A Comparison of Handgun and Tree-Row-Volume Pesticide Applications. T. B. Sutton, Department of Plant Pathology, North Carolina State University, Raleigh 29695. C. R. Unrath, Department of Horticultural Science, North Carolina State University, Raleigh 29695. Plant Dis. 72:509-512. Accepted for publication 19 December 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0509.

Handgun (HG) pesticide applications resulted in greater, but less variable, deposits of chelated micronutrients on apple foliage than applications made with a speed sprayer calibrated to deliver the micronutrients at tree-row-volume (TRV) or 70% TRV (70TRV) rates. These results were consistent on both small and large trees at two locations. Tree-row-volume applications resulted in greater deposits than the 70TRV applications on small trees. Deposit from 70TRV was significantly less than TRV on large trees at one location. Handgun applications of captan resulted in significantly better sooty blotch and flyspeck control than TRV or 70TRV applications, but TRV and 70TRV applications provided acceptable commercial control. Handgun applications of naphthaleneacetic acid resulted in greater fruit thinning than TRV application in one of two tests. There was no difference in the degree of fruit thinning in the other test, but fruit on trees sprayed with the HG were larger. Both HG and airblast applications should be used to evaluate pesticides or growth regulators for activity in the orchard.