Niche partitioning of the genetic lineages of the oak powdery mildew complex

► Erysiphe alphitoides and E. quercicola are responsible of oak powdery mildew disease. ► We tested the hypothesis of niche differentiation between these cryptic species. ► E. quercicola is strictly associated to flag-shoots and prevalent in early season. ► E. alphitoides is released later and dominant at the end of the growing season. ► This spatio-temporal differentiation allows the two species to coexist on oaks.