Seed treatment with systemic insecticides for the control of red-legged earth mite (Halotydeus destructor)

Abstract

Successful control of the red-legged earth mite, Halotydeus destructor (Tuck.) (Acarina : Eupodidae) was achieved by treating subterranean clover, vetch, and pea seed with systemic insecticides before sowing. The most satisfactory measure of dosage was the quantity of insecticide per unit area of seed surface. Residual action in peas for up to one month after sowing was achieved with dimethoate, metyl demeton, phorate powder, and phorate liquid at dosages of 0.3, 1.0, 2.0 and 5.0 grams per .square metre of seed surface respectively. A t these dosages, seedling emergence of peas was reduced by two to seven per cent. Phorate inhibited the germination of cereals to a greater extent than it did legumes. These insecticides may kill the nodulating bacteria of legumes and this is a potential difficult in their use. Dimethoate appeared to be less toxic than either methyl demeton or phorate. Stimulation of bacterial growth can also occur at certain dosages. This problem needs further investigation.