Integrated Pest Management

What is Integrated Pest Management (IPM)?

Mary McKinney-Assistant Supervisor
Park County Weed and Pest Control District

Purple Loosestrife

Weeds have been on the landscape as long as humans have been around to call them such. Weeds can be anything growing where you do not want it or that interferes with your management goals. Weed species that cause environmental or economic harm or harm to humans are considered “noxious” and are regulated by state and federal agencies. These species are usually non-native invasive plants. One thing is for sure-all plants are not created equal neither are the treatment methods used for successful weed eradication. Different weed species require different control methods and in most situations several methods or an “integrated” approach is usually most effective. The integrated approach uses all the tools we have in our “Tool Box” of weed control.


Prevention: By far the easiest form of control!
  • Use of weed free end products (top soil, sand, gravel, trees, shrubs, compost, manure, etc.). Ask your supplier if their product is weed free.
  • Limit disturbances. Disturbed soil is a prime target for new weed species to move into.
  • Ensuring that equipment brought on site is clean of dirt and debris that may contain weed seeds or plant parts. Clean this equipment before moving on to the next location.
  • Don’t purchase or plant invasive species. Replace invasive plants in your garden with non-invasive alternatives. Information is available from Weed and Pest, NRCS, the nursery staff, or you can perform an internet search of the species you are considering.
Cultural: Knowing what previous land use practices were and how this may impact your efforts. Includes burning, grazing, crop rotation, pasture rotation, crop selection, cover crops, etc.
Mechanical: Just as you pictured, these would be practices that involve manual labor…mowing, hoeing, hand pulling, etc. Also includes use of mulch, plastic, and fabrics.
Chemical: Use of herbicides to control weed species. Not all herbicides are created equal!
  • Selective-target only broadleaves or grasses
  • Non-selective-kill everything
  • Pre-emergent-applied before the weeds appear
  • Post emergent-applied after weeds begin growing
  • General use-may be purchased by any person
  • Restricted use-must have a license to apply
Biological Control: Use of a bio agent, insect, disease, pathogen, etc. to control or suppress weed spread). Contact your local weed and pest office for information on available agents and applicability to your situation. Also use of grazing animals (goats, sheep, cattle) to target specific weeds. This eliminates the top growth only. For complex perennials, a combination of methods is necessary for eradication.

Spraying 1Cattle 1Tractors 1






But how do I get rid of the weeds in my pasture?
So which method is the right one for the target species?

It depends on many other variables such as management goals, resources available (time and money), future plans, identification of target species and location to name a few. Here are some guidelines to consider when choosing your treatment method:

  1. Group your weeds into two categories, broadleaf and grass weeds.
  2. Identify the target species: Proper ID will assist you in choosing the right method. Wrong ID=wrong treatment = waste of resources=no control! If you do not know the weed-ask! Weed and Pest, UW-CES, and others in the community may be able to properly identify your “weeds”.
  3. Then consider the life cycle of those plants:
    • Annuals – (complete their entire life cycle in one season) ONLY reproduce via seeds.
    • Biennials – (live 2 seasons usually growing a rosette or cluster of leaves close to the ground the first year and the following season will bolt, flower, set seed and die)    ONLY reproduce via seeds.
    • Perennials – (live longer than 2 seasons).
      simple-having a taproot or fibrous root and ONLY reproduce via seeds.* complex-have creeping underground rhizomatous root systems and reproduce not from growth points on the root located every ½ inch or so, but also via seeds, Take a piece of this root and move it to another area and BINGO! New weed growing where you didn’t have one before.
    • It is crucial to know the life cycle of the target plant in order to choose
      the right treatment method
  4. Cartoon 1Choose the best method for the target species. In general:
    • Annual species respond to mechanical control and cultural controls to a certain extent. Remember the only thing you are trying to accomplish is eliminating seeds. Most annual weeds such as Kochia and Russian thistle can be mowed; however, they will respond to the height of your mower and start producing seed at 3 inches or the height of your mower deck. Depending on the size of the infestations, you may hand pull, mow, hoe, or other mechanical means. If the area is too large, you may want to consider herbicide treatments. Remember that whatever method you choose, there are many seeds left in seed bank of the soil that will also germinate if the conditions are favorable. This could mean flushes of new growth several times throughout the season (or for many years).
    • Biennials also respond to mechanical control as like annuals, they only spread by seed. Manual removal of either annuals or biennials may be time consuming so you may have to consider other methods. If you choose to use herbicide, don’t wait until your annual or biennial weeds are big enough to lose the dogs and kids in. Treat these weeds early!
    • Tap rooted perennials may be mechanically removed (including root. The size of the infestation and the amount of time available will play a role in control/removal methods.
    • Complex perennial weeds such as Canada thistle, Field bindweed, or Whitetop may require chemical treatment as it is almost impossible to remove the entire roots system. The proper herbicide for the intended species is crucial for effective control. Remember some perennials also reproduce by seed so you may have to incorporate mechanical methods as well. Not to mention species such as Field bindweed have seeds that remain viable for 60 years or more!
  5. Consider timing: Proper timing of any method is critical to success. Many complex perennial weeds respond well to fall applications of herbicide.
  6. Evaluate throughout the season determine if your methods are effective. If you had tough perennials remember you may not see results until the following year. Good stewardship is a long term commitment so think long term. Change methods if results are not satisfactory.
  7. Once again, ask for assistance if you need to. Weed and Pest Districts, UW Cooperative Extension, Natural Resource Conservation Service are a few of your options.
  8. Enjoy! Watch the grass grow, play a football game, tend your garden, watch your horses. Don’t forget to keep an eye open for some weedy suspects moving in on your weed free areas! And remember to monitor the areas you treated for satellite plants you may have overlooked.

Common Herbicides

The following are some common general use herbicides. There is no license required to buy or apply these products. The following are general recommendations. Your situation may be unique and have specific elements that require other methods. Always read the label to ensure you are using the product in a manner consistent with that labeling. Consult your Weed and Pest District or other qualified entity for proper selection of herbicides – especially if “noxious” weeds are present.

    • 2,4-D Amine-Selective post emergent herbicide – effective on many annual /broadleaf plants-treated early
      • Has a turf label.
      • Also effective on most biennials when treated in rosette stage – Musk thistle, Houndstongue, Burdock, etc.
    • Weedmaster®-Selective Post-emergent herbicide-effective on many annual weeds and SOME perennial species with repeated applications (Showy milkweed, Field bindweed)
    • Roundup® -Active ingredient Glyphosate
      • Non-selective herbicide – effective on most broadleaf and grass plants.
      • No residual- only kills what is green, growing AND it touches!
      • Good on some perennials in the fall.(Canada thistle)
      • Safe in flowerbeds, gardens, around trees-as long as the herbicide doesn’t contact non-target species!
      • One of the most non-toxic herbicides available. Target a specific enzyme found ONLY in plants.
    • Telar/MSM-Selective-post-emergent (non-crop) herbicide

Common Mistakes

  • Incorrect target ID resulting in wrong treatment method.
  • Improper herbicide selection/timing/application You must match the right herbicide to the right species. Some herbicides have no activity on certain plants. Seek the assistance of qualified personnel such as Weed and Pest in choosing the right product! Herbicides also have specific uses in regard to the areas you may be applying – agriculture use, turf use, range and pasture, aquatic etc. The herbicide labels will always provide this type of information.
  • Bought the cheapest herbicide.
  • If a little works good, than a little more should work even better, NO! More chemical does not necessarily mean better control. Read the Label – Label instructions are requirements, not recommendations! Especially important in treating complex perennials. Many herbicides are slow to act. In the case of those perennials, slower activity is better!
  • Didn’t follow through with retreatment –severe infestations may require several years of treatment!
  • Calf Always consider where the product is to be used. Will it be used near?
    • Ditch banks
    • Ditch banks
    • Riparian areas
    • Gardens
    • Lawns and Turf
    • Pastures
    • Trees
  • Then ask yourself these questions:
    • Is non-target damage acceptable?
    • Long residual desirable?
    • Will anything be planted on the site in the future?
    • Will residuals affect them?
    • Resources- cost/time
    • Tank mixes
    • Best time of year?

Hounds toungeUsed properly herbicides can be an effective tool from your Toolbox. While they may not always be your first option in many instances, (especially for tough noxious species) they are an economical and effective component of an integrated pest (weed) management.

Houndstongue-a biennial noxious weed.