Status of Herbicide Resistance in Montana – Prashant Jha : January, 2014

The International Survey of Herbicide Resistant Weeds is a collaborative effort between weed scientists in over 80 countries.  Our main aim is to maintain scientific accuracy in the reporting of herbicide resistant weeds globally.  This collaborative effort is supported by government, academic, and industry weed scientists worldwide.  This project is funded by the Global Herbicide Resistance Action Committee and CropLife International.

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.


Link to the database: Status of Herbicide Resistance in Montana – Prashant Jha : January, 2014

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