In the Garden:
Southwestern Deserts
January, 2012
Regional Report

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Two limbs arising from the same point grew together, creating a weak area prone to breakage.

Tree Pruning

January and February are recommended months for pruning non-native deciduous shade and fruit trees at low desert elevations. Bare branches allow you to see the tree structure so you can make cuts in the proper locations. As temperatures warm, the tree will start putting forth new growth where you want it.

Wait until the start of summer to prune native desert trees. Pruning is stressful to any plant because you are removing some of its ability to photosynthesize and feed itself. Because desert trees grow vigorously in the summer, helped along by the monsoon season, they more quickly rebound after an early summer pruning than a spring pruning.

If you have never pruned a tree before, first try to find a local demonstration or class, because it is much easier to understand the process and learn how to make effective cuts if you can watch an expert do it. Trees add tremendous value to our landscapes and improper pruning destroys their aesthetics and their health, and often makes them more susceptible to cracking and windthrow during storms. Check with your County Cooperative Extension, city parks and/or water conservation offices, garden clubs, as well as botanical or demonstration gardens. All typically offer some type of pruning guidance at different times through the year.

Before making any cuts, stand back and visualize how and where branches will expand as the tree matures so you can eliminate future problems. It may help to tie a ribbon around branches you wish to remove so that you don't become confused during the pruning because the structure and branches look different from various vantage points.

Always cut back to the joint where the branch meets the trunk or where it meets the next larger branch. Never leave stubs or make flush cuts, both of which eliminate the tree's ability to naturally seal the pruning wound.

Remove no more than one-quarter to one-third of a tree's wood in a season. More than that unduly stresses the tree, eliminates too much of its ability to photosynthesize, and opens the trunk bark up to sunburn. Sunburned tissue cracks, allowing easy entry for pests and diseases that can ultimately destroy your tree.

Remove branches in the order listed below, stopping when you've reached the quota. You can prune other potential problems next year. Have a goal; don't just prune because your neighbor is! You may not need to do more than remove a few branches to improve overall structure.

1. Dead or broken limbs.
2. Crossing limbs. As they mature and widen, they rub against each other, creating weak areas.
3. Limbs arising from the same point. As they mature and widen, they grow into each other, creating a weak spot with heavy weight prone to breakage.
4. Limbs with too narrow or too wide angles of attachment (where they meet the trunk or the next larger branch). A strong angle of attachment is 45 to 65 degrees. Weak angles of attachment are prone to breakage. As the tree grows and branches get heavy, an entire scaffold branch may break, tearing down a chunk of the tree with it. This is common sight during storms.

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