458 



Nofhualive Spccitw — Our Ll^iiii; Rt'.\onrces 



For further int'nrniution: 



Tom Pogacnik 



Bureau of Land Management 



Wild Horse and Buito National 



Program OtTiee 



850 Harvard Way 



PO Box 12000' 



Reno. NV S;95:o 



BLM. 1993. Nmlh report to Congress on the admniistiation 

 of the Wild Free-Roaniing Horse and Burro Aet. Bureau 

 of Land Management. Washington. DC. 70 pp. 



National Academy of Sciences. 1982. Wild and free-roaming 

 horses and huiTOs: final report of the Committee on Wild 

 Free-Roaming Horses and Burros Board on Agriculture 

 and Renewable Resources National Research Council. 

 National Academy Press, Washington, DC. 80 pp. 



Purple 

 Loosestrife 



by 

 Richard Malecki 



National Biological Service 



- n.' 



Purple loosestrife [Lyihnim salicaria). 



Puq^le loose.stiit'e {Lythruni sulicaria) i.s an 

 exotic wetland perennial introduced to 

 Nortii America from Europe in the early 19th 

 century (Stuckey 1980). By the 1930"s, the 

 plant was well established along the New 

 England seaboard. The construction of inland 

 canals and waterways in the 1880"s favored the 

 expansion of purple loosestrife into interior 

 New York and the St. Lawrence River Valley 

 (Thompson et al. 1987). The continued expan- 

 ,sion of loosestrife has coincided with increased 

 development and use of road systems 

 (Thompson et al. 1987), commercial distribu- 

 tion of the plant for horticultural puiposes, and 

 regional propagation of seed for bee forage 

 (Pellet 1977). The plant now occurs in dense 

 stands throughout the northeastern United 

 States, southeastern Canada, the Midwest, and 

 in scattered locations in the western United 

 States and southwestern Canada. Newly created 

 irrigation systems in many of the western states 

 have supported its further spread. 



Puiple loosestrife is a classic example of an 

 introduced species whose distribution and 

 spread have been enhanced by the absence of 

 natural enemies and the disturbance of natural 

 systems, primarily by human activity. Although 

 noted for the beauty of its late summer tlowers. 

 which also provide a nectar source for bees, 

 loosestrife has few other redeeming qualities. 

 Its invasion into a wetland system results in sup- 

 pression of the native plant community and the 

 eventual alteration of the wetland's structure 

 and function (Thompson et al. 1987). Large, 

 monotypic stands not only jeopardize various 

 threatened and endangered plants and wildlife, 

 such as Long's bulrush iScirpiis loiiiiii) in 

 Massachusetts (Coddington and Field 1978). 

 small spikerush {Eleocharis pan'ida) in New 

 York (Rawinski 1982), and the bog turtle 

 (Clemmys muhlenhergii) in the northeastern 

 United States (Bury 1979), but they also elimi- 

 nate natural foods and cover essential to many 

 wildlife, including waterfowl (Rawinski and 

 Malecki 1984). 



Purple loosestrife has many traits that 

 enabled it to become a nuisance in North 

 America. A single, mature plant can produce 

 more than 2.5 million seeds annually; these 

 seeds are long-lived (Welling and Becker 1990) 

 and easily dispersed by water and in mud. 

 adhering to aquatic wildlife, livestock, and peo- 



ple (Thompson et al. 1987). Established plants 

 are tall (about 2 m or 6.5 ft) with 30-50 stems 

 fomiing wide-topped crowns that dominate the 

 herbaceous canopy. A strong rootstock serves as 

 a storage organ, providing resources for growth 

 in spring and regrowth if the aboveground 

 shoots are cut. burned, or killed by application 

 of foliar herbicides. No native herbivores or 

 pathogens in North America are known to sup- 

 press puiple loosestrife (Hight 1990). 



No effective method is available to control 

 loosestrife, except in small localized stands that 

 can be intensively managed. In such isolated 

 areas, the plant can be eliminated by uprooting 

 by hand and ensuring that all vegetative parts 

 are removed. Other control techniques include 

 water-level manipulation, mowing or cutting, 

 burning, and herbicide application (Malecki and 

 Rawinski 1985). Although these controls can 

 eliminate small and young stands, they are cost- 

 ly, require continued long-term maintenance, 

 and in the case of herbicides, are nonselective 

 and environmentally degrading. 



The most promising control measure for 

 puiple loosestrife is the application of classical 

 biological weed-control procedures that use 

 natural enemies like insects, mites, nematodes, 

 and pathogens to reduce weed densities to toler- 

 able levels. Results of insect surveys and 

 screening tests conducted with the U.S. 

 Department of Agriculture's Agriculture 

 Research Service and the International Institute 

 of Biological Control in Europe have identified 

 five beetle species as potential control agents 

 for purple loosestrife. Each species showed 

 enough host specificity for purple loosestrife to 

 be introduced with no ill effects to native North 

 American plants. 



Efforts are under way to rear large numbers 

 of these insect species for further distribution 

 and establishment in other states and provinces. 

 A petition to introduce two of these beetles is 

 under review by the USDA's Animal and Plant 

 Health Inspection Service. Initial collection of 

 these insects in Europe for release into the 

 United States is planned for 1994. 



A cooperative state and federal program for 

 the biological control of purple loosestrife 

 focuses on an international environmental weed 

 problem that cannot be controlled by conven- 

 tional means. With support from federal and 

 state agencies we have brought together an 



