The economic value of glyphosate-resistant canola in the management of two widespread crop weeds in a Western Australian farming system

Multi-species RIM, a bio-economic model that simulates the population dynamics of two annual weed species over a 20-year period, was used to investigate the value of transgenic glyphosate-resistant canola in the management of herbicide resistant annual ryegrass and wild radish in a Western Australian dryland farming system. The perceived advantage of growing this crop is the potential to control post-emergent weeds with the broad-spectrum herbicide glyphosate, and without the yield penalty evident in triazine-resistant canola. We found that the economic value of glyphosate-resistant canola is consistently higher than that of the commonly grown triazine-resistant canola. However, the benefits of glyphosate-resistant canola would need to be weighed up against potential risks to marketability (due to consumer resistance) and risks of increased weed resistance to glyphosate (due to increased selection pressure).