I grafted some apple trees this past spring and have had some difficulties. (basketballs,constant rain, etc) I have also had trouble with new growth getting attacked by some type of fungus or something, and part or all of the leaf turning brown and dying. It starts with really tiny red dots, or sometimes they are more brown. This happens to new growth as it comes out. More established leaves resist it. I assume this is nothing rare for you more experienced guys.

So what should I get and what are the cautions in using it?