Question
Hi, I live just east of Phoenix Ariz. I have 3 fruitless Mulberry trees that are about 30 years old.  I've been trimming back the limbs for alot of years and now I've got these big clumps at the end of big branches.  I'm afraid the clumps are going to be to heavy for the branch, so I'm wondering if it would hurt the tree to cut those off. Every year that I've trimmed the tree it has really come back full and big.  

Answer
Bob,

I'm afraid that if you simply cut off the big clumps, you'd end up with two problems: 1) a large open wound that would be slow (years) to heal which would act as an entry point for some disease , and 2) regrowth of new shoots that might make the old clumps seem like the good ol' times.

So, my limited advice would be to add a pruning step for the next couple years. Do what you usually do since you can predict what the results are going to be, but then after there has been some regrowth, thin the shoots that are produced...remove up to a third of them.  This will keep the weight down.

Also on timing.  I don't know what the growing cycle of Mulberry trees in Phoenix is.  But if they lose their leaves in the fall (?), you should do your heavy pruning maybe a month before they lose their leaves.  The last  part of the deciduous tree growing cycle is used to store energy for next year's growth.  Pruning before that will limit the trees ability to send up new shoots.  It won't stop it, but it will slow it down.

For what it's worth,
Mark in Portland