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![Commonly seen in greenhouse grown big leaf hydrangea (Hydrangea macrophylla). Rarely seen on oakleaf hydrangea (H. quercifolia) Commonly seen in greenhouse grown big leaf hydrangea (Hydrangea macrophylla). Rarely seen on oakleaf hydrangea (H. quercifolia)](images/powdery-mildew/22161DD2C3964DF39A98F053EB87FBF3/04-591b CP NEW_thumb.jpg)
Commonly seen in greenhouse grown big leaf hydrangea (Hydrangea macrophylla). Rarely seen on oakleaf hydrangea (H. quercifolia)
![The symptoms start as small white patches scattered on the leaves. The causal fungus E. polygoni has clear hyphae (threadlike) that can be seen in the infected areas using a hand lens. The symptoms start as small white patches scattered on the leaves. The causal fungus E. polygoni has clear hyphae (threadlike) that can be seen in the infected areas using a hand lens.](images/powdery-mildew/22161DD2C3964DF39A98F053EB87FBF3/11-080 03 CP NEW_thumb.jpg)
The symptoms start as small white patches scattered on the leaves. The causal fungus E. polygoni has clear hyphae (threadlike) that can be seen in the infected areas using a hand lens.
POWDERY MILDEW
Fungal causal agent: Erysiphe polygoni
Hydrangea diseases