This looks like Hydrangea Chlorotic Mottle Virus but that virus only affects  Hydrangea macrophylla , which your Annabelle are not. So I am stumped. I reassigned this question to someone more knowledgeable in hydrangeas.

I also want to know how to treat them. Thank you.

Hi Kathy,

I'm not certain what's going on here. It looks like some kind of virus, which can be spread by insects and contaminated tools. Do you have any other plants that are affected, or is just these hydrangeas?

I'd consider that the most likely explanation. Viruses cannot be treated. Here's a page on the possibilities:

https://www.purduelandscapereport.org/article/viruses-of-hydrangea/

https://www.gardenia.net/disease/mosaic-viruses

I am going to send a photo to a specialist and get back to you. Thanks.

I’m sending a picture of the Limelight hydrangea that’s next to the Annabelles which I think is showing the same signs. The other picture is of the bird feeding station above the hydrangeas. The hanging baskets have lemon sedum in them. This is the first year for lemon sedum. In past years I have always had moss roses in the hanging baskets. I also sprinkle Preen under the bird feeders which I’ve been doing in the past too. I hope this extra info might help. Thank you.

Hi Kathy,

I consulted with a master gardener who works at the University of Minnesota Plant Disease Clinic, sending her your photos. While the cause cannot be absolutely determined without tests, she’s pretty sure this is hydrangea chlorotic mottle virus. She showed it to one of the experts in the lab and he agreed.

This virus is spread by insects and can’t be treated. If the plants are left in place insects may keep spreading the virus to uninfected hydrangeas.

Here’s part of her email:

“Bringing a few small cuttings of symptomatic leaves and stems to the PDC could do ELISA @ $110. Electron microscopy (TEM) to actually see the virus would cost $300.HCMV Is insect transmitted so the shrubs pose a threat to other HTDRANGEAS. They are all susceptible but macrophylla is the most. When positive for virus, the plants should be removed and destroyed. Not composted. For the cost of testing.....new shrubs could be purchased.”

Sorry for the bad news. The best thing to do would be to remove the plants and burn them.

If you choose to test the plants, here’s the clinic website:

https://pdc.umn.edu/

Good luck.

Thank you for your expertise. I’m wondering if this virus would infect/affect other plants in my yard. I hope not! What about the soil; is it infected too? If I remove the infected hydrangeas and plant new hydrangeas, will they survive?

This virus ONLY affects hydrangeas. If you have other hydrangeas, sterilize your pruners and any other tools like shovels that were used on and around the infected plants. Lysol Household Cleaner sprayed or swabbed on tools will do the trick. A 10 percent bleach-water mix also works. Here’s more information:

https://extension.umn.edu/planting-and-growing-guides/clean-and-disinfect-gardening-tools

This virus is spread by aphids as well as contaminated tools. My contact at the Plant Disease Clinic said she would not risk infecting new hydrangeas by replanting in the same spot. Even the smallest root left behind or any contaminated debris could spread the virus to new hydrangeas.

I’m sorry. A couple years ago I had to remove some much-loved peonies because of a similar virus and it was really sad. But it’s the safest thing to do.

Good luck.

Thank you again. Now I’m wondering what to plant in that area after I remove the hydrangeas. Any suggestions? Something similar in height.

Here's some suggestions.

https://mnhardy.umn.edu/shrubs

https://extension.umn.edu/lawns-and-landscapes/trees-and-shrubs-pollinators

https://www.dnr.state.mn.us/treecare/righttree-shrub.html

Thank you.