The best way to fix it is to glue the crack back together, then fiberglass the center section of your wing. You can use thin ca if the crack will seal up real tight, otherwise use thick ca or epoxy. All you need is a two or three inch wide strip of fiberglass all the way around the wing at the center joint. You can adhere the glass with thin ca, or expoxy thinned a bit with alcohol. I prefer the thinned expoxy. I am assuming the wing was not glassed in the middle. If it was, I'd re-glass it.