difficult plum tree pruning job
Portland, Oregon, February, 2016. I have volunteered to help prune a plum tree which has not had maintenance in years. It bears well. The issue is that what was a leader above what I will call the "lower canopy" of scaffolded branches has become a trunk. This upper leader/trunk rises to a newer "higher canopy" perhaps 6-8 feet above. This upper section now bears at least half of the fruit each year. May I remove this upper trunk--around 6 inches in diameter--or will removing this (and the upper "canopy") risk the tree at this point? With it gone the original "lower" tree will be easier to maintain. All advice appreciated.
Multnomah County Oregon
You are correct to concerned about removing major limbs from your plum tree; every pruning cut is a wound to the tree, and removal of major branches can open the tree to major damage via infection, and decay.
It is, unfortunately, extremely difficult to give valid advice about the site-specific pruning needs of a particular tree without a chance to view the plant from several angles, at least via photos. Our suggestion would be to send a handful of sell phone photos by email to the Multnomah County Master Gardener Phone Clinic, and ask them to respond either by email or by phone. They will review your photos and get back to you with specific suggests on on the same working day that you contact them. Their email address is email@example.com; their phone number is 503 445-4608, and they are available weekdays from 10 to 2.