Pruning The Tree
Reasons For Pruning
The main reasons for pruning ornamental and shade trees include safety, health, and aesthetics. In addition, pruning can be used to stimulate fruit production and increase the value of timber. Pruning for safety involves removing branches that could fall and cause injury or property damage, trimming branches that interfere with lines of sight on streets or driveways, and removing branches that grow in to utility lines. Safety pruning can be largely avoided by carefully choosing species that won’t grow beyond the space available to them, and have strength and form characteristics that are suited to the site.
Pruning for health involves removing diseased or insect-infested wood, thinning the crown to increase airflow and reduce some pest problems, and removing crossing and rubbing branches. Pruning can best be used to encourage trees to develop a strong structure and reduce the likelihood of damage during severe weather. Removing broken or damaged limbs encourages wound closure.
Trees have plenty of forms, but the most common types are pyramidal (excurrent) or spherical (decurrent ). Trees with pyramidal crowns, e.g., most conifers, have a strong central stem and lateral branches that are more or less horizontal and do not compete with the central stem for dominance. Trees with spherical crowns, e.g., most hardwoods, have plenty of lateral branches that may compete for dominance.
Pruning for aesthetics involves enhancing the natural form and character of trees or stimulating flower production. Pruning for form can be especially important on open-grown trees that do very little self-pruning.
All woody plants shed branches in response to shading and competition. Branches that do not produce carbohydrates from photosynthesis to sustain themselves die and are finally shed; the resulting wounds are sealed by woundwood (callus). Branches that are poorly attached may be broken off by wind and accumulation of snow and ice. Branches removed by such natural forces often result in large, ragged wounds that seldom seal. Pruning as a cultural practice can be used to supplement or replace these natural processes and increase the strength and longevity of plants.
Pollarding and topiary are extreme examples of pruning to develop a desired, unnatural effect. Pollarding is the practice of pruning trees annually to remove all new growth. The following year, a profusion of new branches is produced at the ends of the branches. Topiary involves pruning trees and shrubs in to geometric or animal shapes. Both pollarding and topiary are specialized applications that involve pruning to adapt the natural form of trees. As topiary demonstrates, given care and attention, plants can be pruned in to any form. Yet just as proper pruning can enhance the form or character of plants, improper pruning can destroy it.
To reduce the time you spend pruning it is best to consider a tree’s natural form. it is very difficult to impose an unnatural form on a tree without a commitment to constant maintenance.