advanced. This indicates that the soil residue of dichlobenil was not 

 sufficient to give season-long control of grass and broadleaf weeds in 

 the first year of use. Repeated annual application would perhaps pro- 

 vide better control than we have obtained. Growers who would like to 

 try dichlobenil might use this material in orchards where weed control 

 programs have already been initiated. In these orchards, the grass and 

 broadleaf weed cover has already been partly eliminated and weakened, and 

 dichlobenil might be more effective. 



Late fall and early winter applications (Nov. 1 to Dec. IS) of gran- 

 ular dichlobenil are suggested for control of quackgrass in orchards. 

 ^Therefore, Regional Specialist Dominic A. Marini and the writer have in- 

 itiated 3 trials to test the effectiveness of early-November and mid- 

 November applications of dichlobenil for grass and broadleaf weed control. 



The results of these trials should be available prior to the fall of 1966. 



I 



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POISON IVY CONTROL TRIALS 



William J. Lord and G. Everett Wilder 

 Department of Plant and Soil Sciences 



& 

 Regional Agricultural Specialist 



A study, recently completed, was conducted to test the effectiveness 

 of 3 herbicide formulations containing amitrole when applied near full 

 bloom for 3 consecutive years, 1963 through 1965, under Mcintosh apple 

 trees for the control of poison ivy. 



The results obtained indicate that unsatisfactory poison ivy con- 

 trol is obtained under apple trees from 1 application of an amitrole- 

 containing herbicide applied near full bloom. However, satisfactory con- 

 trol can be obtained with repeat applications of this material, although 

 it appears that complete eradication of poison ivy by applications near 

 bloom of apple trees requires more than 3 consecutive yearly applications. 

 Without complete eradication, failure to spray on an annual basis would 

 result in a rapid re-infestation of this weed. 



The label for a herbicide containing amitrole has recently been 

 changed, and it now defines "prior to fruit set" as being before 90% 

 petal fall. This permits applications that may be several days later 

 than the treatments applied in these tests. Since poison ivy leaf expan- 

 sion is generally rapid in mid -May, yearly applications of amitrole -con- 

 taining herbicides used just prior to 90% petal fall may result in better 

 control than those obtained in this study. 



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