Purple Loosestrife Control Strategies
Purple loosestrife control strategies: this upright, herbal perennial has continually extended its distribution and now poses a serious danger to natural plant life in shallow water marshes throughout the northeastern and north central regions of North America.
Purple loosestrife is an upright, herbal perennial from Europe that became established in northeastern North America by the early 1800's. By the late 1800's it had spread throughout the northeastern United States and southeastern Canada, reaching as far north and west as Manitoba. It produced few problems until the 1930's when it became assertive in the pastures of the St. Lawrence River. Since then, it has continually extended its distribution and now poses a serious danger to natural plant life in shallow water marshes throughout the northeastern and north central regions. Wetland managers must now cope with purple loosestrife that replaces cattails a native plant.
Research has revealed that Galerucella beetles, insects imported from Europe to feed on purple loosestrife, emerge from hibernation during the first ten days of May. They then start to produce eggs. This time table makes the last two weeks in May the ideal time to relocate the insects to new areas. In 1999, managers selected eleven sites for beetle relocation. Managers moved one hundred beetles to each site in May of that year. Managers checked the sites in May to determine if the Galerucella beetle established a population. Managers found at ten of the eleven sites, adult beetles or their eggs, indicating that releases of one hundred insects is sufficient to establish a population at the release sites. They selected new release sites and the beetle relocation program became established under the guidelines developed from this experience. As a result of this effort seventeen new sites are experiencing biological control of purple loosestrife. They will repeat this cooperative effort next year. Information and procedures to apply for beetles will be published in the Winter 2000-2001 issue of the New York State Ducks Unlimited Newspaper. If successful, these areas would then serve as sources of beetles for further releases in those regions. In total, scientists raised more than 9,880 adult Galerucella beetles on the Wildlife Management Area (WMA) and relocated them across a state and the results begin to show purple loosestrife beginning to disappear. On one WMA most these insects affected the purple loosestrife plants by eliminating them.