Hydrilla is an invasive submerged weed found throughout most of the United States. This is a rooted weed that can grow up to 25 feet long stems. Hydrilla form worls of 4 to 8 leaves around the stem. One distinctive difference between hydrilla and elodea is, the hydrilla leaves have jagged-toothed edges, where the elodea leaf edges are smooth.
Hydrilla aggressively spread through water bodies by fragmentation. Hydrilla stems can grow as much as an inch per day! Once hydrilla reaches the surface of the water, it branches out creating thick coverage. Heavily impacted bodies of water can experience impacts on aquatic life and limited recreational use.
Management of hydrilla can be difficult because this vegetation is capable of growing in low light conditions of 15 feet deep or greater. Hydrilla tubers can also remain dormant in sediment for years.
Non chemical treatment options:
Hydrilla can be cleared by using weed rakes and weed cutters. It is imperative to gather and remove all plant fragments because this weed reproduces through fragmentation.
Grass carp love hydrilla! This is one of their favorite plants to eat. Grass carp should be stocked at rates of up to 15 fish per acre, depending on percentage of plant growth covering a pond.
LakeMats can be used to manage weeds around docks and swimming areas.
Chemical treatment options:
- Sonar is a slow acting herbicide that provides excellent control of hydrilla. The active ingredient is fluridone, which controls hydrilla by inhibiting enzyme activity. The entire body of water must be treated for effective control.
- Aquathol is a fast acting herbicide, providing good control of hydrilla. This treatment is ideal for spot treatment of Hydrilla. Aquathol has no water use restrictions.
- Tsunami DQ provides a quick kill solution for hydrilla. Diquat is the main ingredient in Tsunami.
- Propeller has a moderate reaction time and provides good control of hydrilla. The Propeller granules dissolve in water and are applied via tank sprayer.