Cultural and Physiological Variation Between Isolates of Stemphylium botryosum the Causal of Stemphylium Blight Disease of Lentil (Lens culinaris)

A total of four isolates of Stemphylium botryosum infected lentil were collected from lentil plants showing blight symptoms and grown at different areas of Bangladesh. The isolates were characterized in terms of cultural, morphological and physiological parameters. The isolates varied significantly in their cultural, morphological and physiological traits of colony color, shape, texture, conidia size and radial mycelial growth on culture media. The optimum temperature for the mycelial radial growth of S. botryosum was 25°C and the fungus was grown well in lentil dextrose agar (LDA). The mean length and breadth of conidia was varied from 13.33-16.04 μm and 6.46-9.14 μm, respectively. Mean length of conidia was maximum 16.04 μm in isolate MIH-2 and minimum 13.33 μm in isolate MIH-3. The highest mean breadth 9.17 μm was observed in isolate MIH-2 and the lowest 6.46 μm in isolate MIH-3. All the fungicides tested gave significant reduction in radial mycelial growth over control. Among the fungicides Rovral 50WP (Iprodione) was found to be the most effective fungicide to retard the radial mycelial growth of Stemphylium botryosum.