EFFECTS OF APPLICATION DATE ON THE PERSISTENCE OF CLOFENTEZINE RESIDUES: IMPLICATIONS FOR MANAGEMENT OF RESISTANCE IN THE EUROPEAN RED MITE

Abstract

AbstractThe effects of timing of applications on the persistence of chemical and biologically active residues of clofentezine were tested on apple foliage during two seasons. Residues from prebloom and petal fall applications were less persistent than those in mid-season. Early season applications were toxic to European red mite for 7–21 days but mid-season applications were toxic for as long as 50–62 days. Chemical residue losses were also faster in the early season. Persistence of chemical residues was related to the rate of leaf growth and expansion. In 1991, foliage area expanded 244% per week during the prebloom period, 23% per week at petal fall, and 10% per week in July (mid-season).In a field test, applications of clofentezine at petal fall reduced European red mite populations within 7 days and mite numbers remained below economic thresholds for 6 weeks.