By Steve Swenson, Ecologist, Aldo Leopold Foundation
A successful garlic mustard control program is both preventative (i.e., identifies new populations) and curative (i.e., controls known patches).
Herbicides containing the active ingredient glyphosate are very effective at a 1.5% to 2% rate (brands include Buccaneer, Touchdown, and Roundup). At the Leopold Foundation we add a colorant (Tracer brand) to see where we have sprayed.
A control program is more efficient if it controls all stages of the plant: seedlings, rosette stage, and adults. The is best achieved with herbicide, rather than hand-pulling, mowing, or burning. For us, herbicide application begins late April/early May and continues through early June.
For follow-up, we revisit all treated patches a couple of weeks later to pull and bag any surviving garlic mustard plants.
Yes, an annual investment of time and money is required, but this method will help ensure sure you are not wasting either of these resources in protecting the health of your woods.