   Pruning Fruit Trees - February 3, 1999 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County It's time to think about pruning your deciduous fruit trees. The best time to prune is a few weeks before bud break in spring. If trees are heavily pruned early in winter and a period severe cold follows, then severe cold injury can result. By waiting until just before bud break, the tree recovers from pruning more rapidly. This is because callusing and formation of wound-wood occurs more rapidly on the pruning cuts when the tree is actively growing. Do not hesitate to prune in summer just because it's not the proper season. Broken and/or overly crowded branches should be removed regardless. There are two general strategies that can be used in pruning deciduous fruit trees. Peach, nectarine, sweet cherry, apricot, and fig trees should be pruned using the "open center" method. The "open center" strategy creates a broad vase-shaped canopy allowing in sunlight and improving air circulation. Increased sunlight creates stronger branches and a healthier fruit crop. Increasing air circulation reduces insect and disease potential. A yearly pruning schedule will keep trees producing and in shape with a minimum of work. On the other hand, letting them go for years creates pruning "problems" that can be difficult to remedy. Conversely, apple, pear, sour cherry, and European plum (prune) trees are usually pruned using the "modified central leader method." This method retains the main trunk in the center of the tree as well as some side branches. The side branches are called scaffold branches and should be selected based on their crotch angle and be evenly spaced radiating outward from the main trunk at different heights. The "modified central leader" method results in a sturdy tree that stands up well to harsh weather. Before pruning, clean your tools in a 10% bleach solution to avoid transmitting diseases between trees. Gloves are also a good practice especially if your tools are as sharp as they should be. Pruning cuts also come in two varieties: heading and thinning cuts. A heading cut is typically placed at the tip of a branch to encourage branching below that point. By cutting off the tip, suppressed buds grow out and produce new branches. Newly planted trees usually need to be "headed" to induce branching. Thinning cuts remove side branches (not tips) to open up the crown of the tree. Once a tree begins to produce fruit, you need to understand exactly where fruit is formed on the tree. Peaches, nectarines, and figs produce fruit on the previous year's wood. Apple, pears, apricots, plums, and cherries produce fruit on short spurs for a number of years depending on type of fruit. In general, peaches and nectarines need more aggressive yearly pruning than the spur fruiting types. Ideally, large branches will never have to be pruned because we all prune our trees correctly each year and know exactly what we are doing at all times. So, if one of your neighbors asks you for advice on pruning large branches, do not let them prune it flush to the trunk or main branch. Instead, it should be pruned just beyond the branch collar (swollen area near). The resulting wound has a smaller surface area and will callus and heal over more quickly. By the way, do not use sealants to cover pruning cuts. They are not necessary and can cause decay if applied in thick layers. I could continue with more rules and techniques, but instead here is something to think about: never make a pruning cut without a good reason. Try to understand how trees grow and where they produce fruit. Finally, to get the straight scoop, attend one of the University of Arizona Cooperative Extension fruit tree pruning workshops. The next one will be at Young's Farm in Dewey on February 6 at 10:00 AM, another will follow at the Folded Hills Orchard in Oak Creek Valley on February 20 at 10:00 AM, the final one will be at the Oz Ranch in Chino Valley on February 27 at 10:00 AM. We will also cover fertilization and fruit thinning so come on out and join me at a workshop. The University of Arizona Cooperative Extension has publications on pruning and deciduous fruit tree care. For more information about the pruning workshops or other gardening information, call the Cottonwood Extension office at 646-9113 or E-mail us at mgardener@kachina.net and be sure to include your address and phone number. |