European Red Mite Control in North Carolina Apple Orchards with Early-Season Applications of Acaricides1

Abstract

Orchard experiments were conducted during 1967–68 to determine the proper dosage, timing, and selection of acaricides in early-season treatments for control of panonychus ulmi (Koch) in apple orchards. Petroleum oil spray was more effective in killing over-wintering eggs as the interval between oil application and egg hatch decreased. One gallon of Humble 70-second viscosity oil applied at the tight-cluster or pink stage of fruit-bud development was more effective than 2 gallons applied at the dormant or green-tip stage. Humble 60- or 70-second viscosity oil, Morestan® (6-methyl-2,3-quinoxalinedithiol cyclic S, S -dithiocarbonate), TH 367–1 (2-fluorethyl 4-biphenylylacetate), and demeton + tetradifon were the more effective acaricides when used in only 1 preblossom application. Demeton was more effective than dimethoate as an early-season acaricide. As 1 application, demeton or dimethoate were more effective when applied at the petal fall stage than at the pink-bud stage. Dimethoate applied at the pink-bud stage at the rate of 1 ½ pint per 100 gallons of water gave poor early-season mite control. However, when the dosage was halved and applied at the pink and petal-fall stage, commercial control through June resulted. As 2 early-season applications, demeton or dimethoate were more effective when applied at pink and petal-fall stages than at petal-fall and 1st cover.