Residual activity of insecticides to citrus thrips on lemon foliage

Abstract

The residual activity of insecticides to second instar citrus thrips was measured on lemon foliage in 1998. In April, Dimethoate and Agri-Mek provided only knockdown control of thrips, dropping to <70% mortality by 3 days after treatment (DAT). Baythroid performed slightly better, providing 95% mortality 3 DAT, but by 7 DAT was giving about 74% mortality. Alert, Carzol, Success and AZEXP-2 provided the longest residual activity, lasting 7 days, but began to slip at 14 DAT. AZEXP-1 induced only 74% 0 DAT. Although, residual activity in general was greater in June than April, however this increase in residual activity did not necessarily increase the length of commercially acceptable residual. Agri-Mek and Dimethoate still only provided knockdown activity, and Baythroid was still giving 3 days of good activity. AZEXP-1 performed much better following the June application relative to the April application, providing 3 days of adequate activity. Although we are not certain the reason for this result, it maybe due to the adsorption properties of this chemical relative to leaf physiology. Alert performed similarly in June and April, and Carzol, Success and AZEXP-2 each lasted about 1 week longer.