Identification of Cylindrosporium padi associated with leaf spot disease of cherry in Kashmir Valley, India

Abstract

Cherry an important stone fruit crop has been found to face a serious threat due to Blumeriella leaf spot disease. Survey of cherry orchards in Srinagar, Ganderbal and Baramulla districts revealed prevalence of the disease to varying extent. The disease incidence and intensity ranged from 13.00 to 52.50 per cent and 5.78 to 30.48 per cent, respectively. Maximum disease incidence of 41.02 per cent and intensity of 18.62 per cent was recorded in Ganderbal district, while minimum disease incidence of 18.10 per cent and intensity of 8.4 per cent was recorded in Baramulla district. The disease first appeared as small, circular to irregular, purple red speck on upper leaf surface. Periodical changes in colour, shape and size of the spots coupled with formation of irregular necrotic patches led to pre-mature defoliation. The fungus isolated on Potato Dextrose Agar medium produced compact and circular greyish white fungal colonies composed of hyaline, thick walled, septate and branched mycelium. Acervuli produced after 20 days of incubation at 20±1°C were dark brown to black, circular, discoid and measured 260.50 µm in diameter. Conidia (39.01 × 2.89 µm) were hyaline, bicelled, elongated, curved or flexous with tapered apex and rounded base. The pathogenic nature of the fungus was established on potted cherry saplings of cv. Bigarreau napoleon (Double). Based on morphological characters, pathogenicity test and comparision with the authentic description, the pathogen causing the disease was identified as Cylindrosporium padi (Lib.) P. Karst. Ex Sacc. the anamorph of Blumeriella jaapii (Rehm) Arx.