Potamogeton nodosus
More Info & Photos of American Pondweed
Non-Herbicide Management Options
1. Physical Management Options
American pondweed can be removed by raking or seining it from the pond, but will re-establish from any remaining roots and seeds.
Fertilization to produce a phytoplankton or algal “bloom” to prevent the establishment of most bottom rooted aquatic weeds. This also produces a strong food chain for 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:
Many types of mechanical removal devices are available that cut or chop up aquatic weeds. It is important to remember that many submerged 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:
2. Biological Management Options
Grass carp will seldom control aquatic vegetation the first year they are stocked. They will readily consume pondweed. Grass carp stocking rates to control pondweed 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.
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.
Active ingredients that have been successful in treating this plant include:
- Diquat (Rated: Good)
- Copper Based Compounds (Rated: Good)
- Endothall (Rated: Excellent)
- Fluridone (Rated: Excellent)
- Imazamox (Rated: Excellent)
- Bispyribac (Rated: Good)
- Flumioxazin (Rated: Good)
- Imazapyr (Rated: Good)
- Penoxsulam (Rated: Good)
These ratings are based upon the U.S. Army Corps of Engineers aquatic herbicide trials.
1) Diquat
Diquat is a contact algaecide and herbicide. Contact herbicides act quickly and kill all plant cells they come in contact with.
Common trade or product names include but are not limited to:
2) Copper Based Compounds
Copper Sulfate or “blue stone” is probably the most commonly used algal treatments because of its availability and low cost. Copper sulfate comes in several forms depending on how finely it is ground. Smaller crystals will dissolve easier than larger crystals. In very hard water, it is difficult to use copper sulfate because it binds with the calcium, precipitates out of solution, and renders the copper ineffective as an algaecide.
All copper compounds can be toxic to fish if used above labeled rates and can be toxic in soft or acidic waters even at label rates. Before using copper, it is best to test the pond water’s alkalinity and adjust copper treatments to alkalinity concentrations. For additional information on using copper sulfate, see the SRAC #410 Calculating Treatments for Ponds and Tanks.
Common trade or product names include but are not limited to:
3) 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:
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 can be toxic to fish.
4) 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:
5) 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:
6) Flumioxazin
Flumioxazin is a water dispensable granule that is to be sprayed or injected after mixing. It is a broad spectrum, contact herbicide. Contact herbicides act quickly. Flumioxazin should be applied to actively growing plants and a surfactant (a substance that reduces water tension) will be needed if the herbicide is applied to foliage of floating or emergent plants. Water pH needs to be below 8.5 or flumioxazin will rapidly degrade and lose effectiveness.
Common trade and product names include but are not limited to:
7) Bispyribac
Bispyribac-sodium comes in water soluble powder form in packets. Each packet should be mixed with water first and then sprayed or injected. It is a selective, 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. A surfactant (substance that can reduce the surface tension) will be needed if herbicide is applied to foliage of floating or emergent plants. Common trade and product names include but are not limited to:
8) Imazapyr
The active ingredient, imazapyr, inhibits the plant enzyme AHAS (acetohydroxyaced synthase). Habitat is a systemic herbicide that is effective on post-emergent floating and emergent aquatic vegetation. Imazapyr is effective at low-volume rates and does not contain heavy metals, organochlorides or phosphates, making it safe to humans and livestock. Habitat requires the use of a spray adjutant when applying on post-emergent vegetation.
Common trade or product names include but are not limited to:
9) 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:
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
American pondweed can be produced by seeds or by transplanting entire plants (with roots) during the early spring into shallow, clear water.
Questions?
If you need assistance, contact the Ag & Natural Resources agent in your county or hire a professional.