Hi Bart99. How long has it been since you worked the roots? I don't let them go more than three years or so. They can get out of control.
Thanks for all the replies!!
The tress were in the ground for at least 3 or 4 years. I did a very rough (and major) pruning on the tops last year about this time and hacked away at the roots to get them out of the ground. They spend the last year in pots. So I'd guess you could say that I've never really worked the roots, but
something has happened to them in the last year!
I think my plan going forward is to do a horizontal chop 4 to 6 inches from the soil line, work the roots to eliminate big and twisted (in the wrong direction) ones, and then screw the base of the tree on to a cedar shingle and plant them back out in the garden for at least a year before taking any more action.
Does that make sense?
Also, when I do the horizontal chop, should I just leave the cut surface flat, or nip away at it like you did above?
Thanks again to all, for all the help!