At the concentration used, simazine failed to eradicate the 

 well-established perennial grasses, particularly at Amherst and 

 Acushnet, and dandelions were tolerant to the herbicide. These 

 observations are in agreement with earlier findings by Lord and 

 Wilder and indicate that simazine should be used with a contact 

 herbicide that will eradicate dandelions and improve the control 

 of perennial grasses. 



The unsatisfactory weed control in the dichlobenil plots at 

 Belchertown was due to the tolerance of sweet vernal to this her- 

 bicide. Due to reduced competition from other weeds, the growth 

 of the sweet vernal scattered throughout 19 of the 20 plots was 

 vigorous and the percentage of weed-covered area decreased from 

 95% on May 25 to 43% on October 6. 



Although dichlobenil failed to completely eradicate all the 

 well-established perennial grasses and even though some infiltra- 

 tion of these grasses from the periphery of the plots occurred, 

 the control obtained with this herbicide was comparable to that 

 obtained with spring application of herbicides in other experi- 

 ments by the authors. As the summer progressed, annual broadleaf 



weeds and grasses principally smooth crabgrass, barnyard grass, 



threeseed mercury and yellow foxtail invaded both the simazine 



and dichlobenil plots 



Quackgrass, Kentucky bluegrass, orchard grass, dandelions and 

 sorrel are the predominant weeds in most Massachusetts orchards 

 grown under the sod-mulch system of culture. Since dichlobenil 

 gave outstanding control of these weeds, further testing of this 

 herbicide is warranted. However, lower rates of application must 

 be tested since it is labeled for use in orchards at 4 to 6 lbs ai/A 



SUMMARY 



The effectiveness of fall applications of granular simazine 

 at 3.2 lab ai/A and granular dichlobenil at 8 lb ai/A for the con- 

 trol of grasses and broadleaf weeds in peach and apple orchards 

 was evaluated. Dichlobenil gave outstanding season-long control 

 of perennial grasses and broadleaf weeds except for sweet vernal 

 grass, while simazine failed to provide acceptable control. The 

 control of dandelions, broadleaf plantain, buckhorn plantain and 

 red sorrel with dichlobenil was outstanding. However, further work 

 is needed to determine the effectiveness of dichlobenil at lower 

 rates . 



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