Any way, a few weeks ago we sprayed his lawn with a product called Bonide Weed Beater Ultra. It is a broad leaf herbicide and does not contain 2,4-D. Instead the active ingredient is carfentrazone. 2,4-D acts by causing the plant to grow so fast it outgrows its food supply and dies. Carfentrazone acts by disrupting photosynthesis and causing the cell walls rupture. ALWAYS, always, always follow the directions on the label for application rates, re-entry into the area, and re-application intervals. Also, most herbicides work best when air temperatures are moderate, say below 85 F. And don't spray if it is windy.
You can see by the pictures that the first application really knocked it for a loop but there is still some life in it so we will have to make a second application. The label for the Weed Beater Ultra says you can re-apply in 2-6 weeks but that you should make no more than two applications per season.
I have a problem with garlic mustard. This is a problem in many areas of McHenry County. Garlic mustard is a very invasive weed and poses a severe threat to native plants and animals by aggressively competing for light, moisture, nutrients, soil and space. Where herbicides cannot be used you can hand pull the plants when the soil is wet so that you get the entire root or you can cut the second year stems to the ground to prevent the flowers from going to seed.