Control of the onion thrips, <i>Thrips tabaci</i> Lindeman, and necrotic streak disease, by Pyrifluquinazon application

Abstract

The effectiveness of control by the application of pyrifluquinazon against Thrips tabaci Lindeman and necrotic streak disease were evaluated using field tests on infested commercially grown Welsh onion plants. The population density of the adult and larval thrips were significantly lower in plots with pyrifluquinazon application than in the control plot, and the degree of leaf damage by thrips was maintained from about one-third to one-half in the treated plot compared with the control plot. Furthermore, the percentage and the number of leaves with necrotic streak disease were significantly lower in the pyrifluquinazon application plot than in the control plot. The number of necrotic streak disease spots was significantly lower in the treated plot compared with the control plot. These results indicated that pyrifluquinazon is an effective insecticide for the control of T. tabaci and necrotic streak disease.