Date of this Version
Published in Crop Protection 29 (2010), pp 422–428.
Habitat management techniques to control maize stem borers were tested in eastern (Melkassa and Mieso) and western (Sibu-Sire) Ethiopia. These techniques consisted of using mixed cropping of maize with haricot beans at different maize:bean ratios and a ‘‘push–pull’’ (PP) strategy utilizing Napier grass as a trap plant around maize plots as the ‘‘pull’’ and Desmodium in between maize rows as a deterrent or ‘‘push’’. In Melkassa, pest infestations were too low for the cropping system to significantly affect pests, plant damage and yields while in Mieso, where the pest densities were high, intercropping of maize with beans at ratios of 1:1 to 2:1 significantly decreased borer densities compared to pure maize stands. Chilo partellus (Swinhoe) and Cotesia flavipes (Cameron) were the major stem borer and parasitoid species, respectively, recorded both at Melkassa and Mieso. Borer parasitism was higher at Mieso than at Melkassa and it tended to increase with the increase of haricot bean ratio in the intercropping system. Land equivalent ratios of >1 indicated higher land use efficiency in mixed compared to sole cropping, even if pest densities were low. Establishment of Desmodium and Napier grass in PP trials varied from site to site, and poor establishment was observed in plots with low soil pH. Where yields varied significantly, they were lower in the PP than the sole maize plots. Borer densities were low and mostly not affected by the cropping system. However, in the second season when borer density was relatively high, higher levels of infestation and leaf feeding scores were recorded in the control than push–pull plots.