A genus of fungi in the class Hyphomycetes, occurring in soil and on vegetable matter — many species are plant pathogens, with Alternaria solani causing early blight of potatoes and tomatoes. Some species produce mycotoxins, including alternariol and alternariol monomethyl ether, on foods such as cereals, fruits and vegetables, making them a postharvest and storage concern as well as a field problem. Dark-spored and ubiquitous, Alternaria is the classic storage mould of produce: the black spots on ageing tomatoes and peppers are often its signature.