Missoula County Weed District & Extension

Weed Management


Revegetation

Pseuderoegneria spicata lo-res© Nancy SeilerThe quick and successful establishment of healthy, use/type appropriate vegetation is the ultimate goal for any revegetation project. It is the most effective way to minimize weed invasion and establishment on your site in the long term.  

It is important to note that any form of weed control initiates a disturbance and if there is not good coverage of desirable vegetation, revegetation may be necessary. Revegetation is especially important on sites where noxious weeds like leafy spurge have been established for multiple years because the seed bank of the desirable vegetation has been suppressed and depleted. Once weeds are controlled on these sites, other exotic weeds like cheatgrass establish rapidly.  

Before starting any type of vegetation management or revegetation project, it is important to ask yourself two questions:

  1. "What do you want to grow?"
  2. "What will you be using the site for?

The answers to these questions will help guide your choice of grass and forb species that will be able to thrive under the conditions present at the site.  There are many revegetation mixes so it is important to educate yourself on mixes that are appropriate for your specific use and area. Be very careful using "wildflower mixes" since the term wildflower does not always mean native, and they can often include noxious weed seeds. 

Finally, it is important to record the conditions of your site and your planned uses and goals for your property in a vegetation management plan. This allows you to keep a clear record of the plant community you have and the plant community you are working toward.  Below is an example of a vegetation management plan and a template for you to fill out for your property.

Landowner Vegetation Management Plan - Example
Landowner Vegetation Management Plan - Blank Form

For more information on specific revegetation recommendations:
A Source Guide to Revegetation and Weed Control Options in Missoula County
Revegetation Guidelines for Western Montana
Dryland Pastures Publication
 

 

Mowing

Mowing can reduce seed production of noxious weeds; however, it is not generally effective at controlling weeds when it is the only control tool used. For example, mowing spotted knapweed multiple times a year produces prostrate low flowering plants. In addition, mowing weeds like leafy spurge; stimulate root growth because of their competitive root system. For mowing to be most effective, it is best to raise the mower blade above the desirable vegetation and mow the noxious weeds right below the bud of the plant before it has set seed that year. Remember to integrate mowing with other integrated weed management tools.

Kath.and.spurge

Mowing Publications:

Mowing to Manage Noxious Weeds

Insects

Spurge Bio 1What are Insects and Biological Control?
When we use natural enemies to reduce invasive species populations, we refer to the natural enemies as biological control agents, or sometimes biocontrol agents. Since many serious rangeland weeds are introduced species, they have few established natural enemies on this continent. Biological control can be defined as the use of living organisms to depress the population of a pest. However, biological control could be more accurately called biological suppression, i.e. reducing the population of the target weed to an acceptable level. Often the goal of those who use biological control agents on rangelands is to suppress the alien weeds and at least partially restore the native plant community. It is most effective on dense infestations over large areas.


Click on the noxious weed below for more information on the insects that impact them:

small dalmatiantoadflax
Toadflaxes
 
small leafyspurge
Leafy spurge
 
small spottedknapweed
Spotted 
knapweed 
small stjohnswort
St. johnswort
 

Interested in obtaining insects for your property? Please click here.

Grazing

It has been recognized that grazing animals can influence the mix of plants in the vegetation community. Cattle tend to prefer grass and over time move the plant community towards more woody shrubby plants (browse) and forbs. Sheep tend to graze forbs and goats prefer browse, which over time will increase the grass component of the plant community (See diagram below for further explanation). However, each animal species will utilize all these groups of plants seasonally. Depending on the weed species and the season, it is possible to develop a system to suppress infestations. In recent years, there has been an increased effort to integrate grazing with herbicides and biological controls.

Grazing Diagram

The use of sheep and goats for weed control has gained considerable interest recently due to the increasing problems caused by broadleaf weeds (mainly spotted knapweed and leafy spurge) in the Northwest. Although grazing doesn't kill these plants immediately it will stress the plants and can reduce the soil seed bank over time if animals are introduced while the plants are in flower. In order for grazing to be effective it must continue for multiple years. Intensive grazing can cause soil disturbance and damage to desirable plants so it's good not to let animals stay in one area for too long. Animals are also good at carrying weed seeds from one area to another, either in their fur or in their gut, so caution should be taken when transporting animals that have been grazing noxious weeds to a weed-free area. For detailed information on using sheep and goats for noxious weed control contact the M.S.U. Sheep institute.

Handpulling


SpottedKnapweed-Color400Always wear gloves when handpulling any type of plant. Only handpull weeds with taproots. Examples of common noxious weeds that can be handpulled are spotted knapweed, blueweed and houndstongue. Handpull weeds when the ground is moist which is usually in the spring or fall in Montana. Using a dandelion digger for spotted knapweed and a shovel for houndstongue is recommended. Always make sure to discard the weed properly once it is handpulled. Burning, mulching, or throwing the weeds in the garbage are some examples of disposal. Handpulling is usually more successful on small weed infestations where there is still good coverage of desirable vegetation. Keep in mind that spotted knapweed seeds are viable on average for 8-10 years while houndstongue seeds are only viable for 1-2 years. When handpulling in areas without desirable vegetation, revegetation will be necessary. Handpulling weeds like leafy spurge, which spread by their root system, is not recommended since handpulling these plants can stimulate root growth.

Herbicides

Herbicides create powerful disturbances in a plant community and should only be used as part of a well thought out integrated weed management plan. The goal of the management plan should be to perpetuate a desirable plant community. Herbicides by themselves may start to move a plant community to a desirable state by removing undesirable plants or weeds from the community. If the niches left by removing undesirable plants from the community are not revegeted with desirable plants, they will likely be filled by other undesirable plants like cheatgrass.

Herbicides are chemical compounds that kill or inhibit the growth of plants. Herbicides are one of the many tools used to control Noxious Weeds. Herbicides are classified as either selective, nonselective, contact or systemic.

  • Selective herbicides have the ability to attack weeds while preserving crops or most beneficial grasses.
  • Nonselective herbicides control all types of vegetation and are used to remove the vegetation from an area. An example of a nonselective herbicide is Roundup ®.
  • Contact herbicides are absorbed by the green growing part of a plant (i.e. leaves, flower, stem) and do not move into the roots of the plant. Annual plants are usually controlled by contact herbicides while biennial and perennial plants usually regrow if treated with a contact herbicide.
  • Systemic herbicides move through a plant in two ways. Systemic herbicides can either move from the green growing parts of a plant to the root or move through the soil to the root and then up to the green growing parts of the plant. Systemic herbicides can be used when trying to control annual, biennial or perennial (link to definition page) plants.


To view a list of commercial applicators currently working in Missoula County area, click here. 

Ensuring that your backpack, ATV or truck sprayer are correctly calibrated ensures that you are applying the right amount of chemical to the plants that you are treating.  Check out our Weed Calibration Video series:

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Additional Chapters

Weed Management Mapping

Mapping is an essential component to any successful vegetation management project. By showing you the big picture of your weed infestation, mapping will not only help you plan your weed control strategy, but allow you to evaluate the effectiveness of your control methods. Mapping also helps land managers track the spread of noxious weeds and measure changes in weed abundance. There are numerous techniques for mapping noxious weed infestations. What technique you use depends on the size of the area you are managing, the amount of time you have for mapping, equipment availability and your comfort level with GPS and computer mapping techniques.

For a copy of a simple, but effective monitoring form, click here:  Vegetation Cover Monitoring Form

Education

blanket flower

Education is the first step in Integrated Weed Management

Before you can even start controlling weeds on your property, it is important to educate yourself about all the aspects of weed management. The Weed District is here to help!

 


Five Steps to an Integrated Weed Management Plan:

  1. Establish goals: What do you want to grow? What are you going to use the land for?
  2. Inventory and map noxious weed infestations. Prevent new infestations where possible.
  3. Prioritize small and large weed infestations. Control the small infestations first and then contain the large infestations.
  4. Adopt proper land management practices. Monitor and evaluate changes in vegetation yearly.
  5. Incorporate new strategies and adapt your plan when necessary.



The Missoula County Weed District is working to improve current weed training to increase awareness of weed issues and provide skills in weed management at all levels, from the wider community to specialist weed managers.

For more information contact Steffany Rogge, Education Coordinator at steffany@missoulaeduplace.org
or call 406-258-4211


Notes from future stewards!

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Growing Concern & Grow me Instead 1-5

Growing Concern & Grow me Instead 6-10

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Growing Concern & Grow me Instead 16-20

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