This article is a list of diseases of hydrangeas (Hydrangea macrophylla).
Bacterial diseases
Bacterial diseasesBacterial blight Pseudomonas solanacearumBacterial leaf spot Pseudomonas cichorii
Fungal diseases
Fungal diseasesBud and flower Cercospora hydrangeae Corynespora cassiicola Phyllosticta hydrangeae Septoria hydrangeaePowdery mildew Erysiphe polygoniRoot rot Pythium spp. Rust Pucciniastrum hydrangeaeSouthern blight Sclerotium rolfsii Athelia rolfsii [teleomorph]
Viral diseases
Viral diseasesPhyllody Hydrangea ringspot virus Ringspots Hydrangea ringspot virus Tobacco ringspot virus Tomato spotted wilt virus
References
Common Names of Diseases, The American Phytopathological Society