Almstead Tree & Shrub Care Blog

Thursday, December 20, 2012

Why You Should Prune Your Trees in Winter

When spring comes, we think of all the things we should do in the garden, such as pruning. But winter can be a better time to prune for several reasons.
1. Pruning in winter is like having an x-ray.
In winter, deciduous trees have cast off their coverings, giving us a much better view of their structure. We get a clear picture of the entire tree, allowing us to identify weak branch connections, cracks in limbs, unsafely crossing limbs and dead wood. Winter is the ideal time to uncover and address the structural flaws that can eventually lead to branch or tree failures.
The structure of this tree is revealed by winter.
2. Winter storms are dangerous pruners.
As we unfortunately saw last month, high winds and wet snow put tremendous strain on branches. Though many branches were lost in Hurricane Sandy and the following snow storm, others still need to be removed. Additionally, broken branches should be professionally pruned so that the cut can be in the right place to promote the natural healing process that trees employ. We recommend that you identify and remove dead or cracked branches before winter does its own pruning, which can be dangerous for property, people, and the tree.
3. Your yard won’t mind.
Pruning and removing trees is easier when the ground is frozen. A tree care professional can typically move heavy equipment closer to the trees they are working on without harming lawns or herbacious perennials and annuals. Removing dead trees is often simpler when surrounding trees are bare. Plus, your family will experience less inconvenience when they’re usually indoors anyway.
4. Make spring more beautiful. Many of the flowering trees and shrubs we love, like apples, cherries, and magnolias, have already formed their buds for spring flowers by the end of fall of the previous year. By selectively pruning in winter, we can improve the saturation of flowers and fruit they have in the growing season. Winter is a busy pruning season for orchards!
Proper pruning techniques are important, whether on a shrub or tree. If you do your own shrub pruning, make sure you pick the right season for each shrub and use the proper techniques. For example, pruning early flowering shrubs now (like azaleas) will lead to fewer blossoms. Our local Cornell University Extension has an excellent free guide to pruning that you can download  “An Illustrated Guide to Pruning Trees and Ornamental Shrubs” here.
Before you prune your own trees, make sure you understand proper pruning techniques. Correct pruning, whether to remove dead wood or to improve a tree’s structure, is much more than just picking a spot and sawing away: the placement and execution of a proper cut actually helps the tree with its healing process.
When trees require pruning of high branches or a power saw is needed, it’s time to call a professional. A professional tree care company (and of course I include Almstead), has the right tools, equipment and safety training to do the job.

Tuesday, December 11, 2012

How Trees Respond to Drought

A Longleaf Pine showing the effects of drought.

Although we all know that trees need water, scientists are still discovering new information and implications about the process that allows trees to “drink.” Thanks to recent scientific research, we now have a greater insight into the mechanism of tree death from drought and a new appreciation of how vulnerable trees are.

Trees draw water through their roots and into the thread-like channels of their vascular system that distributes it to their most remote needles and leaves. In order to photosynthesize and grow, trees need to open the stomata (pores) on their leaves to take in carbon dioxide. As they do this, water evaporates. The water loss creates a suction effect that goes down all the way to the roots, where the water is replenished, similar to drinking through a straw.

When water is unavailable, this suction pressure increases, and air is drawn in. The air bubbles clog the channels and make it harder for a tree to get fluid to its leaves – like drinking from a broken straw. This “hydraulic failure” is the reason trees die from drought.
In addition to hydraulic failure, drought can impact a tree’s ability to open its stomata. Even when water is again available, some leaves are unable (or slow) to return to their work of photosynthesis, causing further dieback.

Dr. Brendan Choat from the University of Western Sydney and Dr. Steven Jansen from Ulm University in Germany lead a team of scientists that have studied hydraulic failure in trees worldwide. The results of their research show that about 70% of tree species have very little margin in the amount of drought they can endure before they experience hydraulic failure. Surprisingly, this was true for species that grow in marsh as well as desert. The implications of this research are that a small change in the drought level of an area could have serious consequences for large numbers of trees.

Watering trees in times of drought is extremely important. Even the largest tree typically has its roots concentrated within the top 12” of soil. They have no ability to suddenly find water when that layer is dry. Trees will respond to drought by dropping leaves or needles, and then having whole branches die. The damage can be irreversible.

Sophisticated systems are now available to monitor the moisture content of soil and automatically adjust watering to the appropriate level for plants, lawns or trees. These irrigation systems are now common in arid regions and have been found to reduce total water consumption. Giving trees the right amount of water at the right time can prevent hydraulic failure and also prevent the unnecessary waste of water in landscapes by up to 60%. I believe we’ll see this technology introduced in the northeast over the next decade as water for our landscapes becomes a more precious commodity.