Oakleaf Hydrangea leaf rust spots and holes

Asked May 26, 2020, 8:47 PM EDT

Hi - our oakleaf hydrangea was planted fall 2019. This spring there appeared dark reddish brown spots on the leaves which then disintegrate making holes in the leaves. It is in a northern space, but does get some afternoon/evening sun (pics taken 5/25 7pm). Soil does hold some water. Other than the spots, the plants seems to be thriving in it's location, growing very fast and producing many leaves. I have never owned one, so I don't know if the white fuzziness of the leaves is normal. Stems and branches appear healthy. What is the likely cause of the spots and is this something I can fix? I did find 1 green inchworm, but have not seen any other evidence of insects, larvae, eggs, etc. Thank you for your help, much appreciated.

Baltimore County Maryland

1 Response

The hydrangea looks pretty good. It is normal for the young foliage to be fuzzy.

The spots on the leaves are a symptom of cercospora, a fungal disease. This fungal disease is becoming more common on hydrangeas and different cultivars vary in their susceptibility. Fungicides are not recommended as you would have to spray all season. The leaves do not look bad. Avoid overhead watering and remove heavily spotted foliage during the growing season. If all leaves are affected this is not practical. Simply remove any fallen leaves from around the base of the shrub at the end of the growing season. These sanitation practices will help to manage the disease from year to year. https://www.uaex.edu/publications/pdf/FSA-7570.pdf