Conservation officials say the recent confirmation of invasive mile-a-minute weed in Jackson County marks the plant's continued spread into southern Michigan, but they stress the discovery is consistent with what scientists expected rather than evidence that the vine is spreading faster than anticipated.
The Michigan Invasive Species Program announced this week the aggressive, fast-growing vine was confirmed in Jackson County after a local landowner reported a suspected infestation. The detection represents the first confirmed population of mile-a-minute weed in the county.
According to the Michigan Department of Natural Resources, the newly confirmed population is located just across the county line from established infestations near Albion in neighboring Calhoun County, where the invasive plant has been present for several years.
Katie Grzesiak, terrestrial invasive species coordinator for the Michigan Department of Natural Resources, said the close proximity between the two infestations makes the Jackson County discovery unsurprising.
"It's not spreading more quickly than we would expect," Grzesiak said. "This plant has been in Calhoun County for a number of years, and it's quite close to the Jackson County border."
She said there's less than two miles separating the newly discovered Jackson County population from the nearest known infestation in Calhoun County.
But officials don't know exactly how the plant reached Jackson County.
"There are a couple different options there, and we just aren't sure," Grzesiak said.
The plant's seeds can be dispersed naturally by wildlife, particularly birds that consume the vine's berries before depositing the seeds elsewhere. Human activity can also unintentionally move the species between locations.
"The seeds can get caught in dirt, which gets into people's shoes," Grzesiak said. "The vines themselves or the seeds in dirt can spread on equipment as well, so there's a risk of people spreading it, whether on their own or on equipment, in particular farm equipment."
Although the public announcement was released this week, Grzesiak said the infestation was actually discovered about a month earlier.
Since then, state agencies and regional invasive species organizations have been surveying the surrounding area to better understand the extent of the population.
"So far, there haven't been any new detections outside of that first one that was reported to us by the landowner," Grzesiak said.
The absence of additional confirmed infestations gives officials confidence that they have a clearer picture of the situation, though survey work remains ongoing.
Some of that work depends on cooperation from nearby landowners.
Because much of the surrounding landscape is privately owned, survey crews can't just enter properties to search for additional infestations.
“This is on private land, and in order to access private land, whether it's the Michigan DNR or the Cooperative Invasive Species Management Areas that are doing the majority of the on-the-ground work, we have to have permission in order to access those properties,” Grzesiak said.
The response is being coordinated among multiple agencies, including the Michigan Department of Natural Resources and regional Cooperative Invasive Species Management Areas.
Alongside traditional management techniques, researchers are also evaluating whether a tiny insect could help slow the spread of mile-a-minute weed across Michigan.
Earlier this summer, researchers with Grand Valley State University began releasing the mile-a-minute weevil, an insect that feeds exclusively on the invasive vine. The biological control has already been used in several eastern states where the weed has become established.
Grzesiak emphasized that Michigan's project remains in its early stages.
"We're only a couple of months in at this point," she said. "Right now, it's about monitoring to see how those weevils are surviving, how they're spreading and what kind of damage they're doing to the plants."
Researchers don't expect to draw meaningful conclusions until at least next year, and the study will likely continue beyond that.
"We're relatively certain this weevil is not going to eradicate mile-a-minute weed," Grzesiak said. "What we're hopeful that it will do is help keep those populations to a dull roar so that other management strategies can take place."
If future releases of the bug do occur, Grzesiak said they would likely focus on the state's largest infestations rather than isolated populations like the one recently discovered in Jackson County.
"We still have a lot to learn," she said. "We don't know all the things yet, but that is my guess based on how other biocontrols have worked."
This story is brought to you as part of a partnership between WKAR and Michigan State University’s Knight Center for Environmental Journalism.