Pomegranate decay caused by Pilidiella granati in California
T. J. MICHAILIDES (1), R. Puckett (1), D. Morgan (1)
(1) University of California Davis, Parlier, CA, U.S.A.
Phytopathology 100:S83

During the last decade and after the recent discoveries of the high antioxidant content of pomegranate fruit and juice, the pomegranate industry has increased to >20,000 acres in California. Pomegranates are marketed as intact fresh fruit, extracted arils, or juice. Fruit diseases such as black heart caused by Alternaria spp., Aspergillus and Penicillium rots, are considered the most important diseases of pomegranate fruit. However, in the last two years, another rot caused by a pycnidial fungus Pilidiella granati has been commonly observed in fruit from fields or packinghouses. Pilidiella rot is very different from black heart rot in that it decays the arils and the fruit rind while black heart decays only the arils. On APDA, P. granati produces white to light yellow, leathery mycelia with abundant black, solitary pycnidia of various sizes. Optimum temperature of growth on APDA ranges from 25 to 30°C; the fungus grows at 15°C, but not at 35°C. Although infection needs a wound, infection moved from infected fruit to intact fruits in contact. The pathogen overwinters as pycnidia and mycelia in rotten fruit in the field. It has been isolated also from dying shoots of young pomegranate trees. P. granati is characterized by the hyaline to pale brown conidia (length:width >1.5) in contrast to Coniella spp. which have dark brown conidia (length:width <1.5). To our knowledge, this is the first report of P. granati causing significant fruit rots of pomegranate in California.