Effect of mixed cropping and fungicides on chocolate spot (Botrytis fabae) of faba bean (Vicia faba) in Ethiopia

The effects of four cropping systems: faba bean (FB) alone, FB mixed with field pea (FB:FP), with barley (FB:BA) and maize (FB:MA), and three spray intervals of fungicide (mancozeb) applied at 7, 14 and 21 days at the rate of 2.5 kg a.i. ha(-1) and unsprayed control on FB chocolate spot caused by Botrytis fabae were studied in two cultivars. The experiment was conducted during the 2004 and 2005 cropping seasons at Adet, Ethiopia. The treatments were arranged in a randomized complete block design in a factorial combination with four replications. Treatment effects studied were disease severity, progress rate, area under disease progress curve (AUDPC) and grain yield. In some of the mixed cropping systems, disease severity showed a downward trend. FB:MA mixed cropping had a significant effect on disease severity, AUDPC and disease progress rate. The system reduced the epidemics of chocolate spot and increased FB grain yield. FB:FP increased the disease progress rate and reduced grain yield in both seasons. Short fungicide spray intervals (7 days) reduced the disease severity, AUDPC, and disease progress rate and increased the yield. Both local and the improved FB cultivar CS20DK showed almost similar disease progress rates. Mixed cropping with cereals contributed to the slowing of chocolate spot epidemics and increased grain yield of FB. It also promotes proactive integrated disease management. (C) 2007 Elsevier Ltd. All rights reserved.