Influence of pH and temperature on growth and sporulation of Fusarium oxysporum f. sp. psidii associated with guava wilt complex

Abstract

An experiment was conducted to investigate the effects of atmospheric substrate pH and temperature on the growth, development, and sporulation of Fusarium oxysporum f. sp. psidii, which is associated with the guava wilt complex. The pathogen was isolated from a guava orchard at the Organic Farming Research Centre, College of Agriculture, Navule, Shivamogga, Karnataka which was severely infested with guava wilt complex disease during the Kharif 2023-24. The study revealed that the pathogen can grow over a wide pH range, from 5.0 to 8.5. The maximum dry mycelial weight (549.67 mg) with excellent sporulation was observed at pH 6.5, followed by pH 7.0 (477.67 mg). The lowest growth was recorded at pH 8.5. The optimum temperature range for growth was found to be between 25 °C and 30 °C. The maximum dry mycelial weight of F. oxysporum f. sp. psidii (351.67 mg) with excellent sporulation occurred at 25 °C, followed by 30°C (318 mg). The lowest growth (83 mg) was observed at 40 °C.