This bloomed white but instead of turning red it turned brown. This happened about 2 weeks ago. Another hydrangea behind this one is fully bloomed and has no brown. A fungicide was sprayed on it but that is the only chemicals. What is happening and what can be done?
The flowers browning and declining like this is most likely due to botrytis, a fungal disease. There may also be some scorch as well as some leaf spots on the foliage. Our very wet recent weather has favored the development of many fungal diseases this year, unfortunately. This is no remedy for this. Prune out and dispose of the damaged flower parts. https://extension.umd.edu/hgic/petal-blight-botrytis-shrubs
It can be common for hydrangeas to develop some leaf spots. This will not kill the plants. We also had some hot dry weather. Water during dry periods. No chemical control is recommended.