Zollinger Gives Heads Up On Dicamba Resistance

Richard Zollinger, North Dakota State University Extension Service weed specialist.  (Forum News Service/Agweek/Mikkel Pates)


Heads-up, dicamba-using farmers: Richard Zollinger, a North Dakota State University Extension Service weed specialist, brings home a report from the Western Society of Weed Science conference, March 13-16 in Coer d’Alene, Idaho.

“There were several talks that results had implications to ND growers,” Zollinger says, and he three gig ones:

  1. Around 20% of kochia in Colorado has some level of dicamba resistance.
  2. A graduate student at Montana State University reported dicamba biotypes that were resistant to 2 lbs ai/A of dicamba. They extrapolated that the application rate to cause 90% control (ED90) was 3.55 lbs active ingredient per acre. The student also determined there was a “fitness penalty of about 30%” for some parameters of dicamba resistant biotypes.
  3. Another graduate student from Montana State University documented glyphosate resistant Russian thistle in Washington , Oregon, and Montana.


The scientists are working to monitor the spread of herbicide resistance to weed killers that farmers need to stay productive. Zollinger and NDSU colleagues are among the nation’s leaders in getting the word out about the best management practices to keep those tools available.