Spray Interval Studies on Cotton in Eastern Uganda in 1961-1965

Abstract

Trials on interval of spray and number of sprays carried out over four seasons at Serere Research Station in Eastern Uganda are described. These trials compared the efficiency of control of the main bollworm and bug pests of cotton obtained with DDT at the rate of 1 lb. per acre per application. Spray intervals of 10, 15 and 20 days were used with a fourspray regime, and 14 and 21 days with fourand six-spray regimes. It was found that over a range of climatic conditions the 14/15-day interval gave the best response in terms of increased yields of seed cotton when used with a four-spray regime. The former Uganda standard recommendation of four sprays at 10-day intervals was amended accordingly. With a four-spray regime all intervals gave a reduction in the percentage of stained seed