Diseases and parasitic weeds of sorghum in Tanzania: occurrence and incidence, 1986–1990

Abstract

Sorghum is an important subsistence crop in Tanzania. Surveys were carried out between the 1986 and 1990 crop seasons to determine the prevalence of diseases and parasitic weeds in the major sorghum-growing areas of Tanzania. Twenty diseases of sorghum and three parastic weeds were observed. Grain moulds (several fungi), grey leaf spot ( Cercospora sorghi), anthracnose ( Colletotrichum graminicola), rust ( Puccinia purpurea), leaf blight ( Exserohilum turcicum), ladder leaf spot ( Cercospora fusimaculans), sooty stripe ( Ramulispora sorghi) and zonate leaf spot ( Gleocercospora sorghi), were economically important diseases. Striga asiatica was the most common parasitic weed in Tanzania. Ilonga in the low-altitude (⩽ 1000 m) zone and Hombolo in the mid-altitude (> 1000 m) zone were identified as locations with a high frequency of diseases and striga incidence. These locations were recommended for resistance screening against most of the leaf diseases, grain moulds and S. asiatica.