FURTHER FIELD-EVALUATION OF THE EFFECTS OF REPEATED FOLIAR SPRAYS OF INSECTICIDES OR FUNGICIDES ALONE AND IN ADMIXTURE ON AN ORGANOPHOSPHATE-RESISTANT STRAIN OF THE ORCHARD PREDATORY MITE TYPHLODROMUS-PYRI ON APPLE

In experiments in a commercial apple orchard in southern England in 19 92 and 1993, the effects of a series of four or five foliar sprays of the insecticides chlorpyrifos or carbaryl, or of the fungicides thioph anate-methyl or mancozeb, or of mixtures of each insecticide with each fungicide, on populations of the orchard predatory mite Typhlodromus pyri Scheuten were examined. The effects of a single spray of the inse cticide pirimiphos-methyl, applied pre- or post blossom, were also inv estigated. Mancozeb was harmful to T. pyri, adverse effects being appa rent after two or three sprays. Thiophanate-methyl significantly reduc ed numbers of T. pyri in one experiment. The mixtures of mancozeb or t hiophanate-methyl with chlorpyrifos were more harmful than either prod uct alone. Pirimiphos-methyl, even when applied pre-blossom at the mou se ear growth stage, was harmful leading to increases in pest mite pop ulations. Copyright (C) 1996 Elsevier Science Ltd