Identification of fungal agents of garlic and onion leaf spot and blight in Jiroft, Iran

Garlic and onion are very important crops which are cultivated especially in autumn season in Jiroft region, southeast of Iran. One of the limiting factors for development of cultivation of these crops is fungal diseases such as leaf spot and blight. For identifying the causal agents of this disease, numerous onion and garlic fields were surveyed during 2001-2003 and infected samples were collected and cultured. The fungi Fusarium oxysporom, F. solani, F. semitectum and Rhizoctonia solani were isolated from symptomatic crops. All of isolated fungi were pathogenic on onion seedling. On mature garlic and onion plants a type of leaf blight was observed and Cladasporium cladosporioides was found to be pathogenic and cause this disease. From onion and garlic crops with purple spot symptoms, Alternaria sp isolated and shown to be pathogenic on these crops. A type of leaf blight symptoms was seen on mature garlic and onion plants. Disease symptoms mostly on lower leaves as yellow small leaf spot were observed. Sometimes these spots became larger and caused blight. From symptomatic plants, Stemphylium sp. was isolated and shown to be pathogenic.