15.7 Herbicide Resistance to ACCase Inhibitors

As is true for all herbicides, consistent or near-continuous use of these herbicides has selected for resistant individuals, which soon dominate local weed populations.  In most cases, resistance to ACCase inhibitors is due to a single DNA base change in the gene that codes for the ACCase enzyme.  This reduces its binding affinity for the herbicide (herbicide is unable to bind strongly to it).  In addition, some resistant weed biotypes have been reported with enhanced levels of herbicide metabolism.  Then there is the observation of cross resistance that the animation discussed, where plants that are showing resistance to dims are also resistant to the fops, even though no fops herbicide had ever been applied.

A website has been established and is maintained by a consortium of public and private weed researchers to document and catalog the latest information on herbicide resistant weeds world- wide. The International Survey of Herbicide Resistant Weeds is a collaborative effort between weed scientists in over 80 countries and is located at at www.weedscience.org .  The consortium’s 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.

• Ian Heap.  Director of the International Survey of Herbicide-Resistant Weeds.
  IanHeap@weedscience.org
• Mark Peterson. Chairman of the Herbicide Resistance Action Committee.
  mapeterson@dow.com
• Michael Horak. Chairman of the North American Herbicide Resistance Action Committee.
  michael.j.horak@monsanto.com