Control of Cockchafer Grubs by Seed Treatment

Abstract

IN the Sudan Gezira, cockchafer grubs (white grubs) of the genus Schizonycha (Melolonthinae) can attack the young roots of sorghum (Sorghum vulgare Pers.), causing wilting, stunting and death with attendant poor stands and considerably reduced yields. Older plants with established root systems are less commonly killed, although it is likely that the grubs feed on the roots. Use of powder seed-dressings containing fungicide (thiram or organo-mercurial) and 20–40 per cent by weight of gamma benzene hexachloride (BHC) gave almost complete protection of sorghum seedlings from these pests. In field-plot experiments, BHC-treated seed invariably gave 90–100 per cent stand, whereas fungicide-treated seed gave poor stands of 50–60 per cent in many cases. By ‘percentage stand’ is here meant the percentage of good holes to total holes sown. In some plots BHC seed-treatment resulted in 20–30 per cent increases of grain and straw yields.