Pruning at its best highlighted at tree health clinic

By JULIET BRISKIN | Central Texas Edition

Agronomist Tim Uptmore demonstrates proper tree pruning techniques during the Tree Health Clinic at the Cameron Park Zoo on May 30. According to Uptmore the best time of year to prune trees is between Nov. and Feb. The colder temperatures during the winter lessen insect pressures on the trees and their wounds. -Staff photo by Briskin

June 6, 2002 -- One could not help but notice all the tree trimming going on back in March and April, but according to McLennan County Extension Agent Doug Andrews and agronomist Tim Uptmore the best time to trim trees is between November and February. During a tree health clinic at the Cameron Park Zoo in Waco on May 30, participants learned about proper pruning and shaping techniques, the best time to prune and why.

There are exceptions to the November/February rule, for example, it is best to trim oak trees during July and August because the intense heat of the summer is a deterrent to the nitidolid beetle. This beetle feeds on the fruiting body of the oak wilt fungus and carries it on to other trees. During July and August the beetle is at its lowest numbers therefore reducing the chances of spreading oak wilt.

Tim Uptmore, owner-operator of Brazos Landscapers, presented a pruning demonstration and provided the group with valuable information on the timing of and reasons for pruning trees. "The best time to prune is November through February," explained Uptmore. "At that time our insect pressures are at their lowest."

Uptmore explained that when a tree is pruned it has to kill the cells off from around the wound and heal. "If you prune in the dead heat of the summer and we haven't had rain in two months, you really stress that tree out," he said. "There are times when pruning needs to be done outside the November through February window. It is just not the optimal time."

Uptmore did point out that using the November to February window for pruning is just a guideline and that following the freeze dates is an even better method to use. "We have gone through the last couple of Novembers and haven't had a freeze yet," he explained. "It is better to follow the freeze date so we can be sure it is cold enough to hold back the insect pressure."

Sealing the wound after pruning will help prevent water loss and protect the wound from bugs that are searching for the tree's sweet sap. "When I seal a wound I just like to use good old aerosol paint," he said. "You can go with the products that are made for sealing wounds, but I have found them to be difficult to work with and have a tendency to clog up."

After pruning a limb off it takes about two weeks for the tree to shut off the old cells and for water loss to minimize. "If it is the heat of the summer it is going to take a bit longer," said Uptmore. "Sealing in this situation is necessary; more so than in the winter."

Doug Andrews, McLennan Co. Extension Agent, talks with participants at the Tree Health Clinic at Waco's Cameron Park Zoo during a tour. The zoo features many different varieties of trees both native and non-native to Central Texas. -Staff photo by Briskin

According to Uptmore when pruning a homeowner does not want to prune too far in towards the trunk or too far out away from the trunk. "You could loose a lot of trunk if you prune too far in and seriously damage the tree," he explained. "If you prune too far out you can create a lot of maintenance for yourself when the tree starts budding at the prune site."

The first thing to do according to Uptmore is to look at the tree. It is important to pay attention to previous scars and the branching angle of the limbs. He went on to explain that it is important to determine why the tree is to be trimmed in the first place. "You need to have a good reason to prune, such as raising the canopy or removing problematic limbs," he said.

With big, heavy limbs Uptmore suggested cutting the limb off in increments. "When cutting a big limb it is best to remove the weight by cutting it out towards the end and move in gradually," he said. "By removing the weight of the limb there is less of a chance of doing some severe damage to the bark and the tree at the pruning site. This will make the final prune cleaner and neater."

He also suggested making a cut about one half inch deep through the bark on the bottom side of a heavy limb at the pruning site. This will help avoid ripping the bark off the side of the tree when the limb falls.

Tree selection and maintenance was also discussed during the clinic and Andrews had some valuable tips for tree owners. According to Andrews the best way to fertilize a tree is along the drip line. "Your main feeder roots, those that literally take in the nutrition, are typically going to be in the top portion of the soil," he said. "Maybe down to 18 inches. In most cases nitrogen is going to be the main concern."

Andrews explained that a tree would benefit from spreading the fertilizing out over a couple of months. "You don't have to do it all at once," he said. "The tree could probably use it better if you split the application up."

For more information on tree health and maintenance visit www.mclennan-tx.tamu.edu.