consequence, the residue in the soil under the mulch was less than 

 when simazine v\ras applied on sod or cultivated soil. The question 

 arose whether this accumulation in mulch was of practical signifi- 

 cance. To answer this question, in 1968, we initiated an experi- 

 ment in a block of Richhaven peach trees at the Horticultural Re- 

 search Center using dichlobenil (Casoron*) as the pre-emergence 

 herbicide . 



TREATMENTS 



The trees were planted in the spring of 1968 and 4 bales of 

 hay weighing approximately 40 lbs each were spread over a circular 

 area extending 7 feet from the tree trunk. (A grower would prob- 

 ably apply only 1 bale to a limited area. The amount applied in 

 the experiment was approximately equivalent to one bale on a cir- 

 cular area extending 3-1/2 feet from the trunk.) Eight single- 

 tree replications of the following treatments were established in 

 November, 1968: (A) hay mulch applied only at planting; (B) culti- 

 vation twice annually in May and early July; (C) dichlobenil at 6 

 lbs of active ingredient per acre (ai/A) applied annually; (D) di- 

 chlobenil at 12 lbs ai/A applied annually; (E) dichlobenil applied 

 on mulch at 6 lbs of ai/A; and (F) dichlobenil applied on mulch at 

 12 lbs of ai/A annually. The mulch was removed prior to establish- 

 ing treatments B, C, and D. 



RESULTS 



Leaf injury . Foliar injury symptoms, characterized by leaf margin 

 yellowing (LMY) and leaf tip burn resulted from treatments with 

 dichlobenil (Table 1). 



Table 1. Percent of leaves on terminal shoots of Richhaven peach 

 trees showing leaf injury following dichlobenil usage. 



% leaves showing injury in late Aug.^ 

 Treatment^ 1969 1970 1971 1972 1973 



On bare soil, 6 lbs dichlobenil 

 On mulch, 6 lbs dichlobenil 

 On bare soil, 12 lbs dichlobenil 

 On mulch, 12 lbs dichlobenil 



^Dichlobenil applied annually in mid-November for 5 consecutive 

 years starting in 1968, 



^Three shoots per tree. 



^Mean separation, within columns, by Duncan's multiple range test 

 at the 5% level. 



The mulch application in May, 1968, prevented foliar injury 

 in 1969, even though one dichlobenil treatment was twice the recom- 



