This article is a list of diseases of hydrangeas (Hydrangea macrophylla).
| Bacterial diseases | |
|---|---|
| Bacterial blight | Pseudomonas solanacearum |
| Bacterial leaf spot | Pseudomonas cichorii |
| Fungal diseases | |
|---|---|
| Bud and flower | Cercospora hydrangeae Corynespora cassiicola Phyllosticta hydrangeae Septoria hydrangeae |
| Powdery mildew | Erysiphe polygoni |
| Root rot | Pythium spp. |
| Rust | Pucciniastrum hydrangeae |
| Southern blight | Sclerotium rolfsii Athelia rolfsii [teleomorph] |
| Viral diseases | |
|---|---|
| Phyllody | |
| Ringspots | |
| Tobacco ringspot virus | |