An Evaluation of Sorghum Genotypes and Reduced rates of Fungicide Application against Anthracnose (Colletotrichum sublineolum) Management at Arba Minch and Derashe in Southern Ethiopia

Abstract

Anthracnose disease caused by Colletotrichum sublineolum is a major constraint that limits the production and productivity of sorghum in Ethiopia. A field experiment was carried out in Arba Minch and Derashe during the 2018/19 cropping season to determine the integrated effects of genotypes and reduced rates of fungicide applications on anthracnose disease, growth and grain yield of sorghum. The treatments were composed of four sorghum genotypes and three different rates of Ridomil Gold MZ 63.5% WP (Ridomil), including unsprayed and laid out in randomized complete block design with the factorial arrangement in three replications. Significant (p < 0.001) difference was observed in the magnitude of disease and crop parameters measured among the treatments considered. The disease severities were 22.78, 29.44, 62.22, and 66.11% on Arghiti, Melkam, Seredo and Local cultivar, respectively, because of a combination of Ridomil at the rate of 3 kg ha^-1. These treatment combinations exceedingly reduced area under the disease progress curve and rates of disease progression as well. No statistically significant difference was observed on the grain yield obtained from plots sprayed with Ridomil at the rates of 2 and 3 kg ha^-1 at 14 days intervals. A yield loss of 54.41% was recorded on unsprayed plots of the Local cultivar as compared to well-managed plots of other genotypes. The use of Arghiti and Melkam in combination with Ridomil at the rate of 2 kg ha^-1 was found to be relatively efficient in reducing anthracnose development and gave higher grain yield as compared to the unsprayed plot. Therefore, the use of Arghiti and Melkam in combination with application of Ridomil at the rate of 2 kg ha^-1 for the management of anthracnose could be suggested to sustain the production and productivity of sorghum for the farmers in the study areas and in similar agro-ecology. Further studies should be conducted in similar and other agro-ecologies in Ethiopia for at least one more year with over location to reach a concrete recommendation.