سبب شناسي بيماري پوسيدگي خشك پيازهاي ريزبذري (Onion set) و ارزيابي تحمل نسبي پانزده رقم تجاري پياز نسبت به عامل آن

Etiology of dry rot of onion set and evaluation of tolerance of 15 commercial onion cultivars to the causal agent of the disease

Jiroft and Kahnouj areas have the first grade of cultivation and production of Autumn onion in Iran. In recent years, some leader farmers accepted onion set in Jiroft. Dry rot is the most important disease of onion set in the storage in Jiroft. Samples of the infected onion sets collected and surface sterilized with 1% Sodium hypochlorite cultured on PDA. Isolated fungi purified by single spore method on 2% WA. Pathogenicity test was carried out on onion sets by use of mycelial disc and suspension of the spores (inoculation and soaked) of two cultivars. Based on cultural and microscopic characteristic, causal agent identified as Fusarium proliferatum. This is the first report of Fusarium dry rot of onion set in Iran. Tolerance ratio of 15 commercial onion varieties evaluated in CRD by 5 replicates. Onion sets inoculated by mycelial disks of the pathogen on PDA. Reaction of the varieties evaluated by disease severity (DS) and weight reduction percent (WR) after 14 days of inoculation. The results showed that Pegasus, Nun 1404, White havack and White sun had lowest DS and WR and rated as tolerant, and the other varieties rated as susceptible.