Written by: Wesley L. Gerrin, Sarah F. McNair, James L. Shelton
Muskgrass (Chara sp.) is a species of submerged marcoalgae often seen in Georgia ponds. Chara is classified as a macroalgae, because it does not have a vascular system despite its resemblence to a vascular plant. It can be found in both deep and shallow water, and may be loosely attached to the substrate. Its texture is usually described as grainy or crunchy, and it has a characteristic “musky” odor. Chara has a whorled system of branches around each node with more whorled branchlets along these branches.
Important Characteristics
Coarse “crunchy” texture
Musky Odor
No vascular structures
Similar Species
Stonewort (Nitella sp.) and Coontail (Ceratophyllum demersum) are similar to Chara, but they lack the musky odor and coarse texture of Chara, often being described as soft to the touch. Coontail also has forked leaves, whereas Charas does not have forked leaves.
Mechanical Control Methods: physical removal of plant material from the pond
Mechanical control of Chara is possible, but not feasible as a standalone control method. It can re-establish if any fragments are left behind. Gear should be cleaned thoroughly afterwards to ensure that no remnants are spread or reintroduced after removal. Discard the removed plant material in a location away from other bodies of water to ensure that it does not spread.
Biological Control Methods: use of a biological agent that consumes plant material to control vegetation
Grass Carp are an effective biological control mechanism for this plant. Grass Carp are most effective when they are young and must be restocked every 5-7 years to maintain effective control of most aquatic vegetation. Stocking rates vary depending on infestation density, feeding preference, and growth rates of the plants that need to be controlled. Grass Carp are often used as part of integrated pest management plans that also include chemical control. For specific information regarding Grass Carp stocking rates, refer to Integrating Grass Carp into Pond Management Plans.
In Georgia, Grass Carp must be sterile and may only be purchased from licensed suppliers. A list of these suppliers is maintained by the Georgia Department of Natural Resources and is available on the Warnell outreach website.
Chemical Control Methods: use of herbicides or algaecides to control vegetation
The first step when using an aquatic herbicide is to always read the entire label. Herbicide labels are legal documents that provide important information on how to use the product, including which sites can be treated, treatment rates, and precautionary statements. The label is the law! Consult your county cooperative extension agriculture and natural resources agent, professional consultants, or other qualified authorities for help if something is unclear. Click the linked trade names of the herbicides in this document to see their product labels. Trade names are included for example purposes only, and their inclusion in this document does not constitute endorsement of any product.
Always use herbicides in accordance with the directions on the label. The treatment of aquatic plants with herbicide is most effective when the plant is actively growing. Results of treatment are dependent upon many factors including dose, time of year, stage of plant growth, plant susceptibility, method of application, and water movement.
If the weeds are localized to small areas of the pond, all may be treated simultaneously. If most of the pond is affected, spot treatments that reduce the amount of dead vegetation are suggested. Mass amounts of dead vegetation can deplete oxygen and result in a fish kill. On large infestations, spot treating no more than 1/3 of the total pond is prudent.
Modern treatment plans include practices to reduce the likelihood of developing herbicide-resistant aquatic plants. Strategies may include rotating herbicides with different modes of action, using integrated pest management, applying multiple herbicides concurrently, avoiding repeating treatments too frequently, and consulting with aquatic plant professionals.
Choosing between systemic and contact herbicides depends on the type of aquatic plant, their growth stage, and treatment goals. Systemic herbicides are absorbed and move through the plant’s entire system. Contact herbicides act only on the parts of the plant they touch, so may require multiple treatments to achieve long-term control. Systemic herbicides often act more slowly than contact herbicides. Due to the rapid post-treatment decomposition of plant material, treating large areas with contact herbicides should be avoided to prevent oxygen depletion events and subsequent fish kills.
For more detailed information regarding chemical selection, chemical application, and calculating chemical treatment rates refer to Integrating Chemicals into Pond Management Plans.
Aquatic herbicides have been evaluated and rated either poor (<70% control), fair (70-79% control), good (80-89% control), or excellent (90-100% control) for controlling certain aquatic plants. The herbicides within the following section were all rated excellent for control of this plant. To see the full herbicide rating table, which includes all available aquatic herbicides, refer to the Aquatic Environments section of the Georgia Pest Management Handbook.
Copper Complexes are granular algaecides and herbicides that contain chelated copper compounds. They are non-selective and will cause direct damage to any plant cell tissues they encounter. Copper complexes can be toxic to fish and other aquatic organisms if used inappropriately. Certain water conditions, including low pH and low alkalinity increase the potential toxicity to non-target aquatic organisms. Pond alkalinity and pH must be tested prior to chemical application, and the rate of application must be adjusted according to the product label.
Cutrine Plus®, K-Tea®, and Captain® are examples of trade names of products that use copper as an active ingredient.