I first wrote about garlic mustard in 2001. Since then, this dreadful weed has gotten even worse. Many hundreds of man-hours and dollars have been spent trying to prevent it from choking out more of our native wildflowers.
Garlic mustard, Alliaria petiolata, is not a weed to take lightly; if you have it, control is imperative.
In Illinois, the plant behaves mostly as a biennial. After germinating in the spring, the plant spends its first summer and winter as a rosette of heart-shaped leaves (2-8" long) with coarse, round, irregular teeth on the margins. The following spring, the plants send up a 1-2 foot flowering stalk of small, four-petaled, white flower clusters.
The plant spreads exclusively by seed on the fur of larger animals such as deer, by flowing water, and by human activities. The Illinois Invasive Species Awareness blog at www.illinoisisam.blogspot.com reported in March 2014 that excessive deer populations actually facilitate the garlic mustard invasion.
Seeds disperse when the seedpods burst at maturity in August. Seeds have a 20-month dormancy period and do not germinate until the second spring after ripening. Some plants produce as many as 8,000 seeds! Therefore, the goal of any garlic mustard control program is to prevent seed production until the seed bank is exhausted, usually a two to five-year period. I cannot emphasize the importance of not letting this plant go to seed!
In 2001 I naively thought I could keep ahead of the garlic mustard invasion on my own property by pulling any plants I found. It didn't take long, however, for the hostile weed to win that battle. Our woods are now covered with it!
If you have the time, removal of plants by hand pulling is effective if the root is removed. If the stem snaps off from the root crown of a non-flowering plant, the plant may resprout. Other methods of control include spring burning, cutting flowering stems with a scythe, and herbicides.
The only possible positive of this invasion is that garlic mustard is edible. As the name says, it is a plant in the mustard family with a slight garlic taste. I've used it to make pesto.
"Great Garlic Mustard Hunts" are now held to ensure that this disruptive plant does not overcome our forests. In April and May 2011, the East Central Illinois Master Naturalists harvested 2,740 pounds of garlic mustard. Their hunt was copped off with a celebration and potluck featuring garlic mustard recipes!