what are these blotches and how to combat?

Newbury Park, CA

These blotches recently started appearing. Some are purple and others are brown, as you can see in the photos. Does anyone know what they are and how to combat them? Will a copper fungicide work?

Thumbnail by mwtzzz Thumbnail by mwtzzz Thumbnail by mwtzzz Thumbnail by mwtzzz
Castro Valley, CA

You really cannot catch a break with these!

Most spots on leaves are fungal. Best way to avoid is to discard all infected leaves. Clean up all fallen leaves from ground. Never wet the leaves if late in day when leaves will remain wet for long periods of time.

I wonder if what you have is "Cercospora Leaf Spot (also known as Cercospora hydrangea)". I enlarged your photos and the spots look lavender similar to the spots in the 1st photo in this article.
https://plantaddicts.com/common-problems-with-hydrangea-leaves/

Another
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/spots-on-hydrangea-leaves.htm

Newbury Park, CA

no, I can't catch a break. Your article says it's common for new leaves in the Spring to not have the problem, which is exactly what happened with mine, they started out beautiful and healthy. Then as the season progresses they start getting the spots.

I'll apply a chlorothalonil based fungicide in addition to removing affected leaves and see if that helps.

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