I have no idea about your climate, but where I live I could do it now with no problem if it's the only one it had for the year. If it were going to be the second one for the year I might just remove infected leaves and let it gain strength for the rest of the year.
Most people me included for many years had no idea about the importance of winter treatment of fungus for the new year. The fungus starts to set in around Dec. and is not seen till well into the late spring or early summer and the damage is done. Spray thru the fall and winter and enjoy a beautiful plant all year.
For the last two weeks we had temps every day straight at 107 or more. I am keeping lush THIN moss and super nice leaves all year due to keeping up on the spraying. I show this cause if anyone was going to have leaf scorch it would be me. I do not have it, and anyone that tries to keep a maple show ready thru summer knows it won't be done with moss all year. So far I am keeping that very well mostly due to the new soil and the monthly spray. You be the judge.
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