Ecological Effects of Diquat

Abstract

HERBICIDES exert selective effects on soil microorganisms as well as on higher plants, a fact which is implied by reports that certain soil organisms, and in particular bacteria, adapt themselves and are able to decompose chemicals, such as 2,4-dichlorophenoxyacetic acid¹, methylchloro-phenoxyacetic acid², dalapon³, amitrole⁴, paraquat⁵ and simazine⁶. These direct changes following treatment with herbicides were thought to be only temporary because the activity of the adapted flora declines as the substrate is broken down. But there can also be long term ecological consequences of prolonged use of a particular herbicide. Agricultural enterprises such as intensive cereal production may involve continued use of the same chemical year after year and, consequently, there may be gradual, but cumulative, qualitative changes in the soil microflora.