Maximising the effectiveness of insecticides to control mealybugs in vineyards

Abstract

Mealybugs (Hemiptera: Pseudococcidae) are the most important insect pests in New Zealand vineyards because they vector grapevine leafroll virus, which seriously debilitates vines and reduces wine quality. A field trial was conducted on a commercial vineyard using the insecticides prothiofos (Tokuthion® and buprofezin (Applaud™). Factors tested were the timing and number of applications, water rate (250, 500 or 1000 litres/ha) and inclusion of an alkylsilicone or organosilicone spreader-type adjuvant. Prothiofos was applied in late September (late dormant), while buprofezin was sprayed at late dormant, mid October and late November (pre-flowering). The best treatments for reducing mealybug numbers and proportion of infested leaves were prothiofos at late dormant and two later applications of buprofezin. Two applications of buprofezin were more effective than one, more than halving the number of mealybugs. A water rate of 500 litres/ha was equally as effective as 1000 litres/ha. None of the three adjuvants improved the efficacy of prothiofos or buprofezin.