This document printed from the University
of Illinois Extension Coles County Yard and Garden at http://www.extension.uiuc.edu/coles/
Proper Pruning Promotes Prosperous Trees and Shrubs
January 10, 2009
GOOD NEWS! You gardeners who have been chomping at the bit for Spring can get a taste of it on February 28 when University of Illinois Extension, Coles County Master Gardeners hosts its first-ever Spring into Gardening conference! It will take place at the beautiful new LifeSpan Center north of Sarah Bush Lincoln Health Center. You can read on the internet all the details about the sparkling speakers, delectable refreshments, delightful door prizes and silent auction items, all for only $15.00! You can register and pay in about one minute via credit card and you will receive an email confirmation.
Go to http://web.extension.uiuc.edu/coles/. It's a secure website through U of I. Or you can send a check to the Extension address listed at the end of this article. However, you will not receive a confirmation note. Registration deadline is February 20. However, space is limited so register early. You'll be glad you came!
Proper Pruning Promotes Prosperous Trees and Shrubs
We've all seen large trees that had the tops just whacked off in an ill-advised attempt to shorten them. Don't let this happen to your trees! Topping reduces the ability of a tree to produce food. Shock and long-term declining health resulting from topping can make a tree more susceptible to insect and disease problems and can lead to its eventual death. By removing the branches that protect a tree's crown, topping can lead to sun scalding of remaining branches, making the tree highly vulnerable to insect invasion and the spores and actions of decay fungi.
During the year after topping, numerous water sprouts shoot up like witches brooms. They are weakly attached and grow so rapidly that a tree can regain its original height in a short time with an even more dense and unwieldy crown.
Topping can reduce the value of a large ornamental tree by thousands of dollars. Although tree topping may cost less and take less time and knowledge than using the proper pruning technique, you would be paying for an inferior service which is harmful to your tree.
Pruning hardwood trees and shrubs without showy flowers in the dormant season is so much easier when the leaves are off, because you can visualize the structure of the tree. Dormant pruning also maximizes wound closure, reduces the chance of transmitting disease, and discourages excessive sap flow from wounds. Recent wounds and the chemical scents they emit can actually attract insects that spread tree disease.
In particular, wounded elm wood attracts barks beetles that harbor spores of the Dutch elm disease fungus, and open wounds on oaks attract beetles that spread the oak wilt fungus. Pruning these trees during the dormant season helps prevent spread of these fatal diseases.
Prune flowering trees and shrubs during the dormant season for the same reasons stated above; however, to preserve the current year's flower crop, prune according to the following schedule:
Prune trees and shrubs that flower in early spring (redbud, dogwood, lilac, etc.) immediately after flowering because flower buds form on last year's growth. If you prune during the winter, you'll be cutting off the flower buds!
Many flowering trees are susceptible to fireblight, a bacterial disease spread by pruning. Therefore, you should prune crabapple, hawthorn, pear, mountain ash, flowering quince and pyracantha during the dormant season.
Trees and shrubs that flower in the summer or fall always should be pruned during the dormant season. Flower buds will form on new twigs during the next growing season.
Conifers may be pruned any time of year, but pruning during the dormant season minimizes sap and resin flow from cut branches. Prune dead branches any time of the year.
Does it make a difference where to make the cut? YES! When you prune back to the trunk or a larger limb, look for the swollen area at the branch base (aka the branch collar). Look for wrinkles in the bark and cut just outside the wrinkles. This will promote quick healing. Do not leave a protruding stub or cut flush with the tree.
In most instances, wound dressings are unnecessary, and may even be detrimental. Wound dressings will not stop decay or cure infectious diseases. They may actually interfere with the protective benefits of tree gums and resins, and prevent wound surfaces from closing as quickly as they might under natural conditions. The only benefit of wound dressings is to prevent introduction of pathogens in the specific cases of Dutch elm disease and oak wilt when the trees are pruned during the active growing season.
Narrow branch angles signal a point of future weakness. The reason is that as the two branches grow, neither has sufficient space to add the wood needed for strength. Instead, they grow against each other. The effect is similar to hammering in a wedge.
To prevent this and the expensive problems that are sure to follow, simply remove one of the two branches. For strength, the ideal branching angle approximates 10 or 2 o'clock. Lateral branches should be no more than 1/2 to 3/4 the diameter of the trunk. As the trunk grows it will strengthen the joint by adding wood around the branch — like a dowel in a chair leg.
Cut away rubbing branches to prevent wounds, decay and notches.
Watersprouts and suckers are "parasite" sprouts which occur at the base or inside the crown. They are rapidly growing, weakly attached, upright, and lead to poor, shrubby form if allowed to grow. It is best to remove them as soon as possible.
When a crown is too dense, look for limbs that turn inward, and those that extend beyond the "natural" outline of the crown. Prune back to the trunk or to an appropriate lateral branch. Over-pruning can damage or even kill your tree. Always maintain at least 3/4 of the crown.
Most trees benefit from thinning — removing a portion of the limbs that compete for space and light. Evenly spaced laterals, 8-12 inches apart in the young tree, is a good rule of thumb to help assure an ideal "ladder" at maturity.
Try to imagine what the tree will look like when it is larger. If a limb is headed toward trouble (the house, walkway, sign, etc.), remove as early as possible in the life of the tree. The wound will close more completely when the limb is small, and it is less trouble and expense. Remember, limbs do not move upward as a tree grows in height.
Just like children – If you manage trees' growth habits when they are young, they will grow into strong, well-mannered adults.
REMEMBER to mark your calendar for Saturday morning February 28! It's the U of I Extension, Coles County Master Gardeners First Annual Spring into Gardening Event. And you'll get a chance to experience the beautiful new LifeSpan Center north of SBLHC. Register online at: http://web.extension.uiuc.edu/coles/
