Comparative incidence of maize stem borers on GM and non-GM maize under two smallholder cropping systems in the Eastern Cape province of South Africa

Abstract

The assessment of the comparative performance of technologies, especially, those identified as alternatives, under smallholder farmers' conditions, can enhance the sustainable dissemination and adoption of improved agricultural technologies. To this end, the performance of a genetically modified (GM) stacked-trait herbicide and insect resistant Bacillus thuringiensis (Bt) maize hybrid was compared to a GM herbicide tolerant hybrid, a non-GM hybrid and an open pollinated variety (OPV). The trials were conducted in three localities under natural stem borer infestation in irrigated and nonirrigated (dryland) fields. No stem borer infestation was observed on Bt maize plants from the seedling to the flowering stages in all fields at all trial sites. Stem borer infestation was higher under irrigation compared to dryland conditions. The stem borer complex on non-Bt maize plants under irrigation was dominated by Chilo partellus whilst only Busseola fusca larvae were recorded under dryland conditions. The yield of the Bt maize variety under irrigation was significantly higher than that of the OPV but not different (P>0.05) from that of the non-Bt hybrids. No significant (P>0.05) difference in yield was observed between Bt and non-Bt maize varieties under dryland conditions. The results highlight the need to base dissemination and adoption decisions of relatively expensive agricultural technologies such as GM maize on the results of context specific field trials.