Pruning of fruit trees is important to develop and maintain productive wood that in turn produces high quality fruit. It is usually best to do light to moderate pruning each year rather than do more severe pruning at several year intervals. Pruning can be very confusing and intimidating. There are no specific instructions that describe precisely the pruning process that will be applicable for all fruit trees and all circumstances. Further, even the most accomplished pruners probably would not agree on all the details of pruning an individual tree. I hope to give you some suggestions that will aid you in selecting the proper wood to remove, thus allowing you to prune fruit trees properly with the minimum amount of anxiety.
When is the best time to prune a tree?
There are many times during the year when trees can be pruned. Perhaps the best time, and the time when most trees are pruned, is late winter or early spring. March is an ideal month for several reasons. The chance of winter injury has substantially diminished because the likelihood of receiving extremely low temperatures has passed. It is easy to see the tree structure so that you can see where the appropriate cuts should be made. Finally, leaves and buds have not swollen so they will not be damaged by falling limbs and tree prunings.
Make clean flush cuts that are close to the parent limb. These will heal and callus over. Avoid making cuts where a limb stub is left. These will not heal and they may serve as an entryway for disease. Cuts can be made with either a sharp saw or a pair of lopping shears. Avoid making many small cuts into the shoots that grew last year. If this is done, productivity will be reduced and undesirable branching will result.
Types of Pruning Cuts to Make and Limbs to Remove
- Remove broken or diseased branches. Make clean flush cuts.
- Remove branches that form a sharp angle with the trunk. These are structurally weak and most likely will eventually break.
- Leave branches that are primarily horizontal to about a 45° above the horizontal. Prune out branches that are growing substantially below the horizontal (downward-growing). This wood is weak and the fruit that grow on these will be of low quality.
- Prune out branches in the top of the tree if they become too large and start to shade lower branches.
- Remove all upright shoots (suckers). They are fast growing shoots that will never be productive. Upon occasion, it may be appropriate to leave a sucker or watersprout to replace a major branch. If one of the lowest limbs is weak because of shading, it can be removed. The sucker or water sprout near it can then be bent down to replace it. It must be bent down to a 45° to 60° angle to the vertical to become a useful branch. The bending can be accomplished with string to pull the branch down or by using a limb spreader (a piece of wood with sharpened nails in either end).
- Prune to control tree height and spread. Frequently, trees grow over time and exceed the space allocated to them or they just grow too large for convenient spraying, harvesting, and care. In these cases, containment pruning is appropriate. If a large amount of pruning is required, it should be done over a 2 or 3 year period. It is much easier to cut back lower limbs to restrict spread because they are inherently weak and regrowth is less vigorous. Lowering tree height is more difficult, not only because of the position of limbs in the tree but also because excessive vigor may be stimulated in the tops of trees if too many branches are removed. Try to select a weak side branch that is growing at a 90° angle to the trunk.
- Improve light penetration into the tree. Light is essential for flower bud formation, fruit set, and maturation of high quality fruit. Over time, the interior of a tree can become so shaded that it is no longer productive. Removal of some limbs, especially in the tops of trees, is necessary to allow for adequate light penetration.
- Prune to stimulate growth. There are occasions where the growth on a tree has become weak because of over cropping. In situations like this, it is appropriate to prune more vigorously to encourage vegetative growth. In this situation, one should remove the hanging wood and leave branches that form a 60° angle to the horizontal.
- Remove root suckers at the base of the tree.
Modest annual pruning of apple trees is an important component in having a good and healthy apple tree. If you have fruit trees that need pruning, take the opportunity in March to get them off to a good start.