Studies on fungi associated with tomato fruits and effectiveness of some commercial fungicides against three pathogens

Abstract

Among 39 fungal species and one variety belonging to 16 genera isolated from 116 healthy tomato fruits collected from markets in Assiut, Egypt, during 1994, Aspergillus niger was found to be the most prevalent, being isolated from 84.6% of the samples. Of 11 species recovered from 156 diseased tomatoes, Alternaria alternata, Rhizopus stolonifer and A. niger were the most common and isolated from 52.7%, 35.9% and 25.0% of the samples, respectively. Experiments for comparison of the effects of medium containing tomato juice with synthetic medium on the mycelial growth of nine fungal species indicated that, the tomato juice medium was more suitable for growth of all fungal species. The effect of five commercial fungicides and sodium hypochlorite when applied as post-harvest dips after inoculation was studied in laboratory against A. alternata, A. niger and R. stolonifer. At 10 and 100 micrograms ml-1, neither of the fungicide caused a noticeable inhibition of Alternaria rot. At 1000 micrograms ml-1 benlate, rovral and sumisclex completely prevented Alternaria and Aspergillus rot, whereas cuprosan and ridomil were ineffective against rotting caused by A. niger. Rhizopus rot development was inhibited by over 50% with one treatment only (rovral at 1000 micrograms ml-1). Sodium hypochlorite has good curative properties against fruit rots especially those caused by A. alternata and A. niger.