June 23, 2022 at 11:14 a.m.
Oneida County Land and Water Committee learns about purple loosestrife control
Oneida County Land and Water Committee learns about purple loosestrife control
There are several ways to deal with purple loosestrife. One of those is chemical control. The land and water department does not use herbicides in the fight against this invasive species, Boismenue said.
Another option is to dig the plants out. This is a difficult project, at best, given the massive root system. Because these projects tend to be large, they can require a great deal of manpower, time and resources. However, one other control option has been used in the state with good success.
Biocontrol has proven successful in the fight against purple loosestrife. The Galerucella beetle spends its entire life cycle on purple loosestrife, consuming the plant and stressing it to the point that stands are at least reduced in size when plants are killed by these beetles. The beetles are native to the same places where purple loosestrife is native. However, research has shown beetles do not affect any other plants or any native species. This makes them a great option for control. The beetles can kill plants within a matter of weeks. Of course, it is not in the best interest of any animal to completely deplete its food source, but they are very effective at control.
Boismenue spoke about the Three Lakes project as well as a similar project at the McNaughton correctional facility. In order to grow the beetles to be used for biocontrol, host plants are needed. Boismenue said a hotel in Rhinelander has a stand of purple loosestrife in the back behind their parking lot and those plants are dug up to be used as hosts. The plants are potted and taken to the Petroleum Museum in Three Lakes. This is where the biocontrol tents are located.
There are two tents located at the museum, which is owned by the former president of the Three Lakes Waterfront Association, Boismenue said. Although he is no longer with the association, Boismenue said he continues to be gracious enough to keep the tents on his land. Likewise there is one tent located at McNaughton Correctional Facility where inmates help to rear beetles as well.
Tents are filled with swimming pools. The pools each hold several planters of host plants, mimicking a wetland environment. Boismenue said it is important that tents are tight and secure and even have plastic lining on the bottoms. This ensures no predators can get in and beetles cannot get out.
The beetles are set to arrive soon, she said. Some come from the Department of Natural Resources (DNR), and others are collected at local purple loosestrife sites.
Each plant receives 10 beetles at the outset. Within a few weeks, they have reproduced. Each beetle will have 100-500 offspring in that amount of time. In about a month, she said, the plants are reduced to almost nothing.
"We have lots of beetles that are getting hungry," Boismenue said. "And we have lots of new beetles that are getting hungry. At that point we collect beetles and put them in mesh nettings." From there the netted pots are put into a pickup truck and transported to the boat landing at Town Line Lake. From there the beetles take a pontoon ride to sites where purple loosestrife has run rampant. Canoes are loaded up from the pontoon boat into canoes for the final transport to the wetland areas that have been affected.
Because the beetles have not eaten in a few days, once they are picked from the host plants and put onto the purple loosestrife plants in the wetland areas, they immediately get to work filling up.
The dead potted plants are also taken out of the pots and put into the wetlands, Boismenue said. The reason for this is there may be larvae in the soil of those plants and the idea is to give them the best shot at survival. When they come out of the soil, they will find thriving purple loosestrife to eat at the site where the host plants were placed.
"It's a long process," Boismenue told the committee. "It's exhausting but it's a lot of fun. You never know what you are going to see."
Extra pots of purple loosestrife from Three Lakes will be going to the thoroughfare on the Minocqua Chain, she said, where there are problem areas of purple loosestrife. The pots from the McNaughton Correctional Facility will be headed to Lakes Minocqua and Kawaguesaga.
There are 100 pots currently in Three Lakes. In McNaughton there are 50 pots.
Boismenue spoke with the committee about the life cycle of the Galerucella beetle. She also reassured committee members beetles, when given the option for other types of plants, would go off in search of more purple loosestrife rather than feast on any other native plant. The DNR, she said, had said the beetles would travel up to 10 miles in search of purple loosestrife. She was not sure, however, how they arrived at the number.
At the end of the season, she said, she removes the plants and cleans off the entire root system, making them bare root plants. From there they go into fresh soil. This ensures there is no spiders, snakes, or anything else in the soil that could contaminate the plants to be used for the next year's hosts.
Committee member Bob Thome asked about mosquito spraying and if that effected the beetles. Boismenue said they made an observation a couple years ago on Medicine Lake. The wetland there is divided two by a channel, she said. On one side of the channel, near where a private residence had used the Mosquito Police, Boismenue said, she and staff did not find any beetles thriving. She said there was not so much as a dragonfly in that area. In the other half of the wetland across the channel, she said, beetles were thriving. She called it an "eye opening concern," although it was was simply an observation. However, something similar was seen on Lake Minocqua where a property owner had used a similar mosquito spraying company. Thome sited a similar concern near Kemp Station.
Thome asked whether the department had initiated any conversations with mosquito spraying companies. County conservationist Michele Sadauskas said they had invited companies to attend a meeting a couple of years ago, but none of the companies sent a representative. She said the department would still be open to having a conversation with companies involved regarding where projects such as purple loosestrife biocontrol were happening and she would look to do some outreach. With the use of these chemicals being those companies' livelihoods, however, there was some doubt as to whether or not they would be receptive.
Beckie Gaskill may be reached via email at [email protected].
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