European frog-bit

European Frogbit Control Guide

The European frog-bit is an invasive aquatic plant that grows rapidly and forms dense, floating mats. It can be found in slow-moving waters such as sheltered inlets, ponds, slow-running rivers, and ditches. The European frog-bit can float free or put down roots up to 20 inches long in shallow water. It produces a single two-inch wide white flower with three rounded petals and yellow center. Its leaves are about one inch wide, heart-shaped with purple-red bottoms and a spongy coating along the middle vein. These fast-growing plants form thick mats that reduce biodiversity by crowding out native plants and preventing sunlight from reaching submerged plants. When a large colony of the plant dies and decomposes it removes oxygen from the water, which can affect fish communities and other aquatic life. Dense masses of European frog-bit can hinder swimmers and boaters, prevent other recreational uses of waterways, and clog drainage canals and streams


The European frog-bit is a popular water garden plant that has made its way to larger water bodies. Once it becomes established in the wild, new plants will grow from fragments, seeds and winter buds year after year. The European frog-bit can be spread to new waters by boats and wildlife. Remove and flush all plants and mud from boats, trailers, and shoes before moving to a new water body. Early intervention and management to avoid large invasions is the best prevention.

Biological Control

Beneficial bacteria products and enzymes such as PZ900 feed on nutrients in the water making them unavailable for plant growth. Reducing nutrients can help prevent invasion.

Physical/Mechanical Control

Mechanical removal is usually temporary, the plants will become re-established from dormant buds that break off the original plants, sink to the bottom and become rooted.   Physical removal in conjunction with chemical control will maximize success.

Chemical Control

When used carefully according to the label instruction, aquatic herbicides can be safe and effective management tools. The products that have been successful in treating European frog-bit individually or in combination are Reward and Weedtrine D, and Propeller. A nonionic surfactant Cygnet Plus should be mixed in solution with herbicides when plants are treated.

Reward is a registered label for aquatic use. This contact algaecide and herbicide quickly and effectively kills filamentous algae and all plant cells.

Weedtrine D is a contact, non-volatile herbicide for use in controlling submersed and floating aquatics weeds. Weedtrine-D has rapid absorption and herbicide action.

Propeller is a broad spectrum, fast acting contact algaecide/herbicide. It comes in a water dispersible granule that mixes with water to be sprayed or poured. Propeller should be applied to actively growing plants or algal blooms.

Cygnet Plus is a nonionic wetting agent, sticker, activator, and penetrant all in one. Cygnet Plus increases the effectiveness of herbicides uptake into the plant tissue.