Say you’re taking a stroll through the woods. It’s spring and the wildflowers are out. In fact, there are dense stands of one kind in particular: a thigh-high plant with triangular bright green leaves and pretty white four-petaled flowers. Uh-oh. Your favorite woods have been invaded by garlic mustard, an aggressive biennial that threatens native plants and wildlife in the eastern half of the United States and Canada.
This herb has long been used for medicine and food in its native Europe, Asia, and Africa and was introduced to North America about 150 years ago. It spreads through undisturbed woodland at a rapid clip: between 20 and 120 feet a year.
Garlic mustard outcompetes native plants—from wildflowers to tree seedlings—by taking the available water, light, and space. Butterflies and other wildlife that feed on the disappearing native plants (or on the insects that feed on the plants) are also threatened.
• For small stands, pull out plants by hand. Be sure to get the whole root, as new plants can grow from root pieces. Destroy the plants, especially if they’re flowering.
• Control large stands by cutting plants to ground level so they don’t flower and produce seed. Chemicals or controlled burns can be used in some cases.
• Seeds of garlic mustard can stay viable for more than five years, so no matter what method you use, repeat every year for at least five years to be sure the infestation is gone.
—photo by Tracy Walsh.