Submitted to: Plant Pathology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2009
Publication Date: 1/29/2010
Citation: Chala, A., Prom, L.K., Tronsmo, A. 2010. Effect of host genotypes and weather variables on the severity and temporal dynamics of sorghum anthracnose in Ethiopia. Plant Pathology Journal. 9(1):39-46. Interpretive Summary: Anthracnose is a major fungal disease of sorghum in Ethiopia, where the crop is grown mainly by subsistence farmers as a major staple food crop. Due to the different types of farming systems and climatic conditions under which sorghum is grown, the production of the crop in Ethiopia is often severely infected by anthracnose. In this study, we determined the timing and spread of this disease in four sorghum lines. Among the sorghum lines tested, the Ethiopian line 2001PWColl#022 consistently had the lowest disease levels. Anthracnose infection also appeared later and spread slowly in this Ethiopian line. On the other hand, BTx623 was the most severely infected sorghum line, while the two other Ethiopian lines, AL70 and 2001HararghieColl#12 showed moderate disease levels. This work also showed the effect of sorghum line and weather conditions in the development of anthracnose. Based on the results of this study, the Ethiopian line 2001PWColl#022 will be recommended as a stable source of anthracnose resistance in the region.
Technical Abstract: The severity and temporal dynamics of anthracnose on susceptible (BTx623 and AL70) and resistant lines (2001PWColl#022 and 2001HararghieColl#12) were studied in field plots during the 2007 and 2008 growing seasons in southern Ethiopia. The initial, final, and mean anthracnose severities and area under disease progress curves were used as criteria to evaluate the response of the genotypes. Over the two years, the initial, final, and mean anthracnose severities ranged from 0.88 to 16.13 %, 7.56 to 78.38 %, and 3.57 to 46 %, respectively, while area under disease progress curve averaged for the two years ranged from 221.31 to 2951.88. All the evaluation criteria showed highly significant variations (P<0.0001) among the genotypes, and the Ethiopian genotype 2001PWColl#022 consistently had the lowest disease levels regardless of the evaluation criteria and growing season. The disease appeared rather late and progressed slowly on this genotype. On the other hand, the exotic cultivar, BTx623, showed the most severe anthracnose infection. Initial anthracnose severity was significantly higher and the disease developed rapidly on BTx623 than on the other three genotypes. The other two genotypes showed intermediate response and progression of the disease. Correlation and regression analyses revealed a significantly strong association between rainfall and anthracnose severity but temperature appeared to have little/no impact on the development of anthracnose in the field. The present study confirmed the effect of both host genotypes and weather, particularly rain on anthracnose development. The Ethiopian sorghum genotype 2001PWColl#022 was recommended as stable source of resistance against this important disease.