Abstract
Control of the stem borer, Busseola fusca (Fuller) on sorghum [Sorghum bicolor (L.) Moench] using the most effective and least expensive insecticide was investigated at Halhal Begos and Halhale in Eritrea, 1997-99. The insecticides used were Furadan 5G and Cymbush 1G applied at planting with the seed and 45 days after germination, and Thiodan 35% emulsifiable concentrate and Carbaryl 85% wettable powder applied as sprays to the foliage 30 days and 45 days after germination. All the insecticide treatments significantly reduced stem borer infestation and damage compared to the untreated plots. Furadan and Cymbush gave significantly lower infestation and larval damage. Thiodan and Carbaryl also showed significantly reduced stem borer damage compared to the control, but less reduction than Furadan and Cymbush. There were significant differences in days to heading, maturity, and plant height. Plants in the control plots had later heading and maturity dates and shorter plant height compared to the treated plots. Yield increase due to the use of insecticides ranged from 16.3 q to 29.5 q ha-1 (1639-2950 kg ha-1). Furadan and Cymbush gave a yield increase of 147% and 134%, respectively. There was a significant positive correlation between the number of stem borer larvae, percentage of infestation and damage, and significant negative correlations between the yield and percentage of damage and between the yield and number of stem borer larvae. The economic analysis of the insecticide efficacy showed that Furadan gave the highest benefit of U.S. $465.63 ha-1 over the control.
