n o f a s u r f a c t a n t to c h l o r s u l f u r o n so lu t ions c a n i m p r o v e c o n t r o l but spec ies d i f f e r in t h e i r response ( C h o w and T a y l o r 1980). The a d d i t i o n of C i t o w e t t P l u s at 0 . 1 % (v /v ) d id not i m p r o v e d i f f u s e k n a p w e e d c o n t r o l w i t h c h l o r s u l f u r o n . C h l o r s u l f u r o n at 2 0 - 1 6 0 g / h a w i t h and w i t h o u t s u r f a c t a n t was equa l l y e f f e c t i v e in r e d u c i n g d i f f u s e k n a p w e e d d ry w e i g h t and s e e d l i n g n u m b e r . A h igher c o n c e n t r a t i o n o f s u r f a c t a n t ( 0 . 2 5 - 0 . 5 0 % v / v ) m a y i m p r o v e k n a p w e e d c o n t r o l w i t h c h l o r s u l f u r o n (E. I . d u P o n t de N e m o u r s <5c C o . Inc. 1981). P l a n t response t o c h l o r s u l f u r o n depends on g r o w t h s tage a t the t i m e o f t r e a t m e n t ; seed l ings a r e the mos t s u s c e p t i b l e . A t a l l s i t e s w h e r e c h l o r s u l f u r o n was a p p l i e d most of the k n a p w e e d p lan ts w e r e f u l l y b o l t e d and in the bud s t a g e . T r e a t m e n t of t he k n a p w e e d s w i t h c h l o r s u l f u r o n in the f a l l or e a r l y sp r ing when r o s e t t e s and seed l ings a re the d o m i n a n t g r o w t h s tage may i m p r o v e c o n t r o l . The e x p e r i m e n t a l h e r b i c i d e D P X - T 6 3 7 6 a t 2 0 - 1 6 0 g / h a w i t h 0 . 1 % (v /v ) C i t o w e t t P lus s i g n i f i c a n t l y r e d u c e d d i f f u s e k n a p w e e d dry w e i g h t and p r e v e n t e d seed l i ng e m e r g e n c e fo r 48 days in a l l t r e a t e d p l o t s . Where grasses e x i s t on k n a p w e e d d o m i n a t e d range lands , the range may r e c o v e r a f t e r h e r b i c i d e t r e a t m e n t u t i l i z i n g n a t u r a l seed s o u r c e s . H o w e v e r , as p i c l o r a m is in ju r ious to grass seed l i ng g r o w t h , a p p l i c a t i o n s to bad ly d e p l e t e d range land c o u l d reduce the r a t e of seed l ing e s t a b l i s h m e n t (Sc r i f es and H a l i f a x 1972a). When k n a p w e e d is r e m o v e d w i t h a p i c l o r a m t r e a t m e n t , B. t e c t o r u m c a n r a p i d l y o c c u p y the s i t e and subsequent f o r a g e y i e l d is less than on c o m p a r a b l e s i tes o c c u p i e d by bunchgrasses . R e s t o r a t i o n of range t h a t is h e a v i l y i n f e s t e d w i t h k n a p w e e d r e q u i r e s a h e r b i c i d e t r e a t m e n t and reseed ing w i t h a c u l t i v a t e d grass . C r e s t e d w h e a t g r a s s is ab le to e f f e c t i v e l y c o m p e t e w i t h d i f f u s e k n a p w e e d w i t h o u t h e r b i c i d e t r e a t m e n t (Hubbard 1975) but the c o n t r o l o f he rbaceous weeds a ids in g e r m i n a t i o n and e s t a b l i s h m e n t of p e r e n n i a l grasses and ensures tha t a v i g o r o u s , c o m p e t i t i v e s tand deve lops (Evans et a l . 1970). Where c r e s t e d wheatg rass is to be seeded f o l l o w i n g p i c l o r a m t r e a t m e n t , a de lay o f 6 - 1 2 months is r e q u i r e d (Har r i s and C r a n s t o n 1979). 3 , 6 - d i c h l o r o p i c o l i n i c a c i d c a n e f f e c t i v e l y c o n t r o l d i f f u s e k n a p w e e d a t 150 g / h a , is less p e r s i s t e n t t h a n p i c l o r a m (Na ik e t a l . 1972) and has a s i m i l a r e f f e c t on g e r m i n a t i o n and seed l i ng g r o w t h of b luebunch wheatg rass and c r e s t e d w h e a t g r a s s . If i t was used f o r k n a p w e e d c o n t r o l , reseed ing or s u c c e s s f u l seed l i ng e s t a b l i s h m e n t f r o m n a t u r a l sources c o u l d o c c u r sooner than a f t e r a p i c l o r a m t r e a t m e n t . H o w e v e r , as d e g r a d a t i o n of 3 , 6 - d i c h l o r o p i c o l i n i c a c i d is a f f e c t e d m o r e by c l i m a t i c c o n d i t i o n s than s o i l t y p e ( P i k e t a l . 1977), p e r s i s t e n c e wou ld have to be m o n i t o r e d f o l l o w i n g an a p p l i c a t i o n f o r k n a p w e e d c o n t r o l . C h l o r s u l f u r o n is less p e r s i s t e n t than bo th p i c l o r a m and 3 , 6 - d i c h l o r o p i c o l i n i c a c i d and c o n t r o l s d i f f u s e and s p o t t e d k n a p w e e d a t 2 0 - 1 6 0 g / h a . A g r o p y r o n s p e c i e s c a n t o l e r a t e a p p l i c a t i o n s o f 2 5 - 7 5 g / h a w i t h o u t p h y t o t o x i c e f f e c t s (E.I . d u P o n t de N e m o u r s & C o . Inc. 1981). C h l o r s u l f u r o n c o u l d be used as an e a r l y p o s t - e m e r g e n c e t r e a t m e n t to c o n t r o l knapweeds in reseeded a r e a s . As Schirman (1981) has indicated, control of diffuse and spotted knapweed until June with a herbicide treatment could prevent bolting and seed production for two years. Thus an early season treatment with chlorsulfuron or DPX-T6376 at 20 g/ha or 3,6-dichloropicolinic acid at 150 g/ha could control existing knapweed plants, prevent seedling emergence during the season of treatment and reduce seed production in the following year. Diffuse knapweed and spotted knapweed occupy areas in western North America which differ widely in climate, soils, vegetation and topography. These factors will influence both herbicide performance and plant response. Further evaluations of chlorsulfuron, DPX-T6376 and 3,6-dichloropicolinic acid for knapweed control and soil persistence need to be conducted in other geographical areas. 85 XI. Summary P i c l o r a m and 3 , 6 - d i c h l o r o p i c o l i n i c a c i d a t 2 5 0 - 1 0 0 0 g / h a c o n t r o l l e d d i f f u s e k n a p w e e d f o r 420 days and s p o t t e d k n a p w e e d f o r 300 days . G r a s s y ie lds on d i f f u s e k n a p w e e d i n f e s t e d range w e r e s ix to e ight t i m e s h igher in p i c l o r a m and 3 , 6 - d i c h l o r o -p i c o l i n i c a c i d t r e a t e d p lo ts than in u n t r e a t e d p l o t s . 3 , 6 - d i c h l o r o p i c o l i n i c a c i d a t 150 g / h a s i g n i f i c a n t l y r e d u c e d d i f f u s e k n a p w e e d dry w e i g h t and the numbers of e m e r g e d k n a p w e e d s e e d l i n g s . C h l o r s u l f u r o n and t r i c l o p y r r e d u c e d the dry w e i g h t of d i f f u s e k n a p w e e d at 30 days post t r e a t m e n t but t r e a t e d p lan ts r e g r e w f r o m the c r o w n in the second y e a r . The a d d i t i o n of C i t o w e t t P lus to c h l o r s u l f u r o n d id not i m p r o v e d i f f u s e k n a p w e e d c o n t r o l . A l l r a t e s of D P X - T 6 3 7 6 f r o m 2 0 - 1 6 0 g / h a w e r e e q u a l l y e f f e c t i v e in r e d u c i n g d i f f u s e k n a p w e e d dry we igh t and p r e v e n t i n g s e e d l i n g e m e r g e n c e . T h e e f f e c t of these h e r b i c i d e s on seed g e r m i n a t i o n and r a d i c l e and shoot e l o n g a t i o n v a r i e d w i t h s p e c i e s , h e r b i c i d e and c o n c e n t r a t i o n . R e s u l t s of these e x p e r i m e n t s i n d i c a t e t h a t f u r t h e r e v a l u a t i o n of 3 , 6 - d i c h l o r o -p i c o l i n i c a c i d , c h l o r o s u l f u r o n and D P X - T 6 3 7 6 wou ld be w a r r a n t e d . R e c o m m e n d a t i o n s fo r f u r t h e r r e s e a r c h a r e : 1) A n e a r l y sp r ing ( M a r c h or A p r i l ) or f a l l (September or O c t o b e r ) t r e a t m e n t w i t h one of these h e r b i c i d e s c o u l d improve c o n t r o l of d i f f u s e k n a p w e e d a t l ower ra tes and p r e v e n t b o l t i n g f o r t w o seasons. C h l o r s u l f u r o n c o u l d be app l i ed at l ower spray v o l u m e s (110 L / h a ) and s u r f a c t a n t c o n c e n t r a t i o n s c o u l d be i n c r e a s e d to 0 . 2 5 % or 0 .50% ( v / v ) . D P X - T 6 3 7 6 should be e v a l u a t e d at l ower r a t e s (be low 20 g /ha) to d e t e r m i n e the m i n i m u m e f f e c t i v e r a t e , and fo r r e s i d u a l c o n t r o l of bo th k n a p w e e d s . A s c l i m a t i c and edaph ic f a c t o r s c a n i n f l u e n c e b o t h h e r b i c i d e p e r s i s t e n c e and p lant response , e v a l u a t i o n s of these h e r b i c i d e s fo r c o n t r o l o f d i f f u s e and s p o t t e d k n a p w e e d should be c o n d u c t e d in s e v e r a l d i f f e r e n t a r e a s . 87 BIBLIOGRAPHY Anonymous. 1977. Proceedings Knapweed Symposium, Kamloops, B.C. Anonymous. 1980a. Battle against knapweed a losing one say ranchers. Country Life in B.C., November, 1980, pp. 14. Anonymous. 1980b. Tordon ban aids knapweed. Country Life in B.C., November 1980, pp. 16. Arnold, W.R. and P.W. Santelmann. 1966. The response of native grasses and forbs to picloram. Weeds 14:74-76. Bovey, R.W., B. Burnett, C. Richardson, M.G. Merkle, J.R. Baur and W.G. Knisel. 1974. Occurrence of 2,4,5-T and picloram in surface runoff water in the Blacklands of Texas. J. Environ. Qual. 3(l):61-64. Bovey, R.W., C.C. Dowler and M.G. Merkle. 1969. The persistence and movement of picloram in Texas and Puerto Rican soils. Pestic. Monit. J. 3:177-181. Bovey, R.W., C. Richardson, E. Burnett, M.G. Merkle and R.E. Meyer. 1978. Loss of spray and pelleted picloram in surface runoff water. J. Environ. Qual. 7(2):178-188. Bovey, R.W. and C.J. Scrifes. 1971. Residual characteristics of picloram in grassland ecosystems. Texas Agr. Exp. Sta. B-1111, College Station, Texas. B.C. Department of Agriculture. 1971. Chemical Weed Control Guide. 1972-73, Victoria, B.C. B.C. Department of Agriculture. 1974. Climate of British Columbia. Tables of temperature and precipitation. Climatic normals 1941-1970. Byrd, B.C. and R.W. Colby. 1978. Woody plant control with low volume applications of Garlon 3A herbicide. Down to Earth 34(2):7-10. Byrd, B.C., W.G. Wright and L.E. Warren. 1975. Vegetation control with Dowco 233 herbicide. Down to Earth 30(4):8-12. Campbell, J.B., R.W. Lodge, A. Johnston and S. Smoliak. 1962. Range management of grasslands and adjacent parkland in the prairie provinces. Canada Dept. of Agri-culture, Publication No. 1133. Canada Department of Agriculture. 1976. Glossary of terms in soil science. Publication No. 1459. 88 Chow, P.N.P. and H.F. Taylor. 1980. Improved herbicidal performance of DPX-4189 on oilseed rape by the addition of surfactants. Proc. British Crop Prot. Conf. -Weeds. Vol. 1:23-28. Cornwell, M.J. and P.M.S. Lane. 1981. DPX-4189 - a new herbicide for weed control in cereals. 34th Proc. N.Z. Weed and Pest Control Conf. 203-205. Davis, E.A. and P.A. Ingebo. 1973. Picloram movement from a chaparral watershed. Water Resour. Res. 9(5): 1304-1313. Debona, A.C. and L.J. Audus. 1970. Studies on the effects of herbicides on soil nitrification. Weed Res. 10:250-263. Dow Chemical Co. 1974. Dowco 290 - technical bulletin. Dow Chemical Co. Triclopyr - technical bulletin. E.I. duPont de Nemours & Co. Inc. 1981. Glean - technical bulletin. E.I. duPont de Nemours <5c Co. Inc. DPX-T6376 - a new experimental herbicide. Evans, R.A., H.R. Holbo, R.E. Eckert, Jr. and J.A. Young. 1970. Functional environment of downy brome communities in relation to weed control and revegeta-tion. Weed Sci. 18:154-162. Evans, R.A. and J.A. Young. 1970. Plant litter and establishment of alien annual weed species in rangeland communities. Weed Sci. 18:697-703. Evans, R.A. and J.A. Young. 1972. Microsite requirements for establishment of annual rangeland weeds. Weed Sci. 20(4):350-356. Evans, R.A., J.A. Young and R.E. Eckert, Jr. 1969. Herbaceous weed control and revegetation of semi-arid rangeland in western United States. Outlook on Agriculture 6(2):60-66. Fears, R.D. and R. Dickens. 1978. Aerial application of triclopyr for brush control. Down to Earth 34(3):11-15. Fryer, J.D. 1976. Recent developments in the agricultural use of herbicides in relation to ecological effects. In: Perring, F.H.; Mellanby, K. (Eds.) 1976. Ecological effects of pesticides. Academic Press, London. Fryer, J.D., P.D. Smith and J.W. Ludwig. 1979. Long term persistence of picloram in a sandy loam soil. J. Environ. Qual. 8:83-86. Geronimo, J. 1978. Response of several herbaceous weed species to triclopyr and 3,6-dichloropicolinic acid. In: Abstracts 1978 Meeting Weed Science Society of America. Goring, C.A.I, and 3.W. Hamaker. 1971. The degradation and movement of picloram in soil and water. Down to Earth 27(1):12-15. Gratkowski, H.J., R.E. Stewart and H.G. Weatherly. 1978. Triclopyr and krenite herbicides show promise for use in Pacific Northwest forests. Down to Earth 34(3):28-31. Groh, H. 1944. Canadian weed survey. 2nd Ann. Rep. Can. Dep. Agric. 74 pp. Grover, R. 1973. Movement of picloram in soil columns. Can. 3. Soil Sci. 53:307-314. Haagsma, T. 1975a. Dowco 290 - a coming new selective herbicide. Down to Earth 30:1-2. Haagsma, T. 1975b. Dowco 233 herbicide - a possible new tool in vegetation management. Down to Earth 30(4):22-24. Haas, R.H., C.3. Scrifes, M.G. Merkle, R.R. Hahn and G.O. Hoffman. 1971. Occurrence and persistence of picloram in grassland water sources. Weed Res. 11:54-62. Hamaker, 3.W., C.R. Youngson and C.A.I. Goring. 1967. Prediction of the persistence and activity of Tordon herbicide in soils under field conditions. Down to Earth 23(2):30-36. Hanna, M. 1952. A brief study of the genus Centaurea in British Columbia, with particular reference to diffuse knapweed (C. diffusa Lam.) Graduating essay, Faculty of Agriculture, University of B.C. Harper, 3.L. 1977. Population Biology of Plants. Academic Press, N.Y. Harris, P. and R. Cranston. 1979. An economic evaluation of control methods for diffuse and spotted knapweed in western Canada. Can. 3. Plant Sci. 59:375-385. Hedrick, D.W. 1967. Conversion of sagebrush ranges to productive grasslands, pp. 205-213. In: Proc. Symp. on Herbicides and Vegetation Management, 1967, Oregon State University. Hedrick, D.W., D.N. Hyder, F.A. Sneva and C.E. Povlton. 1966. Ecological response of sagebrush-grass range in central Oregon to mechanical and chemical removal of Artemisia. Ecology 47(3):432-439. Herr, D.E., E.W. Strouble and D.A. Ray. 1966. The movement and persistence of picloram in soil. Weeds 14(3):248-250. Hogue, E.3., W.D. Sargent, Z.L. Lang and 3. Lee. 1982. Comparative extraction efficiencies of picloram residues from a field treated silt loam soil; using alkaline, neutral and acidic solvents, unpublished paper. H u b b a r d , W . A . 1975. Increased range f o r a g e p r o d u c t i o n by reseed ing and the c h e m i c a l c o n t r o l o f k n a p w e e d . J . R a n g e M a n a g e . 28 :406 -407 . J o h n s e n , T . N . J r . 1980. P i c l o r a m in w a t e r and s o i l f r o m a s e m i - a r i d p i n y o n - j u m p e r w a t e r s h e d . J . E n v i r o n . Q u a l . 9 (4) :601-605. J o h n s o n , J . E . 1971. The p u b l i c h e a l t h i m p l i c a t i o n s o f w i d e s p r e a d use o f the phenoxy h e r b i c i d e s and p i c l o r a m . B io S c i e n c e 2 1 : 8 9 9 - 9 0 5 . K e y s , C . H . 1975. E v a l u a t i o n of D o w c o 290 for the c o n t r o l of annua l and p e r e n n i a l weeds . D o w n to E a r t h 31(1): 1-7. K i n g , M . G . and S . R . R a d o s e v i c h . 1979. T a n o a k ( L i t h o c a r p u s dens i f l o rus ) l ea f s u r f a c e c h a r a c t e r i s t i c s and abso rp t i on of t r i c l o p y r . Weed S c i . 27(6) :599-604. K o z l o w s k i , T . T . and S. S a s a k i . 1968. G e r m i n a t i o n and m o r p h o l o g y of red pine seeds in c o n t a c t w i t h E P T C , C D E C , C D A A , 2 , 4 - D and p i c l o r a m . P r o c . A m . S o c . H o r t . S c i . 93 :655 -662 . L e v i t t , G . , H . L . P l o e g , R . C . W e i g e l , J r . and D . J . F i t z g e r a l d . 1981. 2 - c h l o r o - N - ( ( 4 -m e t h o x y - 6 - m e t h y l - l , 3 , 5 - t r i a z i n - 2 - y l ) a m i n o c a r b o n y l ) b e n z e n e s u l f o n a m i d e , a new h e r b i c i d e . J . A g r i c . F o o d C h e m . 29(2) :416-418. L i c h y , C . T . 1980. Todays h e r b i c i d e - G a r Ion. Weeds T o d a y 11(3): 14. L o v e , H . H . 1936. A r e u n i f o r m i t y t r i a l s u s e f u l ? J . A m e r . S o c . A g r o n . 28 :234 -245 . L u t z , J . F . , G . E . B y e r s and T . J . Sheets . 1973. T h e p e r s i s t e n c e and m o v e m e n t o f p i c l o r a m and 2 ,4 ,5 -T in s o i l s . J . E n v i r o n . Q u a l . 2 (4) :485-488. L y n n , G . E . 1965. A r e v i e w of t o x i c o l o g i c a l i n f o r m a t i o n on T o r d o n h e r b i c i d e s . D o w n to E a r t h 2 0 : 6 - 8 . M c C a r t y , M . K . 1979. Y i e l d and q u a l i t y of t w o c o o l season grasses as a f f e c t e d by s e l e c t e d h e r b i c i d e s . Weed S c i . 27 :415 -421 . M c L e a n , A . and L . M a r c h a n d . 1968. G r a s s l a n d ranges in the southern i n t e r i o r of B r i t i s h C o l u m b i a . C a n . Dep . A g r i c . P u b l i c . N o . 1319. M c L e a n , A . and E.W. T i s d a l e . 1972. R e c o v e r y r a t e of d e p l e t e d range s i t e s under p r o t e c t i o n f r o m g r a z i n g . J . R a n g e M a n a g e . 25(3) :178-184. M c L e a n , A . (Ed.) 1979. R a n g e m a n a g e m e n t handbook fo r B r i t i s h C o l u m b i a . M a d d o x , D . M . 1979. The k n a p w e e d s . The i r e c o n o m i c s and b i o l o g i c a l c o n t r o l in the w e s t e r n s t a t e s . U . S . A . Range lands 1 :139-141. M o o r e , N.W. 1967. A synopsis of the p e s t i c i d e p r o b l e m . A d v . E c o l . R e s . 4 :75 -129 . 91 Naik, M.N., R.B. Jackson, J. Stokes and R.J. Swaby. 1972. Microbial degradation and phytotoxicity of picloram and other substituted pyridines. Soil Biol. Biochem. 4:313-323. National Research Council, Ottawa, Canada. 1974. Picloram: the effects of its use as a herbicide on environmental quality, NRC Publication No. 13684. Newton, M. and L.A. Norris. 1976. Evaluating short and long term effects of herbicides on non-target forest and range biota. Down to Earth 32(3): 18-26. Ormrod, D.J. and A.J. Renney. 1968. A survey of weed leaf stomata and trichomes. Can. J. Plant Sci. 48:197-209. Palm, H.L., J.D. Riggleman and D.A. Allison. 1980. Worldwide review of the new cereal herbicide - DPX-4189. Proc. British Crop Prot. Conf. - Weeds. Vol. 1:1-6. Parsons, D.C, L.M. Laukulich and A.L. van Ryswyk. 1971. Soil properties affecting the vegetative composition of communities at Kamloops, British Columbia. Can. J. Soil Sci. 51:269-276. Perala, D.A. 1980. A provisional assessment of triclopyr herbicide for use in lake states forestry. U.S. Dept. Agric, Forest Serv., Res. Rep., NC-180. 7 pp. Piemeisel, R.L. 1951. Causes affecting change and rate of change in a vegetation of annuals in Idaho. Ecology 32(l):53-72. Pik, A.J., E. Peake, M.T. Strosher and G.W. Hodgson. 1977. Fate of 3,6-dichloropicolinic acid in soils. J. Agric. Food Chem. 25(5):1054-1061. Pimentel, D. and CA. Edwards. 1982. Pesticides and ecosystems. Bioscience 32(7):595-600. Popova, A.Ya. 1960. Centaurea diffusa Lam., a steppe-pasture weed in the Crimea (English transl.) Bot. Zh. (Moscow) 45:1207-1213. Radosevich, S.R. and D.E. Bayer. 1979. Effect of temperature and photoperiod on triclopyr, picloram and 2,4,5-T translocation. Weed Sci. 27:22-27. Rahman, A., B.E. Manson and P. Sanders. 1981. Persistence of 3,6-dichloropicolinic acid and dicamba residues in the soil. 34th Proc. N.Z. Weed and Pest Control Conf. 126-129. Ray, T.B. 1980. Studies on the mode of action of DPX-4189. Proc. British Crop Prot. Conf. - Weeds. Vol. 1:7-14. Renney, A.J. 1959. Centaurea spp. infestation in British Columbia. Proc. Joint Meet. North Cent. Weed Control Conf. 16 and West. Can. Weed Control Conf. 10:18-19. Renney, A.J. 1967. Res. Rep. Nat'l. Weed Comm. West. Sec. (Canada):268. Renney, A.J. and E.C. Hughes. 1969. Control of knapweed, Centaurea species in British Columbia with Tordon herbicides. Down to Earth 24:6-8. Reuber, M.D. 1981. Carcinogenicity of picloram. J. Toxicol. Environ. Health 7(2):207-222. Robocker, W.C., D.H. Gates and H.D. Kerr. 1965. Effects of herbicides, burning and seeding date in reseeding arid range. J. Range Manage. 18:114-118. Ryswyk, van A.L., A. McLean and L.S. Marchand. 1966. The climate, native vegetation, and soils of some grassland at different elevations in British Columbia. Can. J. Plant Sci. 46:35-50. Schirman, R. 1981. Seed production and spring seedling establishment of diffuse and spotted knapweed. J. Range Manage. 34(0:45-47. Scrifes, C.J. 1977. Herbicides and the range ecosystem: residues, research and the role of rangemen. J. Range Manage. 30(2):86-90. Scrifes, C.J., R.R. Hahn and M.G. Merkle. 1971a. Dissipation of picloram from vegetation of semi-arid rangelands. Weed Sci. 19:329-332. Scrifes, C.J., R.R. Hahn, J. Diaz-colon and M.G. Merkle. 1971b. Picloram persistence in semi-arid rangeland soils and water. Weed Sci. 19:381-384. Scrifes, C.J. and J.C. Halifax. 1972a. Root production of seedling grasses in soil containing picloram. J. Range Manage. 25:44-46. Scrifes, C.J. and J.C. Halifax. 1972b. Development of range seedlings germinated in picloram. Weed Sci. 20:341-344. Select Standing Committee on Agriculture. 1978. Province of British Columbia. Weed Control in B.C. Smoliak, S.A. Johnston, M.R. Kilcher and R.W. Lodge. 1976. Management of prairie rangeland. Agriculture Canada, Public. No. 1589. Sprout, P.N. and CC. Kelley. 1963. Soil survey of the Ashcroft-Savona area, Thompson River Valley, British Columbia. B.C. Department of Agriculture. Stoddart, L.A., A.D. Smith and T.W. Box. 1975. Range Management, 3rd Edition, McGraw-Hill, New York. Strang, R.M., K.M. Lindsay and R.S. Price. 1979. Knapweeds: British Columbia's undesirable aliens. Rangelands 1:141-143. 93 Suttle, J.C. and D.R. Schreiner. 1982. Effects of DPX-4189 (2-chloro-N-((4-methoxy-6-methyl-l,3,5-triazin-2-yl) amino carbonyl) benzene sulfonamide) on anthocyanin synthesis, phenylalanine ammonia lyase activity, and ethylene production in soybean hypocotyls. Can. J. Bot. 60(6):741-745. Tisdale, E.W. 1947. The grasslands of the southern interior of British Columbia. Ecology 28(4):347-382. Tomkins, D.J. and W.F. Grant. 1977. Effects of two herbicides on species diversity of two plant communities. Ecology 58:398-406. Valentine, K.W.G., P.N. Sprout, T.E. Baker and L.M. Laukulich (Eds.) 1978. The soil landscapes of British Columbia. Resource Analysis Branch, Ministry of the Environ-ment, Victoria, B.C. Vallentine, J.F. 1971. Range Development and Improvements. Brigham Young University Press. Provo, Utah. Vanden Born, W.H. and R.J. Schraa. 1975. Control of 2,4-D resistant weeds in small grains with Dowco 290 herbicide. Down to Earth 31(2):4-9. Watson, A.K. and A.J. Renney. 1974. The biology of Canadian weeds 6. Centaurea  diffusa and C. maculosa. Can. J. Plant. Sci. 54:687-701. Weaver, J.E. and F.E. Clements. 1938. Plant Ecology. McGraw-Hill, New York. Weed Science Society of America. 1980. Herbicide Handbook, 5th Edition. Whitesides, R.E. and A.P. Appleby. 1978. Canada thistle response to Dowco 290. Down to Earth 35(0:14-17. Willis, T.G. 1951. Weeds of range lands in British Columbia. Proceedings and abstracts, Fifth Western Canadian Weed Control Conference. Vancouver, B.C. 1951. Woodward, D.F. 1979. Assessing the hazard of picloram to cutthroat trout. J. Range Manage. 32(3):230-232. Wu, C.C., T.T. Kozlowski, R.F. Evert and S. Sasaki. 1971. Effects of direct contact of Pinus resinosa seeds and young seedlings with 2,4-D or picloram on seedling development. Can. J. Bot. 49:1727-1741. Wyoming Agricultural Experiment Station. 1977. Research in weed science. Research Journal 112:49-52. Wyoming Agricultural Experiment Station. 1978. Research in weed science. Research Journal 119:3-8. Wyoming Agricultural Experiment Station. 1979. Research in weed science. Research Journal 137:3-8. Appendix A Ashcroft and Walhachin sites - pretreatment yields of knapweed and grass, and analyses of variance. Ashcroft site: pretreatment yields. Diffuse knapweed yields (grams/square meter). Treatment Block g/ha 1 2 3 4 x S -control 1 8.36 4.36 6.72 16.64 9.02 2.67 2 9.20 7.12 7.40 27.20 12.73 4.85 3 43.68 7.16 18.92 30.92 25.17 7.85 4 15.40 1.68 14.12 47.24 19.61 9.72 chlorsulfuron 20 6.28 7.68 25.44 37.48 19.22 7.49 40 7.68 22.24 9.76 15.32 13.75 3.26 80 4.16 9.64 16.68 27.88 14.59 5.12 160 1.36 32.72 22.88 24.80 20.44 6.71 triclopyr 250 0.92 18.00 2.12 34.88 13.98 7.98 500 40.16 16.08 19.60 10.08 21.48 6.53 750 3.80 17.72 27.76 29.64 19.73 5.92 1000 19.28 8.00 19.48 19.56 16.58 2.86 96 Ashcroft site: pretreatment yields. Diffuse knapweed yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 x S -3,6-dichloropicolinic acid 250 16.16 8.44 8.12 11.84 11.14 1.87 500 8.00 36.88 24.60 16.60 21.52 6.14 750 14.00 16.04 27.20 19.84 19.27 2.91 1000 14.32 32.28 21.64 19.90 22.01 3.76 picloram 250 8.12 19.72 33.20 19.68 20.18 5.13 500 3.32 7.12 24.60 10.52 11.39 4.64 750 8.16 7.16 30.40 16.24 15.49 5.37 1000 0.92 1.68 15.76 11.88 7.56 3.70 Ashcroft site: pretreatment yields. Grass yields (grams/square meter). Treatment Block g/ha 1 2 3 4 x S -control 1 4.84 10.88 14.84 12.64 10.75 2.19 2 15.92 17.08 23.80 5.24 15.51 3.84 3 8.44 15.60 40.92 6.76 17.93 7.90 4 21.76 3.36 17.76 16.52 14.85 3.99 chlorsulfuron 20 19.16 6.92 3.48 9.12 9.67 3.37 40 7.68 17.40 17.08 15.04 14.30 2.27 80 6.84 19.44 4.64 5.40 9.08 3.48 160 9.84 13.60 3.76 10.20 9.35 2.05 triclopyr 250 11.16 18.40 15.48 8.48 13.38 2.21 500 4.36 12.04 19.48 13.00 12.31 3.17 750 14.92 10.60 7.60 10.32 10.86 0.87 1000 3.76 4.40 3.76 21.88 8.45 4.48 98 Ashcroft site: pretreatment yields. Grass yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 x S -3,6-dichloropicolinic acid 250 9.36 11.24 17.72 21.48 14.95 2.82 500 10.64 24.96 8.08 10.96 13.66 3.83 750 19.48 24.04 6.96 2.96 13.36 5.01 1000 7.52 10.28 9.88 7.88 8.89 0.70 picloram 250 2.96 10.40 6.36 21.28 10.25 3.98 500 10.44 14.72 5.84 26.12 14.28 4.34 750 31.56 7.52 6.24 10.28 13.90 5.95 1000 5.24 8.08 9.16 12.56 8.76 1.51 Walhachin site: pretreatment yields. Spotted knapweed yields (grams/square meter). Treatment Block g/ha 1 2 3 4 x S -control 1 54.20 76.72 16.80 58.24 51.04 12.54 2 7.12 17.68 105.20 32.60 40.65 22.14 3 98.40 4.80 61.00 239.00 100.80 49.90 4 195.08 37.32 32.16 52.00 79.14 38.87 chlorsulfuron 20 173.16 26.16 3.20 43.80 61.58 38.11 40 40.12 93.84 79.40 89.40 75.69 12.24 80 52.48 52.28 132.96 44.20 70.48 20.92 160 37.12 120.60 0.52 109.04 66.82 57.59 triclopyr 250 97.12 56.60 117.76 92.28 90.94 12.71 500 155.40 70.24 69.12 0.44 73.80 31.72 750 1.76 50.92 66.44 0.12 29.81 16.97 1000 35.64 7.76 123.20 82.44 62.26 25.49 100 Walhachin site: pretreatment yields. Spotted knapweed yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 X S -X 3,6-dichloropicolinic acid 250 0.92 85.72 42.48 0.24 32.34 20.35 500 125.60 52.28 99.28 23.08 75.06 23.02 750 0.88 128.00 42.20 21.24 48.08 27.94 1000 36. 44 109.20 77.40 115.88 84.73 18.15 picloram 250 82.24 79.72 30.28 1.92 48.54 19.61 500 1.00 91.48 66.88 1.20 40.14 23.09 750 37.24 32.40 81.00 0.56 37.80 16.54 1000 108.28 25.44 44.20 46.64 56.14 18.01 101 Walhachin site: pretreatment yields. Grass yields (grams/square meter). Treatment Block g/ha 1 2 3 4 x S -control 1 31.32 55.04 47.28 8.88 35.63 10.19 2 4.72 13.24 16.48 16.48 12.73 2.78 3 19.80 5.64 10.60 6.00 10.51 3.29 4 17.80 6.56 4.84 24.40 13.40 4.66 chlorsulfuron 20 9.68 8.68 10.16 47.48 19.00 9.49 40 14.28 0.96 16.44 70.20 25.47 15.30 80 12.40 4.36 3.84 1.60 5.55 2.36 160 7.92 10.60 65.48 47.64 32.91 14.14 triclopyr 250 11.36 7.68 58.04 12.48 22.39 11.93 500 9.48 11.92 51.84 0.76 18.50 11.37 750 7.60 27.52 65.60 9.16 27.47 13.49 1000 11.92 25.28 10.00 24.04 17.81 3.98 102 Walhachin site: pretreatment yields. Grass yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 x S -3,6-dichloropicolinic acid 250 11.96 7.88 60.68 10.68 22.80 12.66 500 5.64 4.84 54.20 88.48 38.29 20.32 750 13.52 5.28 9.40 45.00 18.30 9.06 1000 25.48 8.40 58.48 50.13 35.62 11.46 picloram 250 12.92 19.56 7.40 18.72 14.65 2.83 500 7.96 5.00 19.04 30.16 15.54 5.73 750 2.40 22.76 53.68 90.64 42.37 19.24 1000 7.60 14.60 6.64 21.20 12.51 3.39 103 Ashcroft site: pretreatment diffuse knapweed. Source Analysis of variance - weed yield df Sum SQ MSQ Probability Block Treatment Error (a) Rate R X Block R X Treat Error (b) Total 3 4 12 3 9 12 36 79 12.7 1.33 26.68 2.20 6.30 15.68 34.33 99.20 4.23 0.33 2.22 0.73 0.70 1.31 0.95 1.904 0.149 2.331 0.769 0.734 1.370 0.18274 0.96 0.0249 0.519 0.675 0.225 Source df Analysis of variance - grass yield Sum SQ MSQ Probability Block Treatment Error (a) Rate R X Block R X Treat Error (b) Total 3 4 12 3 9 12 36 79 9.96 15.53 67.05 31.82 82.33 179.29 266.77 652.75 3.32 3.88 5.58 10.61 9.15 14.94 7.41 0.594 0.695 0.754 1.432 1.235 2.016 0.631 0.609 0.691 0.249 0.305 0.052 104 Walhachin site: pretreatment spotted knapweed. Source Analysis of variance - weed yield df Sum S Q M S Q P r o b a b i l i t y B l o c k T r e a t m e n t E r r o r (a) R a t e R X B l o c k R X T r e a t E r r o r (b) T o t a l 3 4 12 3 9 12 36 79 20.84 51.88 271.72 17.14 174.01 212.92 1060.7 1809.2 6.95 12.97 22.64 5.71 19.34 17.74 29.46 0.307 0.573 0.769 0.194 0.656 0.602 0.820 0.687 0.677 0.899 0.742 0.826 S o u r c e df Analysis of variance - grass yield Sum S Q M S Q P r o b a b i l i t y B l o c k T r e a t m e n t E r r o r (a) R a t e R X B l o c k R X T r e a t E r r o r (b) T o t a l 3 4 12 3 9 12 36 79 16.17 23.28 140.5 37.64 143.02 103.67 241.05 705.33 5.39 5.82 11.71 12.54 15.89 8.64 6.69 0.46 0.497 1.749 1.874 2.373 1.29 0.715 0.738 0.097 0.151 0.032 0.266 Appendix B Ashcroft site - post treatment yields of diffuse knapweed and grass (30 days), analyses of variance and multiple comparisons. 106 Ashcroft site: post treatment yields (30 days). Diffuse knapweed yields (grams/square meter). Treatment Block g/ha 1 2 3 4 x S -control 1 24.00 40.52 85.12 93.16 60.70 16.84 2 38.28 25.04 105.68 82.28 62.82 18.81 3 170.00 89.56 47.00 66.40 93.24 27.02 4 100.72 45.32 96.40 28.72 67.79 18.11 chlorsulfuron 20 9.60 61.04 36.24 31.64 34.63 10.55 40 18.48 78.68 25.68 43.80 41.66 13.44 80 14.72 90.80 27.20 35.40 42.03 16.80 160 13.00 52.40 0.92 46.60 28.23 12.58 triclopyr 250 43.28 29.32 19.40 49.28 35.32 6.76 500 12.80 18.72 12.88 29.96 18.59 4.04 750 31.52 37.08 41.36 69.20 44.79 8.38 1000 24.72 29.68 55.24 29.64 34.82 6.91 107 Ashcroft site: post treatment yields (30 days). Diffuse knapweed yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 x S -3,6-dichloropicolinic acid 250 11.64 55.61 26.20 48.40 35.46 10.11 500 2.60 38.52 42.48 25.92 27.38 8.98 750 29.68 11.36 32.36 35.48 27.22 5.42 1000 5.92 47.92 17.28 23.56 23.67 8.87 picloram 250 35.68 34.80 33.52 16.00 30.00 4.68 500 2.72 17.20 31.12 26.88 19.48 6.30 750 14.68 29.60 24.36 28.20 24.21 3.36 1000 7.96 12.24 38.64 39.68 24.64 8.44 108 Ashcroft site: post treatment yields (30 days). Grass yields (grams/square meter). Treatment Block g/ha control 1 2 3 4 2.32 6.76 1.96 8.60 6.88 4.00 19.32 16.88 9.00 23.80 15.92 15.72 1.08 2.72 5.12 7.04 4.82 9.32 10.58 12.06 1.87 4.89 4.17 2.48 chlorsulfuron 20 40 80 160 6.56 9.00 6.12 11.52 17.84 6.08 7.48 0.08 7.52 9.00 8.00 27.28 0.08 5.24 2.36 11.68 8.00 7.33 5.99 12.64 3.67 0.98 1.27 5.58 triclopyr 250 500 750 1000 2.88 4.40 8.96 3.52 11.72 6.00 4.40 0.04 5.20 11.64 0.40 5.24 7.64 2.68 7.44 2.48 6.86 6.18 5.30 2.82 1.89 1.94 L.89 1.09 Ashcroft site: post treatment yields (30 days). Grass yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 x S -3,6-dichloropicolinic acid 250 21.96 9.04 10.88 5.28 11.79 3.58 500 17.68 6.92 2.60 7.52 8.68 3.19 750 12.68 7.60 13.56 3.64 9.37 2.32 1000 4.60 3.64 10.60 6.28 6.28 1.54 picloram 250 9.64 13.56 5.48 4.96 8.41 2.01 500 3.92 8.32 2.20 8.24 5.67 1.55 750 7.68 12.88 0.40 1.40 5.59 2.92 1000 6.76 4.80 0.04 5.36 4.24 1.46 110 Ashcroft site: diffuse knapweed 30 days post treatment. Analysis of variance - diffuse knapweed yield Source df Sum SQ MSQ F Probability Block 3 Control vs Herb 1 Among Herb 3 Error (a) 12 Rates Applied 3 R X Among Herb 9 Error (b) 48 Total 79 1887.4 20781 1360.3 11493 774.8 1681.1 25849 63916 629.2 20871 453.4 957.7 258.3 186.8 538.5 0.66 21.79 0.47 1.78 0.48 0.35 0.59 0.00054 0.71 0.079 0.69 0.95 Analysis of variance - grass yield Source df Sum SQ MSQ Probability Block 3 209.59 Control vs Herb 1 51.39 Among Herb 3 163.9 Error (a) 12 630.9 Rates Applied 3 54.9 R X Among Herb 9 181.1 Error (b) 48 1179.6 Total 79 2471.5 69.9 1.33 0.31 51.4 0.98 0.34 54.6 1.04 0.41 52.6 2.14 0.031 18.3 0.75 0.53 20.1 0.82 0.60 24.6 I l l diffuse knapweed yield (30 days post treatment) -multiple comparisons of main plot means. (Fisher's protected LSD p = .05) Treatment Block 1 2 3 4 > c* control 83. 25 50.11 83 .55 67. .64 71. ,14 a chlorsulfuron 13. 95 70.73 22 .51 39, .36 36, .64 b triclopyr 28. 08 28.70 32 .22 44. .52 33. .38 b 3,6-dichloro- 12. 46 38.35 29 .58 28, .43 27, .21 b picolinic acid picloram 15. 26 23.46 31 .91 24. .58 23. .8 b LSD (.05) weed yield = 23.84 g/m2 LSD (.01) = 33.43 g/m2 * means followed by the same letter are not significantly different (pjf.01) Appendix C Walhach in s ite - post t r e a t m e n t y ie lds of spot ted knapweed and grasses (30 days), analyses of v a r i a n c e and mul t ip le c o m p a r i s o n s . 113 Walhachin site: post treatment yields (30 days). Spotted knapweed yields (grams/square meter). Treatment Block g/ha 1 2 3 4 x S -control 1 106.72 104.80 20.48 154.80 96.70 27.92 2 62.00 149.40 120.00 22.40 88.45 28.54 3 29.20 91.60 66.64 250.28 109.43 48.67 4 90.40 148.00 72.36 31.00 85.44 24.28 chlorsulfuron 20 20.40 74.28 0.04 0.72 23.86 17.46 40 42.52 74.40 51.44 120.36 72.18 17.41 80 72.20 30.20 36.88 67.56 51.71 10.62 160 1.12 56.52 40.28 25.52 30.86 11.76 triclopyr 250 40.12 10.32 32.92 30.08 28.36 6.37 500 87.24 34.84 16.84 43.36 45.57 12.95 750 21.64 20.84 133.68 0.00 44.04 30.30 1000 8.40 54.00 67.60 46.76 44.19 12.69 114 Walhachin site: post treatment yields (30 days). Spotted knapweed yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 X S -X 3,6-dichloropicolinic acid 250 0.00 96.16 36.40 0.00 33.14 22.69 500 0.92 84.40 36.72 73.64 48.92 18.98 750 0.00 51.08 0.00 0.00 12.77 15.96 1000 6.28 70.40 0.00 44.20 30.22 16.57 picloram 250 39.64 25.92 99.40 0.00 41.24 21.06 500 0.00 66.36 44.88 22.04 33.32 14.33 750 156.00 42.56 43.80 0.00 60.59 33.39 1000 55.32 113.48 52.28 7.60 57.17 21.71 115 Walhachin site: post treatment yields (30 days). Grass yields (grams/square meter). Treatment Block g/ha 1 2 3 4 x S -control 1 10.12 9.96 8.64 5.80 8.63 0.99 2 7.28 9.72 10.20 0.72 6.98 2.18 3 8.20 35.40 1.80 10.80 14.05 7.36 4 7.68 0.60 2.36 4.68 3.83 1.53 chlorsulfuron 20 5.12 3.00 4.56 13.00 6.42 2.24 40 15.76 0.72 6.72 14.44 9.41 3.52 80 12.20 6.08 0.40 0.12 4.70 2.85 160 10.36 2.28 4.24 0.40 4.32 2.16 t r i c l o p y r 250 12.52 0.12 8.44 16.44 9.38 3.49 500 9.00 14.48 0.16 5.04 7.17 3.03 750 1.52 29.20 6.08 9.28 11.52 6.10 1000 13.60 19.96 5.72 14.44 13.43 2.93 116 Walhachin site: post treatment yields (30 days). Grass yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 x S -3,6-dichloropicolinic acid 250 0.04 4.40 2.44 11.00 4.47 2.35 500 9.92 8.72 9.32 6.72 8.67 0.69 750 1.60 2.80 19.20 8.00 7.90 4.01 1000 10.32 6.60 5.52 12.88 8.83 1.69 picloram 250 9.60 10.04 2.48 7.72 7.46 1.73 500 21.88 15.68 6.60 12.00 14.04 3.21 750 4.00 7.60 1.44 8.92 5.49 1.70 1000 5.56 8.36 6.68 6.60 6.80 0.58 117 Walhachin site: spotted knapweed 30 days post treatment. Source Analysis of variance - spotted knapweed yield df SSCj MSQ F Probability Block 3 Control vs Herb 1 Among Herb 3 Error (a) 12 Rates Applied 3 R X Among Herb 9 Error (b) 48 Total 79 9184.8 37147 2534.8 26108 2721.4 8444.6 89708 175850 3061.6 37147 844.9 2175.7 907.2 938.3 1868.9 1.41 17.1 0.39 1.16 0.49 0.50 0.28 0.0014 0.76 0.33 0.69 0.87 Source df Analysis of variance - grass yield SSQ MSQ Probability Block 3 Control vs Herb 1 Among Herb 3 Error (a) 12 Rates Applied 3 R X Among Herb 9 Error (b) 48 Total 79 189.69 1.225 148.1 539.9 77.9 298.9 1911.7 3167.5 63.23 1.23 49.37 44.99 25.99 33.22 39.83 1.41 0.027 1.09 1.13 0.65 0.83 0.29 0.87 0.39 0.36 0.59 0.59 118 spotted knapweed yield (30 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block I 2 3 4 X '* control 72 .08 123. .45 69, .87 114 .62 95. 01 a chlorsulfuron 34 .06 58. .85 32. .16 53 .54 44. 65 b triclopyr 39 .35 30. .00 62, .76 30 .05 40. 54 b 3,6-dichloro- 1 .80 75. .51 18, .28 29 .46 31. 26 b picolinic acid picloram 62 .74 62. .08 7, .41 48 .08 45. 08 b LSD (.05) weed yield = 35.93 g/ni LSD (.01) = 50.38 g/m2 * means followed by the same letter are not significantly different (p < .05) Appendix D A s h c r o f t s i te - post t r e a t m e n t y ie lds of d i f fuse knapweed and grass (300 days), analyses of var iance and mul t ip le compar i sons . 120 Ashcroft site: post treatment yields (300 days). Diffuse knapweed yields (grams/square meter). Treatment Block g/ha S -x control 1 2 3 4 9.12 6.12 15.08 9.68 4.88 3.56 6.80 3.08 6.12 3.12 7.12 9.88 5.84 11.80 4.20 4.04 6.49 6.15 8.30 6.67 0.92 1.99 2.35 1.81 chlorsulfuron 20 1.24 40 1.24 80 3.56 160 1.16 3.88 9.04 10.16 10.96 4.12 3.04 5.64 3.32 5.48 5.52 17.32 6.60 3.68 4.71 9.17 5.51 0.89 1.69 3.05 2.13 triclopyr 250 500 750 1000 3.40 5.16 3.72 1.44 3.08 4.12 5.96 5.44 5.40 3.28 8.48 6.12 6.24 3.28 5.12 8.52 4.53 3.96 5.82 5.38 0.77 0.45 0.99 1.47 121 Ashcroft site: post treatment yields (300 days). Diffuse knapweed yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 x S -3,6-dichloropicolinic acid 250 0 0 0 0 0 0 500 0 0 0 0 0 0 750 0 0 0 0 0 0 1000 0 0 0 0 0 0 picloram 250 0 0 0 0 0 0 500 0 0 0 0 0 0 750 0 0 0 0 0 0 1000 0 0 0 0 0 0 122 Ashcroft site: post treatment yields (300 days). Grass yields (grams/square meter). T r e a t m e n t Block g / h a S -x control 1 2 3 4 1.32 1.76 3.04 5.68 2.60 5.64 6.40 3.36 5.16 3.56 4.60 2.12 1.92 3.20 6.36 3.48 2.75 3.54 5.10 3.66 0.84 0.80 0.80 0.74 chlorsulfuron 20 5.20 40 3.32 80 2.60 160 5.16 4.52 3.28 6.08 3.08 1.76 7.04 3.88 3.44 2.84 1.00 1.24 8.44 3.58 3.66 3.45 5.03 0.78 1.25 1.03 1.22 triclopyr 250 500 750 1000 3.76 1.48 3.72 1.44 4.92 5.92 1.32 2.48 2.60 7.04 1.00 1.36 1.32 7.00 1.60 4.72 3.15 5.36 1.91 2.50 0.77 1.32 0.62 0.78 123 Ashcroft site: post treatment yields (300 days). Grass yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 x S -x 3,6-dichloropicolinic acid 250 5.76 6.92 5.76 10.92 7.34 1.22 500 10.08 22.52 8.76 8.92 12.57 3.33 750 7.12 13.44 8.96 8.76 9.57 1.35 1000 5.28 9.92 9.08 10.56 8.71 1.18 picloram 250 5.32 13.68 8.36 12.16 9.88 1.88 500 10.76 9.24 5.92 9.00 8.73 1.01 750 8.56 4.20 14.24 11.00 9.50 2.12 1000 4.32 8.88 11.64 6.16 7.75 1.59 Ashcroft site: grass yield separated by species. (grams/square meter) (300 days post treatment). Treatment Block 1 (g/ha) Stipa comata Sporobolus  cryptandrus Poa secunda control 1 2 3 4 0.80 0.92 1.28 1.20 0.52 0.84 1.76 4.48 chlorsulfuron 20 40 80 160 3.28 3.32 2.60 2.08 1.92 3.08 triclopyr 250 500 750 1000 2.56 0.48 2.36 1.48 0.12 1.20 1.00 1.36 1.32 Ashcroft site: grass yield separated by species. (grams/square meter) (300 days post treatment), (continued) Treatment Block 1 Stipa Sporobolus Poa (g/ha) comata cryptandrus secunda 3,6-dichloropicolinic acid 250 500 750 1000 4.36 8.24 6.56 3.40 1.40 1.84 0.56 1.88 picloram 250 5.32 500 9.56 - 1.20 750 6.80 - 1.76 1000 3.48 - 0.84 Ashcroft site: grass yield separated by species. (grams/square meter) (300 days post treatment). Treatment Block 2 Stipa Sporobolus Poa Poa (g/ha) comata cryptandrus secunda pratensis control 1 1.60 - 1.00 2 4.92 - 0.72 3 3.96 - 2.44 4 2.80 - 0.56 chlorsulfuron 20 1.84 - 2.68 40 2.64 - 0.64 80 2.32 - 3.76 160 - - 3.08 triclopyr 250 1.28 0.16 3.48 500 5.28 - 0.64 750 0.08 - 1.24 1000 1.96 - 0.52 127 Ashcroft site: grass yield separated by species. (grams/square meter) (300 days post treatment), (continued) Treatment Block 2 Stipa • Sporobolus Poa Poa (g/ha) comata cryptandrus secunda pratensis 3,6-dichloropicolinic acid 250 3.84 - 3.08 500 6.44 - 1.00 15.08 750 12.76 - 0.64 1000 8.12 - 1.80 picloram 250 500 750 1000 7.80 6.92 3.36 7.68 5.88 2.32 0.84 1.20 Ashcroft site: grass yield separated by species. (grams/square meter) (300 days post treatment). 128 Treatment Block 3 (g/ha) Stipa comata Sporobolus  cryptandrus Poa secunda Festuca octoflora control 1 2 3 4 3.04 3.48 1.60 .08 2.12 3.00 2.12 chlorsulfuron 20 40 80 160 0.84 5.44 2.64 1.32 0.32 0.24 0.92 1.28 1.24 1.88 triclopyr 250 500 750 1000 1.64 4.48 0.32 0.20 0.96 2.56 0.68 1.16 129 Ashcroft site: grass yield separated by species. (grams/square meter) (300 days post treatment), (continued) Treatment Block 3 Stipa Sporobolus Poa Festuca (g/ha) comata cryptandrus secunda octoflora 3,6-dichloropicolinic acid 250 4.72 - 1.04 500 4.44 - 4.32 750 5.24 - 3.72 1000 7.24 - 1.84 picloram 250 5.00 - 3.36 500 3.64 - 2.28 750 11.04 - 1.44 1.76 1000 - - 11.64 Ashcroft site: grass yield separated by species. (grams/square meter) (300 days post treatment). Treatment Block 4 Stipa Sporobolus Poa (g/ha) comata cryptandrus secunda control 1 0.84 - 1.08 2 2.64 - 0.84 3 4.64 - 1.72 4 2.20 - 1.00 chlorsulfuron 20 1.80 - 1.04 40 0.60 - 0.40 80 0.40 0.60 0.24 160 6.88 - 1.56 triclopyr 250 0.32 - 1.00 500 1.36 0.16 5.48 750 0.20 0.40 1.00 1000 2.04 - 2.68 131 Ashcroft site: grass yield separated by species. (grams/square meter) (300 days post treatment), (continued) Treatment Block 4 (g/ha) Stipa comata Sporobolus  cryptandrus Poa secunda 3,6-dichloropicolinic acid 250 10.60 500 5.08 750 4.96 1000 7.28 0.12 0.36 0.20 0.68 0.20 3.48 3.60 2.60 picloram 250 500 750 1000 11.48 7.92 10.20 5.52 0.60 0.68 0.48 0.80 0.64 132 Ashcroft site: diffuse knapweed 300 days post treatment. Source Analysis of variance - diffuse knapweed yield df SSC» MSQ F Probability Block 3 Control vs Herb 1 Among Herb 3 Error (a) 12 Rates Applied 3 R X Among Herb 9 Error (b) 48 Total 79 14.8 229;0 462.8 202.0 28.8 48.1 214.6 1200.1 4.95 229.03 154.3 16.8 9.6 5.34 4.5 0.29 13.6 9.2 3.8 2.1 1.2 0.83 0.0031 0.0019 0.00049 0.11 0.32 Source Analysis of variance - grass yield df SSQ MSQ Probability Block 3 Control vs Herb 1 Among Herb 3 Error (a) 12 Rates Applied 3 R X Among Herb 9 Error (b) 48 Total 79 47.52 90.61 527.44 67.2 30.87 72.46 355.11 1191.2 15.84 90.61 175.81 5.59 10.29 8.05 7.40 2.83 16.18 31.4 0.76 1.39 1.09 0.083 0.0017 4 <10 0.69 0.26 0.39 133 Analysis of variance Source df SSQ Block 3 1114.7 Control vs Herb 1 4843.8 Among Herb 3 2589.8 Error (a) 12 1673.2 Rates Applied 3 573.4 R X Among Herb 9 663.8 Error (b) 48 6016.3 Total 79 17475 seedling numbers MSQ F Probability 371.6 2.7 0.095 4843.8 34.7 0.00073 863.3 6.2 0.0087 139.4 1.1 0.37 191.1 1.5 0.22 73.8 0.59 0.8 125.3 Analysis of variance Source df SSQ Block 3 185.8 Control vs Herb 1 334.2 Among Herb 3 763.3 Error (a) 12 457.9 Rates Applied 3 35.3 R X Among Herb 9 51.4 Error (b) 48 737.1 Total 79 2564.9 rosette numbers MSQ F Probability 61.94 1.62 0.24 334.15 8.76 0.012 254.43 6.67 0.0067 38.15 2.48 0.013 11.77 0.77 0.52 5.71 0.37 0.94 15.36 134 diffuse knapweed yields (300 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block 1 2 3 4 control 10.00 4.58 6.56 6.47 6.90 a chlorsulfuron 1.80 8.51 4.03 8.73 5.77 a triclopyr 3.43 4.65 5.82 5.79 4.92 a 3,6-dichloropicolinic acid 0 0 0 0 0 b picloram 0 0 0 0 0 b LSD (.05) weed yield = 3.16 g / r r i LSD (.01) = 4.43 g/m2 * means followed by the same letter are not significantly different (p -^ .01) 135 grass yield (300 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block 1 2 3 4 control 2.95 4.50 3.86 3.74 3.76 a chlorsulfuron 4.07 4.24 4.03 3.38 3.93 a triclopyr 2.60 3.66 3.00 3.66 3.23 a 3,6-dichloropicolinic acid 7.06 13.20 8.14 9.79 9.55 b picloram 7.24 9.00 10.04 9.58 8.96 b LSD (.05) grass yield = 1.82 g/m2 LSD (.01) = 2.56 g/m2 * means followed by the same letter are not significantly different (p <.0i) 136 number of diffuse knapweed seedlings/m (300 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block 1 2 3 4 control 35.00 16.00 34.50 17.75 25.81 a chlorsulfuron 2.75 8.00 23.75 59.00 23.38 ab triclopyr 7.75 7.25 23.50 11.50 12.50 be 3,6-dichloropicolinic acid 0 0 0 0 0 c picloram 0 0 0 0 0 c LSD (.05) = 9.09 seedlings/m2 LSD (.01) = 12.75 seedlings/m2 * means followed by the same letter are not significantly different (p <.Q1) 137 number of diffuse knapweed rosettes/m (300 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block 1 2 3 4 control 8.50 8.75 9.50 6.25 8.25 ab chlorsulfuron 3.25 18.00 6.00 6.00 8.31 ab triclopyr 0 5.75 6.25 5.00 4.25 be 3,6-dichloropicolinic acid 0 0 0 0 0 c picloram 0 0 0 0 0 c LSD (.05) = 4.76 rosettes/m LSD (.01) = 6.67 rosettes/m2 * means followed by the same letter are not significantly different (p_jf.05) Appendix E W a l h a c h i n s i t e - post t r e a t m e n t y i e l d s of s p o t t e d k n a p w e e d and grass (300 days) , ana lyses of v a r i a n c e and m u l t i p l e c o m p a r i s o n s . 139 Walhachin site: post treatment yields (300 days). Spotted knapweed yields (grams/square meter). Treatment Block g/ha 1 2 3 4 x S-control 1 14.12 22.48 2.24 26.56 16.35 5.37 2 10.80 27.00 19.84 10.64 17.07 3.95 3 5.64 8.76 4.28 7.24 6.48 0.97 4 4.76 4.92 6.64 45.48 15.45 10.02 chlorsulfuron 20 7.20 10.16 7.16 4.88 7.35 1.08 40 1.28 7.76 4.84 6.48 5.09 1.40 80 3.68 5.20 6.36 8.52 5.94 1.02 160 3.36 7.80 3.04 0.32 3.63 1.55 t r i c l o p y r 250 4.36 12.56 13.40 15.12 11.36 2.39 500 5.12 17.28 1.84 8.84 8.27 3.33 750 9.56 14.08 13.84 0.00 9.37 3.29 1000 2.80 6.08 6.48 14.88 7.56 2.58 140 Walhachin site: post treatment yields (300 days). Spotted knapweed yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 x S-3,6-dichloropicolinic acid 250 0 0 0 0 0 0 500 0 0 0 0 0 0 750 0 0 0 0 0 0 1000 . 0 0 0 0 0 0 picloram 250 0 0 0 0 0 0 500 0 0 0 0 0 0 750 0 0 0 0 0 0 1000 0 0 0 0 0 0 141 Walhachin site: post treatment yields (300 days). Grass yields (grams/square meter). T r e a t m e n t Block g/ha control 1 2 3 4 0.00 2.04 1.44 0.00 0.16 0.12 0.20 1.36 0.40 2.52 0.76 0.92 6.32 0.24 0.00 0.00 1.72 1.23 0.60 0.57 1.54 0.61 0.32 0.34 chlorsulfuron 20 40 80 160 1.56 2.20 2.72 25.04 0.00 0.00 1.12 1.60 0.84 4.28 0.16 5.84 0.12 3.60 1.24 4.04 0.63 2.52 1.31 9.13 0.36 0.95 0.53 5.37 triclopyr 250 500 750 1000 1.48 2.96 3.48 1.20 0.68 1.00 4.00 1.80 2.60 0.00 1.80 2.00 5.52 1.12 8.88 4.80 2.57 1.27 4.54 2.45 1.06 0.62 1.52 0.80 Walhachin site: post treatment yields (300 days). Grass yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 x S-3,6-dichloropicolinic acid 250 6.84 5.96 6.64 1.64 5.27 1.22 500 1.80 4.28 1.40 4.16 2.91 0.76 750 4.32 14.68 34.24 19.40 18.16 6.22 1000 3.68 20.24 5.04 4.56 8.38 3.96 picloram 250 4.84 10.56 2.20 1.68 4.82 2.03 500 2.40 5.44 3.64 5.92 4.35 0.81 750 1.08 2.88 3.16 6.80 3.48 1.20 1000 2.44 2.56 3.12 2.64 2.69 0.15 143 Walhachin site: grass yield separated by species. (grams/square meter) (300 days post treatment). Treatment Block 1 (g/ha) Poa secunda Sporobolus  cryptandrus Agropyron  spicatum Bromus tectorum control 1 2 3 4 2.04 1.44 chlorsulfuron 20 40 80 160 1.56 0.84 0.16 3.36 1.40 1.16 21.68 triclopyr 250 500 750 1000 1.48 2.96 3.48 0.84 0.36 144 Walhachin site: grass yield separated by species. (grams/square meter) (300 days post treatment), (continued) T r e a t m e n t B l o c k 1 P o a Sporobo lus A g r o p y r o n B romus (g /ha ) secunda c r y p t a n d r u s s p i c a t u m t e c t o r u m 3 , 6 - d i c h l o r o p i c o l i n i c a c i d 250 6 . 8 4 - -500 1 .80 -750 4 . 3 2 - -1000 2 . 0 8 - - 1 .60 p i c l o r a m 250 2 . 1 6 2 . 3 6 - 0 . 3 2 500 0 . 6 4 1 .76 750 0 . 4 0 0 . 6 8 1000 0 . 9 6 - - 1 .48 Walhachin site: grass yield separated by species. (grams/square meter) (300 days post treatment). T r e a t m e n t B l o c k 2 P o a Sporobo lus A g r o p y r o n B r o m u s (g /ha ) s e c u n d a c r y p t a n d r u s s p i c a t u m t e c t o r u m c o n t r o l 1 0 . 1 6 -2 - 0 . 1 2 3 - 0 . 2 0 4 - 0 . 3 2 - 1 .04 c h l o r s u l f u r o n 20 -40 -80 0 . 8 4 0 . 2 8 160 0 . 4 8 0 . 2 4 0 . 2 0 0 . 6 8 t r i c l o p y r 250 0 . 6 8 - -500 1.00 750 0 . 3 6 2 . 0 4 - 1 .60 1000 0 . 8 0 1.00 146 Walhachin site: grass yield separated by species. (grams/square meter) (300 days post treatment), (continued) T r e a t m e n t B l o c k 2 P o a Sporobo lus A g r o p y r o n B r o m u s (g /ha ) s e c u n d a c r y p t a n d r u s s p i c a t u m t e c t o r u m 3 , 6 - d i c h l o r o p i c o l i n i c a c i d 250 1 .16 - 0 . 9 6 3 . 8 4 500 - 2 . 4 8 - 1 .80 750 0 . 6 4 0 . 4 8 1 2 . 9 2 0 . 6 4 1000 1.84 1 .52 - 16 .88 p i c l o r a m 250 7 . 8 4 2 . 4 0 - 0 . 3 2 500 5 . 1 6 - - 0 . 2 8 750 2 . 3 6 0 . 2 0 - 0 . 3 2 1000 2 . 5 6 Walhachin site: grass yield separated by species. (grams/square meter) (300 days post treatment). T r e a t m e n t B l o c k 3 P o a Sporobo lus A g r o p y r o n B r o m u s (g /ha ) secunda c r y p t a n d r u s s p l c a t u m t e c t o r u m c o n t r o l 1 0 . 4 0 - -2 1 .56 0 . 6 8 - 0 . 2 8 3 0 . 5 6 0 . 2 0 4 - - 0 . 0 4 0 . 8 8 c h l o r s u l f u r o n 20 - 0 . 8 4 40 4 . 2 8 80 0 . 1 6 -160 5 . 8 4 t r i c l o p y r 250 2 . 2 8 - - 0 . 3 2 500 -750 1.80 1000 - 0 . 3 2 - 1.68 148 Walhachin site: grass yield separated by species. (grams/square meter) (300 days post treatment), (continued) Treatment Block 3 Poa Sporobolus Agropyron Bromus (g/ha) secunda cryptandrus spicatum tectorum 3,6-dichloropicolinic acid 250 - 0.40 1.36 4.88 500 - 0.88 - 0.52 750 - - 34.24 1000 1.88 - - 3.16 picloram 250 0.20 1.52 - 0.48 500 - 0.96 - 2.68 750 - 1.56 1.16 0.44 1000 1.80 0.88 - 0.44 149 Walhachin site: grass yield separated by species. (grams/square meter) (300 days post treatment). Treatment Block 4 (g/ha) Poa secunda Sporobolus  cryptandrus Agropyron  spicatum Bromus tectorum control 1 2 3 4 0.24 6.32 chlorsulfuron 20 40 80 160 1.28 0.28 3.88 0.12 0.44 2.32 0.52 0.16 triclopyr 250 500 750 1000 0.80 0.36 0.28 0.40 2.76 5.52 1.12 0.24 4.04 150 Walhachin site: grass yield separated by species. (grams/square meter) (300 days post treatment), (continued) Treatment Block 4 Poa Sporobolus Agropyron Bromus (g/ha) secunda cryptandrus spicatum tectorum 3,6-dichloropicolinic acid 250 - 1.40 - 0.24 500 - 4.16 750 - - 19.00 0.40 1000 - 4.56 picloram 250 - - - 1.68 500 4.16 - - 1.76 750 2.24 - - 4.56 1000 1.80 - - 0.84 151 Walhachin site: spotted knapweed 300 days post treatment. Source Analysis of variance - spotted knapweed yield df SSQ_ MSQ F Probability Block 3 Control vs Herb 1 Among Herb 3 Error (a) 12 Rates Applied 3 R X Among Herb 9 Error(b) 48 Total 79 244.53 1222.7 949.9 500.2 25.3 36.8 1874 4853.3 81.51 1222.7 316.6 41.7 8.4 4.1 39.0 1.96 29.3 7.6 1.07 0.22 0.10 0.17 0.00016 0.0041 0.41 0.88 0.99 Source Analysis of variance - grass yield df SSQ MSQ Probability Block 3 Control vs Herb 1 Among Herb 3 Error (a) 12 Rates Applied 3 R X Among Herb 9 Error (b) 48 Total 79 6.96 162.3 292.3 293.2 189.4 730.1 704.0 2378.2 2.32 162.3 97.4 24.4 63.1 81.1 14.7 0.09 6.64 3.99 1.67 4.30 5.53 0.96 0.024 0.035 0.11 <10 0.0091 -4 152 Analysis of variance Source df SSQ Block 3 105.25 Control vs Herb 1 1548.4 Among Herb 3 574.2 Error (a) 12 718.1 Rates Applied 3 76.9 R X Among Herb 9 160.7 Error (b) 48 2158.2 Total 79 5341.5 seedling numbers MSQ F Probability 35.1 0.59 0.64 1548.4 25.88 0.00027 191.4 3.19 0.062 59.8 1.33 0.23 25.6 0.57 0.64 17.9 0.40 0.93 44.9 Analysis of variance Source df SSQ Block 3 0.302 Control vs Herb 1 14.46 Among Herb 3 30.25 Error (a) 12 8.18 Rates Applied 3 0.17 R X Among Herb 9 0.58 Error (b) 48 8.05 Total 79 61.99 rosette numbers MSQ F Probability 0.1 0.15 0.93 14.46 21.22 0.00060 10.08 14.79 0.00025 0.68 4.06 0.00023 0.056 0.33 0.8 0.065 0.39 0.94 0.17 spotted knapweed yields (300 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block 1 2 3 4 control 8.83 15.79 8.25 22.48 13.84 a chlorsulfuron 3.88 7.73 5.25 5.05 5.50 b triclopyr 5.46 12.50 8.89 9.71 9.14 ab 3,6-dichloropicolinic acid 0 0 0 0 0 c picloram 0 0 0 0 0 c LSD (.05) weed yield = 4.97 g/m LSD (.01) = 6.97 g/m 2 * means followed by the same letter are not significantly different (p< .05) grass yields (300 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block 1 2 3 4 control 0.87 0.46 1.15 1.64 1.03 a chlorsulfuron 7.88 0.68 2.78 2.25 3.40 a triclopyr 2.28 1.87 1.60 5.08 2.71 a 3,6-dichloropicolinic acid 4.16 11.29 11.83 7.44 8.68 b picloram 2.69 5.36 3.03 4.26 3.84 a LSD (.05) grass yield = 3.81 g/m2 LSD (.01) = 5.34 g/m2 * means followed by the same letter are not significantly different (p_jf.05) grass y i e l d s (300 days post t r e a t m e n t ) -m u l t i p l e c o m p a r i s o n s o f subp lot means (F isher 's p r o t e c t e d L S D p = .05) T r e a t m e n t c o n t r o l 1 2 3 4 c h l o r s u l f u r o n 20 40 80 160 t r i c l o p y r 250 500 750 1000 M e a n * (x) 1.72 a 1 .23 a 0 . 6 0 a 0 . 5 7 a 0 . 6 3 a 2 . 5 2 a 1.31 a 9 . 1 3 b 2 . 5 7 a 1.27 a 4 . 5 4 a 2 . 4 5 a 156 grass yield - sub plots (continued) T r e a t m e n t M e a n * (x) 3 , 6 - d i c h l o r o p i c o l i n i c a c i d 250 5 . 2 7 a c 500 2 . 9 1 c 750 18 .16 b 1000 8 . 3 8 a p i c l o r a m 250 4 . 8 2 a 500 4 . 3 5 a 750 3 . 4 8 a 1000 2 . 9 6 a L S D (.05) ra tes w i t h i n a t r e a t m e n t = 5.43 g / m L S D (.01) = 7.25 g / m 2 * means w i t h i n a t r e a t m e n t f o l l o w e d by the s a m e l e t t e r a r e not s i g n i f i c a n t l y d i f f e r e n t ( p _ f .05). 157 number of spotted knapweed seedlings/m (300 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block g/ha 1 2 3 4 control 12.50 18.25 7.00 17.75 13.88 a chlorsulfuron 3.25 6.75 0.25 0.25 2.63 be triclopyr 11.00 6.00 11.50 1.00 7.38 b 3,6-dichloropicolinic acid 0 0 0 0 0 c picloram 0 0 0 0 0 c LSD (.05) = 5.96 seedlings/m LSD (.01) = 8.35 seedlings/m2 * means followed by the same letter are not significantly different (p <.05) 158 number of spotted knapweed rosettes/m (300 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block g/ha 1 2 3 4 control 1.50 1.25 1.75 2.25 1.69 a chlorsulfuron 1.00 1.00 1.00 1.00 1.00 a triclopyr 2.25 1.00 1.25 1.00 1.38 a 3,6-dichloropicolinic acid 0 0 0 0 0 b picloram 0 0 0 0 0 b LSD (.05) = 0.64 rosettes/m2 LSD (.01) = 0.89 rosettes/m2 * means followed by the same letter are not significantly different (p_^ .01) Appendix F Ashcroft site - post treatment yields of diffuse knapweed and grass (420 days), analyses of variance and multiple comparisons. 160 Ashcroft site: post treatment yields (*20 days). Diffuse knapweed yields (grams/square meter). Treatment Block g/ha 1 2 3 4 x 5-control 1 59.24 27.36 45.20 43.40 43.80 6.52 2 24.28 11.36 45.44 13.96 23.76 7.75 3 54.32 51.88 54.32 19.76 45.07 8.46 4 62.24 19.16 42.02 45.40 42.21 8.86 chlorsulfuron 20 11.08 28.64 46.76 39.76 31.56 6.74 40 12.96 41.68 50.08 32.04 34.19 7.98 80 18.24 41.76 21.88 30.36 28.06 5.22 160 13.80 49.32 50.04 25.84 34.75 8.96 triclopyr 250 25.44 17.00 47.72 34.04 31.05 6.56 500 34.56 21.60 46.88 28.88 32.98 5.34 750 17.60 22.04 52.56 60.44 38.16 10.75 1000 30.88 21.64 36.32 49.52 34.59 5.83 161 A s h c r o f t s i t e : pos t t r e a t m e n t y i e l d s (*20 days ) . D i f f u s e k n a p w e e d y i e l d s ( g r a m s / s q u a r e m e t e r ) , ( con t inued ) Treatment Block g/ha 1 2 3 4 x S -3,6-dichloropicolinic acid 250 0 0 0 0 0 0 500 0 0 0 0 0 0 750 0 0 0 0 0 0 1000 0 0 0 0 0 0 picloram 250 0 0 0 0 0 0 500 0 0 0 0 0 0 750 0 0 0 0 0 0 1000 0 0 0 0 0 0 162 Ashcroft site: post treatment yields (420 days). Grass yields (grams/square meter). Treatment Block g/ha S -x control 1 2 3 4 0.00 6.76 0.00 4.04 3.88 9.08 1.68 4.44 1.68 6.28 9.68 6.36 2.64 5.64 0.00 0.24 2.05 6.94 2.84 3.77 0.82 0.75 2.31 1.28 chlorsulfuron 20 10.28 40 80 160 7.32 11.56 5.12 6.40 10.56 5.12 1.00 5.88 2.24 7.72 11.72 11.76 6.04 9.00 7.60 8.58 6.54 8.35 6.36 1.44 1.72 1.34 2.25 triclopyr 250 500 750 1000 9.56 5.44 7.20 2.04 4.68 5.68 16.08 7.48 1.24 12.00 7.64 1.60 5.48 7.36 1.96 1.32 5.24 7.62 8.22 3.11 1.71 1.52 2.92 1.46 163 Ashcroft site: post treatment yields (420 days). Grass yields (grams/square meter), (continued) Treatment Block g/ha 1 2 3 4 x S -3,6-dichloropicolinic acid 250 25.44 16.68 17.00 25.68 21.20 2.52 500 23.08 22.48 17.64 38.88 25.52 4.62 750 27.72 39.08 23.28 22.72 28.20 3.80 1000 , 25.84 27.88 25.36 27.00 26.52 0.57 picloram 250 10.52 39.64 16.76 35.68 25.65 7.10 500 35.80 26.32 49.44 31.52 35.77 4.95 750 30.48 29.76 23.80 33.80 29.55 2.10 1000 19.40 22.76 23.64 29.04 23.71 1.99 Ashcroft site: grass yield separated by species. (grams/square meter) (420 days post treatment). Treatment Block 1 (g/ha) Stipa comata Sporobolus  cryptandrus control 1 2 3 4 6.76 4.04 chlorsulfuron 20 40 80 160 10.20 7.32 10.52 5.12 0.08 1.04 triclopyr 250 500 750 1000 9.56 5.44 7.20 2.04 Ashcroft sites grass yield separated by species. (grams/square meter) (420 days post treatment), (continued) Treatment Block 1 Stipa Sporobolus (g/ha) comata cryptandrus 3,6-dichloropicolinic acid 250 25.44 500 22.44 0.64 750 27.72 1000 25.84 picloram 250 10.52 500 35.80 750 30.84 1000 19.40 Ashcroft site: grass yield separated by species. (grams/square meter) (*20 days post treatment). Treatment Block 2 Stipa Sporobolus (g/ha) comata cryptandrus control 1 0.20 3.68 2 9.04 0.04 3 1.64 0.04 4 4.40 0.04 chlorsulfuron 20 6.40 40 10.56 80 4.88 0.24 160 1.00 triclopyr 250 4.56 0.12 500 4.76 0.92 750 13.72 2.36 1000 7.48 Ashcroft site: grass yield separated by species. (grams/square meter) (420 days post treatment), (continued) Treatment Block 2 Stipa Sporobolus (g/ha) comata cryptandrus 3,6-dichloropicolinic acid 250 16.68 500 22.48 750 39.08 1000 23.68 4.20 picloram 250 39.64 500 26.32 750 29.76 1000 22.76 Ashcroft site: grass yield separated by species. (grams/square meter) (420 days post treatment). Treatment Block 3 Stipa Sporobolus (g/ha) comata cryptandrus control 1 - 1.68 2 6.28 3 9.68 4 6.36 chlorsulfuron 20 4.92 0.96 40 0.16 2.08 80 7.68 0.04 160 9.32 2.40 triclopyr 250 1.24 500 11.48 0.52 750 7.16 0.48 1000 0.20 1.40 Ashcroft site: grass yield separated by species. (grams/square meter) (420 days post treatment), (continued) Treatment Block 3 Stipa Sporobolus (g/ha) comata cryptandrus 3,6-dichloropicolinic acid 250 17.00 500 17.64 750 23.28 1000 25.36 picloram 250 16.76 500 49.44 750 23.80 1000 23.64 Ashcroft site: grass yield separated by species. (grams/square meter) (420 days post treatment). Treatment Block 4 Stipa Sporobolus (g/ha) comata cryptandrus control 1 0.40 2.24 2 5.64 3 -4 0.16 0.08 chlorsulfuron 20 10.76 1.00 40 5.44 0.60 80 7.28 1.72 160 7.56 0.04 triclopyr 250 5.48 500 6.08 1.28 750 0.48 1.48 1000 0.08 1.24 Ashcroft site: grass yield separated by species. (grams/square meter) (420 days post treatment), (continued) Treatment Block 4 Stipa Sporobolus (g/ha) comata cryptandrus 3,6-dichloropicolinic acid 250 25.68 500 37.48 1.04 750 22.72 1000 22.08 4.92 picloram 250 29.52 6.16 500 26.64 4.88 750 32.96 0.84 1000 24.16 4.88 172 Ashcroft site: diffuse knapweed 420 days post treatment. Analysis of variance - diffuse knapweed yield Source df SSQ MSQ F Probability Block 3 1086.2 362.08 1.02 0.42 Control vs Herb 1 6266.5 6266.5 17.68 0.0012 Among Herb 3 17635 5878.4 16.58 0.00014 Error (a) 12 4254.1 354.5 3.93 0.00033 Rates Applied 3 23.62 7.87 0.087 0.97 R X Among Herb 9 197.35 21.93 0.24 0.99 Error (b) 48 4333.4 90.28 Total 79 33796 Analysis of variance - grass yield Source df SSQ MSQ F Probability Block 3 53.41 17.8 0.66 0.59 Control vs Herb 1 2157.8 2157.8 80.1 <10"4 Among Herb 3 6672.7 2224.2 82.57 Error (a) 12 323.27 26.94 0.80 0.64 Rates Applied 3 217.2 72.4 2.15 0.11 R X Among Herb 9 311.7 34.6 1.03 0.43 Error (b) 48 1618.6 33.7 Total 79 11355 173 Source Analysis of variance - number of bolted plants df SS£ MSQ F Probability Block 3 Control vs Herb 1 Among Herb 3 Error (a) 12 Rates Applied 3 R X Among Herb 9 Error (b) 48 Total 76 390.4 2880 12168 4617.6 1118 3034 8624 32832 130.13 2880 4056 384.8 372.7 337.1 179.7 0.34 7.48 10.54 2.14 2.07 1.88 0.79 0.018 0.001 0.031 0.12 0.079 Source Analysis of variance - number of rosettes df SSQ MSQ Probability Block 3 Control vs Herb 1 Among Herb 3 Error (a) 12 Rates Applied 3 R X Among Herb 9 Error (b) 48 Total 79 6053.4 48020 33858 55452 5530 6788 70062 225760 2017.8 48020 11286 4621.0 1843.3 754.2 1459.6 0.44 10.39 2.44 3.17 1.26 0.52 0.73 0.0073 0.11 0.0022 0.29 0.86 174 Source Analysis of variance - number of seedlings df SSCj MSQ Probability Block 3 Control vs Herb 1 Among Herb 3 Error (a) 12 Rates Applied 3 R X Among Herb 9 Error (b) 48 Total 79 11004 6055.2 4850 11349 644 762 31814 66478 3667.9 6055.2 1616.7 945.8 214.7 84.7 662.8 3.87 6.40 1.71 1.43 0.32 0.13 0.038 0.026 0.22 0.19 0.81 0.99 175 diffuse knapweed yields (420 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block 1 2 3 4 control 50. .02 27. 44 46. 75 30. .63 38.71 a chlorsulfuron 14. ,02 40. 35 42. 19 32. ,00 32.14 a triclopyr 27. ,12 20. 57 45. 87 43. ,22 34.20 a 3,6-dichloro-picolinic acid 0 0 0 0 0 b picloram 0 0 0 0 0 b LSD (.05) weed yield = 14.51 g/m z LSD (.01) = 20.33 g/m2 * means followed by the same letter are not significantly different (p < .01) grass yields (420 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block 1 2 3 4 control 2.70 4.77 6.00 2.13 3.90 a chlorsulfuron 8.57 5.77 6.89 8.60 7.46 a triclopyr 6.06 8.48 5.61 4.03 6.05 a 3,6-dichloro- 25.52 26.53 20.82 28.57 25.36 b picolonic acid picloram 24.14 29.62 28.41 32.51 28.67 b LSD (.05) grass yield = 3.99 g/m2 LSD (.01) = 5.61 g/m2 * means followed by the same letter are not significantly different (p< .01) 177 number of bolted diffuse knapweed plants/m (420 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block 1 2 3 4 control 25 18 27 15 21.25 a chlorsulfuron 19 40 41 30 32.50 a triclopyr 19 12 24 23 19.50 a 3,6-dichloro- 0 0 0 0 0 b picolinic acid picloram 0 0 0 0 0 b LSD (.05) = 15.11 LSD (.01) = 21.19 * means followed by the same letter are not significantly different (p <i.05) 178 number of d i f f u s e k n a p w e e d r o s e t t e s / m (420 days post t r e a t m e n t ) -m u l t i p l e c o m p a r i s o n s of m a i n p lo t m e a n s (F isher 's p r o t e c t e d L S D p = .05) T r e a t m e n t B l o c k 1 2 3 4 c o n t r o l 97 59 56 44 6 4 . 0 0 a c h l o r s u l f u r o n 15 62 68 40 4 6 . 2 5 b t r i c l o p y r 29 62 71 21 4 5 . 7 5 b 3 , 6 - d i c h l o r o - 0 0 0 0 0 b p i c o l i n i c a c i d p i c l o r a m 0 0 0 0 0 b L S D (.05) = 52.37 L S D (.01) = 73.42 * means f o l l o w e d by the same l e t t e r a r e not s i g n i f i c a n t l y d i f f e r e n t (p< .05) 179 number of diffuse knapweed seedlings/m (420 days post treatment) -multiple comparisons of main plot means (Fisher's protected LSD p = .05) Treatment Block 1 2 3 4 control 8 0 75 34 29.25 a chlorsulfuron 0 0 45 40 21.25 b triclopyr 0 0 22 13 8.75 b 3,6-dichloro- 0 0 0 0 0 b picolinic acid picloram 0 0 0 0 0 b LSD (.05) = 23.69 LSD (.01) = 33.23 * means followed by the same letter are not significantly different (p <.05) Appendix G Chlorsulfuron plus surfactant field trial -post treatment yields of diffuse knapweed (52 days), analyses of variance and multiple comparisons. 181 Cache Creek site: chlorsulfuron + surfactant field trial. Source Analysis of variance - diffuse knapweed yield df SS52 MSQ F Probability Block Treatment Error (a) Rate R X TRT R X Block. Error (b) Total 3 1 3 4 4 12 12 39 2119.6 5961.4 1229.4 47818 7500.9 10022 7257 81908 706.6 5961.4 409.8 11954 1875.2 835.2 604.8 1.72 14.55 0.68 19.77 3.1 1.38 0.33 0.032 0.58 < 10"* 0.057 0.29 Source Analysis of variance - number of bolted plants df SS£ MSQ F Probability Block Treatment Error (a) Rate R X TRT R X Block Error (b) Total 3 1 3 4 4 12 12 39 810.8 1040.4 801.2 984 617.6 907.2 1260.8 6422 270.3 1040.4 267.1 246 154.4 75.6 105.1 1.01 3.89 2.54 2.34 1.47 0.72 0.49 0 .14 0.11 0.11 0.27 0.71 182 Source Analysis of variance - number of rosettes df SSQ MSQ Probability Block Treatment Error (a) Rate R X TRT R X Block Error (b) Total 3 1 3 4 4 12 12 39 19426 5336.1 4995.5 44204 12520 32780 15062 134320 6475.3 5336.1 1665.2 11051 3130.1 2731.6 1255.2 3.89 3.20 1.33 8.80 2.49 2.18 0.15 0.17 0.31 0.0015 0.099 0.096 Source Analysis of variance - number of seedlings df SSQ MSQ Probability Block Treatment Error (a) Rate R X TRT R X Block Error (b) Total 3 1 3 4 4 12 12 39 446630 243980 2003500 56701000 975940 1786500 8013800 70171000 148880 243980 667820 14175000 243980 148880 667820 0.22 0.37 1.0 21.23 0.37 0.22 0.88 0.59 0.43 -4 < 10 0.83 0.99 183 Cache Creek site: chlorsulfuron + surfactant tr ial . diffuse knapweed yield (52 days post treatment) -multiple comparisons of means (Fisher's protected LSD p = .05) Treatment Block (g/ha chlorsulfuron) 1 2 3 4 X * S -X 0 130 .24 179, .48 122 .12 190 .36 155 .55 a 17. 18 20 87 .64 32, .44 40 .40 41 .76 50 .56 b 12. 53 40 31 .72 67, .72 54 .96 24 .44 44 .71 b 10. 06 80 31 .92 23, .92 34 .40 76 .52 41 .69 b 11. 82 160 22 .64 23, .64 7 .12 13 .44 16 .71 b 3. 94 0 + 0.1% 115 .92 28, .80 39 .92 128 .56 78 .30 a 25. 60 Citowett 20 + 0.1% 46 .04 32, .48 18 .72 32 .80 32 .51 b 5. 58 Citowett 40 + 0.1% 31 .92 58, .52 19 .44 8 .28 29 .54 b 10. 80 Citowett 80 + 0.1% 25 .84 37. .96 38 .44 7 .36 27 .40 b 7. 29 Citowett 160 + 0.1% 56 .40 5. .84 6 .88 8 .00 19 .28 b 12. 38 Citowett LSD (rates within the same treatment) (.05) = 37.89 g/m (.01) = 53.12 g/m2 * means within a treatment followed by the same letter are not significantly different (p<_.05) 184 number of bolted diffuse knapweed plants/m' (52 days post treatment) Treatment Block (g/ha chlorsulfuron) S -x 0 20 40 80 160 32 32 32 36 24 36 32 32 40 20 24 16 28 20 8 36 12 16 48 8 32 23 27 36 15 2.8 5.3 3.8 5.9 4.1 0 + 0.1% Citowett 56 24 20 26 10.9 20 + 0.1% Citowett 12 28 12 15 4.4 40 + 0.1% Citowett 24 12 16 16 17 2.5 80 + 0.1% Citowett 12 12 16 11 2.5 160 + 0.1% Citowett 36 13 7.9 185 number of diffuse knapweed rosettes/m (52 days post treatment) - multiple comparisons of means (Fisher's protected LSD p = .05) Treatment Block (g/ha chlorsul furon) 1 2 3 4 S -X 0 116 112 56 220 126 a 34.2 20 52 80 42 136 78 a c 21.1 40 48 76 100 100 81 ac 12.4 80 44 16 44 48 38 be 7.4 160 20 36 72 160 72 ac 31.3 0 + 0.1% 56 68 136 264 183 a 40.5 Citowett 20 + 0.1% 8 96 84 152 99 b 29.6 Citowett 40 + 0.1% 24 108 68 68 73 b 17.2 Citowett 80 + 0.1% 12 84 156 96 106 b 29.5 Citowett 160 + 0.1% 36 40 64 36 49 b 6.7 Citowett LSD (rates within the same treatment) (.05) = 54.59 (.01) = 76.53 * means within a treatment followed by the same letter are not significantly different (p_f_.05) 186 number of diffuse knapweed seedlings/m (52 days post treatment) - multiple comparisons of means (Fisher's protected LSD p = .05) Treatment Block (g/ha chlorsulfuron) 1 2 3 4 S x 0 3192 2484 852 3816 2586 a 639 20 0 0 0 0 0 b 0 40 0 0 0 0 0 b 0 80 0 0 0 0 0 b 0 160 0 0 0 0 0 b 0 0 + 0.1% 4496 3408 4424 1140 3367 a 783 Citowett 20 + 0.1% 0 0 0 0 0 b 0 Citowett 40 + 0.1% 0 0 0 0 0 b 0 Citowett 80 + 0.1% 0 0 0 0 0 b 0 Citowett 160 + 0.1% 0 0 0 0 0 b 0 Citowett LSD (rates within the same treatment) (.05) = 1262.45 (.01) = 1765.33 * means within a treatment followed by the same letter are i not significantly different (p_501) 187 Append ix H DPX-T6376 field trial - post treatment yields of diffuse knapweed (48 days), analyses of variance and multiple comparisons. 188 Cache Creek site: DPX-T6376 field trial (48 days post treatment). D i f f u s e k n a p w e e d y i e l d ( g rams / squa re m e t e r ) -m u l t i p l e c o m p a r i s o n s o f means (F isher ' s p r o t e c t e d L S D p = .05 ) * T r e a t m e n t B l o c k g / h a D P X - T 6 3 7 6 1 2 3 4 x S -20 + 0 . 1 % 15 .40 7 3 . 7 2 4 5 . 7 2 4 2 . 2 4 4 4 . 2 7 a 1 1 . 9 3 C i t o w e t t P lus 40 + 0 . 1 % 4 2 . 2 0 2 3 . 9 2 2 1 . 0 4 15 .40 2 5 . 6 4 a 5 . 8 0 C i t o w e t t P lus 80 + 0 . 1 % 3 0 . 2 8 2 3 . 7 6 5 0 . 3 2 4 0 . 4 8 3 6 . 2 1 a 5 . 8 3 C i t o w e t t P lus 160 + 0 . 1 % 3 3 . 0 4 3 1 . 3 6 2 2 . 0 4 3 5 . 3 2 3 0 . 4 4 a 2 . 9 2 C i t o w e t t c o n t r o l 153 .12 111 .84 162 .40 161 .00 1 4 7 . 0 9 b 11 .93 L S D (.05) = 28.65 g / m 2 (0.1) = 40.16 g / m 2 * means f o l l o w e d by the s a m e l e t t e r a re not s i g n i f i c a n t l y d i f f e r e n t (p< .01) 189 Cache Creek site: DPX-T6376 field trial (48 days post treatment). Plant numbers/square meter. Treatment Mature bolted plants Block g/ha DPX-T6376 1 20 + 0.1% Citowett 13 6.25 2.49 40 + 0.1% Citowett 4.25 0.48 80 + 0.1% Citowett 10 6.25 1.31 160 + 0.1% Citowett 3.75 0.25 control 6 9 5 25 11.25 4.66 190 Cache Creek site: DPX-T6376 field trial (48 days post treatment). Plant numbers/square meter. (continued) Rosettes Treatment Block g/ha DPX-T6376 1 S -x 20 + 0.1% Citowett 32 18 17.00 5.43 40 + 0.1% Citowett 26 18 12.75 5.60 80 + 0.1% Citowett 10 24 17 13.25 4.71 160 + 0.1% Citowett 15 7.00 3.08 control 28 15 56 29.25 9.34 multiple comparisons of means (Fisher's protected LSD p = .05)* Seedlings Treatment Block g/ha DPX-T6376 1 2 3 4 x S -0 + 0.1% Citowett Plus 0 a 40 + 0.1% Citowett Plus 0 a 80 + 0.1% Citowett Plus 0 a 160 + 0.1% Citowett 0 a control 3396 2984 2496 1444 2580 b 420.9 LSD (.05) = 580.142 seedlings/m (0.1) = 813.37 seedlings/m2 * means followed by the same letter are not significantly different (p <.Q1) 192 Cache Creek site: DPX-T6376 field tr ial . Analysis of variance - diffuse knapweed yield Source df SSQ MSQ F Probability Block 3 178.2 59.40 0.17 0.91 Rate 4 41596 10399 30.1 < 10"^ Error 12 4148.3 345.69 Total 19 45923 Analysis of variance - number of bolted knapweeds Source df SSQ MSQ F Probability Block 3 1589.6 529.9 1.52 0.26 Rate 4 2252.8 563.2 1.62 0.23 Error 12 4166.4 347.2 Total 19 8088.8 Analysis of variance - number of knapweed rosettes Source df SSQ MSQ F Probability Block 3 3452 1150.7 0.44 .0.73 Rate 4 17637 4409.2 1.70 0.21 Error 12 31048 2587.3 Total 19 52137 193 Analysis of variance - number of knapweed seedlings Source df SSQ MSQ F Probability Block 3 425320 141770 1.0 0.426 Rate 4 21300000 5325100 37.56 < 10'* Error 12 1701300 141770 Total 19 23427000 Append ix I 3 ,6 - d i ch lo rop ico l i n i c a c i d m i n i m u m r a t e t r i a l post t r e a t m e n t y i e l d s o f d i f f u s e k n a p w e e d (45 days) , ana lyses of v a r i a n c e and m u l t i p l e c o m p a r i s o n s . 195 Cache Creek site: 3,6-dichloropicolinic acid minimum rate trial. Analysis of variance - diffuse knapweed yield Source Block Rate Error Total df 3 5 15 23 SSQ 9225.4 19660 9312.3 38197 MSQ 3075.1 3931.9 620.8 F 4.95 6.33 Probability 0.014 0.0024 Analysis of variance - number of bolted diffuse knapweed plants Source Block Rate Error Total df 3 5 15 23 SSQ 1282 1547.3 3570 6399.3 MSQ 427.3 309.5 238 F 1.8 1.3 Probability 0.19 0.32 Analysis of variance - number of diffuse knapweed rosettes Source df SSQ; MSQ F Probability Block 3 19256 6418.7 1.38 0.29 Rate 5 59944 11989 2.57 0.072 Error 15 69992 4666.1 Total 23 149190 196 Cache Creek site: 3,6-dichloropicolinic acid minimum rate trial. (continued) Analysis of variance - number of diffuse knapweed seedlings Source Block Rate Error Total df 3 5 15 23 SSQ 513160 28555000 1170800 30239000 MSQ 171050 5711000 78050 F 2.19 Probability 0.13 73.17 < 10'* 197 Cache Creek site: diffuse knapweed yield (45 days post treatment). (grams/square meter) - multiple comparisons of means. (Fisher's protected LSD p = .05).* Treatment Block (g/ha) 1 2 3 4 X * S -X 3,6-dichloropicolinic acid 0 39.68 161.00 108.08 144.08 113.21 a 26.88 50 44.36 76.16 81.32 133.92 83.94 ab 18.56 100 50.20 35.36 20.56 39.56 36.42 c 6.14 150 42.64 32.76 44.08 107.40 56.72 be 17.08 250 20.44 36.56 26.56 42.80 31.59 c 4.99 picloram 100 20.08 55.24 42.48 72.92 47.68 be 11.17 LSD (.05) weed yield = 37.54 g/m2 LSD (.01) = 51.92 g/m2 * means followed by the same letter are not significantly different (p "^ .05) 198 Cache Creek site: number of bolted diffuse knapweed plant/square meter. (45 days post treatment). Treatment Block (g/ha) * 1 2 3 4 x S -3,6-dichloropicolinic acid 0 44 68 32 24 42 9.6 50 24 12 28 44 27 6.6 100 32 16 16 20 21 3.8 150 44 28 16 72 40 12.1 250 20 28 20 44 28 5.6 picloram 100 8 16 20 48 23 8.7 199 Cache Creek site: number of diffuse knapweed rosettes/square meter. (45 days post treatment). Treatment Block (g/ha) 1 2 3 4 x S -3,6-dichloropicolinic acid 0 76 376 128 228 202 66 50 64 88 248 52 113 46 100 76 156 52 88 93 22 150 56 88 52 44 60 10 250 44 104 24 64 59 17 picloram 100 60 40 88 80 67 11 Cache Creek site: number of diffuse knapweed seedlings/square meter. (45 days post t r e a t m e n t ) - m u l t i p l e c o m p a r i s o n s of means . (F isher 's p r o t e c t e d L S D p = .05 ) . * T r e a t m e n t B l o c k (g /ha) 1 2 3 4 X * S -X 3 , 6 - d i c h l o r o p i c o l i n i c a c i d 0 3548 2940 2424 3364 3078 a 249 50 1748 656 1008 752 1041 b 247 100 840 768 364 508 620 b 111 150 0 0 0 156 39 c 39 250 0 0 0 0 0 c 0 p i c l o r a m 100 0 0 0 0 0 c 0 L S D (.05) = 420.97 s e e d l i n g s / m L S D (.01) = 582.2 * means f o l l o w e d by the same l e t t e r a r e not s i g n i f i c a n t l y d i f f e r e n t (p <.Q1) Appendix 3 Seed germination experiments - number of germinated seeds, radicle lengths/seed and total seedling length/seed, analyses of variance and multiple comparisons. 202 Seed germination experiments  diffuse knapweed Analysis of variance - number of germinated seeds Source df SSQ MSQ F Probability Treatment 3 117.6 39.19 5.29 0.022 Block 3 21.5 7.17 0.97 0.45 Error (a) 9 66.65 358.5 0.98 0.47 Rate 5 1792.3 41.5 47.6 10"* R X TRT 15 622.7 7.68 5.5 < IO"* R X BLK 15 115.2 7.53 1.0 0.45 Error (b) 45 338.7 Total 95 3074.6 Analysis of variance - radicle length/seed Source df SSQ MSQ F Probability Treatment 3 0.237 0.079 10.45 0.0027 Block 3 0.0037 0.0013 0.17 0.92 Error (a) 9 0.068 0.0076 0.71 0.70 Rate 5 1.21 0.24 22.67 < IO"* R X TRT 15 0.204 0.014 1.27 0.26 R X BLK 15 0.336 0.022 2.09 0.029 Error (b) 45 0.482 0.011 Total 95 2.54 203 Analysis of variance - total seedling length/seed Source d f SSQ MSQ F Probability Treatment 3 5.09 1.69 60.18 < • l o - * Block 3 0.31 0.1 3.6 0.059 Error (a) 9 0.25 0.028 0.44 0.91 Rate 5 30.78 6.16 96.1 < i o - * R X TRT 15 6.74 0.45 7.0 < i o - * R X BLK 15 1.96 0.13 2.0 0.034 Error (b) 45 2.88 0.064 Total 95 48 spotted knapweed Analysis of variance - number of germinated seeds Source d f SSQ MSQ F Probability Treatment 3 1083.9 361.3 50.6 < IO"* Block 3 8.11 2.7 0.38 0.77 Error (a) 9 64.3 7.14 1.74 0.11 Rate 5 4129.1 825.8 201.5 < IO"* R X TRT 15 1523.2 101.6 24.78 < IO"* R X BLK 15 43.45 2.89 0.71 0.76 Error (b) 45 184.4 4.09 Total 79 7036.4 Analysis of variance - radicle length/seed Source df SSQ M S Q F P r o b a b i l i t y T r e a t m e n t 3 2 . 1 7 0 . 7 3 2 9 . 6 <! 1 0 " * B l o c k 3 0 . 0 0 7 3 0 . 0 0 2 4 0 . 0 9 9 0 . 9 6 E r r o r (a) 9 0 . 2 2 0 . 0 2 4 0 . 9 2 0 . 5 2 R a t e 5 9 . 9 6 1 .99 7 4 . 7 < 1 0 " * R X T R T 15 2 . 8 4 0 . 1 9 7 . 1 < I O " * R X B L K 15 0 . 4 6 0 .031 1 .16 0 . 3 3 E r r o r (b) 45 1 .19 0 . 0 2 7 T o t a l 95 16 .87 Analysis of variance - total seedling length/seed Source df SSQ M S Q F P r o b a b i l i t y T r e a t m e n t 3 5 9 . 8 2 1 9 . 9 169 .8 < 1 0 " * B l o c k 3 0 . 2 9 0 . 0 9 9 0 . 8 5 0 . 5 0 E r r o r (a) 9 1.1 0 . 1 2 2 . 5 8 0 . 0 1 7 R a t e 5 9 5 . 3 19.1 4 1 8 . 5 < 1 0 " * R X T R T 15 19 .8 1 .3 2 8 . 9 R X B L K 15 2 . 5 0 . 1 7 3 .68 E r r o r (b) 45 2 .1 0 . 0 4 6 T o t a l 95 1 8 0 . 9 205 crested wheatgrass Analysis of variance - number of germinated seeds S o u r c e df SSQ M S Q F P r o b a b i l i t y T r e a t m e n t 3 19.54 6.51 0.71 0.57 B l o c k 3 14.38 4.79 0.52 0.68 E r r o r (a) 9 82.7 9.19 1.19 0.32 R a t e 5 474 94.8 12.38 < 10"* R X T R T 15 276.1 18.4 2.4 0.011 R X B L K 15 99.3 6.62 0.86 0.61 E r r o r (b) 45 344.7 7.66 T o t a l 95 1310.6 Analysis of variance - radicle length/seed Source d f S S Q M S Q F P r o b a b i l i t y T r e a t m e n t 3 7.68 2.56 10.37 0.0028 B l o c k 3 0.81 0.27 1.09 0.40 E r r o r (a) 9 2.22 0.25 2.65 0.015 R a t e 5 23.5 4.71 50.6 < 10"* R X TRT 15 4.58 0.31 3.28 0.001 R X B L K 15 2.18 0.15 1.56 0.12 E r r o r (b) 45 4.19 0.093 T o t a l 95 45.2 206 Analysis of variance - total seedling length/seed S o u r c e df SSQ M S Q F P r o b a b i l i t y T r e a t m e n t 3 59 . 8 5 1 9 , 9 5 14 .59 0 . 00084 B l o c k 3 23 .97 7 . 9 9 5 . 8 4 0 . 017 E r r o r (a) 9 12 .31 1.37 1.71 0 . 114 R a t e 5 154 .01 3 0 . 8 3 8 . 5 < 10" •4 R X T R T 15 22 . 1 9 1.48 1 .85 0 . 057 R X B L K 15 13 . 2 2 0 . 8 8 1.1 0 . 38 E r r o r (b) 45 35 .97 0 . 8 0 T o t a l 95 321 . 5 bluebunch wheatgrass Analysis of variance - number of germinated seeds S o u r c e df SSQ T r e a t m e n t 3 9 1 . 5 3 B l o c k 3 3 0 . 6 2 E r r o r (a) 9 9 . 8 4 R a t e 5 2 3 4 . 2 R X T R T 15 107 .5 R X B L K 15 115 .5 E r r o r (b) 45 2 6 9 . 3 T o t a l 95 8 5 8 . 5 M S Q F P r o b a b i l i t y 3 0 . 5 1 2 7 . 8 9 - 4 < 10 10 .2 9 . 3 3 0 . 0 0 4 1.09 0 . 1 8 0 . 9 9 4 6 . 8 7 . 8 2 - 4 < 10 7 . 1 7 1 .19 0 .31 7 . 6 9 1 .29 0 . 2 5 5 . 9 9 Analysis of variance - radicle length/seed Source df SSQ Treatment 3 1.16 Block 3 0.13 Error (a) 9 1.43 Rate 5 12.61 R X TRT 15 1.85 R X BLK 15 3.07 Error (b) 45 10.3 Total 95 30.54 Analysis of vark Source df SSQ Treatment 3 15.57 Block 3 0.53 Error (a) 9 28.56 Rate 5 314.6 R X TRT 15 88.86 R X BLK 15 68.67 Error (b) 45 161.0 Total 95 677.74 MSQ F Probability 0.387 2.43 0.13 0.042 0.27 0.85 0.16 0.69 0.71 2.52 11.03 < IO"* 0.12 0.54 0.904 0.205 0.89 0.57 0.229 total length/seed MSQ F Probability 5.19 1.64 0.25 0.17 0.055 0.98 3.17 0.89 0.54 62.9 17.58 < 10"* 5.92 1.66 0.097 4.58 1.28 0.25 3.58 diffuse knapweed - number of germinated seeds m u l t i p l e c o m p a r i s o n s of means (F isher 's p r o t e c t e d L S D p = .05 ) * T r e a t m e n t B l o c k (ppm) 1 2 3 4 x * S -c h l o r s u l f u r o n 0 14 20 17 12 1 5 . 7 5 a 1.7 0 .01 14 15 8 8 1 1 . 2 5 be 1.8 0 .1 15 10 18 11 13 .50 a c 1.8 1.0 17 8 17 15 1 4 . 2 5 a c 2 .1 10 13 17 7 14 12 .88 a c 1.4 100 11 12 15 14 13 .00 a c 0 . 9 t r i c l o p y r 0 14 20 17 19 17 .50 a 1 .3 0 .1 13 18 15 13 14 .75 a 1.1 1.0 15 18 12 17 15 .50 a 1 .3 10 15 17 13 17 15 .50 a 0 . 9 100 6 8 6 11 7 . 7 5 b 1.1 1000 0 0 1 0 0 . 2 5 c 0 . 2 209 T r e a t m e n t diffuse knapweed - number of germinated seeds (continued) B l o c k (ppm) S -x 3 , 6 - d i c h l o r o p i c o l i n i c a c i d 0 0 .1 1 .0 10 100 1000 17 12 19 13 10 1 12 19 15 15 7 0 20 20 13 14 7 1 19 12 13 14 5 1 17 .00 a 1 5 . 7 5 a 15 .00 a 14 .00 a 7 . 2 5 b 0 . 7 5 c 1.78 2 . 1 7 1.41 0 .41 1 .03 0 . 2 5 p i c l o r a m 0 0 .1 1 .0 10 100 1000 18 16 11 8 11 2 20 12 13 12 11 0 19 12 13 11 6 1 19 10 11 7 8 1 19 .00 a 12 .50 b 12 .00 b 9 . 5 0 b 9 . 0 0 b 1.00 c 0 .41 1.26 0 . 5 8 1 .19 1 .22 0 .41 L S D ( c o n c e n t r a t i o n s w i t h i n the same t r e a t m e n t ) (.05) = 3.91 (.01) = 5.22 * means w i t h i n a t r e a t m e n t f o l l o w e d by the same l e t t e r a re not s i g n i f i c a n t l y d i f f e r e n t ( p j \ 0 5 ) d i f f u s e k n a p w e e d - r a d i c l e l e n g t h / s e e d (cm) multiple comparisons of means (Fisher's protected LSD p = .05)* Treatment Block (ppm) 1 2 3 4 x* S -chlorsulfuron 0 0.43 0.52 0.54 0.69 0.55 a 0.0 0.01 0.46 0.76 0.56 0.46 0.56 ac 0.0 0.1 0.45 0.46 0.46 0.26 0.41 ac 0.0 1.0 0.40 0.46 0.29 0.43 0.40 ac 0.0 10 0.35 0.39 0.39 0.42 0.39 be 0.0 100 0.38 0.30 0.31 0.40 0.35 b 0.0 triclopyr 0 0.47 0.38 0.55 0.71 0.53 ad 0.0 0.1 0.33 0.55 0.35 0.55 0.45 ad 0.0 1.0 0.41 0.41 0.33 0.47 0.41 ade 0.0 10 0.31 0.34 0.22 0.23 0.28 be 0.0 100 0.22 0.24 0.20 0.22 0.22 b 0.0 1000 0.00 0.00 0.30 0.00 0.08 c 0.0 211 diffuse knapweed - radicle length/seed (cm) (continued) Treatment Block ppm) 1 2 3 4 X * S -X 3,6-dichloropicolinic acid 0 0.45 0.62 0.53 0.47 0.52 a 0.04 0.1 0.30 0.55 0.37 0.43 0.41 ac 0.05 1.0 0.32 0.41 0.36 0.37 0.37 be 0.02 10 0.20 0.22 0.20 0.20 0.21 bd 0.01 100 0.21 0.20 0.20 0.20 0.20 bd 0.01 1000 0.80 0.00 0.20 0.20 0.30 bed 0.20 >icloram 0 0.49 0.51 0.66 0.59 0.57 a 0.04 0.1 0.50 0.44 0.44 0.38 0.44 a 0.02 1.0 0.27 0.33 0.26 0.29 0.29 b 0.02 10 0.21 0.33 0.21 0.23 0.25 b 0.03 100 0.22 0.28 0.20 0.20 0.23 b 0.02 1000 0.20 0.00 0.20 0.20 0.15 b 0.05 LSD (concentrations within the same treatment) (.05) = 0.147 cm (.01) = 0.197 cm * means within a treatment followed by the same letter are not significantly different (pji-05) diffuse knapweed - total seedling length/seed (cm) multiple comparisons of means (Fisher's protected L S D p = .05)* Treatment Block (ppm) 1 2 3 4 X * chlorsulfuron 0 1 .65 2, .21 2. 29 2. 52 2. 17 a 0.01 2 .10 2. .48 2. 16 1. 85 2. 15 a 0.1 1 .80 1, .86 1. 66 1. 33 1. 66 b 1.0 1 .74 1. .68 1. 34 2. 14 1. 73 b 10 1 .50 1. .51 1. 54 1. 51 1. 52 b 100 1 .86 1. .82 1. 63 1. 36 1. 67 b triclopyr 0 1 .63 2. .09 2. 27 1. 97 1. 99 ab 0.1 1 .75 2. ,33 1. 43 1. 55 1. 77 b 1.0 2 .11 2. ,13 2. 11 2. 24 2. 15 a 10 1 .51 1. ,23 1. 38 1. 26 1. 35 c 100 0 .47 0. ,56 0. 85 0. 76 0. 66 c 1000 0 .00 0. .00 0. 60 0. 00 0. 15 c s-x 0.1 0.1 0.1 0.1 0.0 0.1 0.1 0.1 0.0 0.0 0.0 0.1 213 diffuse knapweed - total seedling length/seed (cm) (continued) T r e a t m e n t B l o c k ppm) 1 2 3 4 X * 5 -X 3 , 6 - d i c h l o r o p i c o l i n i c a c i d 0 1 .93 2 . 5 5 2 . 3 1 2 .21 2 . 2 5 a 0 . 1 3 0 .1 1.67 2 . 4 0 1 .83 1.97 1.97 a 0 . 1 6 1 .0 1.39 1 .80 1.37 1 .62 1 .55 b 0 . 1 0 10 0 . 7 0 0 . 7 0 0 . 6 7 0 . 7 9 0 . 7 2 c 0 . 0 3 100 0 .37 0 . 3 6 0 . 6 0 0 . 7 2 0 .51 c 0 . 0 9 1000 0 . 8 0 0 . 0 0 0 . 8 0 0 . 4 0 0 . 5 0 c 0 . 1 9 ( i c l o ram 0 1.66 2 . 3 1 2 . 7 7 2 . 0 4 2 . 2 0 a 0 . 2 3 0 .1 2 . 2 7 2 . 0 5 2 . 3 3 1 .65 2 . 0 8 a 0 . 1 5 1 .0 1.80 2 . 0 7 1 .46 1.94 1 .82 be 0 . 1 3 10 0 . 9 5 1 .36 1.28 1 .19 1.20 c e 0 . 0 9 100 0 .61 0 . 5 9 0 . 6 8 0 . 7 6 0 . 6 6 d 0 . 0 4 1000 0 . 3 0 0 . 0 0 0 . 4 0 0 . 6 0 0 . 3 3 d 0 . 1 3 L S D ( c o n c e n t r a t i o n s w i t h i n the same t r e a t m e n t ) (.05) = 0.36 c m (.01) = 0.48 c m * means w i t h i n a t r e a t m e n t f o l l o w e d by the same l e t t e r a re not s i g n i f i c a n t l y d i f f e r e n t (pj^.05) 214 spotted knapweed - number of germinated seeds multiple comparisons of means (Fisher's protected LSD p = .05)* Treatment Block (ppm) 1 2 3 4 x* S -chlorsulfuron 0 23 22 24 21 22.50 a 0.65 0.01 18 20 20 19 19.25 be 0.48 0.1 21 20 22 20 20.75 ac 0.48 1.0 ' 18 20 22 18 19.50 be 0.96 10 21 17 22 20 20.00 abc 1.08 100 23 18 25 18 21.00 abc 1.78 iclopyr 0 16 16 18 21 17.75 b 1.18 0.1 25 24 20 23 23.00 a 1.08 1.0 20 16 20 20 19.00 b 1.00 10 8 10 15 13 11.50 c 1.55 100 0 0 0 0 0.00 d 0.00 1000 0 0 0 0 0.00 d 0.00 215 spotted knapweed - number of germinated seeds (continued) Treatment Block (ppm) 1 2 3 4 x* S -3,6-dichloropicolinic acid 0 21 20 23 20 21.00 a 0.71 0.1 20 18 22 20 20.00 ab 0.82 1.0 15 22 16 20 18.25 ab 1.65 10 14 19 17 20 17.75 b 1.32 100 5 5 5 3 4.50 c 0.50 1000 0 0 0 0 0.00 d 0.00 licloram 0 23 20 24 22 22.25 a 0.85 0.1 22 22 21 23 22.00 a 0.41 1.0 20 17 18 18 18.25 b 0.63 10 17 19 9 18 15.75 b 2.28 100 0 1 0 3 1.00 c 0.71 1000 0 0 0 0 0.00 c 0.00 LSD (concentrations within the same treatment) (.05) = 2.88 (.01) = 3.85 * means within a treatment followed by the same letter are not significantly different (p_505) 216 spotted knapweed - radicle length/seed (cm) multiple comparisons of means (Fisher's protected LSD p = .05)* Treatment Block (ppm) 1 2 3 4 x* S -chlorsulfuron 0 0.77 0.72 0.90 0.83 0.81 a 0.04 0.01 1.11 0.78 0.86 0.71 0.87 a 0.09 0.1 0.76 0.71 0.80 0.73 0.75 a 0.02 1.0 1.62 0.58 0.85 0.61 0.92 a 0.24 10 0.50 0.89 0.88 0.66 0.73 ac 0.09 100 0.51 0.70 0.45 0.39 0.51 be 0.07 triclopyr 0 1.30 1.28 1.4 1.83 1.45 a 0.13 0.1 0.50 0.56 0.54 0.44 0.51 b 0.03 1.0 0.23 0.87 0.24 0.12 0.37 b 0.15 10 0.20 0.20 0.21 0.21 0.21 c 0.00 100 0.00 0.00 0.00 0.00 0.00 c 0.00 1000 0.00 0.00 0.00 0.00 0.00 c 0.00 217 spotted knapweed - radicle length/seed (cm) (continued) Treatment Block ppm) 1 2 3 4 S -X 3,6-dichloropicolinic acid 0 1.09 0.93 1.13 1.31 1.12 a 0.08 0.1 0.43 0.52 0.56 0.49 0.49 b 0.03 1.0 0.36 0.27 0.32 0.31 0.32 b 0.02 10 0.30 0.35 0.32 0.36 0.33 b 0.01 100 0.20 0.20 0.20 0.20 0.20 be 0.00 1000 0.00 0.00 0.00 0.00 0.00 c 0.00 >icloram 0 1.20 1.11 1.51 0.98 1.20 a 0.11 0.1 0.41 0.54 0.48 0.56 0.50 b 0.03 1.0 0.29 0.30 0.39 0.37 0.34 bd 0.02 10 0.40 0.33 0.20 0.40 0.33 bd 0.05 100 0.00 0.30 0.00 0.20 0.13 cd 0.08 1000 0.00 0.00 0.00 0.00 0.00 c 0.00 LSD (concentrations within the same treatment) (.05) = 0.23 cm (.01) = 0.31 cm * means within a treatment followed by the same letter are not significantly different (p_f.05) spotted knapweed - total seedling length/seed (cm) multiple comparisons of means (Fisher's protected LSD p = .05)* Treatment Block (ppm) 1 2 3 4 x* S -chlorsulfuron 0 3.39 2.71 3.24 3.35 3.17 ab 0.01 3.57 3.28 3.64 3.21 3.43 a 0.1 3.49 3.10 3.49 3.33 3.35 ab 1.0 3.08 2.84 3.15 2.52 2.89 be 10 2.41 2.90 2.65 2.66 2.66 c 100 2.52 2.32 2.11 1.93 2.22 d triclopyr 0 3.47 3.44 3.99 4.16 3.77 a 0.1 1.70 2.45 2.63 1.97 2.19 b 1.0 0.95 1.14 1.1 0.46 0.91 c 10 0.20 0.20 0.21 0.21 0.21 d 100 0.00 0.00 0.00 0.00 0.00 d 1000 0.00 0.00 0.00 0.00 0.00 d 0.1 0.1 0.0 0.1 0.1 0.1 0.1 0.2 0.1 0.0 0.0 0.0 219 spotted knapweed - total seedling length/seed (cm) (continued) Treatment Block (ppm) 1 2 3 4 x* S -3,6-dichloropicolinic acid 0 1.96 3.28 2.91 4.09 3.06 a 0.44 0.1 2.18 2.40 2.36 2.18 2.28 b 0.06 1.0 0.61 0.91 0.82 0.84 0.80 c 0.06 10 0.30 0.35 0.32 0.36 0.33 d 0.01 100 0.20 0.20 0.20 0.20 0.20 de 0.00 1000 0.00 0.00 0.00 0.00 0.00 e 0.00 ticloram 0 3.07 2.88 3.22 4.14 3.32 a 0.28 0.1 1.71 1.86 1.88 1.95 1.85 b 0.05 1.0 0.81 0.93 1.21 1.06 1.00 c 0.09 10 0.40 0.33 0.20 0.40 0.33 d 0.05 100 0.00 0.30 0.00 0.20 0.13 de 0.08 1000 0.00 0.00 0.00 0.00 0.00 e 0.00 L S D (concentrations within the same treatment) (.05) = 0.31 cm (.01) = 0.41 cm * means within a treatment followed by the same letter are not significantly different (p_<.05) 220 crested wheatgrass - number of germinated seeds multiple comparisons of means (Fisher's protected LSD p = .05)* Treatment Block (ppm) 1 2 3 4 X * S -X chlorsulfuron 0 18 19 16 14 16.75 a 1.11 0.01 20 16 16 14 16.50 a 1.26 0.1 17 14 16 15 15.50 a 0.66 1.0 14 13 14 19 15.00 a 1.35 10 8 15 18 18 14.75 a 2.36 100 19 13 12 12 14.00 a 1.68 triclopyr 0 20 19 16 19 18.50 a 0.87 0.1 13 16 14 11 13.50 b 1.04 1.0 19 17 17 20 18.25 a 0.75 10 17 20 14 19 17.50 b 1.32 100 11 15 12 9 11.75 be 1.25 1000 8 8 8 11 8.75 c 0.75 221 crested wheatgrass - number of germinated seeds (continued) Treatment Block ppm) 1 2 3 4 X * S -X 3,6-dichloropicolinic acid 0 19 18 20 16 18.25 a 0.85 0.1 17 5 11 12 11.25 c 2.46 1.0 11 16 14 16 14.25 be 1.18 10 18 14 16 20 17.00 ab 1.29 100 16 10 13 15 13.50 c 1.32 1000 10 8 13 15 11.50 c 1.55 >icloram 0 19 20 22 18 19.75 a 0.85 0.1 14 21 13 18 16.50 ac 1.85 1.0 15 16 15 13 14.75 be 0.63 10 10 15 7 15 11.75 b 1.97 100 15 10 14 14 13.25 be 1.11 1000 11 13 7 9 7.31 d 1.72 LSD (concentrations within the same treatment) (.05) = 3.94 (.01) = 5.26 * means within a treatment followed by the same letter are not significantly different (p_J>05) crested wheatgrass - radicle length/seed (cm) multiple comparisons of means (Fisher's protected LSD p = .05)* Treatment Block (ppm) 1 2 3 4 X * chlorsulfuron 0 0, .60 2. 16 1. .86 1 .41 1, .51 a 0.01 2, .19 2. 03 1. .75 2 .21 2, .05 b 0.1 1, .78 2. 04 2. .38 1 .71 1, .98 b 1.0 1. .58 1. 38 1. .51 I .42 1, .47 a 10 1, .14 1. 07 1. .43 1 .36 1, .25 a 100 0. .58 0. 82 0. .70 0 .67 0, .69 c triclopyr 0 2, .13 1. 45 0, .82 1 .36 1, .44 a 0.1 1. .25 1. 21 0. .64 1 .46 1, .14 a 1.0 1, ,43 0. 83 1. .16 1 .54 1, .24 a 10 0. .24 0. 20 0. .20 0 .26 0, .23 b 100 0. .21 0. 20 0, .23 0 .20 0, .21 b 1000 0. .21 0. 11 0. . 18 0 .25 0, .19 b s -x 0.3 0.1 0.1 0.0 0.0 0.0 0.2 0.1 0.1 0.0 0.0 0.0 crested wheatgrass - radicle length/seed (cm) (continued) Treatment Block (ppm) 1 2 3 4 x* S -x 3,6-dichloropicolinic acid 0 0.99 1.41 2.41 0.60 1.35 a 0.3 0.1 0.81 1.56 2.05 2.22 1.66 a 0.3 1.0 1.14 1.31 1.61 1.50 1.39 b 0.1 10 0.76 1.09 1.64 1.59 1.27 b 0.2 100 0.87 0.62 0.68 0.89 0.75 c 0.0 1000 0.21 0.15 0.14 0.18 0.17 c 0.0 picloram 0 1.33 2.34 2.19 1.47 1.83 a 0.1 0.81 2.19 1.34 1.87 1.55 a 1.0 0.66 1.36 1.15 1.13 1.08 b 10 0.38 0.47 0.63 0.61 0.52 c 100 0.11 0.17 0.15 0.19 0.16 c 1000 0.15 0.15 0.14 0.22 0.17 c 0.2 0.3 0.1 0.0 0.0 0.0 LSD (concentrations within the same treatment) (.05) = 0.43 cm (.01) = 0.58 cm * means within a treatment followed by the same letter are not significantly different (p_<.05) crested wheatgrass - total seedling length/seed (cm) multiple comparisons of means (Fisher's protected LSD p = .05)* Treatment Block (ppm) 1 2 3 4 x* S -chlorsulfuron 0 7.70 6.95 3.25 4.56 5.62 b 1.0 0.01 5.55 5.26 5.19 7.62 5.91 ab 0.5 0.1 5.30 7.59 7.43 7.41 6.93 a 0.5 1.0 6.14 4.77 5.34 5.14 5.35 b 0.2 10 3.90 4.44 5.37 6.49 5.05 b 0.5 100 2.50 4.39 3.25 4.27 3.60 c 0.4 triclopyr 0 3.27 3.85 6.01 5.34 4.62 a 0.6 0.1 4.12 4.72 3.65 6.65 4.79 a 0.6 1.0 5.23 5.06 5.29 7.51 5.77 a 0.5 10 3.02 2.07 2.74 3.28 2.78 b 0.2 100 2.24 2.35 2.64 2.54 2.44 be 0.0 1000 1.68 1.11 1.45 1.62 1.47 c 0.1 225 crested wheatgrass - total seedling length/seed (cm) (continued) Treatment Block ppm) 1 2 3 4 S -X 3,6-dichloropicolinic acid 0 3.63 5.81 4.63 6.95 5.26 a 0.72 0.1 3.87 6.12 7.92 7.04 6.24 a 0.87 1.0 5.07 6.26 7.02 7.47 6.46 a 0.52 10 3.92 5.43 6.18 7.02 5.64 a 0.66 100 4.70 4.28 5.80 6.45 5.31 a 0.49 1000 2.13 2.98 2.71 3.91 2.93 b 0.37 >icloram 0 3.79 7.21 4.33 5.26 5.15 a 0.75 0.1 4.12 6.45 5.55 7.27 5.85 a 0.67 1.0 4.61 5.90 5.32 6.17 5.50 a 0.35 10 3.01 3.53 3.51 3.41 3.37 b 0.12 100 2.15 1.82 2.61 2.25 2.21 be 0.16 1000 1.65 1.55 1.67 1.51 1.60 c 0.04 LSD (concentrations within the same treatment) (.05) = 1.27 cm (.01) = 1.7 cm * means within a treatment followed by the same letter are not significantly different (pjf.05) bluebunch wheatgrass - number of germinated seeds multiple comparisons of means (Fisher's protected LSD p = .05)* Treatment Block (ppm) 1 2 3 4 x* S -chlorsulfuron 0 8 10 5 11 8.50 a 1.3 0.01 8 3 3 9 5.75 a 1.6 0.1 8 7 6 2 5.75 a 1.3 1.0 9 3 7 7 6.50 a 1.2 10 3 6 6 5 5.00 a 0.7 100 8 8 6 6 7.00 a 0.5 triclopyr 0 8 11 12 7 10.75 a 0.9 0.1 11 1 3 4 4.75 b 2.1 1.0 5 8 2 5 5.00 b 1.2 10 6 6 2 2 4.00 b 1.1 100 2 0 4 4 2.50 be 0.9 1000 1 0 2 1 1.00 c 0.4 227 bluebunch wheatgrass - number of germinated seeds (continued) Treatment Block (ppm) 1 2 3 4 x* S -3,6-dichloropicolinic acid 0 7 8 11 8 8.50 a 0.87 0.1 9 6 3 3 5.25 abc 1.44 1.0 4 5 3 4.00 be 0.41 10 3 3 4 3.50 be 0.29 100 3 6 6 2 4.25 be 1.03 1000 10 3 5 5.50 ac 1.55 dcloram 0 11 8 9 10 9.50 a 0.65 0.1 12 7 10 3 8.00 a 1.96 1.0 7 5 5 12 6.75 a 0.85 10 7 9 6 5 7.25 a 0.95 100 4 10 6 6 6.50 ac 1.26 1000 6 4 3 1 3.50 be 1.04 LSD (concentrations within the same treatment) (.05) = 3.48 (.01) = 4.65 * means within a treatment followed by the same letter are not significantly different (pj>05) 228 bluebunch wheatgrass - radicle length/seed (cm) m u l t i p l e c o m p a r i s o n s of means (F isher 's p r o t e c t e d L S D p = .05 )* T r e a t m e n t B l o c k (ppm) 1 2 3 4 X* S x chlorsulfuron 0 0 . 8 8 0 . 9 6 2 . 8 8 0 . 6 6 1 .35 a 0 . 5 2 0 .01 1 .30 0 . 2 3 0 . 8 3 1 .62 0 . 9 9 ab 0 . 3 0 0 .1 0 .91 1.07 0 . 6 0 0 . 8 5 0 . 8 6 ab 0 . 0 9 1.0 1 .02 0 . 6 3 1.01 0 . 6 9 0 . 8 4 ab 0 . 1 0 10 0 . 2 0 1 .08 0 . 5 5 0 . 7 0 0 . 6 3 b 0 . 1 8 100 0 .31 0 . 5 4 0 . 2 0 0 . 2 2 0 . 3 2 b 0 . 0 8 triclopyr 0 0 . 7 5 0 . 6 3 0 . 9 7 1 .14 0 . 8 7 ac 0 .11 0 .1 0 . 6 4 0 . 2 0 0 . 9 0 1 .30 0 . 7 6 ab 0 . 2 3 1.0 0 . 7 8 0 . 9 5 1 .45 0 . 9 4 1 .03 a 0 . 1 5 10 0 . 2 0 0 . 2 5 0 . 2 0 0 . 3 5 0 . 2 5 be 0 . 0 4 100 0 . 2 0 0 . 0 0 0 . 2 0 0 . 2 3 0 . 1 6 b 0 . 0 5 1000 0 . 3 0 0 . 0 0 0 . 2 0 0 . 2 0 0 . 1 8 b 0 . 0 6 a 229 bluebunch wheatgrass - radicle length/seed (cm) (continued) Treatment Block (ppm) 1 2 3 4 S -X 3,6-dichloropicolinic acid 0 1.00 2.88 1.50 0.96 1.59 a 0.45 0.1 2.46 0.32 0.20 0.23 0.80 b 0.55 1.0 1.10 0.74 0.65 0.33 0.71 b 0.16 10 0.40 0.67 1.05 0.23 0.50 b 0.17 100 0.20 0.32 0.23 0.90 0.41 b 0.16 1000 0.20 0.20 0.20 0.34 0.24 b 0.04 picloram 0 0.89 1.02 1.45 2.26 1.41 a 0.31 0.1 0.73 1.20 1.31 0.86 1.03 ad 0.14 1.0 0.94 1.34 0.86 1.23 1.09 ad 0.11 10 1.01 0.52 0.68 0.64 0.71 bd 0.10 100 0.23 0.27 0.28 0.28 0.27 be 0.01 1000 0.20 0.20 0.20 0.20 0.20 be 0.00 LSD (concentrations within the same treatment) (.05) = 0.68 cm (.01) = 0.91 cm * means within a treatment followed by the same letter are not significantly different (pjf.05) bluebunch wheatgrass - total seedling length/seed (cm) multiple comparisons of means (Fisher's protected LSD p = .05)* Treatment Block (ppm) 1 2 3 4 x* S -chlorsulfuron 0 9.24 6.77 5.93 6.26 7.05 ab 0.01 9.04 2.60 8.73 10.23 7.65 a 0.1 7.80 8.90 7.63 7.55 7.97 a 1.0 7.32 8.10 5.89 5.77 6.23 ab 10 2.73 6.30 5.18 3.62 4.46 be 100 2.98 3.40 1.93 1.52 2.46 c 0.7 1.7 0.3 0.9 0.8 0.4 triclopyr 0 9.01 8.56 10.22 5.84 8.41 a 0.9 0.1 7.16 0.80 6.50 8.55 5.75 a 1.7 1.0 5.68 8.53 8.60 8.04 7.71 a 0.6 10 5.42 6.65 8.05 6.40 6.63 a 0.5 100 4.30 0.00 2.55 4.13 2.75 b 0.9 1000 2.30 0.00 4.15 2.50 2.24 b 0.8 231 bluebunch wheatgrass - total seedling length/seed (cm) (continued) Treatment Block (ppm) 1 2 3 . 4 x* S -3,6-dichloropicolinic acid 0 7.42 10.25 9.35 7.44 8.62 a 0.71 0.1 11.46 5.52 3.17 2.60 5.69 b 2.03 1.0 7.43 6.84 6.45 8.70 7.36 ab 0.49 10 2.37 7.13 7.63 3.58 5.18 b 1.30 100 3.47 6.48 6.60 8.85 6.35 ab 1.10 1000 4.18 5.87 4.23 6.32 5.15 b 0.55 ticloram 0 9.37 8.44 6.31 6.54 7.67 a 0.74 0.1 8.08 10.73 7.47 8.43 8.68 a 0.71 1.0 7.81 9.90 7.54 9.23 8.62 a 0.57 10 9.70 6.59 8.13 8.28 8.18 a 0.64 100 2.58 5.13 5.35 5.58 4.66 b 0.70 1000 1.55 2.63 3.30 1.20 2.17 b 0.48 LSD (concentrations within the same treatment) (.05) = 2.69 cm (.01) = 3.59 cm * means within a treatment followed by the same letter are not significantly different (p_<05) 

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