English

Abstract

Arvi (Colocasia esculenta) is widely cultivated sweet and starchy corms as a staple food in most of the African and Asian countries. Black rot caused by Ceratocystis fimbriata is the most damaging post-harvest disease of Arvi in many countries. In June, 2019, the black rot disease symptoms were noticed on edible corms of Arvi for sale in different vegetable shops in Faisalabad, Pakistan. These symptoms were comprised of small, brown to greenish, slightly sunken spots or lesions which later on enlarged as black rot on the harvested corms. A comprehensive study was initiated to explore the pathogen associated with symptomatic corms. White to grey mycelia and black perithecia with long necks were observed within the lesions. The isolated pathogen was identified as Ceratocystis fimbriata based on morpho-physiological characteristics. Pathogenicity was proved on inoculated corms at 26±2°C and 70% relative humidity (RH) in plant growth chamber. The fungus was further tested for growth and reproduction physiology under different growth media and environmental parameters. A significant interaction between mycelial growth and culture media was observed. Highest mycelial growth (9 cm) of C. fimbriata was showed by Potato Carrot Agar (PCA) and lowest growth (0%) was observed on Water Agar (WA). There was a significant correlation between Temperature, RH, and hydrogen ion (pH) concentration responsible for the growth of C. fimbriata at (P < 0.01). The optimum fungal growth (8.75, 8.96, and 8.95 cm) was measured at 25°C, 70% RH, and pH 8 respectively. The paper may act as basic resource for future research on the epidemiology of this disease.