Alternaria leaf spot of cotton with special reference to Zimbabwe

Abstract

Leaf spots caused by Alternaria macrospora and A. alternata are common in cotton crops around the world. Both species are, however, usually considered to be minor pathogens of Upland cotton (Gossypium hirsutum) but A. macrospora causes premature defoliation with resulting yield loss in cultivars of G. barbadense in Israel and in the USA. A. macrospora is also able to cause defoliation in Upland cotton if the crop is. predisposed to infection by environmental or physiological stress. In Zimbabwe the main predisposing factor is potassium deficiency. The paper discusses the disease in Zimbabwe against the background of work reported from other countries on its effect on yield and on its epidemiology and control.

Notes

Present address: University of Reading, Department of Agriculture, Earley Gate, Reading RG6 2AT, UK.