WHO KNEW That Garlic Mustard Could Be So Hard to Control?

Each May, roughly 30 neighborhoods in Hanover tackle the garlic mustard that has established nearby. Some neighborhoods now have a team of folks who regularly help to pull and remove it from both their neighborhood and nearby forest. The plant is easy to identify and easy to remove but persistent; you are guaranteed that it will pop up in successive years. The plant is biennial; that is, has a 2-year lifetime.

What makes this plant so successful at invading? The awesome biology of this plant has several attributes that make the plant super successful. First, it is here without the 69 insect predators that keep it in check in its native Europe countryside – where you’ll only see it in small clumps mixed in with other plants. Second, the plant’s roots exude chemicals (glucosinolates) that are toxic to Arbuscular Mycorrhizal Fungi (AMF). These fungi play a critical role in providing both water and nutrients (like nitrogen from nitrogen fixing bacteria) to hardwood seedlings, such as sugar maple, red maple and white ash. Thirdly, the plant seeds are viable for at least 10 years, so plants will keep returning annually. Fourth, the plant self-pollinates and can make > 1000 seeds. Finally, it hinders local diversity, as the plant foils the native West Virginia white and similar butterflies to lay eggs on its leaves (instead of toothwort, a native mustard plant), but the larvae don’t mature, so there is a loss in forest wildlife. Since the plant is a biennial, this year’s seeds will be the base for mature plants the year after the next year. So it has an up and down cycle. If you ignore it for a year it will return with vigor.

Bright side – after 10 years of pulling the plant, some large colonies of the plant in Hanover are now much smaller.

How we all can help reduce the problem: Learn to recognize the plant; It should be blooming soon. Look for it in your neighborhood or along the trails in town. Pull it and put it in a plastic bag to dispose of it.