Prevalence of Cassava Bacterial Blight in Kenyan Coast, Its Characterization and Early Management in Planting Materials

Abstract

Cassava (Manihot esculenta) is one of the major crops among the roots and tubers consumed in Kenya and Africa at large. It is one of the strategic food security crops in rural livelihoods. The crop is faced by biotic constraints that hinders its maximum productivity. These include Cassava bacterial blight (CBB) caused by Xanthomonas axonopodis pv. cassavae and Xanthomonas axonopodis pv. manihotis, as one of the major cassava diseases after cassava mosaic disease and cassava brown streak disease. Cassava bacterial blight is distributed in 24 countries in Africa and this is due to sharing of infected cuttings among farmers. In Kenya, cassava bacterial blight was first reported in 1980 in the Western region. Lack of healthy clean planting cassava materials, lack of resistant cassava cultivars and poor seed system for cassava are contributing to the spread of the disease nationwide. This study was conducted to determine the prevalence of cassava bacterial blight in Kilifi and Taita Taveta counties, the existence of the two bacterial pathovars causing CBB, characterizing them and using tissue culture technique to manage the disease. The study involved a focused group discussion and a baseline survey in the two counties. This involved purposive random sampling where 250 cassava farmers were selected and interviewed using a semi- structured questionnaire. Disease assessment was done to establish prevalence as well as sample collection from cassava fields. The collected samples were isolated in the lab and the pathogens were characterized using cultural methods. Tissue culture experiment was set in the laboratory in which raised plants were subjected to a treatment of three antibiotics at optimized concentrations of 5mg/l, 10mg/l, 15mg/l, and 20mg. /l to eradicate CBB causing bacteria and raise healthy cassava seedlings.