Control Eelgrass

Eelgrass can be found across much of the U.S., but it is most common in the northeast, upper midwest, and Florida. Because of eelgrass’s creeping root systems, it is difficult to eradicate this plant completely. The following options can be considered for how to control eelgrass, also called Vallisneria or wild celery.

Click here to read more about identifying this plant.

 

Manual/Mechanical Control:

If you are considering how to remove eelgrass, physically raking this plant and digging up the roots can be a somewhat effective method of control. While physically removing eelgrass can be difficult, it is the most sure Vallisneria control method. Eelgrass can re-grow from any roots or fragments remaining in the water.

 

Herbicide Control:

There are multiple options for how to kill eelgrass that may offer some control. Mostly these herbicides can brown and damage the Vallisneria, but they likely will not result in full control. Using a combination of products can give better control than one product alone.

1. Aquathol K/Super K (for ponds or lakes) – liquid that is diluted with water and sprayed or granules that are broadcast over the plants.
2. Semera or Flumigard (for ponds or lakes) – granules that are dissolved and mixed or liquids that are mixed and diluted with water and sprayed over the plants (early morning is best), fast-acting.
3. Dibrox (for ponds or lakes) – liquid that is diluted with water and sprayed over the plants, fast acting.
4. Hydrothol (for lakes) – granules that are broadcast over the plants.

 

Algaecide Control:

Copper algaecides have been shown to kill eelgrass plant cells. While generally unable to provide complete control, copper algaecides can be used to boost the effectiveness of the herbicides above in Vallisneria control. They also help provide control of algae that will grow in and on the eelgrass plants.

1. Mizzen *Max label rate* (for ponds or lakes) – liquid that is diluted with water and sprayed over the plants.
2. Copper sulfate *Max label rate* (for ponds or lakes) – granules that are broadcast in the target area.

 

Treatment Tips:

When treating eelgrass,

• Treat when the plants are established and actively growing.