Strategies to Confirm and Manage ALS-Resistant Common Chickweed in Wheat in Kentucky (2013-2014)

During the past growing season a number of wheat fields had common chickweed that was not controlled with Harmony Extra or Finesse. Both products control weeds by inhibiting the Acetolactate Synthase (ALS) enzyme. While ALS-resistant chickweed has not been confirmed in Kentucky, there is mounting evidence that such resistance may be present. This resistance was first reported in New Zealand and in Europe in the mid 1990's and is now present in Virginia, Maryland, Delaware, North Carolina, and Pennsylvania. There are a number of reasons why Kentucky growers should be concerned about this potential problem. The fact ALS-inhibitor herbicides are applied to 75 to 80% of KY wheat acres places high selection pressure for developing ALS resistance. The ALS-inhibitor herbicides are prone to developing resistance and are considered a high risk for resistance compared with certain other groups of herbicides. As the name implies, common chickweed is a widespread problem weed. It tends to be more competitive compared with several other broadleaf weeds that occur in wheat in Kentucky. OBJECTIVES: This research will be conducted to help confirm the presence of ALS-resistance in common chickweed in Kentucky and to compare herbicide options for managing this problem weed in wheat.