Why be concerned about the occurrence of weed resistance?
The reasons for concern probably vary depending upon one’s position (producer, agrichemical retailer, crop consultant, etc.), but practically all reasons can find common economic grounds. If previously controlled weed species are no longer controlled by a particular herbicide, the return on the herbicide investment is greatly reduced. Agrichemical retailers and crop consultants may find themselves the recipients of producer frustration and anger should the problem develop in one of their customer’s fields. This anger may lead to a lost account for the retailer. Weed resistance may dramatically reduce the effectiveness of a particular family of herbicide chemistry, thus reducing the useful life of these herbicides and adversely effecting the industry as a whole. Before entering into a discussion of how weed resistance develops, we should first define some terms often encountered when discussing how herbicides work. Herbicide mode of action may be defined as the metabolic or physiologica
