The Weed Control Toolbox

If there’s one thing that makes weeds impressive it’s that they can survive. Granted, noxious weeds have a leg up because they don’t have the natural predators here that they once had on their home continents. But even still, these highly evolved plants that we love to hate have figured out how to grow and spread quickly, persist in a wide range of conditions and out-compete many (but not all!) native plants. This is a daunting realization when you are staring at a creeping expanse of white-top like it's The Blob, and we’ll be the first to tell you that weeds in the Methow should be accepted as a fact of life - you are never going to permanently eradicate all of them from your land.

It’s also a fact of Methow life that weed control is important and very do-able. By learning some basic information about weeds, prioritizing your time and efforts, and taking a multi-pronged approach to fighting weeds, you can find the balance in controlling weeds and giving native plants a chance to thrive.

The Top Ten Tools of the Weed Control Trade
To solve a problem well you often have to come at it from multiple angles. The same is true with getting rid of weeds - using one weed control method is rarely effective. You might see or hear the terms “Integrated Weed Management” or “Integrated Pest Management” in your battle against weeds. This simply means to use a combination of tools based on the types and numbers of weeds you have, the size of your site, your goals and capabilities. Here’s our list of ten effective ways to prevent, reduce and manage the spread of weeds.

Tool #1 - Educate Yourself
Identify which weeds grow on your land and collect some basic information about each weed’s life cycle. You can use our online weed guide and use our Additional Weed Control Resources page for a list of books and local experts. Call or email us with questions; stop by our Weed & Native Plant Education Booth that’s at the Twisp Farmers Market every year from mid-May to mid-June; or hire us to do a weed inventory on your property. Talk to your neighbors as they might be dealing with the same weeds and can give you first-hand tips.

Before you start spending every afternoon pulling cheatgrass, prioritize your work by going after the “noxious”, highly invasive weeds first and catching new invaders before they spread. Make a simple plan for yourself by listing and prioritizing all the weeds you know of, perhaps even plotting their locations on a basic sketched map of your property. If you have a large property or a lot of weeds, create a realistic zone or just pick one weed (after you’ve prioritized your weeds!) that you can focus on, and simply leave the rest of the property alone until you are ready to tackle more.

Tool #2 - Plant Competing Vegetation
Planting non-weeds (a native plant or a cultivated variety that will do well here and won’t become weedy) is the best way to control weeds. Promptly fill any disturbed soil with desirable plants or seeds, whether it’s after you’ve built a driveway or after a session of weed-pulling. It’s handy to always have a bag of native grass or wildflower seed at the ready so that you can sprinkle seeds onto exposed dirt. See the Additional Weed Control Resources for where to get seeds and plants.

Tool #3 - Pull Weeds by Hand
Hand pulling is an excellent way to control any weed with a taproot or shallow root system (these are typically annuals and biennials but not always). Ideally, you should pull them throughout the spring and early summer, when the soil is moist, and before seeds form. Make an effort to get the entire root system out of the ground. Plants without seeds can be left on the ground or piled and composted. Plants that have flowered should be bagged and put in the trash, or burned, because there’s a chance they’ve already gone to seed. Hand pulling creates small soil disturbances; consider reseeding as you weed.

Tool #4 - Hoeing
Hoeing works well for annual weeds with weak roots, especially very young seedlings. People commonly use either scuffle or stirrup hoes in garden beds or aisles, and then pick up the loosened weeds. Again, the bare, loose soil can create favorable conditions for new weeds to sprout, so either reseed or mulch or cover the soil (with newspaper or cardboard, e.g.) after hoeing.

Tool #5 - Work the Soil
Cultivation - tilling, discing or plowing - is used on large-scale agricultural lands. It’s a great way to kill certain weeds, especially when it is followed by a planting of a cover crop to compete with weeds and recondition soil prior to agricultural use (or native plant restoration). Usually, repeated cultivation is necessary to reduce weed seed banks and prevent new weeds from establishing. Tilling or breaking up the soil is almost never advocated when there are rhizomatous weeds present, unless you can commit to regular cultivation. Weeds like quackgrass, whitetop, and Russian knapweed spread via any part of their root and cultivation breaks their roots into many tiny pieces, effectively spreading them like wildfire.

Tool #6 - Mowing
Mowing can effectively reduce seed production but timing is critical. Mow when plants have begun blooming but have not yet set seed - it’s usually a very short window, especially for grass species. Plan to mow more than once because different weeds bloom at different times and some species react by sending out flowering shoots at ground level. Weed whackers, heavy-duty mowers, and tractor mowers work well for this. Take care to avoid harming native plants.

Tool #7 - Covering Soil
Plastic sheets are often used to convert weedy soil to soil that’s ready to be cultivated. There are a variety of types available, and non-plastic coverings, like newspaper, cardboard, or thick layers of mulch can also be effective on small areas such as flower or vegetable gardens. Woven black plastic (also known as landscape fabric or weed barrier) allows air and water to pass through, preserving beneficial microorganisms in the soil below, but reduces light and heat which any plant, even weeds, need to survive. Very tough weeds like quack grass will grow right through woven plastic; for these weeds use solid plastic sheets. Plastic sheets do not always kill weed seeds in the soil.

Tool #8 - Grazing Animals
Grazing was used for weed control in the past and is making a bit of a comeback today. Within portable fences, moved often, small herds of sheep or goats (even one or two animals) can control weed species by eating them. Grazers often prefer young, tender plants but with careful planning, monitoring and frequent moving you could keep a lot of weeds from blooming throughout the spring and summer.

Tool #9- Biocontrols (Miniature Grazing Animals)
Biocontrols (aka bioagents or biological control agents), are typically very small plant-eating insects imported from a particular weed’s native land. Extensive research and tests done by the USDA and state extension agencies have resulted in the successful use of numerous biocontrols that are available to the public. Many biocontrols are “weevils;” these tiny beetles burrow into a plant’s stem, root, or seed-head and eat. Here in the Methow Valley, the “knapweed seedhead weevil,” Larinus minutus, is quite a popular “tool” for successfully reducing knapweed.

Biocontrols are most effective on sizable populations of target weeds, at least an acre or more. Weevils will only stay where you put them if there is enough "food" for them to eat, so they move around depending on weed infestations. The good news is that so many knapweed weevils have been released in the Methow over the last 10+ years that you might already have some. Split open a knapweed seed-head this summer and see if you can see a little black beetle!

The Regional Biocontrol Project run through the Ferry County Extension office for both Okanogan and Ferry counties, is the source of FREE biological agents (aka biocontrols) for certain weeds, such as St. Johnswort, diffuse & spotted knapweed, Dalmatian and yellow toadflax, and Canada and musk thistle. If you have a sizable infestation of any of these weeds on your property, one acre or more, it’s worth looking into this resource. Biocontrols are available on a first-come, first-serve basis. Go to the website or contact Dale Whaley, 509-745-8531.

Tool #10 - Herbicides
Herbicides present difficult questions for backyard stewards and gardeners. They can be effective weed killers but their negative side effects on human health and our ecosystem can be huge. We advocate using herbicides only after other methods have been explored, and only for the toughest weeds such as Russian knapweed and whitetop.

Different products bring varying levels of risk. Weigh the pros and cons, talk to local experts, and make an informed decision. The Okanogan County Noxious Weed Control Board is a great place to start. Ask them which herbicide to choose, which licensed applicator to hire, or courses offered in homeowner application. They even offer free on-site consultations.

If You Decide to Use Herbicide....

  • Use it as a transition to more desirable vegetation, not as regular maintenance.
  • Thoroughly read labels and research the use and effects of any product applied to your land. For instance, some herbicides are “broad-spectrum” meaning they’ll kill everything, and others are “selective” to broadleaf plants so they don’t affect grasses; the latter being useful if you want to hit whitetop but not hurt bluebunch wheatgrass. Some only kill the plant but don’t prevent seeds from germinating. Some herbicides are widely available; others require an applicator’s license.
  • Choose products and time applications carefully to get the best results with the least amount of chemicals. A general recommendation is to treat weeds while they are actively growing, though many thistles including knapweed can be treated in the fall.
  • Spot-spray or paint herbicide onto leaves to get good results with little herbicide and to avoid good plants.
  • After an initial application has time to work, survey the weeds’ status; you may need to follow up with other types of weed control or an additional application of herbicide.
  • Some herbicides must be mixed with a surfactant or sticker, which spreads and adheres herbicides to leaves.
  • Dye added to the mixture helps show where spray is going, which is especially helpful if you are “spot spraying,” and trying to avoid native plants.
  • If you must spray a large patch of weeds, a backpack sprayer makes mixing and carrying herbicide easier.

Alternative Sprays
Horticultural vinegar, which is concentrated at 20%, is becoming a popular alternative to chemical sprays. It has shown promising results in controlling many weeds, including tough rhizomatous weeds like Canada thistle. Household vinegar is typically concentrated at 5% and is less effective. Though horticultural vinegar is available online, it has not been evaluated and licensed for herbicide use by the Environmental Protection Agency. Use it with care, as contact with it can harm skin and eyes.

Follow this link to Additonal Weed Control Resources for helpful publications, lists of licensed professionals, the Pacific Northwest Weed Management Handbook and more.

The Seedhead


Scientific Name: Tribulus terrestris

Puncturevine is an annual weed that sprouts and grows from seed every year and then dies. Starting from the central sprouting point at the root, stems spread out radially, staying low to the ground when the plant has direct sunlight. Dense mats can form with leaf-covered stems trailing out like runners, except the plant does not send roots from these stems. Mats start small and can grow quite large to several feet in diameter. In the shade, the same thing happens but the stems can grow slightly upright instead of flat to the ground.

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Tumble Mustard

Tumble Mustard

Scientific Name: Sisymbrium altissimum

Tumble mustard is widespread across the Methow, mostly in open, disturbed (or burned) sites such as roadside ditches, residential areas in the shrub-steppe, ranch and Ag land, and post-fire areas.

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Scientific Name: Bromus tectorum

Cheatgrass is probably the most common plant in the Columbia Basin, and it's one of the most widespread invasive (non-native) grasses in North America.

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Diffuse Knapweed

Diffuse Knapweed

Scientific Name: Centaurea diffusa

Diffuse knapweed is a biennial thistle that can mature and flower at a wide variety of heights - anywhere from a few inches to a few feet tall.

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Russian Thistle

Russian Thistle

Scientific Name:Salsola kali (also Salsola tragus and Salsola iberica)

Russian thistle is least noticed when it is young - slender, green and soft - and most noticed when it's a large, spiny, brown tumbleweed.

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Baby's Breath

Baby's Breath

Scientific Name: Gypsophila paniculata

Baby's breath is an easily recognizable addition to the Methow Valley's list of weedy plant species.

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Scientific Name: Cardaria draba

Whitetop is a perennial, which in this case is continually expanding downward and outward.

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