Physical Control

Hand pulling or digging is most effective where infestations are small and composed of one to two year old plants without a well developed root system. Removal of as much of the root system as possible while minimizing soil disturbance that may favor purple loosestrife re-establishment is recommended. Roots and stems should be burned or bagged and disposed of in the trash to prevent re-growth. During flowering, stems can be cut to remove inflorescences and prevent seed production and spread. As with pulling and digging, cut stems should be disposed of to prevent re-sprouting. Burning favors purple loosestrife spread and is not recommended unless burning is used to remove old plant litter to improve herbicide contact with actively growing stems. Livestock grazing of purple loosestrife has not been studied, but it is likely not practical, considering the wetland habitats it invades. Similarly, control using tillage is not practical and the mechanical disturbance is more likely to spread the weed than control it.

Flooding populations with one foot or more of water for two consecutive years reportedly reduced purple loosestrife density. All seedlings have been killed with eight weeks of flooding at all depths tested. Three years of flooding with 16 inches of water reduced purple loosestrife density and increased cattail density threefold. However, flooding may threaten some desirable species and alter community composition, and may increase spread by increasing the area of moist, bare soil for seedling establishment. Flooding after purple loosestrife removal may prevent its regeneration from seeds.

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Last Modified: 08/12/2008