First report of spinach leaf spot caused by Stemphylium sp. Subgroups C2 and E3 and pathogenicity comparison of the pathogen with related pathogens

Leaf spots on spinach were found in three greenhouses in Hokkaido and Iwate, Japan, in 2011–2012. Three isolates obtained from the lesions were classified into Stemphylium sp. Subgroups C2 and E3, based on morphology and molecular analyses. We compared the three isolates with two reference isolates belonging to Subgroup C2 from Welsh onion and leek in terms of pathogenicity. All five isolates caused leaf spot symptoms on spinach and leaf blight on Welsh onion in inoculation tests. This is the first report of spinach leaf spot caused by Stemphylium sp. Subgroups C2 and E3.