Spots and dots on hydrangeas

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Have you noticed leaf spots on your hydrangeas this summer? It could be Cercospora, a fungus.
Have you noticed leaf spots on your hydrangeas this summer? It could be Cercospora, a fungus.
Contributed photo

This summer has been tough. Tough on people and tough on plants. We had record-breaking temperatures that lasted way too long, with way too little rain. One plant that really suffered includes our beloved hydrangeas.

I have received many emails and calls on hydrangeas with leaf spots. This leaf spot is called Cercospora, a fungus. It does affect all of the hydrangea species we grow here including smooth, panicle, oakleaf and bigleaf types. I see it more commonly on smooth and bigleaf types of hydrangeas.

The disease usually starts in July and lasts until October. But the good news is the disease is considered an aesthetic problem only. We do not recommend any fungicides to be sprayed. The best way to reduce the occurrence of this leaf spot is to plant hydrangeas in the correct location, which is shade or at least afternoon shade.

Reduce overhead watering, so if you water your hydrangeas try to limit the water to the base of the plant by using soaker or drip hoses. If you have overhead irrigation, try to water early in the morning so the foliage will dry quickly. Splashing water can also spread the disease. Humidity can also play a role in keeping leaves wet. Don’t we wish we had a cure for that!

This leaf spot disease tends to start on older foliage first and then spread up the plant. Removal of the older leaves can also help reduce the spread. Initial spots are purplish in color, and as the circular spots enlarge they can turn tan or gray in the center.

If you are in the market for a new hydrangea, select a cultivar that is less susceptible to this disease. A few of these include “Blue Bird” and “Forever Pink.”

This fall it is very important to rake up and remove all fallen leaves since the fungus can overwinter in our climate.

For more information on gardening contact the Wilson Extension master gardener volunteers on Wednesdays, 1-3 p.m., at 252-237-0113 or email them anytime at wilsonemgv@hotmail.com.