Physiological Characteristics of Colletotrichum gloeosporioides: The Causal Agent of Arecanut Leaf Spot

The experiment aimed to study the physiological characteristics of the Colletotrichum gloeosporioides at College of Horticulture Bagalkot, Karnataka, India. During 2024, the pathogen was cultured in 40 ml of potato dextrose broth and its dry mycelial growth was recorded over 20 days at two-day intervals. The highest mycelial growth was recorded on the 12^th day after incubation (DAI) with a dry weight of 284.7 mg, followed by the 10^th day with 246.3 mg. The study also examined the pH effect on mycelial growth. The pathogen exhibited the highest dry mycelial growth at pH 6, with a weight of 362.3 mg, followed by pH 7, which showed a mycelial weight of 314.7 mg. The least mycelial growth was recorded at pH 10, with a weight of 176 mg. Temperature also played a crucial role in the growth of C. gloeosporioides. The optimal temperature for the growth of C. gloeosporioides exhibited the highest mycelial growth at 25°C, reaching 290.5 mg. The next most favourable temperature was 30°C, where the growth measured 214.3 mg. There was no growth observed at 40°C and 45°C. Therefore, the temperature range of 25 to 30°C was considered optimal for the growth of pathogen. The maximum growth (88.3 mm) under alternate cycles of 12 hours of darkness and 12 hours of light, with excellent sporulation. It can be concluded that Colletotrichum gloeosporioides exhibits its highest growth potential at pH 6, 25°C and under alternate cycles of 12 hours of darkness and 12 hours of light.