by Thomas Fryd
Since most trees may be pruned satisfactorily at any month during the year, the time selected can be governed by practical consideration. Maples, walnuts and birches, which bleed from pruning cuts made during late winter or early spring, should be pruned when in full leaf. Pruning and the subsequent treatment of wounds are probably the most important practices in proper maintenance of trees. August is a good month for pruning shade and ornamental trees. In Mid America our trees at this season usually have their “tongues hanging out” and welcome the loss of some foliage as a means of conserving their moisture supply. Weakened and dead branches are easily detected at this season.
Wounds do not heal as rapidly in the fall as they do in the spring but some new cambium growth is produced before cold weather sets in. Fall pruning permits prompt removal of branches which have died during the summer or been broken by wind. These branches are potential hazards during winter ice and wind storms. Dead wood should be removed as soon as possible because it is unsightly, hazardous and serves as a host for insect pests and fungus diseases.
Dead wood in trees is probably a result of one of the following conditions: a deficient or over supply of moisture; lack of adequate or suitable plant food: mechanical damage to the roots resulting from digging operations: poisonous elements in the atmosphere or soil; insufficient aeration of the roots because of changes in the grade; a very dense crown; mechanical, fire or storm injury to trunk or branches; self-girdling, roots: or attack by insects and diseases.
Trimming Pointers
Pin oaks and hard maples are usually more attractive as lawn specimens if not trimmed too high, but it is nice to have the low- branches high enough to allow the lawn mower operator to pass beneath without having his hat knocked off, especially if you happen to be the operator.
White birch as a specimen should be allowed to grow naturally with its branches down to the ground. Small flowering trees such as red bud, dogwood, crab apples and hawthorns are usually best trimmed to a single trunk, permitting the development of a well-rounded crown.
Some thinning out of branches is usually good practice in order to permit better air circulation and give the lawn a chance to see the sun at least part of the time. It is frequently necessary to remove a branch here and there to give better balance to the shape of the tree. This often means removal of branches on the north side of trees, which is usually the heaviest side. This is because when trees are growing most rapidly our prevailing winds are generally southerly.
Besides thinning out branches, cut back long straggly branches to prevent possible breakage due to excessive weight.
Suckers on the main trunks of ornamental trees should be removed each season. When it has been necessary to cut back a tree severely the suckers which appear on the branches should be allowed to remain in order to prevent sun scalding of the bark. This is particularly true in the case of thin-barked trees such as hard maples.
Tree Cavities
Tree wounds usually callus over more quickly when no dressing is applied, but since rapid healing is less important than preventing possible entry of wood-destroying fungi into the scar, it is best to use a tree wound dressing.
Conifers such as pines and spruces are not so apt to be attacked by wood-destroying fungi as our common deciduous trees. After removing one of their branches, simply smear the scar with the exuding resins, which will usually prevent decay.
Shade tree “dental work,” the removal of decay and the filling of the cavity, is the most sensational operation of the arborist. Not all of the type of work done in the past has been justified and although methods are much improved today. Cavity filling is still not a cure-all for tree pains.
When wood-rotting plant fungi have entered a valuable tree through a break in the bark, the usual plant fungus treatment of excavating the discolored wood and filling the cavity with some permanent material is to be recommended. Since this type of work is usually expensive because of the time required, it is not advisable to spend money for surgery on weak or on inferior trees such as poplar, ailanthus, box elder and black locust.
Cavity filling in trees as well as proper pruning is a scientific operation and should be entrusted only to reliable arborists.
About the Author:
Various methods have been published on
plant fungus treatment. Most of these methods can be found on our evergrowing library at http://www.plant-care.com/lawn-fungus-identification-and-treatment.html.
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Gardening
