Traditionally rust and smut fungi (Pucciniomycotina and Ustilaginomycotina) are considered gall causers, but only as far as they cause conspicuous swellings of plant parts. By this limitation an arbitrary division is created in the rusts, that does no justice to their biological importance. Even more arbitrary is the admission of a small part of powdery and downy mildews (Erysiphales and Oomycetes).
The large group if infections that best can be taken together as leaf spots never has got a place in the literature on plant galls, even though they easily fit within the broad definition of galls that generally is used. Possibly the exclusion of this species-rich group is to be explained on practical grounds. Even today little accessible comprehensive literature is available. Although completeness is a total illusion, in this site it is tried to treat these fungi as well.