Early detection and management of herbicide resistant weeds

Abstract

Small weed patches may be noticed in fields after herbicide application, but they typically do not have a significant impact on the season’s crop yield. As a result, they are usually not treated as a threat to future yields. However, if these patches harbour weed biotypes resistant to one or multiple herbicides, resistance alleles can spread both spatially (via various dispersal pathways, including seed transport by machinery and commodity contamination) and temporally (through seed persistence). This poses a significant threat to herbicide-based weed management. Once these populations spread and cover a large enough area, eradication becomes improbable despite all the resistance management efforts. Therefore, a proactive and collaborative endeavour is needed to detect and manage small and patchy resistant weed populations. In this paper we review the current potential of weed resistance detection using imagery and molecular markers as well as possible weed management approaches. Finally, we advocate for the use of a combination of these techniques to manage herbicide resistant weeds when populations are small. This multifaceted approach is presently not applicable to all resistance mechanisms, and all weed species located in any crop, but could initially focus on biotypes and species that are easy to detect and represent the greatest threat.