Increasing herbicide-resistant strains of kochia, Russian thistle, wild oat, and Persian darnel are evident in Montana farm fields. Wild oat resistance to multiple modes of action including ACCase- and ALS-inhibitor herbicides is of increasing concern for predominantly cereal-based cropping systems of Montana. Furthermore, the recent evolution of glyphosate-resistant kochia (first weed to develop glyphosate resistance in Montana) and presence of auxinic (dicamba and fluroxypyr)- and ALS-inhibitor-resistant kochia is a potential threat to Montana cropping systems. Kochia resistance to auxinic herbicides was found in a few Montana wheat fields in 1995, although the extent of infestation is limited. Glyphosate and ALS-inhibitor (multiple-resistant) kochia biotypes were found in chem-fallow (wheat-fallow rotation) fields in northern Montana (2012/2013) and expected to be more widespread in occurence. Further spread of glyhosate-resistant kochia is a potential threat to the sustainability of glyphosate-resistant (Roundup Ready®) crops including corn, alfalfa, and sugar beet grown in Montana. More importantly, there is lack of POST herbicides in sugar beet production other than glyphosate and triflusulfuron (ALS-inhibitor herbicide) which are effective on kochia. Therefore, it is crucial for sugar beet growers to better manage the resistant weed seed bank in crops (corn, wheat/barley: more effective alternative modes of action available) grown in rotation with glyphosate-resistant sugar beet.