Symptomatology of Cassava Mosaic Disease and a Proposal for Further Study to Categorize the Variants

Abstract

VARIOUS differences in the symptomatology of the cassava mosaic disease complex have been observed in many African countries. Storey and Nichols (1938) believed that these variations were due to differences in strains of the causative agent. They categorized the strains as follows: (a) A severe strain, which induced severe leaf chlorosis. Chlorotic areas are usually large and uniformly distributed but sometimes localized; (b) A mild strain, which induced slight chlorosis, with the affected areas slightly yellower than normal. The chlorotic areas were small, and either generally distributed or localized. In this category some infected plants can be symptomless.