If the forks look prone to splitting, a light thinning near the ends is in order. That would at the same time reduce owner's fear of size, and arborist's concern of failure from defect. Picture #4 looks like a bad fork form here. Job looks like 1 hour's worth of light thinning/reduction; should be a worthwhile investment for owner.
Tie in 2/3 of the way up and use a pole pruner; easy enough if you know how to preserve the shape of the tree. mikey, your #5 is my #1; totally within ANSI standards, see 5.3.3, 5.6.2 and especially 5.6.4.1 Reduction, and very different from topping.
Yes justify every cut; lessening stress on a defect is justifiable. yes work proactively, lack of damage is no reason to do nothing. Please don't take my word for it; here's Gilman from:
http://hort.ifas.ufl.edu/woody/pruning/ Reducing the canopy
Objectives: There can be several objectives of reduction pruning 1) reduce tree size; 2) reduce a portion of the tree to provide clearance from a structure; 3) reduce a portion of the canopy to **minimize risk of failure.
Properly done, this provides a more pleasing, unpruned natural look to the tree compared to topping. **Many people would not know a canopy was reduced in size following appropriate moderate canopy reduction.
Introduction: Trees sometimes grow larger than desired for aesthetic or safety considerations. These trees may interfere with overhead utility wires, grow into buildings or other trees, or become hazardous because of their size, length, or condition. **Reduction pruning is used to reduce the size of a tree by decreasing the length of one or many stems and branches.
Reduction pruning performed after the tree has become too large could require the removal of large diameter stems. The resulting wounds can be accompanied by decay, cracks, and sprout development. Therefore, **it is preferable to perform reduction before the tree has become too large for its environment. Proper reduction pruning reduces size while more-or-less maintaining a tree's form and minimizes regrowth.
Execution: Sometimes the entire canopy of a tree must be reduced in height or spread, such as for utility line clearance or to **minimize risk of failure. Portions of the canopy, such as ***individual limbs, can be reduced in order to balance the canopy or to reduce likelihood of breakage on limbs with defects such as cracks and included bark or those that have grown to become too long.***
Reduction is best accomplished by cutting limbs back to their point of origin or back to a lateral branch capable of sustaining the remaining limb and assuming apical dominance of the limb. When a branch is cut back to a lateral, no more than one-fourth of its foliage should be removed. A common rule of thumb is that the remaining lateral branch must be at least one-third the diameter of the removed portion, but **this rule can vary with species, age, climate, and the condition of the tree. Consideration must also be given to the ability of the species to sustain this type of pruning. Species that are known to decay quickly from these types of cuts should be reduction pruned more conservatively than more decay resistant species.
Bodean, post a pic of a twig and a leaf if you still don't know what it is.
Mike and Brian, perhaps you want to tell Dr. Gilman why he is wrong. I know firsthand that he is open to input from arborists in the field if they have something useful to say.
