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Cotton algae (Pithopora spp.) is a coarse algae with branching filaments that resemble cotton when the water is squeezed out. When pulled apart, it is evident that filaments are branching and tightly woven together like a web. The branching also appears like “split ends” at the end of the filaments. Often, swollen reproductive cells called akinetes are visible. Cotton algae forms thick floating mats or sheets that are usually yellowish to dull green.
Mechanical Options
Cotton algae can be raked from the pond or strained out with nets or seines. Dyes or physical barriers which shade out the pond can be used with moderate success.
Information on Mechanical Treatment of Aquatic Vegetation
Grass carp will consume cotton algae, but it is not a preferred food source. Please see the section on this website about grass carp and their use in controlling Aquatic Vegetation for more information.
Information on Biological Treatment of Aquatic Vegetation
Chemical Options
The active ingredients that have been successful in treating cotton algae include: copper based compounds (E), alkylamine salts of endothall (G), flumioxazin (G), and diquat (G). E = excellent, G = good
Information on Chemical Treatment of Aquatic Vegetation
Return to Filamentous Algae page