Alternaria and Stemphylium species associated with leaf blight and fruit rot of field-grown tomatoes in Australia

Abstract

Field-grown tomatoes with fruit rot and leaf early blight symptoms were sampled from New South Wales and Victoria, Australia, in 2022 and 2023. Alternaria alternata, A. arborescens, A. fructicola, and Stemphylium eturmiunum were isolated from black, sunken lesions on the fruit. Alternaria alternata, A. lycopersicifolia and an unidentified Alternaria sp. were isolated from leaf lesions. Alternaria alternata, A. arborescens and S. eturmiunum are known to cause foliar and postharvest diseases of tomato, globally. The pathogenicity of A. lycopersicifolia and A. fructicola on tomato leaves and fruits was confirmed by Koch’s postulates. Higher than expected species diversity was detected among fungal species associated with symptomatic tomato leaves and fruits. This is the first report of S. eturmiunum on tomato in Australia. The prevalence of these species and the potential risks posed by mycotoxin contamination are needed to assess their impact on the tomato industry.