The influence of climate on the incidence and severity of some tropical crop diseases

Abstract

ABSTRACTAgriculture in tropical countries produces many of the world's most valuable crops, but productivity is limited by a multiplicity of different diseases, many of which have been inadequately studied. Certain characteristics of tropical climates have a fundamental influence on the incidence and severity of many of these diseases. The main seasonal variations which control crop growth and disease epidemiology depend on differences in moisture availability rather than daylength and temperature differences. Marked dry seasons hinder the survival of many pathogens outside hosts unless they can produce drought‐resistant spores. In many tropical areas continuous cropping throughout the year is possible, enabling disease epidemics to continue without interruption over long periods.Much agriculture in the tropics is at fairly high altitudes enabling temperate crops to be grown, but low temperatures may present special disease hazards. Violent storms are a feature of many tropical climates and have been implicated in the spread of many bacterial diseases. Drought is a factor which influences the severity of many root diseases. The various effects which moisture, as rain or dew, temperature and cropping cycle can have are illustrated by discussion of sigatoka disease of bananas (Mycosphaerella musicola Leach), South American leaf blight of rubber (Microcyclus ulei (R. Henn.) Arx) and coffee berry disease (Colletotrichum coffeanum Noack).