SCREENING OF FUNGICIDES FOR MANAGEMENT OF CHOCOLATE SPOT (Botrytis fabae Sard.) OF FABA BEAN IN BALE HIGHLANDS, SOUTHEASTERN ETHIOPIA

hocolate spot is a major yield limiting factor in the main faba bean growing regions of Ethiopia resulting up to 62.1% of yield losses. Therefore this experiment was initiated to evaluate the efficacy of different fungicides, their spray rates and frequencies for the management of chocolate spot of faba bean (Botrytis fabae Sard.) in Bale highlands. A total of 13 treatments, combinations of three fungicides (rexduo, revolution and jeba), two spray rates (0.25 lt/ha and 0.5 lt/ha) and two spray frequencies (14 and 21 days) with the addition of one unsprayed control, were arranged in randomized complete block design with three replications at Sinana Agricultural Research Center (SARC) and Madda Walabu University Research Site (MWURS) during 2019/20 main cropping season. The statistical analysis showed significant differences among treatments in the faba bean chocolate spot incidence, severity, AUDPC, disease progress rate and grain yield. The lowest mean disease severity, 19.0% at SARC and 12.19% at MWURS, and the lowest mean AUDPC, 11.44% days at SARC and 7.02% days at MWURS, were recorded from plots treated by revolution at rate of 0.5 lt/ha. Whereas, the highest mean chocolate spot severity, 94.20% at SARC and 73.45% at MWURS, and the highest mean AUDPC, 52.79% days at SARC and 36.63% days at MWURS, were recorded from control plots. The lowest mean chocolate spot PSI, 9.82% was recorded from revolution treated plot at rate of 0.5 lt/ha with every 14 days interval, while the highest mean, 83.85% was recorded from untreated plots. The lowest mean disease progress rates of, 0.008 and 0.015 gompit per day were calculated from plots treated with revolution and rexduo respectively, at rate of 0.5 lt/ha with every 14 days interval, whereas the highest mean, 0.063 gompit per day was calculated from control plots. The highest mean grain yield of faba bean, 6584.44 kg/ha and 6368.94 kg/ha were recorded from revolution and rexduo treated plots at rate of 0.5 lt/ha respectively, while the lowest, 2634.09kg/ha was recorded from control plots. Final PSI, AUDPC and disease progress rate of faba bean were very highly significant (p<0.001) and strong negatively correlated with pods per plant, grain yield and hundred seed weight of faba bean. Linear regression estimates indicated that - 110.40 kg/ha, -114.49kg/ha and -95.83kg/ha yield loss were predicted on rexduo, revolution and jeba sprayed respectively for every unit increase of AUDPC (% day). The maximum relative grain yield losses, 66.30% and 62.74% were recorded from jeba treated plot at rate of 0.25 lt/ha with every 21 days interval and unsprayed plots respectively. Whereas, the lowest, 9.20% and 10.61% were calculated from rexduo treated plots, at rate of 0.5 lt/ha with every 14 and 21 days intervals in the mentioned order. The highest net profit and marginal benefit, 156,327.1ETB and 96,751.4 ETB per hectare bases respectively, were recorded from revolution sprayed pots at rate of 0.5 lt/ha with every 14 days interval. Application of revolution at rate of 0.5 lt/ha with every 14 days interval as first option and application of rexduo and revolution at rate of 0.5 lt/ha with every 21 days interval as second and third option respectively are recommended because of their profitability at current market prices. Additional as they gave the best protection against chocolate spot of faba bean than other treatments. However, further study has to be done under several seasons and locations to confirm the recommendation of the present finding.