I have a hydrangea in a pot (2 year). Over night this week it developed white lacy looking marks all round the upper edge of every single leaf .other hydrangeas in close proximity do not have this problem. Can you help !
Hard to say from just a description but it could be scale (insects) or mildew (a fungal disease). Here’s a link to an article that you may find helpful:
https://homeguides.sfgate.com/white-speckled-fungus-hydrangeas-34056.html