Posts Tagged ‘prunning’

Over pruning is one of the worst and most common mistakes in tree maintenance. Why is it so common? There is a general lack of understanding about how a tree functions or a lack of current information about tree health. Unfortunately, myths often guide tree pruning.

I want my grass to grow better. Can you really thin my tree?

I want to remove most of the lower limbs, to see my house better.

Myths to Avoid

• “Remove one-third of the top growth when transplanting to offset root loss”
• “Prune heavily to offset construction injury or soil compaction”
• “Prune heavily to help the turf grow”

Except in very rare circumstances, there is no valid reason to over prune a tree. The Tree Care Industry Association’s (TCIA) standards for tree care specify that no more than 20-30% of the foliage should be removed in any year. Over pruning has a detrimental effect on tree health, structural integrity, and aesthetic value.

Dangers of Over Pruning

1. Large or Profuse Cuts Lead to Decay - Any cut made on a tree is a wound that must be healed. The fewer cuts made the better. Smaller cuts throughout the tree’s life are better than large cuts that should have been made many years ago when the tree was small. One large poorly made cut or too many cuts in the wrong places can ruin a tree for life.
2. Reduced Food Production - The foliage is what actually produces food for the plant. Fertilizer is not tree food. It is absorbed through the roots and contributes elements that a tree’s foliage needs to produce food through photosynthesis. Removing a large amount of the foliage significantly reduces the tree’s ability to produce food. This creates an unhealthy and unbalanced condition in most instances. It actually stunts the growth of the tree in many cases. Food storage is reduced in any year the tree is over-pruned and the loss is compounded if over-pruning is done year after year.
3. Sunscald and Interior Sprouting - Any significant reduction in crown thickness will generally cause profuse interior sprouting and allow excessive sunlight penetration through the remaining canopy and onto the bark. If too much foliage is removed, it creates an imbalance in the roots to foliage ratio, so the tree reacts by using stored food to regrow its foliage. In proper pruning, the tree reacts by producing mostly tip growth. If improperly pruned, the tree reacts by producing mostly interior growth with very little tip growth. This is especially true with trees that have sunlight sensitive bark such as Red Oak. If a Red Oak’s bark is normally in a shaded area and it is suddenly exposed to full sun, the bark and cambium layer directly under the bark can burn along the length that is exposed to full sun (sunscald). This in turn creates other unhealthy conditions that affect health and longevity. Exposure to full sun can cause interior sprouting in an attempt to protect the bark! Sometimes it saves the bark and cambium from sunscald if the sprouts can grow quickly enough to shade the limb and if they are not constantly removed.
4. Increased Annual Maintenance Costs - Since over pruning creates excessive sprouting, constant pruning is required to maintain the aesthetic qualities of the tree. Constant pruning means a higher maintenance budget. Good pruning practices reduce the need for constant attention and reduce expenditures for tree maintenance.
5. Increased Risk of Wind Damage - Trees with high canopies encounter higher wind stresses, especially when raised beyond what would be considered a balanced height. The proper canopy to trunk ratio is 2/3 canopy to 1/3 trunk. If a tree is located close to a street, alley or walkway, the limbs must be maintained at an appropriate height. In these instances, there is no alternative. Excessive raising of low limbs increases the stress load on the trunk and roots. As long as both are strong, this may not be a problem, but if either the trunk or roots contain decayed, damaged, or weak areas, these problems could result in the trunk breaking or the tree falling over.
6. Reduced Limb Strength Leading to Breakage - In the same manner, individual limbs are subject to higher stresses if too much of its foliage and lateral growth have been removed. Trees that contain long limbs with foliage only on the tips will be more likely to break than limbs that contain many smaller, outward growing limbs and an even amount of foliage. The even amount of outward growth and foliage help distribute the stress load from high winds along the entire length of the limb instead of concentrating it at the tip.

In summary, over pruning causes:

• Excessive wounds that must be healed
• Reduced food storage
• Increased interior sprouting
• Decreased tip growth
• Increased end weight on limbs
• Increased chances of sunscald/sun injury
• Increased maintenance expense
• Increased chances of wind or ice damage
• AN UGLY TREE!

By: Steve Houser

In order to know how to properly prune any plant, a basic understanding of the characteristics and growth habit of the plant in our area is required. A Crepe Myrtle is not quite like any other local plant in how it grows, and is therefore not like others when considering how they can be pruned. A Crepe Myrtle is an ornamental plant that blooms profusely throughout most of the growing season. They can grow to over 25’ tall, are very hard wooded and the small twigs or old seed pods do not produce new growth in the spring (like most plants). Tip growth normally dies back approximately 7-12 inches in the winter months. If a Crepe Myrtle is not tip pruned by spring, the new growth will emerge approximately 7-12 inches from the old seed pods. This leaves dead tips as it emerges in the spring. Since Crepe Myrtles are rapid growers, the new growth will rapidly obscure the view of the dead tips within a few months. The dead tips are of no great consequence to the overall health of the plant. Aesthetically, the dead tip is not attractive for the first few months of the growing season. They are also known for producing root sprouts that grow upward from the outward growing roots or near the root collar (or root crown).

The three factors that must be considered in the pruning of Crepe Myrtles are health, aesthetics and cost or time to maintain the desired condition.

Crepe Myrtles are hardy plants that can sustain moderate freeze damage or severe reductions in size (even to the ground level) and in most cases, still grow back. Crepes that are planted north of our area can encounter freeze damage to the top growth, but are like an annual in that they can grow back from their roots. From a pure health prospective, they should be maintained in the same fashion as a shade tree by removing crossing limbs and canes (if practical), removing root sprouts, structural pruning, and basic deadwood removal. This type of pruning can be done anytime of the year and is the most beneficial to the long term health and longevity of the plant

From an aesthetic point of view, tip pruning of Crepes can be utilized to make them more attractive. Proper tip pruning should be accomplished in late January thru March, but not after the new shoots have emerged in the spring. Current research shows that tip pruning (or heavy pruning) at other times of the year, may increase the odds of freeze damage. Tip pruning should be to approximate pencil size twigs and in a rounded form. Some Crepes may end up columnar in shape, but in any event, the top growth should not be cut flat because it encourages all the blooms to be at one height. Severe cutting back is not attractive, reduces food storage, encourages poor branching structure and should be avoided. Since all Crepe Myrtles will have dead tips in the spring, removal of pencil size twigs avoids viewing the dead portion and is more aesthetically pleasing. The best show of flowers can be obtained by constantly removing the spent seed pods (dead heading) throughout the growing season, although it can be very time consuming.

The amount of time (or cost) required to achieve a positive effect is much less for small (or medium) size Crepe Myrtles. Large or tall Crepes can be structurally pruned as noted above, however, tip pruning can be very time consuming (or costly) and is not of much benefit to the overall health. Severely cutting back the trunks will reduce the amount of time (or cost) to maintain them, but it is not what is best for the plants structure or health.

In summary, if you are concerned about only health, prune it like a small shade tree. If you are concerned with the aesthetics, prune it like a small shade tree and also tip prune. If you really want show, prune the seed pods as they die. Each step beyond leaving them alone involves more time and cost. What is right for you depends on your personal preference, the characteristics of the plant, the site and of course, and the budget.