ALS inhibitors, Glyphosate, Kochia, Herbicide resistance, Photosystem II inhibitors, Synthetic auxins

Herbicide resistance in weeds is evolving rapidly worldwide complicating weed management and threating agricultural sustainability and food security. Resistance has been reported to all known herbicide modes of action and no new mode of action has been marketed in the past 25 years. Though most reported cases of resistance involve a single herbicide site of action, multiple-site resistance is increasing.  As an example of the progression from single to multiple site resistance, this paper reviews the evolution and implications of herbicide resistance in kochia [Kochia scoparia (L.) Schrad.), a common and economically important weed in the North American Great Plains.