Extension Viewpoints: Alternatives to herbicides for weed control


By Ethan Proud

PREVIEW Columnist

Weed control and herbicides are synonymous in some circles, though they don’t have to be. In fact, herbicides are one tool for weed control, and many different tools can be utilized. 

For effective weed management on your property, you should utilize more than one control method. This means blending cultural, mechanical, chemical and sometimes biological controls. Chemical control encompasses both organic and synthetic herbicides. You read that right: Organic does not mean chemical-free. It only means that these chemicals are not synthesized in a lab. 

Regardless of whether you choose organic or synthetic, reading the label is of vital importance and home remedies should not be used. Mixing vinegar and Epsom salt as the Internet suggests will only burn down the top portion of a deeply rooted perennial and is not effective. Not only that, but vinegar can also kill beneficial soil microorganisms. Horticultural vinegar (or acetic acid) can be purchased for those wishing to use vinegar and will come with a label attached so you can remain within compliance of the law. 

So what if you don’t want to use chemicals, whether organic or synthetic? You are in luck. There are three other control methods which can work great together. Hand-pulling and mowing are incredibly effective on annuals, biennials, and short-lived perennials on small acreages. Mechanical controls are not recommended for deep-rooted, persistent perennial species such as leafy spurge and Canada thistle. However, with enough diligence, control can be achieved. 

Solarization can be effective to control these species as it blocks the sunlight they need to thrive. To utilize this method, take a black tarp and roll it out over the infestation. It will take multiple years to control the species and will kill anything beneath the tarp, so reseeding is necessary. Monitor the perimeter of the tarp to remove any shoots that may be creeping out from underneath it or sprouting several feet away.

Biological controls (insect herbivores or plant pathogens) may also be employed to suppress an infestation, though few will actually collapse a population. In Archuleta County, two biocontrols are available through the Weed and Pest Department during certain seasons: field bindweed gall mites and Canada thistle rust fungus. Both of these controls are host-specific and cannot complete their life cycle on another plant. Controls for other weeds are available through the Palisade Insectary.

The last control method is cultural and is by far the most important. It includes replanting native species, rotational grazing and cleaning your gear after leaving an infested site. Skipping this step will mean an ongoing battle with invasive species.

Archuleta County Weed and Pest is your local resource for managing noxious weed populations and controlling other pests.