Septoria are Ascomycete pycnidia-producing fungi that causes numerous leaf spot diseases on field crops, forages and many vegetables including tomatoes which are known to contract Septoria musiva from nearby cottonwood trees, and is responsible for yield losses. The genus is widespread, and estimated to contain 1072 species. Pycnidia produce needle-like pycnidiospores. Septoria leaf blotch is a fungal disease due to Zymoseptoria tritici, anamorph Mycosphaerella graminicola, that affects wheat and occasionally other grasses. It is the major disease of wheat in the UK.