Common Foliar Pathogens of Oaks (Multiple species) - Some of the most common and easily noticeable diseases of oak trees include foliar fungi known as leaf spots. Thesefungi infect the leaves, and in some cases the twigs and buds, of oak trees causing discoloration, spotting, anddefoliation. Several fungal species cause leaf spots. Some of the most prevalent are Tubakia (Tubakia spp.), Anthracnose (Apiognomonia spp., Discula spp.), tar spot (Trabutia quercina), oak leaf blister (Taphrina caerulescens), and oak rust (Cronartium spp.). Similarities exist across these different species regarding spread, damage, and control.Repeated outbreaks of leaf spots, particularly in combination with other stresses, can lead to tree decline over time.