Onion root & basal rot fungal diseases and their infection rate in Zanjan provience

Onion (Allium cepa L.) is one of the most important vegetables cultivated in Zanjan province. Fungal diseases, pests and weeds cause considerable damage to quantity and quality of this crop. The present study, addresses identification important fungal diseases of onion, their, distribution and their economical importance in fields and storerooms. Randomly collected leaf and bulb samples, carrying disease symptoms from 44 fields, and 10 storerooms, were transferred to zanjan plant disease laboratory to determine fungal agents and subsequently for possible pathogenicity test if it was applicable. The percentage of infection in the fields and the percentage of infected fields for each fungal pathogen were estimated by counting the number of infected plants and number of infected fields, respectively. In addition, post harvest diseases of onion was investigated by collecting samples from storerooms, isolating of pathogens and estimating the percentage of infection. Results showed that red root disease caused by Pyrenochaeta terrestris, and basal rot caused by Fusarium oxysporum were the most frequent diseases of onion in the fields with 9.9 and 2.8 percent infection, respectively. Post harvest diseases of onion, however, caused mainly by Fusarium oxysporum and Botrytis sp and occurred in a lesser extend in storerooms. The overall loss was estimated up to 22.7 percent by these fungal diseases.