Healthy trees are an asset. They provide cooling shade, a habitat for birds and can increase the value of your property. There are some very good things you can do to promote healthy, long‑lived trees - And there are a number of things you will want to avoid – So here is a brief description of Arboriculture distilled down to the very basic good and bad. We will start with the bad.
Bad For Trees
Topping and stubbing are examples of removing large branches from mature trees. A topped tree is a disfigured tree and although topping may have been intended to help the tree, the opposite is the result. Topping trees creates a severe energy deficit by removing the leaf surface area and by creating numerous large wounds that require energy for compartmentalization. In addition to disfiguring the crown, topping is a common stress factor that can predispose mature trees to dieback and decline. If trees survive topping, they will develop multiple branches or suckers, at or near the pruning cut. These branches generally are weakly attached and are prone to failure. The location of the topping cuts may also prevent the tree's natural defense system from doing its job. Finally, topping trees represents an unwarranted expense. A topped tree will often grow back to its original height quickly, and it will be denser than one that has been pruned correctly. In the end, you are left with a bigger problem than if you just left the tree alone.
Lawn mowers and string trimmers hitting the bark of the tree can severely damage the inner bark and cambium near the soil line. This damage invites insects and fungi infestation as well as disruption of the flow of water, nutrients and vital elements. The best advice is to remove sod from around the base of the tree and replace with mulch.
Water and air, the two basic needs for strong, healthy roots do not easily penetrate compacted soil. Soil compaction can be caused by heavy equipment used near a tree, concrete over the root zone; even foot traffic can cause soil compaction. Do not store items by the tree.
Take Care with New Plantings
Do not plant a new tree with a wire basket, rope, or anything that may constrict or "girdle" the roots. Girdled roots seriously affect the health and the stability of a tree. Plan where you want to plant a new tree based on its type and mature size. Be cautious when planting trees near a home foundation, patio, driveway, under power lines, or under a home's eaves.
Excessive Soil and Mulch
Too much fill over a newly planted tree's roots can cause damage, and may even kill some species. Take care not to plant a tree too deep in the ground.
Good For Trees
Pruning/Thinning – Properly!
Pruning is needed to remove dead, diseased, injured, broken, rubbing and crowded limbs. No more than twenty percent of the live crown should be removed during any single operation. Selective thinning of the crown should be concentrated on branch ends. Thinning the outer portion of the crown will improve light and air penetration and reduces the weight of that portion of the branch which is most prone to breakage. Many arborists incorrectly thin trees by stripping interior portions of the crown. This technique is bad because it promotes growth at branch ends and reduces branch taper, which actually increases the frequency of limb failure during storms. To thin properly, make sure at least one third of the branches should are left on the lower fifty per cent of a leader in order to encourage taper and reduce risk of breakage.
When to Prune
Tree pruning to remove hazardous limbs or dead and diseased branches can be done at any time. Light pruning can usually be done at any time. Large cuts are best made in late winter or early spring. Correct pruning is more important than timing. Some species, such as White Birch, Ash and Elm, should be pruned during the dormant season only.
The most beneficial time to water trees is in the early morning. Water slowly or use drip irrigation until the water has been moistened down to the roots. Do not allow water to puddle - This is wasteful and can be detrimental to root growth and function. Trees demand one inch of irrigation water per week during the growing season when rainfall does not occur. This is equivalent to 700 gallons of water per thousand square feet of root zone.
Tree Nutrition and Fertilizing
Trees require certain essential elements to function and grow. Fertilizing a tree can increase growth, reduce susceptibility to certain diseases and pests, and can help reverse declining health. Specific fertilization specifications should be based on soil analysis
There you go - all the basics, in a nutshell...