The fungus growth can enlarge to cover the whole leaf. The infected tissues will curl, lose their natural luster, yellow, and die. Both powdery and downy mildews produce a white, fuzzy mycelial growth on the surface of the host. Erysiphe cichoracearum 2. Fungus spores are produced in a chain on a single conidiophore.
Lesions tend to be circular and spread across leaf veins.
Fungus mycelium and spores are external to the host. Host tissues usually yellow after fungus growth is evident. Bremia lactucae 2. Fungus spores are produced singly on a branched conidiophore. Lesions tend to be angular and confined within leaf veins.