Spring in the woods is full of return events: the drumming of a sapsucker, wood frogs in a vernal pool, bloodroot and trout lily in blossom. And garlic mustard greening up, in some places in overwhelming numbers.
Garlic mustard (Alliaria petiolata) is one of the most destructive of several invaders of our forests. Its time is now.
Settlers brought garlic mustard to North America for culinary purposes. (More on that later.) It long since left the kitchen garden, and is found now in sun or shade (but mostly shade), along roads and rivers, and in nearly every state and several Canadian provinces.
Garlic mustard is a biennial species, blooming and then dying in its second growing season. In its first year, seedlings grow as a low, circular arrangement of leaves, each leaf rounded with a scalloped edge, and smelling of garlic. The plants will stay greenly petite through the growing season and over the winter.
In their second year, which began a couple of weeks ago for year-one plants, the stems begin to elongate. The new leaves they bear are triangular or heart-shaped, toothed, and also with a strong garlic odor. Soon the plants will burst forth in dozens of small, four-petaled white blossoms on stems up to three feet tall.
The cycle will end, unhappily for those who care about our woods, with seeds — hundreds of seeds per plant, carried in needle-shaped pods held upright on the stem.
It is during the plant's brief flowering season that it is most easily controlled. As a publication by Wisconsin Family Forests says: "Petals white and four. Still in doubt? If garlic smell, pull it out." But why pull it out? To protect native biodiversity in our forests.
Unless quickly eradicated, garlic mustard can take over forest floors, shading out the wildflowers we so look forward to and inhibiting germination of tree seedlings (including sugar maple seedlings!). It can also impact already present woody neighbors, by wielding what some people have called chemical warfare. In a one-two-three punch, roots of garlic mustard release a toxin; the toxin kills fungi that help trees take up nutrients; tree vigor declines as a result.
In our part of the range of the pest, hand pulling still seems to be the best method for controlling garlic mustard, and the best approach to hand-pulling is "early detection-rapid response." Make a mental note of any plants you see in your woods or favorite hiking spot, and visit those locations each April and early May to pull all the plants you can.
Put the pulled plants in plastic bags, and leave your pickings in the bag until the plants have rotted. Don't leave them in the woods, as some plants will have enough energy left even after pulling to develop seeds, and seeds can remain viable for five years or more. And don't move seeds around. Keep people and pets out of infested areas during flowering and seed season.
You can practice hand-pulling this spring (and find out just how easy it is and how much fun it can be when done with others) at several regional garlic mustard pulling days scheduled by the Vermont Nature Conservancy. The organization's Dave McDevitt (802-265-8645, ext. 26, or dmcdevitt@tnc.org) will be leading pulling parties at Quarry Hill in Pownal on April 24, 29, and May 7, and at Equinox Highlands in Manchester on May 5, 20, and 29, and again in early June.
And to find our why the settlers might have brought the cursed thing here to start with, see our Web site (at www.bccdvt.org/PDFs/knotweed_squares_recipe.pdf) for a recipe for garlic mustard pesto created by chef Bruce Kennedy. It's a small consolation for the changes this species has wrought in our woodlands, but better than none.
Shelly Stiles is the district manager of the Bennington County Conservation District, whose mission is promoting rural livelihoods and protecting natural resources in Southwestern Vermont. See our new Web site at www.bccdvt.org.
This column appeared in the Bennington Banner in April 2009, as one of the BCCD's Conservation Currents pieces, a bi-weekly feature written by BCCD board and staff members since August 2006.