Effects of Sowing Dates and Fungicide Application on Chocolate Spot (Botrytis fabae Sard.) Disease of Faba Bean (Vicia faba L.) in Western Ethiopia

Abstract

Faba bean (Vicia faba L.) is a cool legume crop grown in the highlands of Ethiopia, and chocolate spot disease (Botrytis fabae Sard.) occurs in wide areas. There is a shortage of recorded data about the impact of chocolate spot disease on faba beans and their management practices in Ethiopia. The objectives of this study were to assess the influence of sowing dates and the frequency of foliar fungicide (mancozeb) application for the management of chocolate spots and determine the association of sowing dates with chocolate spot disease occurrence. The experiment was conducted in the 2019 and 2020 growing seasons at two locations in Shambu and Guduru, western Oromia, Ethiopia. The mean disease severity, AUDPC, and grain yield were found to be statistically significant differences ( $P<0.05$ ) among the treatments at both locations and years. A highly negative correlation of AUDPC with a grain yield was obtained for both locations and years. A high infection rate, disease severity, AUDPC, and low grain yield were recorded from the unsprayed treatment. Three applications of mancozeb spray on the first July sowing date have effectively reduced disease severity and significantly increased yield. However, cost-effective and environmentally eco-friendly disease management is an issue that has to be further investigated.