Physical and chemical methods of disease control (2)

Abstract

Sulphur was probably one of the first substances to be used as a fungicide as well as an insecticide, acaricide and general fumigant, and other early fungicides include copper sulphate, zinc chloride and mercuric chloride, the last named being used as a wood preservative in the early eighteenth century. These were followed by Bordeaux mixture and lime-sulphur in the late nineteenth century, and formalin, copper carbonate dusts and organo-mercurials (1913) as seed treatment chemicals. Organic fungicides — thiram, chloranil, dichlone and others — were developed from the mid-1930’s onwards, and captan, one of the most successful of them, was produced nearly 20 years ago. The many new crop protection chemicals which have been tested in recent years include guanidines, heterocyclic nitrogen compounds, quinones, phenols and antibiotics. It is sometimes said that new conventional fungicides superior to those already known are unlikely to be discovered, and that future research should be concentrated on systemic fungicides. The latter have given very promising results, but there would appear to be scope for systemic and non-systemic fungicides, or perhaps mixtures of the two. Interesting accounts of the development of fungicides are given by Horsfall (1956: a chronology of fungicides), McNew (1959) and McCallan (1967).