Management Practices for Controlling Various Thrips and Their Transmitted Tospoviruses in Tomatoes: 1. Chemical Control

Abstract

Thrips are insidious insects having a minute size and excellent hiding capability. They are difficult to see with the naked eye. They are polyphagus and cause serious economic damage by feeding on foliage and transmitting viral pathogens. In south Florida, tomato plants were seriously damaged by tospoviruses vectored by thrips in the 2014–15 vegetable growing season. In our recent survey of commercial tomato fields, we recorded three species of thrips including melon thrips, common blossom thrips and western flower thrips. The latter two species were reported to be the most efficient in transmitting tospoviruses in tomatoes. In an effort to develop an integrated management program for controlling thrips and tospoviruses, we conducted three studies to evaluate insecticides belonging to diverse modes of action under field conditions. In the first study, we used insecticides alone, in combination or in rotation as a foliar spray. In the second study, we used premixed products as foliar sprays. In the third study we used insecticide as a soil drench at planting followed by two drip applications at 14 and 28 days after planting. After four weekly applications in the first study, all insecticide treatments significantly reduced melon thrips as observed in the postspray samples. In the same postspray samples, common blossom thrips and western flower thrips were absent in spinetoram, flonicamid, spirotetramat + spinetoram, clothianidin + malathion, chlorpyrifos, and bifenthrin treated plants. In the second study, melon thrips were significantly reduced by spinetoram followed by cyantraniliprole. In this study, insecticide treatments did not reduce the flower thrips population. Insecticide treatments in the third study did not reduce tospovirus incidence in tomatoes.