Phragmites is one of the Top 20 invasive plants in northwest Michigan. The Top 20 list was developed in 2010, when ISN partners met and discussed known invasive plants in the region and chose 20 that posed the greatest threat to our fantastic habitats. Level of “importance” of these 20 plants varies within the region, though phragmites, Japanese knotweed, Oriental bittersweet, and garlic mustard have risen to the top as very invasive species that are not completely established in the landscape. The Top 20 list does not include Early Detection/Rapid Response species–non-native plants that are causing problems in other, similar areas, but are have not arrived or are not well established in northwest Michigan. Early Detection species are at even higher priority than the Top 20 so we can act quickly to control them before they become firmly established and do the damage to our habitats.
ISN had some big goals!
When partners met this midsummer, garlic mustard, invasive phragmites, Japanese and giant knotweed, and Oriental bittersweet were identified as our highest-priority plants for the region. We then surveyed over 10,290 acres and 170 miles of shorelines–including shores of rivers, inland lakes, and Lake Michigan–to look for top-priority invasives. Though specifics varied by county, removing these plants from high quality natural areas and areas that would increase spread by the invaders (like roadsides) were made the main target for treatment.
Using grant money to protect high-quality habitats
Partners decided which areas that had been surveyed or had reported populations should be treated, many of which were public lands and State Game Areas. We applied for Aquatic Nuisance Control permits from the Michigan Department of Environmental Quality, gathered appropriate permissions, and coordinated treatments. This year, we were able to treat approximately 3,160 acres of high-priority invasive plants in the region to safeguard these crucial native habitats.
We’re also seeing some amazing native plant regrowth in areas that are now nearly phragmites-free! Many partners, like Portage Lake Watershed Forever, have seen similar results.
The Japanese knotweed project is newer and the plant is even harder to control than phragmites, often taking three or four years to control. With continuing to work with the DNR for best treatment options, we are hoping to see significant dents in treated knotweed populations come spring.
Garlic mustard is possibly the easiest to see great preliminary results with, though true control requires more time due to a long-lasting seed bank. This year, volunteers at the Tippy Dam pull in Manistee County reported that populations of this target plant were much lower than in previous years from pulling alone. Herbicide treatments this fall should help stem the tide of seedlings, making next spring’s work bees that much more effective! Similar results from pulling were seen at the Great Garlic Mustard Hunt in Grand Traverse County, and area where garlic mustard is still an early-stage invader.
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