Invasive Plant Management: Where to Begin?

Have you ever been faced with a task that was seemingly insurmountable? Maybe felt an overwhelming sense of responsibility for something entirely impossible to control? This is precisely how many public land managers feel every day as they struggle to maintain and restore quality fish and wildlife habitat among a world of progressively formidable invasive plant species.

Invasive plants that we (everyone) commonly refer to as “weeds” can be a mammoth problem because of their adaptability and competitive advantage over native plant species. While weeds are present and troublesome across the world, in the US, the western states struggle particularly due to dry climate. Weeds have adapted to dryland famously and express astronomical seed production, germination success, early germination before native plants, and furious growth rates in some instances.

Healthy grasslands are a prime example of an ecosystem highly susceptible to noxious weeds. Where healthy native grass stands occur, weeds may commonly be found interspersed, but in relatively manageable numbers. However, if a major disturbance occurs that destroys or inhibits those native grasses from quick regrowth, the seed bank from noxious weed species can be activated and flourish immediately, forming dense monocultures in one season.


To some, this may sound like the plot from a horror movie. The problems that noxious weeds impose on quality habitat are all too real. For readers that are members of the Rocky Mountain Elk Foundation, the July-August, 2017, edition of Bugle Magazine presents a two-article special on noxious weeds that puts the potential impacts and the struggle for control into clear perspective.


Control methods such as pulling and spot spraying can be effective in quality habitats, but where to begin tackling major weed infestations can be mentally crippling. Nothing is more humiliating and defeating to a public land manager than failing to keep ahead of the weeds. On more than one occasion I have felt as though I failed the wildlife, taxpayer, and fellow sportsmen and women upon finding a noxious weed hell of Canada thistle, Russian thistle, and kochia on public land under my supervision. Recovering from the initial shock, I try to keep cool, consider the options, and make a game plan. The best place to start? Somewhere! More specifically, here are a few tips and considerations to get you moving.


Herbicides are quick, and generally effective, but application methods can be costly depending on habitat type, the presence of sensitive desirable species, and the acreage needing treatment. Keeping noxious weeds from flowering is key, but I find that broadleaf herbicides like Amine 2-4-D are most effective when it’s hot and dry (July – August). Unfortunately, by this time of the year, a lot of weeds are already flowering. Even if flowers are immature and have not been pollinated, seeds may be viable. Hitting weeds in the early, rosette stage (March – May) can help get ahead of the game.


I recommend learning about the plants you are treating before diving into a treatment. Timing can be critical, and for plants like Canada thistle that reproduce through roots, not just via seed, a fall application before green thistle dies back for winter can give you an advantage in the coming spring.


Goats have proven a useful tool in mowing through vegetation. Anyone unfortunate enough to have goats trespass onto their property can attest to their voracious appetite. Goats can clear vegetation to the ground in little time allowing for effective herbicide treatments behind grazing. Furthermore, appropriately timed grazing may knock back noxious weeds long enough to allow desirable species time to germinate and stand a chance of competing, and possibly thriving.

Some commercial outfits rent goat herds specifically for weed control. I am unsure of what a common rate may be for this service, but it is certainly something to consider if you would rather avoid applying herbicides, but maintain a chance at success. Prepare for several seasons of grazing.


Keeping vegetation mowed back is a good option for weed control, but have you ever mowed a plant like yellow starthistle? If so, you know darn well that it takes to a pruning by flowering aggressively. The next thing you know, its three inches tall in full bloom. Mowing is best used in combination with herbicides. Herbicide applications are more efficient and effective when the vegetation is low and plants have less mass to treat. A couple seasons of mowing and herbicide application can be quite effective, but you have to be willing to give up usable wildlife habitat during treatment to be successful.



Disking and harrowing can be used to keep noxious weeds from establishing. Regular cultivation activates the seed bank, allows plants to grow, then uproots them before they flower. Like mowing, this method requires habitat to be essentially lost during treatment, but disking can significantly tax the seed bank, allowing for reseeding with native, desired grasses and forbs.

One disadvantage is the potential for erosion. If rain or snow melt could cause runoff problems and scour the habitat area, particularly if runoff could enter a stream, you may want to select another method.

That sums up some common, effective approaches to noxious weed control, which fit cooperatively with the grassland management techniques discussed in the previous post. The severity of an infestation can help determine the best course of action, but I like to approach it as though I were considering surgery to correct a medical crisis. When possible, go with the topical treatments before digging in to remove an organ.

If you want to get serious about habitat improvement, accept up front that the weed control battle requires commitment. There will be no instant gratification (except maybe from herbicide-shriveled weeds), so settle in for a long-term game. I recommend making fast friends with folks who either have the farm equipment you need, or those willing to volunteer their time pulling weeds. And, as always, feel free to consult your friends on the Pheasants Forever chapter habitat committee.

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