Biology and Pathogenicity of Phomopsis cinerascens, the Causal Agent of Fig Canker in Fars Province of Iran

Estahban is the main rainfed rig producing region in Fars province of Iran with an acreage of more than 20,000 ha propagated by stock. Since its first discovery back in 1979, rig canker became the major plant disease in this region and now has expanded to other fig growing areas in the province. Infection by the causal agent results in canker formation and killing of young and old branches. The pathogen was isolated on potato dextrose agar plates and pure cultures of it were used for further studies. The fungus produced numerous pycnidia in culture containing mainly single celled alpha spores. Occasionally filliform beta spores were also observed. Only a spores were capable to germinate on various culture media. No sexual stage of the fungus could be detected in nature and on culture medium. The fungus was pathogenic only on detached or intact fig branches. Based on cultural, morphological and pathological characteristics the fungus was identified as Phomopsis cinerascens. The fungus overwintered under natural conditions only as dormant mycelium on infected branches which under optimum relative humidity and temperature conditions produced new pycnidia bearing spores that were exuded in white to creamy cirri. Overwintered pycnidiospores produced in the previous season did not survive during the dormant period. Pruning cuts made in early fall remained receptive to the pathogen until mid spring and the pathogen could not infect plants in late spring or summer during the active growth of the host plants. Late pruning in the winter was recommended to manage this disease.