Rotating Herbicides Urged

Our weed control researchers at NDSU keep reminding county extension agents of the growing threats of weed resistance to commonly used herbicides. Those of us in the western part of North Dakota commonly think of weed resistance as a problem for crop growers in the eastern part of our fair state and producers of adjoining states. However, it was in 2009 when resistance of green foxtail to some ACCASE (Group 1) herbicides was first documented in the Minot area. Since then, green foxtail resistance to popular herbicides such as Puma and Axial has been identified throughout most of northwest and some of central North Dakota. It appears other herbicides such as Select and Assure II, also numbers of Group I, still have good activity along with those in Group 2 which are referred to as ALS inhibitor herbicides. These include Everest, Silverado, Rimfire Max, Goldsky and others.

Dr. Richard Zollinger, NDSU Extension weed specialist, suggests several approaches to combating weed resistance. He emphasizes the benefits of early detection. This usually can be done from the combine. Small weedy spots in the field eventually encompass the whole field.

Rotating the chemistry or groups of a herbicide can be accomplished through crop rotations. For example, a producer could use Roundup or Ignite in Roundup Ready or Liberty Link canola this year and Everest in wheat planted next year.

Another option to combat herbicide resistance is to tank mix herbicides with different modes of action. This is an expensive option for wheat but may be more practical for some of the higher valued crops.

When possible, tillage is another option of reducing the survival of resistant weeds. Burn down herbicides along with late planting can be considered but likely a low priority for crops which grow best under the customary cool conditions for May and June.

If you are looking for more information on herbicide modes of action and how each herbicide is classified, there is a page in the new NDSU Weed Control Guide which will give answers to your questions. Dr. Zollinger does not foresee new active ingredients on the horizon so it will be important to study all options to prevent weed resistance. Rotating herbicides of different modes of action will be the best and likely the least costly option.

Volunteer Control Program

Fran Bosch, Williston Vector Control District 1 director, recently announced that the district is offering a voluntary control program to townships. The effort would include application of a larvicide along both county and township roads. For more details, you can reach Fran at 577-4563.

Last summer was a great time to experience the outdoors of this area. Although much of the late spring and early summer was very wet, the grass was tall and green and mosquitoes were few. Much credit for the lack of mosquitoes is certainly due to the knowledge and efforts of the people who guide the vector control project. Even though the snowfall this winter has been minimal, there remain many water ponds which will make good habitat for mosquito and black flies (buffalo gnats) propagation. Let’s hope Mother Nature and Fran’s crew can keep those biting blood suckers at a minimum.