As winter continues to slip into the rear-view mirror. pesky plants such as garlic mustard shake off the last flakes of snow and begin their invasive ways. Garlic mustard is known to stay green all year long even under the snow making early spring detection possible. While having a long growing season is advantageous to the plant, it is also advantageous to the homeowners who can find it before our native plants emerge. If you have noticed garlic mustard on your property, now is the perfect time to act.
Garlic mustard is an introduced plant in the mustard family and was commonly used as a spice by our ancestors who brought it to America hundreds of years ago. To be sure, many recipes call for the use of garlic mustard as an ingredient. Besides the fact that it is edible, garlic mustard dominates the forest floor and displaces our native woodland plants. The loss
of plant diversity threatens native insects making food sources harder to find for butterflies. Even high-quality woodlands are vulnerable to infestations as experienced in North Oaks over the last 10 years, especially in disturbed areas and along forest edges.
Knowing the extent of the problem on your property is a great place to start. Sometime during the next few weeks, take a stroll around your property and make a mental note of where the garlic mustard is present. When you find an infestation, remove plants that are producing seed first, working from the least infested areas to the most infested area. Plants can easily be hand pulled if soils are moist. Then remove other plants, again starting with the least infested areas first. For large areas, herbicide use may be necessary as a last resort. Herbicides can be effectively used in early spring. Garlic mustard remains green throughout the winter and is one of the first plants to break dormancy making identification in early spring easy. By applying herbicides to these larger areas in the early spring other native plants are not affected since they have not yet started growing. Follow all label instructions closely and make sure the product you are using is suitable to the task.
Garlic mustard’s quick spread is due to its ability to produce hundreds of seeds per plant. It is a biennial and starts out as a small low plant in the basal rosette stage with kidney shaped leaves. In the spring of the following year, the plant sends out a flowering stalk. Garlic mustard is usually the only tall, broad-leafed, four petaled white woodland plant flowering in the last half of May making it easy to identify in the forest. The seed pods form near the top of the stalk, ripen, and then drop to the ground in fall covering the forest floor with thousands of seeds.
The trick to knocking back garlic mustard is to cut down the flowering stalks after they have elongated but before the white flowers have opened, in the last half of May. You may have to repeat this procedure twice during the spring as some plants tend to produce a second flowering stalk. This practice effectively eliminates the potential of the plant to produce and disperse seed giving you the edge on management. The other positive of removing the flowering stalks in the spring is that they can be left behind on site to wither away.
If you can’t manage the problem until after the seed pods have ripened, you can still make an effective dent into your eradication program. By bagging the flowering seed pods after they have been cut, you can effectively eliminate seed germination. Bagging flowering stalks in the spring may also not be a bad idea since some garlic seed pods have been known to establish even after flowering stalk have been removed.
Continue to monitor these sites, and your whole woodlands, in the following years to manage any new infection centers. Removing one or two plants now can save having to remove hundreds or even thousands of plants later.
I have seen this plant spread very quickly in a few short years and its consequences may equal or exceed those of buckthorn. Do your part by keeping this plant at bay. Watch for its spread on your property and act accordingly and this pest can be kept in check. If you would like more information on garlic mustard identification or control, please contact Mark Rehder the City Forester at 612-760-3519.
— Mark Rehder, North Oaks City Forester