Growing Wisdom

Controlling Purple Loosestrife, Lythrum salicaria

During the second half of summer you might notice purple flowers blooming in vast expanses near or in wetlands. Purple loosestrife is a wetland plant that was introduced in America in the 1800s. It first began spreading along the roads along our highways and was even sold as an exotic plant. This plant forms dense virtually impenetrable stands which in turn create poor habitats for our native fauna and force out the native flora.

Endangered plants and animals are at the most risk from the pressure purple loosestrife puts on the ecosystem.

Thousands of seeds are spread from each plant. The high number of seeds make it nearly impossible to control this plant once it has become established.

Control
There are currently 4 species of beetles that have been approved by the United States Government to help combat purple loosestrife. The beetles help control this plant by different methods There are two leaf-feeding beetles, one root-boring weevil and one flower-feeding weevil. Galerucella pusilla and G. calmariensis are leaf-eating beetles. These two beetle will eat the leaves and new shoots of the plant and impact seed production in a major way. Hylobius transversovittatus feeds at the root level. Once these beetles hatch they impact the plant under ground by eating the root tissue. As the beetle continues to feed on the roots, the impact will eventually will lead to the complete destruction of mature plants. The flower-feeding weevil, Nanophyes marmoratus, severely reduces seed production of purple loosestrife. Of course without seeds, you have no new plants.

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At the New England Wild Flower Society in Framingham, Massachusetts they are working on growing one of these beetles and then releasing them in areas heavily infested with purple loosestrife. You can see how this is being done in the video below. If you have this plant in your own yard you can dig it out and then put it in a bag. Do not put this in your compost pile as the seeds can be spread.


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