Trees are meant to grow in a natural environment where they thrive without any intervention. They are not adapted to live in commercial landscapes where the growing conditions are vastly different. Routine maintenance is the best way to acclimate trees to the less than ideal conditions of an urban or suburban landscape. However, the wrong kind of maintenance can result in permanent damage. Learn more about the most common tree care mistakes seen on commercial properties.
Pruning alters both the form and growth of the plant. When trees are pruned, less foliage is available to support growth and development. If executed incorrectly, removing even one large limb can be significant enough to permanently injure a tree. Improper cuts including topping can result in dead wood or branches that are prone to failure.
An understanding of how to properly execute pruning cuts is as important as knowing when and why. Care should be taken to minimize wound size and loss of live branches. Industry standards have specified that no more than 25% of the crown should be removed, but age and condition of the tree will also impact the extent of pruning recommended.
Planting Too Deep
Whether a tree was just planted this season or 20 years ago, if it has been planted too deep, it is likely to develop problems. Tree roots thrive in shallow soil where ample water, oxygen and warmth are available. Roots are deprived of these resources when they are buried too deeply and will struggle to grow. Sometimes, they will even begin to grow up and back toward the trunk, creating a girdling root. A girdling root will encircle part or all of the trunk, restricting movement of water and nutrients throughout the tree.
When planting, the tree’s root flare (where the tree widens at the base) should be level with or slightly above the soil surface. If the root flare is not visible on a tree that has already been planted, excavation of the soil around the base of the tree is recommended. Any girdling roots uncovered should be removed carefully to minimize injury to the trunk.
Too Much Mulch
Over-mulching has become so widespread that many people believe mulch piled high against the trunk is how it’s ‘supposed to look.’ In actuality, ‘volcano mulching’ is harmful to tree health. This practice keeps the bark moist. Bark is not able to tolerate continuous moisture and wet bark is subject to attack by fungi, insects and decay.
A 3-4” layer of organic mulch applied from just off the trunk to the outer dripline will help moderate soil temperatures and conserve moisture without injury to the tree. Wood chips are an excellent choice!
Damage from Equipment and Machinery
When lawnmowers or string trimmers bang, gouge or scrape a tree, the bark and underlying cambium layer can be irreversibly damaged. Mechanical damage to the cambium layer impacts the flow of water and nutrients throughout the tree, threatening virtually every vital tree process. The wounded area also serves as an entry point for wood-rotting organisms and decay fungi. Since turf receives regular maintenance, repeat damage is likely, which further compounds the problem.
A protective layer of mulch around trees and planting beds will not only create a healthier growing environment, but also serve as a visual reminder to keep equipment away. Since young trees are particularly vulnerable to mechanical damage, fencing, tree protection or guards around the trunk can be useful as long as they are properly maintained.
Over (or Under) Irrigation
When trees get too much or too little water, the ultimate result is reduced photosynthesis, which limits the ability to grow and thrive. Many commercial properties utilize irrigation systems, which are a great way to monitor the amount of water trees and shrubs receive. However, irrigation systems are often set on a schedule and never adjusted for weather or plant needs, causing more harm than good.
Whatever type of irrigation is used, the amount of water applied should match species requirements and prevailing weather conditions. Consideration should be given to landscape design so that species requiring more water are not in the same watering zone as those that don’t perform well in wet soils. If using overhead or sprinkler irrigation, be sure to direct water away from direct contact with the trunk and leaves as this can lead to disease and decline.