Reference my article Garlic Mustard in which I mentioned the paper “introducing evidence toward the negative effects of the invasive plant garlic mustard (Alliaria petiolata) on native mycorrhizal associations.” Now Douglas Main has written for the National Geographic:
“The plant produces an abundance of glucosinolates, a family of sulfur-containing chemicals present in many types of mustards, which generally have a pungent smell and sharp taste. They give horseradish its kick and make yellow mustard spicy. But in the case of garlic mustard plants, the glucosinolates are also excreted by the roots, killing some of the symbiotic mycorrhizal fungi that most native plant and tree species partner with to draw nutrients from the soil. Garlic mustard, like other members of its family, do not need these fungi to thrive.
The decreased abundance and diversity of these fungi can last for many years after the plant is removed.
There’s also some research showing that this fungi-killing power perhaps weakens native plants and makes germination more difficult, although the scientific record is mixed as to how serious the effect is.”
Two-Year Life Cycle
Now is the time to watch for garlic mustard plants. It grows as a biennial. The first year, it lays low to the ground, forming small, rosette-like leaves. The plant develops its leaves, stems, and roots. In the early spring, the second year, it blossoms. It can be one single stem with a flower or a number of stems with all kinds of flowers.
Understory of Ironwood (Ostrya virginiana)
According David Gossman, GCI Solutions, Inc, “do not cut your understory of ironwood (Ostrya virginiana) or eastern hop-hopbeam, if you have any. It used to be something that foresters suggested removing because it uses resources without creating value. Turns out, if you look for garlic mustard under ironwood trees, you will see little or none. There is some sort of naturally controlling agent there.”