Winnebago County is being taken over by alien invaders! Invasive alien plants, that is. Take a walk along the Wiouwash Trail. Here you should see native prairies and forests since this land hasn’t been cultivated or disturbed for many years. What do you see instead? Wooded areas have been overgrown by buckthorn, wild grape vines and garlic mustard. The prairies are overgrown with trash trees and weedy shrubs.
The same is true for forgotten areas behind garages and along fence lines. Buckthorn and garlic mustard are especially sneaky at hiding in shady areas in the back of flower beds or right next to multi-stemmed shrubs like lilac, spirea, dogwood and highbush cranberry.
Many invasive plants arrived in the United States from Europe. They were either brought over intentionally as ornamental or useful plants for gardens, or unintentionally when seeds hitchhiked with some other cargo or plant. The problem is that the natural controls, insects or other predators, did not come with the plants, allowing them to grow unchecked.
Garlic mustard is a prime example. European settlers brought it to the new world as a cooking herb and it has been slowly spreading west and northward ever since. It crowds out native woodland plants like trillium, bloodroot, trout lily, anemone, spring beauty and wild ginger.
The roots of garlic mustard emit a chemical that kills the fungi in the soil that should have been food for many tiny insects. When the smaller insects die, the larger insects that eat them die, then the birds that eat the insects starve and the effects move on up the food chain.
Garlic mustard attracts butterflies to lay eggs, but a chemical in the plant poisons the eggs or the larvae so butterflies never form.
You can help control garlic mustard by pulling it whenever you see it. It pulls up easily in early May just before and during flowering. Do not compost the plants or let them lay on the ground, as they will continue to grow and set seed even after being uprooted. Each garlic mustard plant produces several hundred seeds which are viable in the soil for up to seven years.
To see what garlic mustard looks like, the Invasive Plants Association of Wisconsin has good photos on their website: www.ipaw.org.
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