WEEDING invasives

You are not alone. Whatever undesirable, aggressive plant has raised your ire, rest assured there’s a tactic for thwarting it. In the worst of cases, your solution may be to simply move those few plants worth rescuing and clearing a whole site.


Invasives management is usually not a one-shot deal. The seed bank (the seeds retained in the soil) can sprout new plants for years to come. Wind, water, birds, and other animals may keep importing fresh seed. For best and lasting results, identify and learn about the particular invasive you’re dealing with and the specific strategy most effective in its control by visiting Invasive.org where recommended practices are kept up to date based on the latest scientific research. Perhaps even more importantly, volunteer your labor in exchange for valuable training and experience the next time your local nature center or county park conducts a “weed out” or controlled burn.


PREVENTION: The USDA Animal and Plant Health Inspection Service monitors the import of goods that might introduce new invasive exotics to our continent. You can do similar good by not introducing organic materials to your neighborhood indiscriminately. Transporting firewood, transplanting species from other parts of the country, sending seeds through the mail, moving a boat from one lake to another, even dumping bait in your garden can spawn problems you cannot begin to foresee. Each of these scenarios has actually resulted in the introduction of species which have negatively impacted habitat, agriculture, fire patterns, erosion, water quality, livelihoods, recreation, and tax rates.


Manual Control

Simple extraction works for shallow-rooted plants. If they have already flowered, bag them to prevent ripening seeds from infesting anew. Composting seldom produces enough heat to kill invasive species’ seeds, so either bury your seed-bearing weed harvest deeply, burn it, or send it to the landfill. Small tree seedlings can be pulled with a pair of pliers.

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Chemical Control

Herbicides can be applied to leaves (foliar treatment) or freshly cut stems or trunks. The liquid can be applied by pump spray, paint brush, or sponges attached to grilling tongs (jokingly called the Tongs of Death). The goal is to use the least toxic chemical in the most focused application with the most efficacious timing. Some pesticides affect only select types of plants, and others are non-selective. Only a few are approved for aquatic environments.

The ponytail method (demonstrated above) is particularly useful in excising invasives that spread by root, such as grasses. By isolating the “bad” plant, tying its stems in ponytail fashion, and then cutting a flat top above the tie, you can use a minimal amount of herbicide (applied by sprayer or brush) to the freshly cut cluster of stems.

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Mechanical Control

Pictured here are a few of the tools at your disposal. A Weed Popper designed to remove Dandelions from the lawn is just as good at extracting other flowers of a similar size.

Loppers cut young saplings whose bare wood can then be treated with herbicide. Weed Wrenches get rid of saplings even faster by extracting them down to the root. Chainsaws make fast work of shrubs and trees, but if you can’t manage wielding one of these, you could just “hack and squirt” — a technique of removing bark and treating the cambium beneath with herbicide (note that colorant added to herbicide helps in monitoring its application). Girdling (cutting a ring of bark around a tree) and treating with herbicide may work even more effectively.

Flail mowers (aka brush cutters) tackle scrubby situations, whether attached to a tractor or when walked behind like a conventional mower.

Ponds and lakes can be weeded in an ongoing basis with a Lake Rake (Lake Razor) or mechanical harvesters. (Lake weeds make rich compost for the vegetable garden.)

* * *Temperature Control

Heat from the sun (solarization), captured beneath clear plastic which has been well sealed along all edges, can “bake” plants into submission as well as neutralize some of the weed seeds in the top couple inches of soil. How many weeks it takes to do so will depend on site conditions and how much sunlight is available.

A weed torch (weed wand) emits a propane flame from a long-handled nozzle, allowing you to burn weeds in situations where mechanical methods won’t work or chemical means aren’t desirable. The device is often used where roots grow amongst and under rocky or paved surfaces.

A drip torch is used to facilitate a controlled burn by dribbling lighted fuel along the windward edge of a field, forest, or wetland. Controlled burns are conducted to set back or destroy woody species invading an opening and some herbaceous species (non-woody plants whose top dies to ground level in winter). A controlled fire is also sometimes prescribed in a preemptive move to prevent uncontrolled wildfires.

Note: A fire allowed to “burn hot” in any one spot, such as a campfire, will sterilize the ground so that nothing will grow in that location for years.

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Light Control

Sometimes referred to as “smothering,” the act of denying light to a plant is more akin to starvation. Whatever you can do to deny photosynthesis will eventually kill even the hardiest weed. Black agricultural film (plastic) or old carpet (a cost-free and long-lasting resource) can be used to cover large areas. If you or the neighbors find either to be unsightly, an inch of woodchips can be overlain to beautify the scene. After a year or more, you can expose all or part of the covered site and sow or plant into a perfectly prepared soil bed.

A single tenacious plant (I’m picturing a particular Yucca in a friend’s yard) can be killed by cutting and covering it with whatever light-denying invention or ornament you devise.

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Biological Control

Biocontrol utilizes insects, fungi, microbial diseases, or animals to set back a particular plant species. Oftentimes a biocontrol is found in the country where the invasive plant originated. Extensive research is done before importing and releasing an exotic species into our environment to guarantee it will not damage native species, crops, or ornamentals sold by the nursery trade.

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