Non-Herbicide Management Options
1. Physical Management Options
Chara can be removed by raking or seining, but is difficult to control because it re-establishes from spores and fragments.
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:
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 Muskgrass. Grass carp stocking rates to control Muskgrass 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 (the list is at the end).
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 Chara include:
- Copper Based Compounds (Rated: Excellent)
- Alkylamine salts of Endothall (Rated: Good)
These ratings are based upon the U.S. Army Corps of Engineers aquatic herbicide trials.
1) 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:
2) Alkyl amine salts of Endothall:
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.
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.
Chara can be propagated by collecting and transplanting whole plants into areas of shallow, clear water. Chara prefers hard or alkaline waters.
If you need assistance, please contact the Ag & Natural Resources agent in your county or hire a professional.