There is no silver bullet when managing invasive weeds. What has been proven effective for managing noxious weeds is the use of several combinations of control, called integrated weed management. By using several techniques to control weeds you reduce the chance that weed species will adapt to the control techniques, which is likely if only one technique is used. For example, if a herbicide is used over a long period of time, a weed species can build up a resistance to the chemical.
A long-term integrated weed management plan, that considers all available management control techniques or tools to control weeds, can be developed for a particular area. Any integrated weed management plan or strategy should focus on the most economical and effective control of the weeds and include ecological considerations.
The long-term approach to integrated weed management should reduce the extent of weeds and reduce the weed seed stock in the soil. It should consider how to achieve this goal without degrading the desirable qualities of the land, such as its native ecology or agricultural crops. When using any of the following methods of control to eradicate or manage invasive weeds, the use of revegetation should also be a key component of your weed management plan.
Many landowners may unknowingly plant invasive plants because they are attractive. Salt cedar, toadflax, common tansy, and yellow flag iris are just a few examples of beautiful plants that are highly invasive. To be aware of the Montana state noxious weed list (link) and what is on your property is very important. If you educate yourself regarding those weeds, know what your long-term wish is for your property, and learn how to put an integrated weed management plan together to effectively manage your property, you will be well on your way to eradicating invasive weeds.
Herbicides are chemicals approved by the EPA to control invasive weeds. These chemical formations are designed to work specifically on target plants with minimal impact to non-target plants, animals or humans unless they are improperly applied (always follow label instructions). The MWCA will not provide herbicide recommendations due to many soil, climate and invasive plant variables. Please contact your local weed district to ascertain your herbicide needs.
The use of insects, fungus, or sheep and goats to manage or control invasive weeds. This method of control can be very effective on certain species of invasive plants, such as leafy spurge, toadflaxes and knapweeds.
Mowing can prevent the production and spread of seeds if timed correctly. In general, mowing just prior to, or at the time of flowering will provide the best results. Many farmers use cultivation to control weeds through tilling at appropriate times. However, be aware that given the tenacity of some of our invasives, many will learn to adapt to flowering beneath the mower height- such as knapweed!
Some invasive weeds can be hand-pulled. However if invasive weeds have creeping, extensive root systems, this method is not only ineffective, but can make the problem worse. Hand-pulling only works for tap-rooted weeds and small infestations; it is extremely labor intensive.
Once weeds are eradicated from a location, it is imperative that the right plants fill the space. Often times when you get rid of a target weed or create a disturbance, other weeds come in and take over, such as cheatgrass. By learning what plants might grow and compete well with your target invasives, you can create an environment that prevents invasives from getting a foothold.
Prevention – The best form of control is not to let weeds propagate in the first place! This is done through education and awareness and maintaining vigorous, healthy vegetation that will compete with weeds.
Leafy spurge is one of the worst noxious weeds we have in Montana! It has extensive root systems of up to 30 feet deep, making it extremely difficult to control.