Insecticides for the Control of the Spread of Groundnut Rosette Disease in Uganda

Trials described show that control of the secondary spread of groundnut rosette virus, which is transmitted by Aphis craccivora Koch, is possible with insecticides. In six trials carried out in the period 1965–1970 insecticides tested included dimethoate, phosphamidon and dicrotophos as emulsion concentrates and ulv formulations, menazon as a wettable powder, endosulfan and phenthoate as an emulsion concentrate and aldicarb as a granular formulation. Menazon, at a rate of 294 g a.i./ha applied four times at ten day intervals starting ten days from the germination (emergence) of the crop, was the most efficient insecticide overall in reducing rosette attack. In two trials it was shown to be very effective at rates of 196 and 147 g a.i./ha. Endosulfan and dimethoate and to a lesser extent phosphamidon were also successful as emulsion concentrates and in the instance of dimethoate and phosphamidon as ulv's. Dicrotophos was promising in the two trials in which it was used, but phenthoate was not. Aldicarb, used as a side dressing, was inadequately tested. Ulv application was quick, simple and efficient and has much to recommend it in Uganda conditions. Insecticides significantly reduced the percentage plants attacked in growth up to harvest. There were improvements in kernel quality, shelling percentage and yield. It was concluded that in most seasons even on well grown and well tended crops spraying was worthwhile.