Busseola fusca (Fuller) is a serious pest of maize and sorghum in Tanganyika where it occurs mainly at altitudes of 4,000 ft. and over.
Laboratory work on the life-cycle and on the diapause of the larva is described. Diapause is terminated by contact with water.
Field work at Nzega, Western Province, indicates that the first sowings, made within two to three weeks of the beginning of the rains, are likely to be heavily attacked by larvae of the first generation. These are the progeny of a “raininduced” flight of adults of Busseola derived from diapause larvae in the maize and sorghum left in the fields from the previous season, the larvae being induced to pupate when the stems are wetted by rain.
The number of generations in the main crop season, November–June/July, is two. A third generation occurs in sorghum tillers produced after June/July.
No alternate hosts of importance comparable with maize and sorghum have been found.
Cultural control by burning the crop residues left in the field after harvest, in order to destroy the diapause larvae, is not practicable in peasant agriculture as these residues are required for such purposes as palisading, building of contour banks and for grazing cattle and goats during the dry season.
Chemical control of the first generation of Busseola in young maize can be achieved by the application of a dust containing 2·5 per cent. DDT into the funnel of the plant. In 13 experiments on peasant-owned plots at Mbeya, in which a dust containing 2·5 per cent. DDT was applied four times, at weekly intervals, beginning about 18 days after germination, and at the rate of 10 lb. per acre, the average weight of maize cobs from 100 plants was increased from 12·46 to 22·82 kg., an increase of 83·1±19·0 per cent. Factors other than Busseola which affect the yield are discussed and it is suggested that control measures would probably be worthwhile only where a combination of a suitably fertile soil, early planting and adequately distributed rainfall obtains.
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