Herbicide-resistant weeds: Management strategies and upcoming technologies

Abstract

Herbicides have contributed to substantial increase in crop yields over the past seven decades. Over reliance on herbicides for weed control has led to rapid evolution of herbicide-resistant (HR) weeds. Increased awareness of herbicide resistance and adoption of diversified weed control tactics by farmers is critical to manage HR weeds. HR weed management must include both chemical and non-chemical methods as well as the best management practices to prevent evolution and spread of HR weeds. The severity of the HR weed problem has also renewed efforts to discover new technologies. One technology will be a new generation of crops with resistance to glyphosate, glufosinate and other existing herbicides (e.g. ALS inhibitors, 2, 4-D, dicamba, HPPD inhibitors, and ACCase inhibitors). These stacked-trait crops will provide new options with existing herbicides, but will not be the total weed management solution because several weeds have already evolved resistance to these herbicides. Another technology in the early stages of development that has potential to combat HR weeds is the use of RNA interference (RNAi) technology. The use of RNAi involves the topical application of doublestranded RNA (dsRNA) to interfere with the expression of herbicide resistance genes in weeds to reverse the resistance. RNAi is a revolutionary technology for resistant weed management, but is still years away from commercialization. While no new herbicides are on the horizon, in the near future, the HR management strategies must utilize an array of tools to disrupt HR weeds from evolving and spreading, with the ultimate goal of not allowing any weeds to survive and set seed.