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How to Control Water Stargrass

water star grass in water

Heteranthera dubia

More Info & Photos of Water Stargrass

Non-Herbicide Management Options

1. Physical Management Options

Water Stargrass can be removed by raking or seining it from the pond, but will re-establish from any remaining roots.

Fertilization to produce a phytoplankton or algal “bloom” prevents the establishment of most bottom rooted aquatic weeds and produces a strong food chain to the pond fish.

Non-toxic dyes or colorants prevent or reduce aquatic plant growth by limiting sunlight penetration, similar to fertilization. However, dyes do not enhance the natural food chain and will suppress the natural food chain of the pond.

Some examples of non-toxic dyes and other products include but are not limited to:

  • Aquashade
  • Blue Springs
  • Crystal Blue

Many types of mechanical removal devices are available that cut or chop up aquatic weeds. It is important to remember that many plants regrow from fragments, so removal of cut fragments may be necessary to keep from spreading the unwanted plant.

Companies that make cutters and rakes include but are not limited to:

  • Cutting edge
  • Jenson Lake Mower
  • Midwest Aqua Care
  • WeedRoller

Physical barriers are also used to eliminate plants by shading the bottom. These work well for swimming areas, docks, etc. but must be kept clean of any buildup of sediment and debris.

Some examples of companies that make these mats are:

  • Lake Mat
  • Lake Bottom Blanket

2. Biological Management Options

Grass carp will seldom control aquatic vegetation the first year they are stocked. They will consume Water Stargrass. Grass carp stocking rates to control Water Stargrass are usually in the range of 7 to 15 per surface acre. In Texas, only triploid grass carp are legal and a permit from the Texas Parks and Wildlife Department is required before they can be purchased from a certified dealer (list at end of packet).

Herbicide Control Options

Always read the product label for directions and precautions, as the label is the law. Click on the name of the product to see the label. Read the label for specific water use restrictions.

The active ingredients that have been successful in treating Water Star Grass include:

  • Endothall (Rated: Excellent)
  • Fluridone (Rated: Excellent)
  • Glyphosate (Rated: Good) where it is emergent
  • Imazamox (Rated: Excellent) where it is submerged
  • Penoxsulam (Rated: Excellent)

These rating are based upon the U.S. Army Corps of Engineers aquatic herbicide trials.

1) Endothall

Dipotassium salts of endothall comes in both liquid and granular forms. It can be mixed with copper compounds for additional effectiveness. Contact herbicides act quickly and kill all plant cells that they come into contact with.

Common trade and product names include but are not limited to:

  • Aquathol K
  • Aqualthol Super K

Alkyl amine salts of endothall come in both liquid and granular forms. It is a contact herbicide.

Common trade and product names include but are not limited to:

  • Hydrothol 191

Hydrothol can be toxic to fish.

2) Fluridone

Fluridone is a broad spectrum, systemic herbicide. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides.

Common trade and product names include but are not limited to:

  • Sonar
  • Avast

3) Glyphosate

Liquid glyphosate formulations and have been effective on Water Stargrass above the water line, but ineffective on plants in the water. They are broad spectrum, systemic herbicides. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides. An aquatically registered surfactant (see the label) will have to be added to the glyphosate solution for good results.

Common trade or product names include but are not limited to:

  • Rodeo
  • Aquamaster
  • Eraser AQ
  • Touchdown Pro
  • AquaNeat
  • Refuge

4) Imazamox

Imazamox is a broad spectrum, systemic herbicide. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides. An aquatically registered surfactant (a substance that will release the surface tension) is needed for application.

Common Trade of product names include but are not limited to:

  • Clearcast

5) Penoxsulam

Penoxsulam is a broad spectrum, systemic herbicide. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides. It may be sprayed directly onto emergent plants or applied directly into the water. Penoxsulam should not be applied in areas where it will be diluted rapidly. This herbicide will need a registered surfactant (see the label) for leaf and exposed sediment applications.

Common trade and product names include but are not limited to:

  • Galleon

Precautions

One danger with any chemical control method is the chance of an oxygen depletion after the treatment caused by the decomposition of the dead plant material. Oxygen depletion can kill fish in the pond. If the pond is heavily infested with weeds, it may be possible (depending on the herbicide chosen) to treat the pond in sections and let each section decompose for about two weeks before treating another section. Aeration, particularly at night, for several days after treatment may help control the oxygen depletion.

One common problem in using aquatic herbicides is determining area and/or volume of the pond or area to be treated. To assist you with these determinations see SRAC #103 Calculating Area and Volume of Ponds and Tanks.

Many aquatically registered herbicides have water use restrictions (See General Water Use Restrictions).

To see the labels for these products click on the name. Always read and follow all label directions. Check label for specific water use restrictions.

Cultivation Options

Water Stargrass can be propagated by transplanting entire plants with roots into clear, shallow water.

Questions?

If you need assistance, contact the Ag & Natural Resources agent in your county or hire a professional.

2023 Aquatic Webinars

Apr. 18: Pond Stocking 

May 16: Aquatic Plant ID & Management Options

Jun 20: Fish Management Strategies

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Photo Credits: The majority of the aquatic plant line drawings are the copyright of the University of Florida Center for Aquatic Plants (Gainsville). They are used with permission.

Aquatic plant photographs were provided by David Bayne, Jim Davis, Kelly Duffie, Billy Higginbotham, Michael Masser, John Clayton, Chetta Owens, Diane Smith, Joe Snow, Don Steinbach, Bridget Robinson Lassiter and Peter Woods.

You may use these photos, so long as you give credit to AquaPlant.

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