If the loosestrife cannot be controlled, then efforts should be concentrated on keeping it out of the highest quality areas. Mowing, burning, and flooding have been found to be largely ineffective. Cutting followed by flooding so that cut plant stalks are completely immersed has shown some success. However, flooding may encourage the spread of purple loosestrife from seed present in the soil. Cut plant parts may also root.
Mature plants can withstand short-term immersions.
Burning has been ineffective, as there is no good time during the year for burning. Burning also stresses native plants and may subsequently enhance loosestrife spread. Hand removal is recommended for small populations and isolated stems. Plants should be pulled, prior to seed set, with minimal disturbance to the soil. Pulling after seed set will scatter seed.