By Gayle Nelson, U.C. Master Gardener of Napa County
Armed with a little knowledge and time, any homeowner can prune his or her own fruit trees. Here's a multi-point primer to get you started, beginning with some actions to take well before you prune.
Keep fruit trees under six feet in height. Train the tree in the first few years to create a strong scaffold and branch structure. This balanced, open structure and short stature will make future care easier and minimize the potential of a ladder mishap.
Thin fruit early so that remaining fruits are five to six inches apart. Discarding fruit may seem wasteful, but thinning allows the remaining fruit to develop to full size and reduces the risk of disease transmission and broken limbs.
Prune regularly. Begin right after new trees are planted and continue pruning thoughtfully throughout the tree's life. Pruning establishes a sound structure, promotes air circulation, balances shade and sun and encourages fruit production. Numerous books and online resources can advise you on how to prune each type of fruit tree correctly. Typing “UC fruit tree pruning” into your search engine will yield University of California-sanctioned publications, articles and videos for guidance.
Understand the difference between dormant pruning and summer pruning. Dormant pruning takes place in winter when the tree's leaves have fallen and you can see the branch structure clearly. Pruning during dormancy helps manage fruit production and guide the structure. It invigorates the tree, spurring growth the following spring.
Summer pruning manages the size of the tree. You can prune any time from spring through summer to train young trees, reduce tree height and improve sunlight access.
Learn some tree anatomy. Mastering such terms as scaffold branch, lateral branch, node, fruiting wood and fruit spur, water sprout and branch collar will help you understand your tree's growth cycle.
A scaffold branch is a main structural limb. Lateral branches emerge from the scaffold branches but are not as strong or upright. A node is where a leaf attaches to the shoot. Fruit spurs are short branches that produce the flowers and fruit on most trees. Water sprouts are vigorous vertical shoots that emerge from a tree's trunk or branches. They rarely produce fruit. The branch collar is the enlarged woody tissue where the branch attaches to the trunk.
Tackle some pruning vocabulary. A leader is a dormant, upright stem that usually becomes the main trunk in a tree trained to a central leader or modified central leader. “Open center” is a method of training in which three to five primary scaffold branches are developed low in the tree and the center of the tree is kept open. A thinning cut—removing a branch or cutting it back to a lateral branch—improves light penetration. Thinning, in contrast, is selective pruning done to improve branch spacing, direct growth, eliminate weak or defective branches and reduce the end weight of branches.
Assemble the right tools. Bypass hand pruners and loppers do essentially the same job but on different-size branches. A pruning saw is handy for removing larger limbs. Wearing gloves and personal protection equipment such as safety glasses is good practice.
Keep tools clean, oiled and sharp. If the tree is diseased, sanitize tools between cuts to keep the condition from spreading.
Allow plenty of time for pruning. Gather your tools and sanitizer. Now take a long look at the tree. Are there any dead or broken branches, crossing limbs or vertical water sprouts? Does the tree seem lopsided? Begin at the back of the tree or near the bottom to get a feel for the process.
Work from the inside out. Never leave a stub. When heading, cut back to an out-facing bud. When thinning, cut outside the branch collar and don't seal or paint the cut. Downward bending branches eventually lose vigor and stop producing fruit. Cut off the downward-hanging part.
Learn where your tree produces its fruit. Apples and pears bear differently than peaches and nectarines.
Do most of the pruning in the top of the tree so the lower branches are exposed to sunlight. Sun-exposed wood remains fruitful and produces the largest fruit. Shaded branches eventually stop fruiting and will never produce again without drastic topping. Balance is the key, and practice helps you get it right.
Take time to inform yourself, and you can readily manage your own fruit trees, relying on the research and recommendations of the University of California Cooperative Extension.
Workshop: SORRY The “Fruit Tree Pruning and Grafting” on Saturday, January 21, 2017 is full please see our website calendar for other workshops at http://ucanr.edu/ucmgnapa
There will be another Fruit Tree Workshop covering "10 Thing to Know about Fruit Trees" held in Yountville on Sunday, February 12, 2017, 1-3 pm. Contact Yountville Recreation, Adult Programs for details.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.