Many invasive plants upset local ecosystem

The list of invasive species is long, and it affects all gardeners, said Ruth Marshall , a volunteer with the Southeast Wisconsin Master Gardeners program since 2004.

“They take over our native plants and kill them. They will kill a lot of plants that are pollinators that nature depends on. … It’s important to keep our native plants for biodiversity,” she said.

Marshall, who lives and gardens in Nashotah, started an invasive species group for the master gardeners program.

Invasive plants she is most concerned about are garlic mustard, dame’s rocket, Queen Anne’s lace, common buckthorn, Oriental bittersweet and creeping Charlie. “Garlic mustard is a biennial, and it should be taken out by the roots, whether it’s small or large. If you have large ones (second-year growth), those are the most important to remove. She said if you have dame’s rocket (left) in your yard, you can dig it out or cut it down before or after it blooms. While cutting it down won’t kill it, it may keep it from producing seeds that will spread. If you run into Queen Anne’s lace (right), Marshall suggests hand-pulling it. “You see it all along the highways and it gets quite tall. Those I hand-pull, and you have to make sure you get all the roots out, and the best way to do that is to pull it when the soil is moist.” Common buckthorn, which is considered a tree, is on Marshall’s list because it can get large and spreads by seeds, so it “can really take over a garden. Some people use buckthorn as a barrier, and that’s not good because the seeds go everywhere. There are other shrubs that are beneficial to insects rather than buckthorn. “I cut it, then I treat it with an herbicide that has an oil-based solution. I paint it on the outer edge of the plant, which is the live part.” Oriental bittersweet is a vine that climbs up trees and can harm them when it gets larger. To get rid of this plant, dig it out or hand-pull seedlings. Cut the base of the vines strangling trees, allowing upper foliage to die back. Creeping Charlie (left) is a small plant, but it has a big impact as it gets into everything. You can pull it up any time you see it,” she said. Kelly Kearns of the Wisconsin DNR added to the list and said the following plants are considered invasive and can be found in both city and rural areas and that gardeners should consider removing them if possible.

Garden Invasives: Eurasian bush honeysuckle, Japanese knotweed, Japanese barberry, burning bush, bishop’s goutweed and purple loosestrife.

She also listed major invasive plants that spread on roadsides.

Invasives mainly on roadsides: Cutleaf teasel, wild parsnip, spotted knapweed, phragmites, leafy spurge, Canada thistle and crown vetch.