Management of Chocolate Spot ( Botrytis fabae L. ) on Faba Bean in Bale Highland’s, Ethiopia

Abstract

Field experiment was conducted at Sinana Agricultural Research Center in the 2014 main cropping season with the objectives wasto study the reaction of faba bean varieties to infection of the chocolate spot and to assess yield losses caused by chocolate spot (Botrytis fabae) of faba bean four varieties. The highest mean final disease severity at (118 DAP) 38.29% was recorded on the main plots of the local variety and lowest mean final disease severity 32.75% was on the main plots of the variety Mosisa. The maximum Area Under the disease progress curves (AUDPC) was calculated on the unsprayed plots of local variety and Walki, which were 1817%-days and 1716.42%- days respectively. On unsprayed plots of variety local chocolate spot development was increasing at a rate of 0.03 units per day. For the variety local, chocolate spot severity index assessed from 90 DAP had significant negative correlation with yield and had highly significant negative correlation with hundred seed weight with coefficient of correlation ranging from(r=-0.67 to r=-0.62, P<0.05 and r–0.71 to r=-0.75, P<0.01) for yield and hundred seed weight, respectively. The linear regression of AUDPC better described the relationships between faba bean yield and disease severity compared to percent severity index for the variety Shallo. The estimate showed that for each unit increase in percent of chocolate spot AUDPC, there was a grain yield loss of 1.19 kg/ha The estimated slope of the regression line obtained for the variety Shallo was -1.19. Based on coefficient of determination (R2) value, the equations explained about 78% of variation in yield due to chocolate spot severity. Maximum relative grain yield losses of 47.8 and 46.7% were recorded due to chocolate spot severity on the varieties Mosisa and Sinana local, respectively.