Questions about pruning columnar apple tree
About 8 years ago I bought a columnar apple at the Garden Show in Seattle and planted in in our narrow side yard. It has wonderful apples (as long as I use the apple-maggot traps, and sometimes I put "footies" on the fruit).
The tree has a columnar shape with six very upright branches.
The problem is that it has grown to be very, very tall. Much taller than the 10' I was told to expect. All 6 branches extend about 18 feet up. We can't pick any of the fruit from the top half of the tree because we don't have a ladder than long and even if we did you couldn't get me to climb it.
So, I'd like to cut off each of the six branches at about 10 feet. Does this make sense, or will it result in the tree sending out dozens of little branches from that cutoff point?
Many thanks for any advice you can provide.