Purple Loosetrife Eradication Program

Combating Purple Loosestrife

A Brief History

During the 1800's, purple loosestrife (Lythrum salicaria) arrived in America, most likely in the form of seeds in the ballast of ships. Its spread into our wetlands has become a countrywide problem. It aggressively out competes and displaces native vegetation; it’s dense growth above and below water eliminates food, nesting, swimming, and shelter for wildlife.  Forming a monospecific stand and thereby reducing the diversity of natural wetland plant communities; purple loosestrife is shifting the ecological balance of our native wetlands at an alarming rate.

PLC vs. the Purple Scourge

In 1998, several concerned PLC members organized the Purple Loosestrife Awareness Committee (PLAC) and formulated plans to take a stab at controlling Purple Loosestrife in the Watershed. Members began their efforts by digging and topping plants but found that efforts at large sites were labor intensive and results were discouraging. The need to take some effective action was important.

Recognition that Purple loosestrife has no natural insect enemies on this continent, and that in Europe and Asia several native beetles, Galerucella spp. being one of them, have kept loosestrife under control for years; prompted years of research at Cornel University on the topic of the exclusive feeding habits of the beetle on Purple Loosestrife. In 1992 both Canada and the United States began importing and releasing beetles in areas where loosestrife was running rampant. In New Hampshire, the DOA (Department of Agriculture) and DOT (Department of Transportation) started introducing beetles around 1996 on state-owned properties, with encouraging results.

In 1999, the PLC's Purple Loosestrife Awareness Committee (PLAC) and the PLC board decided to introduce beetles in several wetlands in the watershed that had large amounts of loosestrife. The PLC joined the DOA as the first community based conservation organization in NH to release beetles for control; it since has been a model for other organizations. Encouraged by initial results, the PLC continued to receive beetles from the State and release them in additional impacted wetlands over the next two years.  

In 2000 and 2001, the DOA trained individuals and groups how to raise Galerucella spp. beetles. To ensure an ongoing supply of beetles for our watershed, the PLC began a three year stretch of raising beetles; with mixed results. Once some release sites had adequate beetle populations, enabling us to harvest beetles from one site to release at others; we stopped our beetle raising program.

We currently have approximately twenty beetle release sites in the Watershed; New Boston, Francestown, Weare, Goffstown, Greenfield and Manchester. Success of beetle damage at sites varies depending on age of the beetle population and fluctuating environmental conditions; but overall, we are pleased with our results. In addition to beetle control, digging of roadside plants and solo plants in new sites has slowed the spread of Purple Loosestrife monitored areas.

In 2004 the Purple Loosestrife Awareness Committee changed its focus to encompass additional invasive species that are in the watershed. We changed our name to reflect this, and are now the PLC’s Invasive Species Committee (ISC).

Contact the PLC

Want to learn more about the use of the beetle Galerucella spp. in the effort to control purple loosestrife? You can borrow the 30-minute video Restoring the Balance and Biological Control of Purple Loosestrife, which documents how a loosestrife infestation at the Montezuma Wildlife Refuge in central New York was managed using beetles.

Want help identifying plants or deciding how to control Loosestrife in your yard? .> contact us

Want a lecture and PowerPoint presentation about Purple Loosestrife for your garden club, school class or organization? > contact us

For More Information

Excellent resource page from University of Minnesota; includes identification, biological controls, alternative plantings: http://www.seagrant.umn.edu/exotics/purple.html

Information about biological control of Purple Loosestrife using beetles: http://www.nysaes.cornell.edu/ent/biocontrol/weedfeeders/galerucella.html

Information through the UNH Cooperative Extension Purple Loosestrife information page: http://extension.unh.edu/Pubs/HGPubs/altinvs2.pdf

Know Your Loosestrife!

There are a number of yellow and magenta blooming native loosestrifes that also inhabit wetlands that are not invasive. However, the three species of loosestrife that do threaten our wetlands are Lythrum salicaria, Lythrum virgatum, Lythrum alatum, and their cultivars.

Why should you be concerned about cultivars of purple loosestrife? Even though horticultural varieties are said to be sterile and incapable of pollinating other plants, they are in fact capable of cross-pollinating and producing at least 1,500,000 seeds per plant! Gardeners sometimes report having several plants in their garden that never set seed. However; honeybees, the main pollinators of loosestrife, commonly travel up to five miles and carry pollen to plants elsewhere, aiding the spread of loosestrife in natural areas. So, if you see one plant, remove it now – before it has the opportunity to cross-pollinate!

Purple Loosestrife has many cultivars; some of the more common ones are include Morden Pink, Pink Spires, Dropmore, and Morden Gleam. For a list of purple loosestrife cultivars to avoid, visit www.seagrant.umn.edu/exotics/purple.html. Always read the labels of wildflower seed mixes and don't buy any that include purple loosestrife.

Take Action - What You Can Do!

Combating Purple Loosestrife

• If you need help identifying purple loosestrife, call the PLC's resident loosestrife consultants.
• If you have small amounts of loosestrife, dig it up (be sure to get all the roots!), wrap it securely in a plastic bag, and dispose of it with your trash. Do not compost it!
• If your property has a lot of loosestrife and you would like to consider releasing beetles to control it, contact the PLC.
• If your property is currently loosestrife free, beware of inadvertently introducing it.
• Imported loam or fill may contain loosestrife seeds so monitor the site for new loosestrife plants and remove them immediately.
• Avoid nurseries illegally selling purple loosestrife (Lythrum salicaria) and its cultivars. The propagation, sale, purchase, and transportation of these and other exotic aquatic species of plants are prohibited by law in NH. You can get a full list of these cultivars from NH DES by calling 271-2963, or contact the PLC. We can also suggest alternative plants.
• Be on the lookout for pioneering plants or isolated small colonies, especially along the roadside or in areas otherwise free of purple loosestrife. Dig, bag and dispose of plants properly. That one single plant that you drive by everyday will spread quickly into adjacent wetlands and disturbed areas. Catch it while you can!

For More information

Search the NHDES website at http://www.des.state.nh.us/.

The Law

RSA 430:55 governs the handling of 35 New Hampshire prohibited plant species, including purple loosestrife. There are two parts to this statutory authority that affect us:

Part 3802.01 states that The sale, distribution, purchases, propagation, transportation, and introduction of these species (including Purple Loosestrife) in New Hampshire are prohibited by law. Don’t hesitate to voice your concern over the selling of loosestrife cultivars at a garden center, violations can be reported to the NH Department of Environmental Services (NHDES) at 271-3414.

Part 3802.02 states that persons shall be exempt from the rule stated above for a number of purposes, including transportation and disposal; as long as one can ensure that viable living parts, seeds or propagules do not escape. Don’t hesitate to dig, properly bag and transport purple loosestrife to your transfer station for disposal!

Garden Alternatives

If you've discovered purple loosestrife in your garden, don't despair, you can get rid of it! There are many attractive alternatives to purple loosestrife, both herbaceous perennials and woody shrubs that are magnificent in the garden without being invasive or damaging to the natural environment. The following list includes a variety of plants that share the upright, bold, self-assertive growth habit that is characteristic of purple loosestrife. Blooms range from purple to hues of blue and red.

Contact the PLC

Want a display board and notebook of color photos of alternatives to review for your library, school, or Garden Club? PLC can provide loaned material or provide a speaker to address your club about Purple Loosestrife and its alternatives. .> contact us

For more information

Your County Extension: http://ceinfo.unh.edu/Counties/Hillsborough/loosestr.htm

NH DES: http://des.state.nh.us/factsheets/bb/bb-45.htm

New England Wild Flower Society (508) 877-7630  sells propagated wildflowers and distributes the pamphlet, Nursery Sources: Native Plants and Wildflowers: http://www.newfs.org