Invasives Part 2: Non-chemical and chemical ways to eliminate non-native invasive plants

By Will Danforth
©2025 Telegraph Publishing LLC

There are ways to eliminate non-native invasive plants from your landscape. The method you choose should be right for the plant, for your particular environment and for you.

Non-chemical approaches

With over 100,000 man-made chemicals in the environment, most with untested and unintended consequences, it’s best to avoid chemicals whenever possible.

• Hand-pulling. Always the first choice, though not always feasible. Use on smaller infestations of perennials and young shrubs: garlic mustard and wild chervil; honeysuckle, barberry, burning bush, buckthorn, and multiflora rose. You can try a weed wrench on larger shrubs. Since this approach might not get the roots, it may require repetition.
• Smothering with black plastic or cardboard. This will require a full season at least, and be sure to dispose of the plastic.
• Repeated mowing or brush-hogging. This takes multiple years; time it so as not disrupt nesting birds. Note that two-cycle engines, if used, are bad polluters.
• Goats: They’ll eat just about anything! But you’ll need to corral them.
• For biennials: These plants only live for two years. so cut them off in their second year before they seed, and they’re done. Some are garlic mustard, wild chervil and poison parsnip, which has a sap that delivers a mean burn in sunlight! To deal with poison parsnip, wear long sleeves and cut on a cloudy day, then collect and burn it. And return, since it often blooms again.

Chemical approaches

Sometimes you’re faced with two lousy choices: use an herbicide or resign yourself to a monoculture that will inhibit a functioning environment. Since we depend on nature for our lives, I always choose a functioning environment. And one can minimize the use of chemicals.

• The herbicide I prefer is generic glyphosate, but recent changes in regulations have complicated this discussion immensely. Glyphosate binds to soil readily and has a shorter half-life than the other common choice,Triclopyr, so it’s less residual in the environment. Both, importantly, kill the roots.
• Cut and dab. Woody shrubs that are too large to pull by hand can be cut with a lopper or handsaw and “dabbed” with a “Buckthorn Blaster”  — an envelope licker with a sponge on the end. Use a 30% solution. One cup will treat hundreds of plants, and there’s no collateral damage. It’s most effective in the fall, when shrubs are pulling their energy into their roots for the winter.
• Foliar spray. It’s important to understand a plant’s life cycle so you can spray it at the key time. Spray in low wind, don’t use more than recommended, use cardboard to protect the “good” plants. However, collateral damage is inevitable. Using a “licensed applicator” will cost money, but they use a less toxic mixture (the surfectant in retail mixes is more toxic). And you’ll save the time!

You must treat Japanese knotweed, Asian bittersweet and purple loosestrife foliarly since the smallest nodes or root pieces can resprout.

The last in our series, which will run on Monday, Oct. 6,  we’ll look at individual species and get into more detail on their lifecycle and ways to make it go easier for you. Check the pix on vtinvasives.org and use Sept. to sharpen your eye for when October arrives and the invasives say, “Here I am!”

• Part 1 on Monday, Sept. 22: Let’s eliminate non-native invasives to benefit Vermont’s biodiversity.
• Part 2 on Monday, Sept. 29: Non-chemical and chemical methods to get rid of invasive plants.
• Part 3 on Monday, Oct. 6: Tackling those colorful ones that still need to go.

Will Danforth is a board member at the Grafton Nature Museum.