Plant Invaders of Mid-Atlantic Natural Areas

Swearingen, J., K. Reshetiloff, B. Slattery, and S. Zwicker. 2002. Plant Invaders of
Mid-Atlantic Natural Areas. National Park Service and U.S. Fish & Wildlife Service, 82 pp.

J. Story, U of MT

Spotted knapweed, a member of the aster family, was introduced unintentionally from Eurasia as a contaminant of alfalfa and from soil used as ship ballast. It poses a threat to natural communities such as barrens, fields, meadows and forest edges because it captures moisture and nutrients, forms a deep taproot and spreads rapidly through seed. Several insect species are being used as biological control agents.

Prevention and Control
To avoid transporting seed and infested soil, do not graze livestock in infested areas -- especially when seeds are present -- and use certified weed-free hay. Plants can be pulled by hand in small infestations, ensuring removal of the entire crown and taproot. Several herbicides are effective but require repeat applications. Clean shoes and clothing when leaving infested areas.

Native Alternatives
After eradicating, plant area with native vegetation appropriate to site conditions. Refer to References.

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