The technique of using barley for algae control in the UK has developed quickly since the early 1990s, where it is widely used in many bodies of water, including large reservoirs and canals. In general, it is thought that fungi decompose the barley in water, which causes a chemical to be released that prevents the growth of the algae. The specific chemicals have not been identified (oxidized polyphenolics and hydrogen peroxide are two decomposition products that have been suggested), and it is not clear whether the chemical is exuded from the barley itself or if it is a metabolic product produced by the fungi. The activity of barley straw is usually described as being algistatic (prevents new growth of algae) rather than algicidal (kills already existing algae).