Recent advances in the chemical control of the sorghum shootfly

Abstract

The introduction of high yielding sorghum hybrids in the mid-1960s indicated that the new cultivars were highly susceptible to insect pest attack. Use of chemicals for the control of the snootily, Atherigona soccata (Rondani), became necessary to realise a full yield potential. This paper briefly reviews the earlier work on conventional foliar sprayings and dustings of the available insecticides which generally failed to give an effective control of the shootfly. Work carried out in the early 1960s showed that the application of phorate, disulfoton, aldicarb and carbofuran granules in the soil at the time of sowing was very effective in controlling the pest. Recently two more insecticides, viz. isofenphos and fensulfothion have been found to be equally effective. However, the cost of applying these insecticides is rather high. Seed treatment with carbofuran at 5 parts a.i. per 100 parts of seed proved to be highly effective and economical. It is now being widely used by farmers in the major sorghum growing area of the country. It has been found that dosage of carbofuran can be further reduced by using a 6:4 mixture of treated and untreated seed. Trials have been conducted to determine the residues of effective insecticides in the soil and in plants at different intervals. Investigations have also been carried out to establish the correlation between the residues of different insecticides in plants and their efficacy in controlling the shootfly. A future strategy for the chemical control of the shootfly is outlined.