Endothall and fluridone are both highly effective on hydrilla. A few other plants are also highly susceptible and a few more are moderately susceptible. Many plants will not be affected at all. Those that are susceptible have seed banks and/or nearby populations that can re-colonize the treated areas once the herbicide treatments have stopped. Impacts on aquatic life other than plants is very limited.
Endothall is a selective contact herbicide that kills the growing green vegetation that it contacts by disrupting photosynthesis. Hydrilla is much more sensitive to the effects of endothall than most native plants. The chemical degrades naturally by bacterial action in the water and has a half-life ranging from 5 to 8 days. The commercial name is Aquathol K (active ingredient dipotassium endothall 40.3%). We obtain Aquathol K from United Phosphorous, a company based in Pennsylvania. Read more about endothall. Follow links in the side bar to read information its legal use.
Fluridone is a selective systemic herbicide that has been used to control invasive plants, including hydrilla in lakes in New York and in other parts of the United States. The chemical is a slow-acting herbicide, effective over long time periods at very low concentrations. It is absorbed through submersed shoots and roots, and is then transported throughout the plant, where it disrupts photosynthesis. Evidence of plant damage may appear within 7-10 days of application, but 30-90 days of continuous application is required to kill the plants. Locally, the Hydrilla Task Force has used multiple formulations of fluridone products (commercial name Sonar). These include Sonar Genesis (liquid formulation) and Sonar One/Sonar H4C (pellet formulations). Read more about fluridone. Follow links in the side bar to read about its legal use.
Last updated May 2, 2017