Garden Talk - Garlic mustard-a threat to recognize and eliminate

Gardeners tend to be conservation-minded, sharing the goals of soil health and plant health, heritage and diversity. All of those values are threatened by garlic mustard, a good-looking, but insidious invader.

Garlic mustard is a European plant. Not surprisingly, in the U.S., it showed up first in the East, then progressed to portions of the Midwest. Iowa counties north of Henry County have been organizing garlic mustard pulls for several years, but it is now time for Henry County to recognize this invader.

Why should we be concerned about this newcomer? Scientists at Michigan State University tell us that ?it readily invades forested habitats where it can displace native plants, compete with timber species regeneration, alter soil composition and structure, impact natural associations between plants and fungi, and result in cascading ecosystem impacts.?

Whether we care about spring wildflowers, oak seedlings, or just general environmental health, we need to obstruct this invader.

Garlic mustard plants develop on a two-year cycle. Seedlings first present a pair of kidney-shaped leaves and are hard to distinguish from other plants. However, first-year plants grow into clusters, or rosettes, of true green leaves, rounded in shape and scalloped or serrated along their edges. If crushed, the leaves do indeed smell like garlic. These plants emerge early, ahead of the first wildflowers to bloom, another characteristic helpful in identification.

On second-year plants, the leaf form is more triangular, the edges are more sharply serrated, and the plants send up stalks supporting white flowers resembling those of yarrow. After the flowering stage (April to June), abundant seed production is conducive to dispersion. Each mature plant produces hundreds of seeds.

Garlic mustard is highly opportunistic and competes vigorously with other plants. Strategies for removal depend upon the concentration of plants. If it shows up in spots, then pulling plants in spring is best. The pulled plants must be bagged and discarded. Unfortunately, this bad actor belongs in the landfill, not the compost pile.

If you become aware of an area carpeted by garlic mustard, then you will need different strategies, possibly including fire or herbicides, and some expert assistance.

Even in areas that have been thoroughly cleared, garlic mustard?s seed banks may persist for as long as five to 10 years. However, the plant population in subsequent years should be lower.

The good news is that the populations of trillium and tiny oak trees will gradually rebuild if garlic mustard?s progress can be arrested.