Blumeria graminis

Blumeria graminis is a fungal species in the powdery mildew family Erysiphaceae that causes powdery mildew disease on cereal grasses, producing a thick white mycelial growth on host leaves that typically turns tan or brown as the infection progresses. It attacks wheat, barley, rye and other grasses in the grass family, and for centuries was considered the only powdery mildew fungus capable of infecting grasses, though its genus is now known to include at least seven further species. Because it has been a management priority for wheat growers for millennia, more than one hundred resistance genes have been identified and bred into wheat varieties, and growers also rely on fungicides and silicon based treatments that strengthen a plant's own defenses. The fungus can nonetheless evolve to overcome individual resistance genes over time, keeping it an ongoing challenge for cereal agriculture worldwide.