Working together to strengthen and support noxious weed management efforts in Montana.

Chemical Herbicide Weed Control

Chemical herbicides are important tools for controlling noxious weeds. It is important to understand the effects and limitations of those used for control of noxious weeds. Herbicides are categorized as selective or non-selective. Selective herbicides kill a specific type of plant, for example, 2,4-D kills only broadleaf plants. Herbicides are also selective based on the rate of which they are used. Non-selective herbicides such as Roundup will kill all plants that come into contact with it. See herbicide labels for complete information on herbicide use.  The label is the law.

Certain herbicides require licensing and training, and it is very important to follow all label and site restrictions when using these products. An herbicide is a tool that will create a weed-free window of opportunity. The success of a weed control program is determined by the management strategies which are used following the application. A multifaceted approach might include proper grazing practices, re-seeding, hand pulling, and other integrated control methods.

For those who are concerned about the dangers of herbicide use, it is important to remember that these chemicals undergo stringent testing by the EPA, and they are designed to affect plant systems, not mammals. Most broadleaf herbicides are growth regulator products, meaning they accelerate cellular activity and respiration in broadleaf plants. When used according to label instructions, herbicides are very low in toxicity to fish, animals, and humans as well as the environment.

Successful Weed Management Principles for Herbicide Usage

Once the decision has been made to utilize herbicides as the method for control of noxious or nuisance weed species; there are 3 basic principles that need to be fundamentally addressed for successful applications. These standard principles are:

  • Proper herbicide choice for the target species of concern
  • Proper timing of herbicide application(s)
  • Proper “consistent” application technique
  • Additional site conditions/factors may also need to be considered to assure the most effective herbicide application out comes such as; soil type, slope, existing vegetation (target and non-target plants). Please contact a local weed management professional for technical assistance.

The herbicide industry continues to improve upon its products and new and improved herbicides are coming out each year, as well as generics.  All state-listed noxious weeds can be treated and managed by herbicides at this time, please check with your local weed professional to obtain the proper herbicide and rate for your target species, and please remember to calibrate your sprayer for the best possible application.

Visit the MWCA web page with information about How To Calibrate Spray Equipment.

Visit the Montana Department of Agriculture page for information about pesticide enforcement.

National Pesticide Information Center