Further investigations on the biology of Phomopsis cinerascens, the cause of fig canker in Iran

Abstract

Fig branch canker is a major disease in most parts of Iran, especially in Estahban (Fars province), which has the largest area of dry fig plantations in that country. In 1999–2000 a general survey was conducted in rainfed fig plantations throughout Fars province. In this survey Phomopsis cinerascens was consistently isolated from the cankers. . The fungus produced pycnidia containing α-conidia on active cankers from fall to mid spring. No β-conidia were found under natural conditions, but many isolates produced β-conidia intermixed with α-conidia in culture. Only α-conidia germinated on agar medium. The optimum temperature for growth, pycnidial formation and pycnidiospore germination was 25°C. Pathogenicity tests revealed that the fungus infected inoculated branches at 15–25°C but no infection occurred at 5°C or at 30°C or higher. Under field conditions, the pathogen infected branches from fall to mid spring, but little infection occurred in summer. The pruning wounds remained receptive to the pathogen from fall to mid spring. Pycnidiospores that over-summered on trees or on branches lying on orchard floors were not viable. Infected branches under moist conditions produced new pycnidia containing viable conidia. Mycelia are considered important for over-summering the pathogen in Fars province.