Herbicide test targets invasive species in Solon Springs
An herbicide called Garlon was used in Lucius Woods Park this month to combat buckthorn and honeysuckle, invasive plant species seeking to get a foothold in Solon Springs.
Garlon, with the active ingredient triclopyr, was applied to the leaves and cut stumps of invasive plants in a roughly 0.34 acre, or 15,000-square-foot, area July 20. The herbicide was used in a remote area of the park not far from the nature trail, according to county director of forestry and natural resources, Jon Harris.
Signage in the park remains in place to warn visitors to avoid those areas, he said.
This is the latest foray in the county's fight against buckthorn. Volunteers have pulled up the aggressive, woody plants by hand, but made little headway.
"We could keep an entire crew of 30 people busy down there for a couple of months," Harris said.
Since fall of 2015, the park has been the site of twice-a-year grazing by a herd of goats targeting the same invasive plants.
County Board Chairman Mark Liebaert said the small-scale application of Garlon is just a test.
"It's an experiment that's worthwhile trying, especially if it turns out the goats work as well," he said., favoring that solution.
A 1994 Douglas County ordinance prohibits the use of herbicides or pesticides without an exemption. In March, however, the Douglas County Forest, Parks and Recreation Committee gave the Garlon application a green light.
"To be honest, I don't know how we're going to get rid of buckthorn," said Liebaert, chairman of the committee. "We're trying to figure out what to do."
The approval wasn't taken lightly.
"Any time you bring up, we call it the 'H' word here, it brings up a lot of discussion," Harris said.
Two different methods of killing the tough, woody pests are under scrutiny during this experiment — poison and digestion.
The goat herd eats buckthorn, honeysuckle and pretty much everything green in its path.
Timing is crucial, said county Parks and Recreation Supervisor Mark Schroeder, to get the biggest impact on the target plants, but leave native plants unharmed.
To date, the twice-a-year applications have cost the county about $6,500.
The bill to design, implement and assess the herbicide experiment is $2,500, Harris said.
University of Wisconsin-Extension weed specialist Mark Renz and horticulturalist Jane Anklam staked out nine different plots in the park. Three received cut-stump applications, three had herbicide applied to the foliage of invasive plants, three were not treated.
In addition, Renz and Anklam took an inventory of all the plants in the test areas, as well as a spot that receives goat treatments, to gauge the effectiveness of the methods.
According to the National Pesticide Information Center, triclopyr ultimately degrades into carbon dioxide, with a half-life of up to 10 days in water and 90 days in soil. It is "slightly to practically" nontoxic to birds, "practically" nontoxic to water fleas and "moderately toxic" to fish.
Liebaert said that this is not an attempt to gut the county's pesticide ordinance.
"The county is still supportive of the ordinance we have in place, which prohibits the use of herbicides and pesticides without an exemption," the county board chairman said. "In the real world, exemptions are what have saved this ordinance."
Past exemptions have included approval for herbicide use on a profuse stand of Japanese knotweed at a forest landing and treatment aimed at halting the spread of phragmites in St. Louis Bay.
"The alternative of them spreading so fast and so far was too great a chance to take," Liebaert said.
Just how much damage can invasive species do?
According to the Wisconsin First Detector Network, buckthorn and honeysuckle can outcompete nearly all native plants, adapt to various soil types and sunlight conditions, and shrug off diseases until they're the only plants standing. That can affect soil and water quality, which impacts wildlife.
Take a walk through a pristine northern forest and one in the southern part of the state, Renz said, and the impact becomes clear.
"The importance of controlling invasive species has grown in urgency," Harris said, and Douglas County is testing all the tools it can to protect its nearly 290,000 acres of land.
Lucius Woods Park is the current battleground.
"I don't know what the answer is here," Liebaert said. "The reality is this buckthorn is taking over everything. Between the two (buckthorn and honeysuckle), they may be the only plants left."