Apple scab, Fungicide treatments regulary starting when leaves are 3/4 out. You may be able to protect some new growth this year, but it probibly would not do much good.
It'l live trough it, more an aesthetic problem then anything else.
Best to have a licensed contractor do it, probibly under $40/app if you were in MKE, WI. they get sprayed 3-4 times a year here.
I use a mix of banner max and generic 3336. Seen real good results with Eagle, but it is hot on barberry. Eagle wont control anthracnose either so I dont use it currently.
If you use pesticides, read the label.
For it is the law.