Magnaporthe grisea, also known as rice blast fungus, rice rotten neck, rice seedling blight, blast of rice, oval leaf spot of graminea, pitting disease, ryegrass blast, Johnson spot,[1][2][3][4][5][6][7] neck blast,[8][9][10][11] and Imochi (Japanese:稲熱) is a plant-pathogenic fungus and model organism[12] that causes a serious disease affecting rice. It is now known that M. grisea consists of a cryptic species complex containing at least two biological species that have clear genetic differences and do not interbreed.[13] Complex members isolated from Digitaria have been more narrowly defined as M. grisea. The remaining members of the complex isolated from rice and a variety of other hosts have been renamed Magnaporthe oryzae, within the same M. grisea complex.[13] Confusion on which of these two names to use for the rice blast pathogen remains, as both are now used by different authors.