You can do things to prevent the establishment and spread of many noxious weeds and reduce the cost of the required control efforts. Two ways to prevent the establishment of noxious weeds is to create an environment that prevents many of the germinating seedlings or existing perennial plants from producing seed and carrying out actions to prevent the spread of seeds and/or viable plant parts to infest new locations. The following are some options to make a site resistant to noxious weed infestations and options to prevent transporting noxious weed seeds to a new site.


Nature abhors a vacuum. Vegetation of some type will tend to fill in bare areas or areas that are sparsely vegetated. It is important to have desirable vegetation with good vigor to provide competition from the invasion of undesirable vegetation such as noxious weeds. Noxious weeds that are not controlled produce large quantities of seed. These seeds will remain viable for many years until the conditions are right for germination. 

The sites in the County with the most persistent noxious weed problems have a poor stand of grass or grass stands that lack vigor and do not compete well with invading weeds, especially the non-native aggressive noxious weeds.

Grass Seeding

Many of these sites will require grass seeding to provide the competition needed to keep most of the noxious weeds under control. Once the grass is established the population of noxious weeds will decrease reducing the effort needed to control the surviving noxious weeds.


Alfalfa is not a good competitor of musk thistle. Musk thistle should be under control before a field is planted to alfalfa. Alfalfa fields have enough open areas that musk thistle thrives. The first cutting of alfalfa may result in some of the musk thistle flowers being cut off. This does not prevent seed production since the plant will produce new flowers and go to seed. After the grass and other desirable vegetation is established only limited control should be required if the vegetation is managed well.

Grazing Management

Over-grazing of pastures reduces the vigor and competitiveness of grass. Grazing management that includes rest periods for regrowth and replenishment of root reserves in the fall maintains vigorous growing vegetation that will compete well with noxious weeds. It will not eliminate the noxious weeds but will reduce the number that will have to be controlled. Cool season grass, such as smooth bromegrass, needs to be fertilized in order to maintain its productivity and vigor. You may contact the Cooperative Extension Service or the Resource Conservation Service for assistance in planting of grass and other vegetation and the management of pastures.

Dissemination Control

Many people do not realize that preventing the dissemination of seeds and viable plant parts to non-infested sites is also a critical part of an effective noxious weed control program. Musk and plumeless thistle and the knapweeds are spread only by seeds. Canada thistle and leafy spurge can also be spread to new sites by segments of their roots. Many of man's activities can spread the seed or viable plant parts to a new site.


Any machinery, equipment, trucks, fencing material that have been used in a noxious weed infested area should be thoroughly cleaned before it is moved to a new site. Grain and seed suspected to contain noxious weeds should be treated by using a seed cleaner. Screenings left after the treatment should be destroyed. There are no known acceptable method to treat the following:

  • Hay
  • Manure
  • Nursery Stock
  • Sod
  • Soil
  • Straw
  • Other Similar Material

Such article should not be moved from the location at which they initially became infested, but may be utilized at that location for commonly recognized purpose.

Sellers of Forage, Grain, Seed & Sod

Farmers who sell hay, straw, sod, grain or seed should take the actions needed to prevent the dissemination of noxious weeds to the buyers. The noxious weeds could be controlled prior to the harvest of the crop. Grain and seed could be cleaned prior to its sale. The Authority will inspect fields, upon request, prior to harvest and certify them noxious weed free if no noxious weeds are found or if the necessary treatment is completed.


Buyers and users of these articles should insist that they are noxious weed-free. Mulching of newly seed areas may start new noxious weed infestations. Individuals and governmental bodies should use a noxious weed-free mulch to prevent infesting new areas. The State Roads Department has initiated a policy of using noxious weed-free mulch on state road seedings.