Algaecide or algicide is a

biocide A biocide is defined in the European legislation as a chemical substance or microorganism intended to destroy, deter, render harmless, or exert a controlling effect on any harmful organism. The US Environmental Protection Agency (EPA) uses a slig ...

used for killing and preventing the growth of

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

, often defined in a loose sense that, beyond the biological definition, also includes

cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blu ...

("blue-green algae"). An algaecide may be used for controlled bodies of water (reseviors, golf ponds, swimming pools), but may also be used on land for locations such as turfgrass.

Types

Inorganic compounds

Some inorganic compounds are known since antiquity for their algicidal action due to their simplicity. * Copper(II) sulfate remains "the most effective algicidal treatment". A related traditional use is the

Bordeaux mixture Bordeaux mixture (also called ''Bordo Mix'') is a mixture of copper(II) sulphate (CuSO4) and quicklime ( Ca O) used as a fungicide. It is used in vineyards, fruit-farms and gardens to prevent infestations of downy mildew, powdery mildew and other ...

, used to control fungus on fruits. * Hydrated lime, as a biocide, is allowed in the production of organic foods.

Barley straw

Barley

straw Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number ...

, in England, is placed in mesh bags and floated in

fish pond A fish pond or fishpond is a controlled pond, small artificial lake or retention basin that is stocked with fish and is used in aquaculture for fish farming, for recreational fishing, or for ornamental purposes. Fish ponds are a classical g ...

s or water gardens to help reduce algal growth without harming pond plants and animals. Barley straw has not been approved by the United States Environmental Protection Agency (EPA) for use as a pesticide and its effectiveness as an algaecide in ponds has produced mixed results during university testing in the United States and England. It is unclear how straw actually works. Peinture algicide et fongicide

Synthetic algicides

Synthetic algicides include: * benzalkonium chloride – "quat" disinfectant that attacks membranes * bethoxazin – "new broad spectrum industrial microbicide" in 2012, noted as "Canceled in U.S." in 2022 PubChem-EPA query * cybutryne – banned since 2023 in ship paint *

dichlone Dichlone (trade names Phygon and Quintar) is a fungicide and algicide of the quinone class. It is a general use fungicide applied to fruits, vegetables, field crops, ornamentals, and residential and commercial outdoor areas. It is also used to c ...

– quinone fungicide/algaecide, not persistent in soil * dichlorophen – also kills invertebrate animals and bacteria * diuron – herbicide/algaecide, inhibits photosynthesis * endothal – herbicide/algaecide, inhibits protein phosphatase 2A * fentin – quinone fungicide/algaecide, discontinued * isoproturon – selective substituted urea herbicide, discontinued * methabenzthiazuron – substituted urea herbicide, discontinued * nabam – fungicide/algicide discontinued in the EU over cancer * oxyfluorfen – herbicide, "very toxic to aquatic life with long lasting effects" * pentachlorophenyl laurate * quinoclamine – herbicide/algicide, not used in most of the EU * quinonamid * simazine – herbicide/algaecide, inhibits photosynthesis * terbutryn * Tiodonium

References

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External links

National Pesticide Information Center (NPIC)
Information about pesticide-related topics.