Pruning - Types of Pruning Cuts
There are two types of pruning cuts, thinning and heading. Thinning is the removal of the entire branch or limb at its base. Thinning cuts are employed to remove an entire limb or branch where crowding occurs. Heading is cutting back a portion of a branch to just above a healthy bud or side branch. Heading cuts are useful for shortening branches or to redirect their growth.
Pruning decisions can be made easier by understanding how the tree or branch responds to a particular pruning cut. This will depend on the age of the individual branch being pruned and on the severity of the pruning cut.
The youngest growth, located at the end of each branch, is simply a shoot with undeveloped buds. These buds will grow into additional spurs or shoots in the coming growing season. Spurs are simply short shoots that stop growing soon after bloom. A heading cut in new shoots stimulates the remaining buds to grow into long, leafy shoots rather than spurs. If left unpruned, these buds develop into spurs that bear flower buds. Spurs and short shoots are more likely bear flower buds in contrast to long or vigorous shoots which typically develop only leaf buds.
The current season shoots are connected to one-year-old sections, and one-year-old sections are connected to two-year-old and older sections. Because they already have laterally developed spurs and short shoots, a heading cut into the one-year-old and older sections does not stimulate the growth of new shoots. Instead, it invigorates existing spurs and shoots in close proximity to the pruning cut. This type of pruning is done to shorten branches. A severe heading cut in the oldest section of the branch can be overly invigorating, and it may be better to remove the entire branch with a thinning cut.
When removing a large limb, a three-step process of removal will guard against bark tearing, which is a wound that is not likely to heal. First, make an undercut halfway into the branch, about one foot out from the base of the limb. Second, cut downward into the branch at a point one inch out from from the first cut. Cut all the way through the limb. The weight of the branch will most likely cause it to separate from the tree while the cut is being made. The remaining 12″ stub can then be removed without damaging the bark. Make this final cut at a point just outside the bark ridge or branch collar to promote healing. The collar is the ring of ridges that encircle the base of the branch. Cutting too deep into the collar inhibits healing of the wound. Avoid leaving stumps since this will encourage the growth of watersprouts. Watersprouts arise from latent buds in the stump and grow into vertically oriented shoots that are slow to bear flowers. Make clean cuts that are nearly flush with the adjacent branch to prevent watersprouts.
If a tree has only vigorous shoots and watersprouts, it is beneficial to keep a few since they eventually develop flower buds. Removing all shoots that do not conform to the ideal can lead to the removal of all potential fruit bearing branches.
Treating pruning cuts with a wood dressing or sealant is not necessary since it does not promote wound healing or prevent wood infection.