Evaluation efficiency of severity of angular leaf spot in common bean based on diseased and healthy leaf area

Abstract

This study compared severity of angular leaf spot in common bean lines, based on the healthy and diseased leaf area, andthe graded scale. We used 12 common bean lines in the dry and rainy seasons. Two contiguous experiments were conducted in eachseason, with and without chemical control of the pathogen. We evaluated the percentage of the healthy and diseased leaf area; severitybased on a graded scale and the area under the disease progress curve; and yield. The diseased or healthy leaf area is efficient toevaluate the severity of angular leaf spot with a sample of 20 to 30 leaflets per plot. For all traits, the results of central and borderareas did not differ, indicating that the evaluation of border rows is unnecessary and, finally, the severity assessment of the upper planthalf can discriminate the lines more efficiently.

Keywords

• Phaseolus vulgaris
• Pseudocercospora griseola
• healthy and diseased leaf area
• graded scale
• severity.