PROTECTION OF SORGHUM AGAINST SOIL FUNGI, SOIL PESTS AND COVERED SMUT BY COMBINED INSECTICIDE-FUNGICIDE SEED DRESSINGS

Treatment of sorghum ( Sorghum vulgare ) seed with fungicide dressings controlled covered smut ( Sphacelotheca sorghi ), the major disease of sorghum in the Sudan, and usually resulted in appreciably better stands. In the Sudan Gezira, powder dressings containing 20–40%γ-benzene hexachloride (γ-BHC) applied at the rate of 1g./1b. of seed effectively protected sorghum seedlings from root attack by chafer grubs ( Schixonycha sp.) and significantly increased stands and yields. No certain evidence of this effect was obtained with dolichos bean ( Dolichos lablab ) or groundnut ( Arachis hypogaea ), and the different responses shown by these plants as compared with sorghum are attributed largely to differences in seed germination and root system. An application rate of 0·08 %γ-BHC/seed was sometimes slightly but appreciably phytotoxic to sorghum in the field and more markedly so in greenhouse experiments. A powder containing 25% thiram and 20%γ-BHC applied at the rate of 1g./1b. of seed is recommended as the standard seed dressing for sorghum in the Sudan.