Biology and Biological Control of Purple Loosestrife

Abstract

The use of trade, firm, or corporation names in this publication is for information only and does not constitute an endorsement by the U.S. Department of Agriculture. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, sex, religion, age, disability, political beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at 202-720-2600 (voice and TDD). 202-720-5964 (voice and TDD). USDA is an equal opportunity provider and employer. T he Forest Health Technology Enterprise Team (FHTET) was created in 1995 by the Deputy Chief for State and Private Forestry, USDA, Forest Service, to develop and deliver technologies to protect and improve the health of American forests. This book was published by FHTET as part of the technology transfer series. Cover photos: purple loosestrife—Eric Coombs; purple loosestrife beetle—S. Schooler; purple loosestrife weevil—Mark Schwarzlaender. Figure 2. Map of purple loosestrife distribution in the United States and Canada. INTRODUCTION Overview Purple loosestrife, Lythrum salicaria (Figure 1), is a member of the Loosestrife family (Lythraceae). It is a large, perennial, wetland plant that can grow up to 9 feet (3 m) tall. It was introduced to the northeastern United States and Canada in the 1800s from Europe, probably as seed contained in soil used as ship's ballast. It was also brought to North America for ornamental and medicinal purposes. Once established in North America, this invasive weed quickly spread in wetlands and waterways. It is reported in nine Canadian provinces and in the United States it occurs in all states except Florida and Hawaii (Figure 2). Although purple loosestrife is declared noxious in 23 states and 5 Canadian provinces, it is still sold as an ornamental plant in some places. In its native range, purple loosestrife occurs from the United Kingdom west to western Russia and from Finland in the north to southern Europe and northern Africa in the south. Once established, purple loosestrife quickly crowds out most native vegetation, such as sedges, rushes, cattails, and other wetland plant species. At high densities, purple loosestrife can create near-monocultures. In addition to the loss of native biodiversity, purple loosestrife harms waterfowl nesting habitat, has negative impacts on some amphibians and algal communities, reduces water …