Evaluation of Common bean Cultivars and Fungicide Spray Frequency for the Management of Anthracnose (Colletotrichum lindemuthianum) in Ambo, West Shewa Zone, Ethiopia

Abstract

Bean anthracnose caused by Colletotrichum lindemuthianum (Sacc. & Magnus) is one of the most devastating seed-borne diseases of common bean (Phaseolus vulgaris L.) in Ethiopia. Therefore, an experiment was conducted at Ambo University Experimental Research Farm during the main cropping season of 2014 to evaluate four common bean cultivars (Chercher, Awash Melka, Awash-1 and Mexican-142) and the efficacy of the fungicide, Folpan (80 WDG) at the rate of 2.6 kg/ha at four spray intervals (every one week, two weeks, three weeks and unsprayed-control) under field conditions for the management of bean anthracnose and their impact on yield and yield components. A total of sixteen treatments were laid out in a Factorial arrangement in Randomized Complete Block Design (RCBD) with 3 replications. The anthracnose severity, incidence, infected pods per plant and area under disease progress curve were the highest in susceptible cultivar Awash-1 followed by Mexican-142, Awash Melka and Chercher in unsprayed plots. The anthracnose severity was substantially reduced by 76.89% and resulted in increased seed yield (4 tons/ha) in Awash Melka when sprayed at weekly intervals compared to unsprayed plots. The anthracnose severity and area under disease progress were the recorded highest in unsprayed plots and reduced seed yield in susceptible cultivars Awash-1 and Mexican-142. Interaction effect of cultivars with spray intervals of fungicide showed significant variation in pods per plant, discolored seeds and seed yield and infected pods per plant; while it has no significant effect on seeds per pod and hundred seed weight. The relative yield loss of 51.89, 39.43, 27.5 and 22.97% were recorded from Awash-1, Mexican-142, Awash Melka and Chercher unsprayed plots, respectively. Economic analysis revealed that the highest net benefits were obtained from Awash Melka when sprayed at every one week and two weeks intervals (47,912 and 44,700 birr/ ha) followed by Chercher (42,662 and 41,373birr/ha) and the least was obtained from Awash-1 unsprayed plot (birr 10,935/ha). Highest marginal rate of return was obtained from Awash-1 sprayed at every three weeks interval (374.3%), but the lowest was obtained from Chercher with spray of fungicide at every three weeks intervals (Birr 10.88%). The relatively resistant cultivar Awash Melka with spray of fungicide at weekly intervals reduced anthracnose epidemic and increased seed yield, yield components and accrued higher net return. The results of the present study provide empirical evidences that the response of common bean cultivars to weekly and two weeks spray intervals of fungicide application found to be effective in reducing anthracnose severity, increased seed yield and reduced yield loss attributed to anthracnose in common bean cultivars under field conditions in Ambo University. Spraying Folpan fungicide at weekly and two weeks intervals had a favorable effect in reducing anthracnose epidemics. Further, cost effective and feasible integrated management options need to be developed for common bean anthracnose in the country.

Keywords: Common bean, cultivars, anthracnose, Colletotrichum lindemuthianum, management, fungicide, spray intervals, yield and yield loss.