First report of Alternaria dumosa causing orange leaf spot disease in Iran.
Surveys for disease in three species of wild and cultivated orange, i.e. Citrus aurantium (sour orange), C. macroptera (wild orange) and C. sinensis (sweet orange), were conducted in the summer of 2012. Symptoms of foliar disease were commonly observed in several parts of Fars province, Iran. On young leaves, lesions first appeared as small brown to black spots, which soon became surrounded by yellow haloes. Lesions expanded into irregular necrotic areas that could involve large portions of the leaf. A dark green-olivaceous fungus with profuse golden brown, branched, and septate hyphae was consistently isolated from the infected tissue on PDA. The fungus produced conidia that were morphologically identified as an Alternaria species. Morphological characteristics of the colonies on PCA and V8 agar media after seven days indicated typical characteristics of A. dumosa. This is thought to be the first report of Alternaria leaf spot on orange caused by A. dumosa in Iran.