Alliaria petiolata, otherwise known as garlic mustard, is an invader from Europe that has established populations in much of the eastern United States and many states westward. They can grow annually, perennially, or biennially in their native range but are typically obligate biennials in the US, meaning they complete their lifecycles in two years . Seedlings germinate in the wet spring, and remain as rosettes over the winter until the following spring when they bolt and flower. Like other members of the family Brassicaceae, garlic mustard flowers are radially symmetrical and comprised of four petals. Once pollinated either through self or cross fertilization, its carpels form fruits called siliques which dehisce at the end of the growing season to release its seeds. This is important as they can only propagate by seed which can travel several meters away from their parent. Seeds can also spread longer distances by hitchhiking on passing animals and people.
My technique for harvesting was to hold the main axial stalk firmly and close to the ground, wiggle, and pulling straight up.
Garlic mustard does not have a vast network of roots, so plants pull right up with minimal collateral damage. Since they do not propagate vegetatively, you don’t have to worry about leaving bits of root around like you would with Phragmites.
Ecological impacts and management
Native plants suffer the brunt of garlic mustard invasions because of their susceptibility to lose soil nutrients, light, moisture, and space from direct competition. In addition, garlic mustard roots also release chemicals that harm neighboring plants and mycorrhizal fungi which results in the inability of the roots of neighbors to take up water and nutrients. Related to the threat to native flora is the subsequent threat to native fauna which rely on native plants for food, pollen, and nectar.
Further bolstering the fitness of garlic mustard in the new world is its release from co-evolved enemies. Members of the Brassicaceae family produce secondary compounds called glucosinolates which are distasteful to herbivores and toxic at high levels (relative to body size), but tasty to people. Herbivores in the US have not adapted or evolved to consume garlic mustard which increases survivorship of garlic mustard to reproduction.
Garlic mustard can be eradicated through tough and diligent removal efforts. Chemical removal of rosettes in their first year is possible, but the presence of native flora must also be considered. Repeated mechanical removal prior to seed production and release is necessary to stop the entrenchment of the next generation, and harvest will bring a new and interesting ingredient to the dinner table.
UPDATE: We also encourage you to check out http://garlicmustard.org/ to see how you can contribute to valuable scientific research while you harvest your next meal!