A Future for Ultra-Low Volume Application of Biological and Selected Chemical Pesticides

Abstract

A project to improve the yields of cotton in Rhodesia and Nyasaland involved a study on a key pest, the Red Bollworm (Diparopsis castanea), which included laboratory studies to determine the impact of certain insecticides, a change in spray equipment to minimise exposure of the operator to the spray and timing of sprays to control the first instar larvae. Later it was noted that the spray deposits of insecticide formulations that were mixed with water, were removed by rain. This ultimately resulted in insecticide pollution in rivers. Small scale farmers also had difficulty obtaining sufficient water to spray with a knapsack sprayer, so trials using an ultra-low volume using an oil-based formulation showed similar yields. Hand carried sprayers with a rotary atomiser powered by batteries to apply sprays with specific size range of droplets were used effectively on cotton. ULV sprays had already been recommended to control locusts and further research showed that an electrostatic sprayer could also apply ULV sprays very effectively. By avoiding using a water-based formulation, the insecticide was more effectively applied.