Illinois Natural History Survey - University of Illinois

Limited Control Methods -- The Case for Biological Control

Vast stands of loosestrife defy most control efforts. Hand picking is recommended as the first line of defense, but this method works only in the very smallest stands. Burning simply annoys the plant. Above-ground stems and foliage die every winter anyway, leaving intact root crowns. Burning in late winter only burns those parts that are already dead, serving no purpose. Flooding may kill the plant in some cases, but not all. Many sites are filled with loosestrife in standing water. In addition, flooding may kill the very native plants that are already threatened. Although there are available herbicides applying those herbicides by hand is impractical and costly, and aerial application kills the same native plants that are already threatened by loosestrife. That's why biological control has been welcomed -- it is the only alternative in this case!

The photograph below shows a mature stand of purple loosestrife in full bloom in northern Illinois. These plants are growing on a floating mat and access to them is difficult if not dangerous. Management by any other method but biological control is not really possible.

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