I have a 5yo Lapin that is approx. 10 feet tall. The top 2 feet of the central leader leafed out very meekly this spring and those leaf starts have now died back. Two short scaffold branches (both about 24 inches in length, 1 mid tree and the other 18 inches from the top of the leader)also did not bud out. The remaining 5 scaffold branches (most of which are double the length or more of the 2 which did not make it) look fine and have some fruit. The tree had an almost double leader look to it last year and I pruned this second "leader" off in February. Was this pruning the likely cause of the current tree distress? If not, any ideas as to cause? Should I be worried?