Mycosphaerella graminicola, synonym: Septoria tritici, is a species of filamentous fungus, an ascomycete in the family Mycosphaerellaceae. It is a wheat plant pathogen causing septoria leaf blotch that is difficult to control due to resistance to multiple fungicides. The pathogen today causes one of the most important diseases of wheat (Stukenbrock et al. 2010).
In 2011, Quaedvlieg et al. used a new combination for this species: Zymoseptoria tritici (Desm.) Quaedvlieg & Crous, 2011 (Quaedvlieg et al. 2011).
