FATAL beauty
Invasive species can cause havoc in your backyard and far beyond
Whenever someone mentions invasive species of plants, I think of my friend Mary, who has the most beautiful gardens. ♦ One day, years ago, another gardener suggested she take home a small garlic mustard plant, as it was edible. ♦ She planted that little seedling in her yard, and it spread with abandon. ♦By the time she found out that she had planted one of Wisconsin’s most invasive species – it was too late. ♦ It was everywhere. And since then she’s spent many hours trying to get rid of it.
Kelly Kearns, an invasive plant coordinator with the Wisconsin Department of Natural Resources, said people do occasionally end up with invasive species in their yards because they don’t know what the plant is or how it will affect their landscape. But that’s not the norm.
In most cases, she said, these plants reproduce either by seed or vegetative reproductive structures, such as roots, or rhizomes.
And when they do reproduce, they can cause havoc in gardens in cities, rural areas, parks and even forests.
So what exactly is an invasive species?
Kearns gives the legal definition as a “non-native species that cause harm to the environment, to the economy or to human health.
“Take buckthorn for example,” she said. “It gets into a forest and spreads by seed and outcompetes with the other species there and causes mature trees to slow their growth as it’s taking in the nutrients and water. It also shades out the smaller plants, including tree seedlings, so it prevents tree regeneration
“Wildflowers are also typically eliminated pretty quickly, and it also changes the composition of the soil in its favor, which in turn makes it harder for the natives to grow.”
A lot of invasive species threaten our area – 145 “regulated” plants, to be exact, said Kearns.
“Eighty two species are classed as ‘prohibited’ in all or part of the state, meaning that they are not yet known in the state, or are only in a few areas so they could potentially be eradicated’ and they legally must be controlled.
“Sixty three are classed as "restricted" statewide, meaning they are too widespread and/or abundant to realistically expect that they can be controlled except at the local level. We encourage people to control them, but they are not required to.”
Kearns said both the prohibited and restricted species cannot be sold, purchased, brought into the state, moved from one spot to another, given away or planted.
But there are some exceptions.
Some species have a wide variety of cultivars, but only some of them are considered invasive, Kearns said.
“For example, Japanese Barberry has 80 cultivars, 25 of those are regulated, all the rest are not,” she said.
“Burning bush is also on the list and has different cultivars, most of which are exempt from the regulation,” she said. “But there are lots of cultivars, and we don’t yet know exactly which ones are invasive. If people are concerned about this plant, they are better off not buying it. Research is being conducted, and hopefully information will be available in the near future.”
Another exception is plants in the “phase-out period.”
“For plants that were regulated in 2015, we gave nurseries time to sell out their stock or what they had in their fields,” she said.
Kearns added that in addition to invasives already here, new plants are making their way into our area.
“A few that are starting to spread in some areas and are spreading rapidly include teasels, Japanese hedge parsley, wild chervil, poison hemlock, garden valerian and celandine,” she said.
So how do we get rid of these plants?
Kearns said the best method is to keep the seeds from spreading and to dig out the plants.
“What I do in my garden is to remove seed heads before they seed and put them in the garbage. I dig out the rest of the plant and let it lie out in the sun for a couple of days and then I put them in the compost. If they’re dry, their roots won’t cause a problem,” she said.
But there are cases in which gardeners have to take it a step further, she added.
“If your population is too large to pull, you will have to use herbicides. Use them according to directions on the label so that it’s effective. It must be mixed correctly and applied at the right time of the year.”
Another way to ward off these species is to establish a healthy native plant and animal community on your property, said Jill Hapner, executive director of the Southeastern Wisconsin Invasive Species Consortium Inc.
“This can be done by choosing native tree, shrub and herbaceous species that are adapted to your particular soil type. Always ask for the Latin names (genus and species) of plants before purchasing and planting them and make sure they are not listed as an invasive species.”
Hapner said this is important because native plants have formed interdependent relationships with native wildlife over thousands of years, and therefore offer the most sustainable habitat. And with these plants in place, it will be more difficult for invasive species to take root. Education and volunteers also help, she said.
“At SEWISC our first line of defense is education,” she said. “We try to teach people how these plants harm the environment. The second line of defenses is tackling infestations of different kinds of plants,” she said.
In 2011, 2012 and 2013 more than 150 volunteer residents throughout the eight county Southeastern Wisconsin region drove their roadways to map invasive plants, Hapner said.
“We have shared the maps created by those local residents and are working with our local government roadway crews to minimize the spread of these species through properly timed management,” she said.
The species they looked for were common and cut-leaved teasel, common reed grass, Japanese knotweed and wild parsnip.
In nature centers, parks and backyards, one of the most problematic plants is garlic mustard. For that reason, an annual pull-a-thon is held.
In spring the invasive species consortium held a Garlic Mustard Pull-A-Thon, which lasted about 21⁄2 months, Hapner said. Teams recruited funds for education and competed to pull the most bags of garlic mustard and dame’s rocket.
“This year our winner is the River Revitalization Foundation Team, whose 87 team members pulled 11,040 pounds of garlic mustard and raised $345 in donations."
Collectively, 842 residents formed 12 volunteer teams this year, raising funds and awareness while controlling 36,585 pounds of garlic mustard and dame's rocket in our natural areas, she said.