Question
My 2 yo columner apple tree has leaf wilt on at least 3 branches at the ends of the limbs about 8-10 inches down. they turn brown and fold down like closing an umbrella. I have flowers but no fruit.  What is causing this I see no visable insects or webs.

Answer
Patricia:
If the branch tips (woody portion) themselves are also dying and turning brown, this may be a disease called Fire Blight. Examine the twig closely and you might see where the brown portion meets the green (healthy) portion.  In your case, best to first find this transition area, then backup 6-10 inches into the green portion and snip out that dying branch with some pruners. Be sure to spray pruners with rubbing alcohol between each cut to sanitize the blades.  Collect all of the branches and burn them or bag up for garbage collection.

Also, if you have the opportunity, you can "Google" images of fire blight to compare.

Hope this helps
Steve