Evaluation of the reaction of elite cassava genotypes to cassava brown streak disease at the national crops resources research institute, Uganda.

Abstract

Cassava brown streak disease continues to be a major constraint to cassava production in East Africa, causing up to 100% yield loss. Disease resistance is be the most effective way of managing this disease. The main objective of this study was therefore to contribute towards the development of cassava varieties that are resistant to cassava brown streak virus disease. Seven (7) elite cassava genotypes and 3 released varieties used as local checks were inoculated with CBSD using the grafting technique and then screened for CBSD resistance. The experiment was set up in a Randomized Complete Block Design (RCBD) with two replicates at the National Crop Resources Research Institute (NaCRRI). Each replicate consisted of 10 plots of 5 rows x 6 plants with spacing of 1m between plants and rows. Data on CBSD was collected at 3, 6 and 12 months after planting. Results indicated that foliar and root incidences and severities varied significantly among genotypes (p<0.05). All genotypes had CBSD foliar symptoms with incidence ranging from 3.2%-93.9% and severity ranging from 1.0-2.835. There was a positive relationship between disease incidence and severity at 3MAP, 6MAP and 12MAP in most genotypes except UG 1200193 at 3MAP with 1.6% mean incidence and 1 mean severity. Genotype UG 120198 had both low foliar and root mean incidence and severity and therefore should be used as a parent in further development of resistant varieties.