Experiments of the Aerial Application of Insecticides on the Tea Garden

The control effects of three acaricides and one insecticide on some pests of the tea garden were examined by aerial spraying. The pesticides used were Estox (O, O-dimethyl-S-(1-methyl-2-ethylsulfinyl)-ethyl phosphorothioate), Ekatin (O, O-dimethyl-S-2-(ethylthio)-ethyl phosphorodithioate), and Delnav. (S, S'-p-dioxan-2, 3-diyl bis (0, 0-diethyl phosphorodithioate)), and Malathion (O, O-dimethyl-S-(1, 2-dicarboethoxy) ethyl dithiophosphate). Acaricides, i. e. Estox, Ekatin, and Delnav, were applied at the rate of 3l/10a.; and the effects on the tea red spider mite(Tetranychus kanzawai KISHIDA) were examined. Insecticide was applied at the rate of 2.5, 3, and 3kg/10a. with 3.0, 2.0, and 1.5% dust of Malathion, respectively; and the effects on the tea cochlid (Phrixolepia sericea BUTLER) and green fly (Empoasca onukii MATSUDA) were tested. The following results were obtained. 1. The application of the three acaricides reduced the population of the tea red spider mite. But the effect of Delnav was not found 20 days after application. The effect of Estox application at the rate of 3l./10 a. was slightly lower than that of 6l. /10 a. 2. The application of Malathion dusts remarkably reduced the population of the tea cochlid and the green fly, but it did not so much reduced that of the tea leaf miner. 3. The amount of emulsion fell on the tea leaves was generally uniform in the field; but in case of Estox application at the rate of 6l./10 a. the emulsion was inclined to drift to the lee. 4. Malathion dusts fell, uniformly and the difference in the amount of dust adhered on the tea leaves between the rate of 3kg./10 a. and of 2.5 kg./10a. was not detected in this experiment.