The Brown Streak Disease of Cassava Distribution, Climatic Effects and Diagnostic Symptoms

Abstract

Brown streak disease of cassava (Manihot utilitarianism Pohl.) was first recorded and described by Storey in a progress report published in 1936[1]. There appear to have been no other published accounts. The Amani work up to 1936 had demonstrated that the disease was perpetuated through vegetative propagation and transmissible through grafting; and in the absence of any visible parasite the causative agent was assumed to be a virus. Later work led to a strong suspicion that a White-Fly (Bemisia sp.), was the vector of the virus in the fie1d[2]; but confirmation or this had not been obtained before the late war interrupted controlled experimental studies of the disease, and it has not been possible, up to the present, to resume them. The information contained in this paper, therefore, 'is based mainly on field observations. A considerable amount of information relative to geographical distribution, climatic effects and symptoms of the disease has accumulated since Storeys original publication and is set out in this paper.