Hello!

Your hydrangeas have bacterial leaf spot.

looks like you are doing all the right steps to control.  My only question is how are you watering the plants?  By avoiding watering the leaves will help greatly.  Our heavy rains wont help. 

Here is a detail for treatment;

Here are some tips for treating bacterial leaf spot on hydrangeas:

• Remove infected parts: Cut out and destroy any infected leaves, stems, or other plant material.
• Apply fungicide: Spray new leaves, stems, and limbs with a fungicide that contains chlorothalonil, mancozeb, or thiophanate-methyl every 10–14 days, starting before the first signs of leaf spots. This can help prevent the disease from spreading to new leaves, but it won't fix damaged areas.
• Isolate the plant: Keep the infected plant away from other plants for a while.
• Avoid overhead watering: Water the plant at the base or use drip irrigation to reduce the risk of spreading the disease.
• Improve air circulation: This can help reduce humidity and moisture levels

Also, here is a link for specifics on bacterial leaf spot;
https://www.uaex.uada.edu/publications/pdf/FSA-7570.pdf

I hope this helps!

Thank you for contacting us and let me know if you have any other questions.  Good luck!

Can I apply the fungicide while the hydrangeas have blooms?  To date, I have stopped applying it once the blooms start to appear and don’t spray again until blooming is over. I always water at the base—never the foliage. Just can’t seem to get ahead of this.

Hello again,

Yes, you can apply the fungicide while the plant is blooming.  We normally suggest you follow the manufactures recommendations.  

Also, by using the fungicide, not watering leaves, mulch, improve the air circulation and remove any infected leaves you should see an improvement next year.  Note, it is not uncommon with wet, cool springs and then hot summers to have bacterial leaf spot.  With our weather it may be hard to completely avoid.

Good luck!