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MADISON – Purple loosestrife is in full bloom across Wisconsin and state invasive species officials are asking the public to help control these non-native plants. Citizen help is crucial for preventing and controlling most invaders.
“Purple loosestrife is easiest to find when it’s flowering,” says Brock Woods, who coordinates Wisconsin’s efforts to control this invader. “This exotic perennial has bright, pink-purple spikes and the ability to overrun thousands of acres of wetlands. Now is a crucial time to look for it, report it and take action to prevent its spread.”
For more than 10 years, special beetles have been released to feed on purple loosestrife and control its spread. Monitoring of these natural insect enemies has confirmed that they only live on this plant and successfully decrease its size and seed output.
This process proves an effective and environmentally sound control of the plant and although it does not completely eliminate the invasive, citizens can combine other traditional methods of removal to further prevent plant size and spread, including digging, cutting and using herbicides. They may also start new local biocontrol beetle populations.
According to Woods, beetles are reducing purple loosestrife stands in many areas, but are still missing or too few in other stands. Most beetles have been raised and released on local loosestrife by citizens participating in the Department of Natural Resources and University of Wisconsin-Extension Biocontrol Program. Free equipment and starter beetles are available through the DNR. For more information search the DNR website dnr.wi.gov for “purple loosestrife” or “purple loosestrife biocontrol.”
What you can do now
• Note and report where you see uncontrolled purple loosestrife. Plants without controlling beetles are typically more than 4 feet tall with flower spikes exceeding a foot in length and intact lower leaves. Citizens can report purple loosestrife on public or private land. To report loosestrife-or any invasive species you see, go to the DNR home page and search the key words, “reporting invasives.” Choose your habitat type, then click and fill out the Report Form. You can also send an email to Invasive.firstname.lastname@example.org with the exact location, land ownership if known, population size, your contact information and a good photo. Call 608-267-5066 for more reporting information.
• Pull small loosestrife plants with one or two stems to eliminate them on your property or where you have landowner permission. Check next year for any more new plants
• Cut off the flower spikes of plants that will not be pulled or immediately controlled in other ways to eliminate this year’s seed crop. Once flowering, assume that seeds may also be falling. Securely bag all cut flower spikes, label as “Invasive Plants” and put them in the trash. Composting will not kill the seeds. According to Woods, one mature, uncontrolled loosestrife plant can produce more than 2 million seeds, which can last in the soil for years, so it’s important to remove flower spikes before seeds fall.
• Treat your own plants with a homeowner-approved herbicide such as Roundup. If there is open or standing water near the plants, use an herbicide labeled for use near water and get an aquatic plant management permit from the local DNR aquatic plant management coordinator.
• Raise your own biocontrol beetles to reduce purple loosestrife dominating or threatening your local wetlands!