AT A GLANCE
What Causes a White Coat on Hydrangeas?
The white coating is real mildew. The fungus infested usually the leaf tops of hydrangeas and can appear dirty brown in addition to white. If you don't act quickly, the fungus will cause the leaves to dry up and curl up.
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How can I successfully remove the white plaque?
You can treat powdery mildew on hydrangeas with sulfur. If you'd rather try home remedies, you can too milk and water in a ratio of 1:10 and spray the affected parts of the plant with it. To the to successfully remove powdery mildew, you should repeat the application several times until the white film has disappeared.
What can I do to prevent powdery mildew?
The mushroom for the mildew and thus the white coating is responsible for spreading at humid, warm weather. On rainy days in spring and summer, make sure that the hydrangea is as sheltered as possible and does not get wet from the rain. Also at Pour you should make sure, especially in warm temperatures, that you water from below and that the leaves do not get wet.
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Other causes of white plaque
A white coating on hydrangeas can also be a infestation with Mealybugs act. If you look closely you can see the little hairy ones pests and can clearly distinguish them from powdery mildew.
