ABSTRACT
Worldwide there are very few herbicides formally registered for use in cassava. This considerably limits their use, yet many farmers are using herbicides that were found to be effective without obviously damaging the crop. Most of these herbicides are applied preemergence and followed by manual or mechanical weeding once the cassava has formed a canopy. Taylor et al. (2004) considered herbicide-resistant cassava as an option with the current production practices. Herbicide-resistant or -tolerant cassava would allow the use of post-emergence herbicides and reduce the labour in weeding. The ex ante impact of introducing herbicide-resistant cassava in Colombia was estimated to bring about 15-25% cost savings for cassava producers, with a benefit to Colombia’s economy of US$300 million over a 14-year period (Pachico and Rivas, 2003). Additional benefits would be positive environmental effects through a reduction in tillage and manual or mechanical weeding, leading to less erosion and soil loss.
