Severity of Chocolate Spot (Botrytis fabae) Disease on Yield and Yield Components of Faba Bean (Vicia Faba L.) Varieties at Guduru District, Horro Guduru Wollega Zone, Western Ethiopia

Chocolate spot (Botrytis fabae Sard.) is one of the major diseases threatening faba bean (Vicia faba L.) production and limiting its productivity in Ethiopia. The yield losses reach up to 100% on susceptible cultivars. Although a number of faba bean varieties with good yield potential have been released, their reaction to this major disease and yield performance are little understood in western Ethiopia. Thus, chocolate spot severity on 14 improved faba bean varieties and one local cultivar were tested under natural infections at Guduru district in Horro Guduru Wollega zone of western Ethiopia. The experimental site was located at longitude 36o39’28.8”-37o40’11.2”E and latitude 9o9’24.6”-10o20’59.9”N with altitudes range from of 1500-2450m and annual range of rainfall 900mm-2000mm with temperature range of 15oC -25oC as well as 262km distance from Addis Ababa capital city of Ethiopia. The field experiments consisted of 15 treatments (14 varieties and a local cultivar) are laid out in a randomized complete block design (RCBD) with three replications during the 2017/18 crop season. The data were analyzed by SAS computer software version 9.1.3. The onset and progress of chocolate spot severity was assessed (with a 1-9 scale) and yield and yield components were recorded and statistically analysed. The varieties varied significantly (P < 0.05) in disease severity, grain yield, pod per plant, plant height and hundred seed weight. Degaga, Gora, Bulga-70 and Holeta-02 varieties were exhibited moderate to lower resistance to chocolate spot disease, whereas, Mesay, local cultivar and Kasa varieties were highly susceptible to chocolate spot disease. The yield performance of Gora and Degaga were also superior at the study area 993.33kg/ha and 941.83kg/ha, respectively and thus, are recommended for faba bean production in western Ethiopia. The effect of chocolate spot disease on yield and yield components from coefficient determination of linear regression show that grain yield was more stressed by disease than other yield components. Generally, the study indicated that improved faba bean varieties reacted differently to chocolate spot disease. Keywords: Botrytis fabae, yield, disease severity, Vicia faba