Optimal use of pesticides for controlling insect pests in apple orchards

In considering the possibility of controlling the spray volume of pesticides according to cultivation period, actual spray volumes for controlling insect pests were investigated in an apple orchard in the city of Gongju in Chungnam province. Before the flowering period, a spray volume of 3721/10 a was sprayed in the middle of April, whereas 449-452 1/10 a was sprayed from June to August when the leaves and fruit were luxuriate. Though 372 1/10 a, much less than the standard spray volume, was used for controlling moths around the middle of April, more than the amount of the active ingredients sufficient for LC₉₅, 0.018 kg a.i./10a, was attached in all treated plots. In mid-July and late August, however, the standard spray volume, 450 1/10 a was sprayed, but the amount of the active ingredients in several plots was less than that inquired for LC₉₅. This result showed that it was impossible to increase the treatment efficiency of the active ingredients by simply increasing spray volumes. It was identified that the more the amount of the active ingredients (kg a.i) per unit area (10 a) was, the better were the control effects against insect pests. Regarding the results of using insecticide spray to control aphids, A. citricola in the middle of June, the amounts of the active ingredients in several plots were under 0.010kg a.i./10a for LC₉₅ so that less than 80% of the control value was shown after seven days of treatment. However, with the exception of three plots, all other plots that were sprayed with more a larger amount of the active ingredients and showed a 100% control value against A citricola.