Purple Loosestrife  (Lythrum salicaria)

DESCRIPTION

The Purple loosestrife (Lythrum salicaria), a beautiful but aggressive invader, arrived in eastern North America in the early 1800's. Plants were brought to North America by settlers for their flower gardens, and seeds were present in the ballast holds of European ships that used soil to weigh down the vessels for stability on the ocean. Since it was introduced, purple loosestrife has spread westward and can be found across much of Canada and the United States. Purple loosestrife grows an impressive four to seven tall. It grows prolifically in wetlands and other moist areas. Each mature plant produces 30 or more spikes and can produce over 2.5 million seeds per year. 

(Source: 1. Purple loosestrife: what you should know, what you can do, Minnesota Sea Grant, http://www.seagrant.umn.edu/exotics/purple.html; 2. Great Lakes Indian Fish & Wildlife Commission (GLIFWC) Exotic Pest Plant, http://www.glifwc.org/epicenter/; 3. Figure: Structure, growth forms, and field identification characters, USGS Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria) in North American Wetlands, http://www.npwrc.usgs.gov/resource/1999/loosstrf/field.htm#fig2).

IMPACTS

The Purple Loosestrife is a very hardy perennial which can rapidly degrade wetlands, diminishing their value for wildlife habitat. Wetlands are the most biologically diverse, productive component of our ecosystem. Hundreds of species of plants, birds, mammals, reptiles, insects, fish and amphibians rely on healthy wetland habitat for their survival.

However, when purple loosestrife gets a foothold, the habitat where fish and wildlife feed, seek shelter, reproduce and rear young, quickly becomes choked under a sea of purple flowers. Areas where wild rice grows and is harvested, and where fish spawn, are degraded. An estimated 190,000 hectares of wetlands, marshes, pastures and riparian meadows are affected in North America each year, with an economic impact of millions of dollars.

Purple loosestrife also invades drier sites. Concern is increasing as the plant becomes more common on agricultural land, encroaching on farmers' crops and pasture land.

(source from: Purple loosestrife: what you should know, what you can do, Minnesota Sea Grant, http://www.seagrant.umn.edu/exotics/purple.html)

Since its introduction purple loosestrife has had no problem spreading. One stalk can produce up to 3,000,000 lightweight seeds with a very high germination rate. New plants can even sprout from the roots or runners of other plants. Roadside ditches serve as excellent habitats for this water loving plant. These ditches also provide pathways between wetlands for the purple loosestrife to travel, and spread through. Since this plant can also regenerate from stem cuttings lawn mowing along the ditches also helped in the spread of purple loosestrife.

Humans have also played their part in the spread of these invasive plants across North America. Since the purple loosestrife has such a lovely purple flower a number of folks have planted them in ornamental gardens. Greenhouses have even been found selling the plant or putting its seeds in wildflower mixes. 
(Source from Invasive Exotic Plants of Canada: Fact Sheet No.4,  http://24.43.80.213/nbs/IPCAN/factpurp.html)

Distribution of purple loosestrife (Lythrum salicaria), broad-leaved cattail (Typha latifolia), and reed canarygrass (Phalaris arundinacea), in the Northern Hemisphere (after Hultén 1964, 1971). 
Shaded areas indicate zones of more or less continuous distribution; dots represent collection sites; solid lines indicate probable outer distribution boundary; dashed lines are tentative outer limits.

In areas too heavily infested to pull, cut or dig plants, these control techniques can still be used to control plants that may sprout as a result of seeds escaping the area. Watch drainage ditches or streams leading from heavily infested areas, as new purple loosestrife colonies are likely to become established there. Pulling, cutting, or digging plants in these more manageable infestations will limit the spread of purple loosestrife beyond the area of heavy infestation.

DIGGING & HAND PULLING
Pulling purple loosestrife by hand is easiest when plants are young (up to two years) or when in sand. Older plants have larger roots that can be eased out with a garden fork. Remove as much of the root system as possible, because broken roots may sprout new plants.

CUTTING
Removing flowering spikes will prevent this year's seeds from producing more plants in future years-- remember each mature plant can produce over 2 million seeds per year. Also, remove last year's dry seed heads, as they may still contain seeds. Finally, cut the stems at the ground to inhibit growth.

BIOLOGICAL CONTROL In areas of severe purple loosestrife infestation, manual and chemical control efforts are ineffective and may in fact contribute to the problem. However, the use of specially selected insects that feed on purple loosestrife is being studied to determine the effectiveness of this method for long-term control in these higher density areas. Bio-control works by using a plant natural enemies against it. In 1992, five insect species which feed on purple loosestrife in Europe were approved as bio-control agents in North America. These species are Hylobius transversovitta tus, a root-mining weevil, Galerucella cal mariensis and Galerucella pusilla, two leaf-eating beetles, and Nanophyes marmoratus a flower-feeding weevil.	Link
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Approval followed five years of rigorous testing to make sure the insects did not feed on agricultural crops, and had no significant impact on wetland species other than purple loosestrife. For example, bio-control began in Vermont in 1995 with the release of three European insect species (two leaf-eating beetles, and one stem boring weevil) by the U.S. Fish and Wildlife Service. In July 1996, the Vermont Department of Environmental Conservation Began releasing two species of leaf-eating beetles (Galerucella spp.). Since 1996, 140,000 beetles have been released into purple loosestrife infested sites in 38 towns. These beetles will continue to be released, and their impact monitored annually. Dramatic success has already been shown with biological control in Vermont. In 1997, 2,000 beetles were released into a wetland overrun with purple loosestrife at the Rutland State Airport. By 2000, there was a 95% reduction in purple loosestrife's growth rate and a 88% decrease in inflorescence length. Native plants are already showing signs of recovery.

CHEMICAL CONTROL
If an infestation is in a dry, upland area, and on your own property, an approved herbicide can be applied to individual plants by selective hand spraying. Broadcast spraying is not recommended as it kills all broad-leaved plants, leaving the area open to further invasion from nearby sources of purple loosestrife. This also provides an opportunity for seeds present in the soil to sprout.

YOU CAN HELP

REPORT Watch for purple loosestrife, and report locations where it is found to the Department of Environmental Conservation, or/and Sea Grant Office.
Request  Ask your local garden center or nursery to stop selling purple loosestrife and its varieties (If you find it). Horticultural varieties of purple loosestrife were once thought to be sterile, but recent studies have shown that this is untrue.
Replace  Landscape with native plants instead of purple loosestrife. Several colorful native plants thrive in the same habitat as purple loosestrife. Examples which are readily available include:

• Cardinal Flower (Lobelia cardinalis) produces a spike of brilliant scarlet flowers.
• Blueflag (Iris versicolor) is a native iris with large, showy, purple- veined, blue flowers.
• Monkey Flower (Mimulus ringens) has pairs of violet and yellow flowers arranged along a tall stem.
• Blue vervain (Verbena hastata) exhibits stunning spikes of blue flowers

THINGS TO KEEP IN MIND

THE BEST TIME TO CONTROL purple loosestrife is in late June, July and early August, when it is in flower. Plants are easily recognized, and it has not yet gone to seed. Once flower petals start to drop from the bottom of the spike, the plant begins to produce seed. Control activities can continue during this time, but require greater care so seeds are not shaken from the plant. At sites where plants have gone to seed, remove all of the flowering spikes first by bending them over a plastic bag and cutting them off into the bag. Further cutting of stems or pulling can now take place without fear of spreading the tiny seeds.

PROPER DISPOSAL of plant material is important. Put all plant pieces in plastic bags (vegetation rots quickly in plastic) and take the bags to a sanitary landfill site. Be sure the landfill site doesn't require bags to be broken open for composting. Composting is not advised, as purple loosestrife seeds may not be destroyed and the thick, woody stem and roots take a long time to decompose. If facilities exist in your area, incineration is an effective way to dispose of plant material.

BE AWARE that your clothes and equipment may transport the small seeds to new areas. Thoroughly brush off your clothes and equipment before leaving the site.

KEEP SITE DISTURBANCE TO A MINIMUM. Wetlands provide habitat for many native song birds, waterfowl, mammals, amphibians, and fish which depend on native wetland vegetation. Wetlands are also home to many rare and delicate plants. Take care not to trample or damage native vegetation when controlling purple loosestrife.

Source from 1. Purple loosestrife: what you should know, what you can do, Minnesota Sea Grant, http://www.seagrant.umn.edu/exotics/purple.html; 2. Vermont Agency of Natural Resources, Department of Environmental Conservation, http://www.anr.state.vt.us/dec/waterq/ans/plpage.htm)

Purple Loosestrife: Ontario Federation of Anglers and Hunters 
    http://www.invadingspecies.com/index.cfm?DocID=24&Plant=Loosestrife
This site provides brief description of purple loosestrife and Ontario distribution map.

Mapping Purple Loosestrife (Great Lakes Indian fish and Wildlife Commission 
    http://www.glifwc-maps.org/
Through a GIS mapping interface, this Great Lakes Indian Fish and Wildlife Commission database depicts the known Wisconsin/Upper Michigan distribution of purple loosestrife, one of the most pervasive non-native plant species in the Great Lakes region. Users can view, query and print maps that also illustrate existing and potential biological control sites

Purple Pages: Michigan State University
    http://www.msue.msu.edu/seagrant/pp/
This page introduces the Purple Loosestrife Project at Michigan State University. You can learn more about the biological control project, which engages citizens and young adults in the control of purple loosestrife using the plant own natural enemies.

Purple Loosestrife: Great Lakes Indian Fish & Wildlife Commission
    http://www.glifwc.org/weeds/epicenter/
This page includes useful information concerning the exotic plant in the ceded territories of northern Minnesota, Wisconsin, and Michigan. Also includes natural history, distribution, control, links, and bibliography. 

Purple Loosestrife Control Agents: Montana War on Weeds
    http://mtwow.org/bio-control-purple-loosestrife-links.htm
This site includes origin, ecology, distribution and spread, control methods, and introduced control agents. They explain European natives (a weevil and two beetles) were introduced in 1992 as part of a 5-15 year program to control purple loosestrife ( Weevils: Hylobius transversovittatus and Nanophyes marmoratus; Beetles: Galerucella calmariensis and G. pusilla)

Purple Loosestrife, Noxious Weed Identification: King County, Washington
     http://dnr.metrokc.gov/wlr/LANDS/Weeds/lstrife.htm

Purple Loosestrife: What You Should Know, What You Can Do: Minnesota Sea Grant
   http://www.seagrant.umn.edu/exotics/purple.html
This page includes history of introduction in North America, guidelines for distinguishing loosestrife from native look-alikes, and information on various control methods.

Purple Loosestrife in the Great Lakes Region: Great Lakes Information Network (GLIN)
    http://www.great-lakes.net/envt/flora-fauna/invasive/loosestf.html
This site provides overview, general resources, and related resources of purple loosestrife.

Purple Loosestrife: National Agricultural Pest Information (NAPI)
    http://ceris.purdue.edu/napis/pests/pls/index.html
This site provides very detailed maps of U.S. purple loosestrife distribution and biocontrol release, facts, news and related sites.  

Element Stewardship Abstract for Lythrum salicaria :TNC Wildland Weed Management and Research Library   http://tncweeds.ucdavis.edu/esadocs/documnts/lythsal.html
This site includes general information, and detailed control information. 

Species Abstracts of highly Disruptive Exotic Plants at Effigy Mounds National Monument, Lythrum salicaria: US Geological Survey, Northern Prarie Wildlife Research Center      
    http://www.npwrc.usgs.gov/resource/othrdata/exoticab/effilyth.htm
This site provides general description, biology/ecology, distribution, control, and references.

Purple Loosestrife Online Brochure: Wisconsin Department of Natural Resources   
    http://www.dnr.state.wi.us/org/land/er/invasive/info/loose2.htm
This site provides general and regional information, current extent, and control methods. 

Purple Loosetrife Info Centre (Manitoba Project)
    http://www.dnr.state.wi.us/org/land/er/invasive/info/loose2.htm
This site provides useful bibliographic references, resource materials, news, and brochure.

Purple Loosestrife: Lakehead Region Conservation Authority
   

Purple Loosestrife Project K12 Educational Materials (Free): Michigan Sea Grant.
  
1. Activities for Young Adults (Grades 6-12)

2. Activities for Young Children (Grades 4-6)
Upper Elementary Unit Purple Loosestrife Project Summaries

Teachers can use this Purple Loosestrife Project (PLP) materials in a variety ways. All PLP educational activities are hands-on, and very useful in teaching environmental stewardship and controlling its spread. Its learning activities focus on wetland stewardship, habitat protection, and biological control of this invasive nuisance species.
(*Note: Anyone interested in controlling invasive purple loosestrife now has a comprehensive publication to guide them - The Cooperator's Handbook, Link, http://www.miseagrant.umich.edu/pp/ch_orders.htm).

Link   http://www.miseagrant.umich.edu/pp/activities.html