I have a crabapple tree that is at least 20 years old... this year I had a major attack of the scab disease... my leaves have gotten brownish to black spots and almost all the leaves and fruit have fallen off... I know I can't stop was has occurred but is there anything I can do now to prevent this from happening next year and if there is nothing I can do now, what should/when - I do next year to prevent this from reoccuring... thank you