Controlling Invasive Plants

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How Can I Cut and Treat Small Infestations of Phragmites?

Because 80% of the phragmites biomass is in the underground rhizomes (roots), nonchemical controls have little effect. Pulling is usually impossible, because the roots grow to a depth of ten feet. Pulling results in broken root fragments which will sprout into more phragmites. Mowing weekly for years may control small patches, but this is only practical on dry land. Mowing a few times a year may actually stimulate more growth. Putting herbicide on the plants in August through September is the most effective way to eliminate phragmites. Small infestations of phragmites can be treated by cutting individual stalks and putting a drop of herbicide inside the stem. This is particularly effective when the phragmites have not yet formed monocultures (places where only phragmites grow) and are still mixed with desirable native plants.

August and September are the best months to treat phragmites, after the seed heads have developed and before the first killing frost. Cut the stem a few inches above ground and put a few drops of glyphosate herbicide directly into the hollow stem. Two to three years of treatment are generally required to eliminate the phragmites.

When herbicide is sprayed onto plants, surfactants (soap-like chemicals) are added to enable the herbicide to penetrate the waxy coating on the leaf. However, surfactants may harm amphibians, fish, and other wetland animals. Surfactants are not necessary if the herbicide is placed on a cut stem, minimizing harm to native wildlife and nearby native plants. Current research suggests that glyphosate herbicide without surfactants controls phragmites without harming wetland animals, and will kill any plants that absorb the herbicide. Because glyphosate herbicide affects metabolism in plants but not animals, it has very low toxicity to humans. Cutting and treating small infestations of phragmites effectively eliminates the plant using very small quantities of herbicide; often requiring as little as a spoonful of herbicide for small patches of phragmites.

North Oakland Headwaters Land Conservancy (NOHLC) has prepared a pamphlet entitled A Homeowner's Guide to Small-Scale Phragmites Control

This pamphlet explains what herbicide to purchase, how to dilute the herbicide, and how to cut and treat the phragmites. For a minimal donation to cover costs, NOHLC also offers a starter kit to control invasive plants, which contains a plastic dropper bottle with a little biodegradable purple dye to make the herbicide more visible and easy to use. Homeowners will need to purchase the herbicide online or from local stores.

How Can I Treat Large Infestations of Phragmites?

Integrated pest management strategies can be used to control large monocultures of phragmites. Because 80% of the phragmites biomass is in the underground rhizomes (roots), mowing is not sufficient to eliminate phragmites. Mowing weekly for years may limit the growth of phragmites, but this is only practical on dry land, and mowing a few times a year may actually stimulate more growth. Integrated pest management strategies for phragmites require the use of herbicide. To minimize the use of herbicide, dead standing stalks are generally removed by mowing or controlled burns in the winter or spring, followed by spraying herbicide on the plants in August through September. To control all the phragmites, three years of treatment are generally required. Spraying phragmites in standing water, where phragmites often is found, requires a permit from the MDEQ.

The Michigan Department of Environmental Quality has prepared A Guide To the Control and Management of Invasive Phragmites

This booklet describes the problems posed by phragmites, and how to treat phragmites using integrated pest management strategies.

Homeowners often prefer to hire an experienced licensed contractor to obtain a permit and treat their phragmites. Many homeowner associations are working together to recommend a single contractor to their residents, thereby obtaining a group discount for permit fees and phragmites treatment.

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