I have a tree in my front yard that is in dire need to be trimmed. I was told by someone that came to spray my ash tree that it was a kind of crab apple and could only be trimmed during certain times of the year or it would develop some kind of I don't know infection that would cost an arm and leg to get rid of. Need help figuring out when I can and can't trim it. Thanks to any and all input. If needed I can take some pics of tree