Here's another picture...

brewcider:

From your photos it seems the trees are really close so I assume they are on some extremely dwarfing rootstock?

I see you still have the sales tags on the trees. Were these recently purchased and planted? Were they container
grown trees?

If they were purchased in containers, were they leafed out better when you bought them? I have to wonder if they were
potbound and thus your problem is a root issue? Where I work (at a large nursery) I deal with BB and caontainer plants all the time. Plants held too long in a container
can really develop circling roots. Just a thought as this may not be your problem.

I agree with SA. Probably a root problem if the trees are newly planted. I've had the same thing happen on new plantings until the roots catch up with the top growth. To avoid some of that, I'll prune new trees that have limited roots to get them in balance.

Thanks for your replies! I believe you both are correct about root problems. The trees have been in the ground for 3 years, but they've been in less than ideal conditions. They didn't have any mulch till a couple months ago. They also had only a couple drippers (2 hours with 2 1-gallon drippers, or 4 gallons per tree) on them that were close to the trunk and they got frequent shallow waterings. My soil is like concrete when it's dry. So I think the roots couldn't grow outwards. Now I have 4 drippers that circle around further from the trunk and I'm giving them deep waterings (4 hours with 4 1-gallon drippers, so 16 gallons per tree each time I water). I also added 6 inches of mulch and I also wet the entire area with the garden hose to get some activity going. I can chop off the top half of the trees if that's what you suggest.