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The War on Garlic Mustard… Hopeless Endeavor or Effective Management?

Our community is witnessing an onslaught by an advancing green army of garlic mustard (Alliaria petiolata) that is smothering parts of our backyards and parks. It has been a particularly bad year for this delicious invasive plant introduced over 100 years ago. Recently a volunteer at the Urban Ecology Center asked, “Why are you putting so much effort into removing this stuff, when you’ve been pulling it for years without any noticeable effect?” In other words, are we pulling this stuff just so we can feel good or are we actually having an effect on the ecosystem? Before analyzing this question, it’s important to know the enemy. Called “sauce-alone” in Europe (a sauce in and of itself) garlic mustard was introduced to Long Island in 1868 as a flavoring for fish and meat. Considered a delicacy, it was boiled like spinach, eaten raw on salads, sauteed in stir-fries, and used as a spice to mask the “off-flavor” of bad meat. However, it is an extremely aggressive plant that wreaks havoc on local plant communities. A biennial, it spends its first year developing a strong root system. Because it remains green throughout the winter, it can take advantage of the first spring rays before anything else has sprouted, sending a leafy shoot up to three feet high. Other early-spring wildflowers such as bloodroot, Dutchman’s Breeches, spring-beauty, wild ginger, hepaticas, toothworts, and trilliums are robbed of sunlight, space, water, and soil. Garlic mustard has the added advantage of being a prolific breeder that can self-pollinate. A single plant can produce thousands of seed that may remain viable in the soil for up to seven years. Ironically, it avoids areas of full sun, so it was the re-forestation of the Midwest and Northeast that allowed it to spread. Why is garlic mustard not a problem in Europe? For one thing, 30 European species of insects alone feast on it, while here there are no known natural predators. Grazing mammals like deer are turned away by the strong garlicky scent and flavor but become excellent dispersers of seeds that stick to their coats. So, are we wasting time pulling garlic mustard only to see it pop back in full force year after year? Some members of the community don’t think so. Kim Forbeck, Land Steward at the Urban Ecology Center points out that recent conditions (moisture, temperature, etc.) must have been ideal for garlic mustard, resulting in a population explosion. “We are probably seeing several years worth of mustard seeds from the seed bank blooming right now,” says Forbeck. “By concentrating our efforts on high-quality areas where native plants are successfully establishing themselves, we are already noticing subtle changes. We have done well (in Riverside Park) with other invasives like honeysuckle and buckthorn, and I am confident that we will do the same with garlic mustard.” The preferred method of removing garlic mustard? Good old-fashioned elbow grease — pulling them by the roots, bagging them and sending them directly to a landfill. After pulling, “we should immediately replant native species,” says Else Ankel, former director of the Urban Ecology Center. “Pulling garlic mustard leaves behind soil and space for them to re-colonize. Healthy plant communities are more difficult for invasives to take over.” According to the Invasive Plants Association of Wisconsin website, “The key to garlic mustard control is to attack early, before it has a chance to become widespread. If the woods are already infested, be prepared for a long battle. However, this battle can be won! It just takes time and persistence. If you have a healthy woods, it will be difficult for garlic mustard to get started.” The DNR is studying several European mustard-munching insects as candidates for release as bio-control but that wouldn’t be ready for several years. In the meantime, Ankel noted a possible hidden weapon in our arsenal. “Garlic mustard makes a delicious pesto [see recipe] and if restaurants began using it, they would want to harvest plants at a young age when they are most flavorful and before they go to seed.” After all, it is impossible to underestimate the power of economics and of the human appetite. For further information on garlic mustard and other invasives, check out the Invasive Plant Association of Wisconsin website, www.ipaw.org. Much of the information in this article came from the Secrets of Wildflowers, by Jack Sanders. To become involved with invasive species removal in Riverside Park, contact Kim Forbeck at the Urban Ecology center, 414/964-8505.