|fwg is a long-term project of the ottawa field-naturalists' club|
Garlic mustard (Alliaria petiolata)
Garlic Mustard is a shade-tolerant biennial plant that thrives in woodland settings. It is considered a serious invasive pest of natural areas, particularly woodlands, displacing native flora and severely reducing species diversity. Its aggressive, rapid growth allows it to form dense carpets that prohibit growth of other species.
Recent research shows that Garlic Mustard can release chemicals that destroy the mycorrhizal fungi that many trees depend on for nutrients. When Garlic Mustard invades a site, growth of tree seedlings is reduced. Like many non-native plants, Garlic Mustard has few natural enemies to help keep it in check.
Garlic mustard at the FWG
Garlic Mustard grows mainly in the Ash Woodlot at the FWG, although in recent years we've found patches in our Old Field habitat and at the end of our Amphibian Pond.
Our control strategy is based on the fact that this plant is a biennial, so preventing seed production should eventually eliminate it. We spend several weeks in May pulling out plants that are blooming. During the summer, our student employee or volunteers monitor the various patches for later blooming plants and any others that we missed in spring.
Strategy promoted by the Stewardship Network
Plants are bagged and removed from the site. In previous years, we left pulled plants on the ground assuming that they would not be able to develop to the point of producing seed. We now know that this is not true, and ALL plants must be removed from the site.
Recognizing garlic mustard in spring
Garlic mustard is one of the first plants to come up in the spring. Rosettes appear around the same time as Trilliums and other early spring wildflowers. We've found it helps to get an early start on weeding, but it's easy to confuse small Garlic Mustard plants with other species.
Here are photos of all the rosette-type plants growing in our woodlot in early May. Garlic Mustard is the only real invasive. Motherwort is not native and we usually weed it out as well, but so far it hasn't spread as aggressively as Garlic Mustard.