Oh boy, this is a handful! Everyone's situation is different. By that I mean, varieties are effected differently, as stated environmental factors such as rain effects trees differently from year to year, and site factors such as where hosts may be in relation to the trees that are effected by CAR will all be big variables. Also, what is your tolerance for it? Are these for deer or for your use? Is CAR effecting your trees so bad that you are getting poor fruit, no fruit, or just some leaf spotting?
If, and that is a big if, you need to spray, EBDC fungicides as mentioned above,( I'd recommend Vintage, Baylethon or Procure) are the most effective class of fungicides for CAR. They need to be applied at pink and 7-10 day intervals through 2nd cover. Strobilurin fungicides (Sovran, Flint) provide moderate protection. However, though I do have varieties such as Gala, Fuji, Idared, etc. that are susceptible, I do not have many hosts near by and I can get away with using Sovran which is part of my normal spray program. On a wet year I will throw down some Vintage or Procure which have good kickback coverage along w/ good protection.
My best advise is to figure out how bad it is in your orchard(s), decide what your tolerance is, work on environmental factors, such as cutting out Red ceder, and then if needed spray. Of course the first step would have been to plant disease resistant varieties in the first place, which I would love to see discussed more rather than talking about the umteen million varieties we have planted. For deer/ habitat managers your first choice for trees should be the many great disease resistant trees available today imo.
If you are going to spray you also may need a pesticide license to even purchase some of these fungicides in your state.
