8 - 



and in established plantings 

 of non-bearing and bearing 

 trees. In some of these 

 trials dichlobenil applica- 

 tions, 4 to 7 1/2 times the 

 recommended rate of 4 lbs. of 

 active ingredient per acre 

 caused no injury to young 

 trees . 



In spite of the reported 

 tolerance, symptoms of dichlo- 

 benil injury in grower orch- 

 ards are frequent, especially 

 when dichlobenil is applied 

 with a hand-operated or 

 tractor-mounted spreader. We 

 also have experienced this 

 difficulty in 1967, at our 

 Horticultural Research Center, 

 where dichlobenil was applied 

 with a hand-operated spread- 

 er under plum, peach and 

 cherry trees. Phy totoxi ci ty 

 symptoms were very prevalent 

 on plum trees during the 

 summer of 1968, and again in 

 1969, although no further 

 treatments were applied. 

 Cherry trees also exhibited 

 injury symptoms in 1968 and 

 1969, but symptoms were 

 almost non-existent in 

 peaches in either year. There 

 are many variables such as 

 rate of application, weather, 

 soil type, soil climate and 

 soil microorganisms that af- 

 fect the rate of loss or in- 

 activation of herbicides in 

 soil. Nevertheless, the pres- 

 ence of injury symptoms in 

 grower orchards and in our 

 trials has raised questions 

 as to tolerance of fruit 

 trees to dichlobenil and 

 if the injury is harmful to 

 the trees . 



Fig. 2 

 1 eaves 

 is the 



Dalapon injury on EM VII 

 The marginal necrosis which 

 distinguishing symptom of dala 



pon injury can be noted 



********** 



Fig. 3. Dichlobenil injury on Mcin- 

 tosh apple leaves. The yellowing 

 which is the distinguishing symptom of 

 dichlobenil injury can be noted. The 

 leaf on the leaf shows more severe in- 

 jury - marginal necrosis and interveinal 

 yel 1 owi ng . 



