CONTROL OF SEED-BED LOSSES OF GROUNDNUTS BY SEED TREATMENT

Fungicide treatment of groundnut ( Arachis hypogaea L.) seed usually reduced seed-bed losses and improved emergence, plant populations and yields of this crop when cultivated under rain in the sandy soils of Kordofan (west-central Sudan) or under irrigation in the alkaline clay soils of the Gezira. These beneficial effects were greatest with slightly damaged seeds, such as would occur with machine sowing, but were present even when selected undamaged seed was sown by hand; they were attributed to protection against a number of soil micro-organisms, including Aspergillus niger van Tieghem, A.flavus Link and Rhizopus spp. Agrosan GN (organo-mercurial, 1% mercury equivalent) or 50% thiram powder, both applied at the rate of 1 g./lb. of seed, are suggested as suitable dressings for groundnut sowing seed in the two areas studied. Combined fungicide-insecticide dressings containing up to 40% by weight of γ-BHC did not control a late attack of wilt, due to root attack by cockchafer grubs ( Schizonycha sp.), which developed some 8 weeks after sowing in the Gezira.