Targeting Invasive Plants

My latest article, Plant Pests, is featured in the Green Thumb Guide of the Spring 2009 issue of Nature’s Garden, one of the most popular Better Homes and Gardens gardening magazines, on newsstands now. The Nature’s Garden website offers a place to share your nature photos, to keep a journal, or to participate in garden forums. Take a few minutes now to check it out.

For those of us in the conservation trenches, it’s a watershed moment when magazine editors acknowledge that some plants that are still being sold in garden centers across the nation are actually thugs that can drive out native vegetation and destroy habitat. Let’s support those who do.

But many invasive plants have been here so long that people mistake them for natives. One of the earliest harbingers of spring (just 50 days away) in our area is the invasive Garlic Mustard (Photo credit: Olivia Kwon). Like many plants that have taken over our woodlands, Garlic Mustard arrived in America with the European colonists, who innocently planted it in their herb gardens. Now found all across the Northeast, the South, and parts of the Midwest, Garlic Mustard is spread by tiny seeds that are produced by the thousands on a single plant. The seeds are spread by birds, as well as forest and domestic mammals. They can stick to shoes, socks, and pantlegs, so that people hiking through the woods may, unintentionally, carry them far and wide.

Garlic Mustard exudes a chemical that kills off the competition by preventing the germination of native plant and wildflower seeds. Its own seeds can survive on the forest floor for five to ten years. But the situation isn’t hopeless.

In our woods, we never had a problem with Garlic Mustard, until the deer ate all of the Virginia Creeper. Apparently the large leaves of that plant provided sufficient shade to inhibit Garlic Mustard seeds from sprouting. Local land stewards advised us to weedwhack our acres of mustard every year, so that we would eventually be cutting only first-year plants (Garlic Mustard is a biennial that sets seed in the second year). This is a long-term approach, with the goal of eventually exhausting the seed bank. And, so far, it’s been working. We have also managed to keep the mustard from crossing a mulch path that separates it from an area of the woods where native violets and White Snakeroot abound.

In the garden itself, we pull the plants by hand, an inexplicably satisfying experience. This is best done after a rain, when the roots come out of the ground with little effort. If seed has already set, even if the seed pods are green, DO NOT put Garlic Mustard on the compost pile.

To watch a video designed to help identify and control this pest, click

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