Survey of the market diseases and aflatoxin contamination of tomato (Lycopersicon esculentum MILL) fruits in Sokoto, northwestern Nigeria

A survey of the market diseases and aflatoxin contamination of tomato fruits was conducted in Sokoto in northwestern Nigeria in 2001 and 2002, respectively. Rotten tomato fruits sold at five different markets in Sokoto town, located at Central market, Kasuwar daji, Mabera, Minanata and Arkilla were heavily contaminated with moulds. Eight different fungi were found associated with the rotten tomato fruits sold in the five different markets. The associated fungi were Aspergillus niger, Aspergillus ochraceous, Aspergillus flavus, Aspergillus fumigatus, Penicillium citrinum and Helminthosporim fulvum, Curvularia lunata and Sclerotium rolfsii. A. flavus and A. niger have the highest rate of occurrence among the isolated fungi, while S. rolfsii was the least encountered. Pathogenicity tests revealed that of all the isolated fungi, A. ochraceous, A. flavus, Sclerotium rolfsii and P. citrinum were highly pathogenic with the first three leading to rapid disintegration of treated fruits in 3‐5 days. A. niger was moderately pathogenic, while H. fulvum was least pathogenic on tomato fruits. Aflatoxins were detected from the sampled diseased‐marketed tomato fruits and also from the marketed rotten tomato fruits after autoclaving for 15 minutes at 121°C.