Fungi Associated with Storage Rots of Onion Bulbs in Sokoto. Nigeria

A survey of fungi associated with postharvest deterioration of onion bulbs was conducted in Sokoto, north-western Nigeria in 2010. Rotten onion bulbs sold at five different markets: Sokoto central markets, Kasuwa daji, Gawon nama, Arkilla and Mabera were infected with eight species of fungi: Aspergillus niger, A. flavus, A. fumigatus, Alternaria porri, Rhizopus stolonifer, Fusarium oxysporum, and Penicillium citrinum. Of these, A.niger, A.flavus and A.porri were the most frequently isolated fungi. Penicillium citrinum was the least encountered fungus. Pathogenicity tests revealed that all the isolated fungi were pathogenic on onion bulbs however; A. porri, R. stolonifer and P. citrinum were the most pathogenic leading to rapid disintegration of the infected bulbs within 21 days of inoculation. While A. niger was the least pathogenic. The implications of the findings in relation to post harvest handling of onion bulbs and mycotoxin production were discussed.