Tooele Transcript Bulletin – News in Tooele, Utah

March 6, 2014
How to prune fruit trees for productivity

While you are going to get a lot of information about proper pruning of common fruit trees in this article, I want to point out a great hands on opportunity for you to put into practice what you’ll read a bit later. This Saturday, March 8, there will be two free pruning demonstrations, one at my home at 10 a.m., and one at Wade Bitner’s home at 2 p.m.  My orchard (apples, peaches, pears, cherries, apricots, nectarine) is about 10 years old. Wade’s is about 25 years old and is all apples, along with some blackberries. Pruning approaches are a bit different with these two age groups. So, choose the one that is closer to your situation, or come to both! For more information, check the “Bulletin Board” in this paper as well as the end of this article. I’ll see you at the pruning demonstrations!

Before we get into the specifics of fruit tree pruning, a couple of things are in order. First, the workshop, led by Wade Bitner last Wednesday night, was strongly attended. Obviously, there’s a lot of interest in the subject, and growing tree fruit in a backyard or small setting is appealing to a lot of folks. Second, Wade hit it out of the park with his presentation and ability to communicate his knowledge and experience. He is formally educated in this area, did fruit production for a living, and was a long-term Extension Agent for USU. Credit is due to Wade for much of the content of this article simply because I’m going to pass on much of what was conveyed last week, along with throwing in some of my insights and experience on the topic of successful fruit production.

Let’s start with some of the general practices you’ll put to use in pruning your tree. To begin with, fruit trees are pruned for production, not shade. In fact, the tree is pruned to maximize exposure to the sun, as well as air movement through the tree. Fruit trees are actually heavily cultivated and pruned, and if done properly, will not be especially attractive except to those fellow orchardists that know the tree is being positioned for strong production! Fruit sugar, necessary for great taste, can only be produced through photosynthesis, and that means a sufficient amount of leaf surface per piece of fruit must get sunlight. Suffice it to say that it’s helpful to think of your fruit tree as a solar collector, with sunlight being converted to materials the tree needs as well as creating sugar in the flesh of the fruits.  There are only so many resources to go around in producing fruit, so you’ll need to thin your fruit very early on to assure that you get both sizable and sweet fruit. A good rule of thumb is that about 4/5 of original fruit will need to be thinned out, and to keep the remaining fruit an average of 6 inches to 8 inches apart.

No matter what type of fruit tree you have, it needs proper nutrition to produce well and be healthy. Fortunately, this is pretty easy to accomplish. Ammonium sulfate is readily available and contains 21 percent nitrogen per volume unit (Hence the 21-0-0 labeling). For a moderate-sized tree, about a quart of dry fertilizer applied on the surface of the ground at the drip line of the tree canopy (about where the outermost limb tips are farthest out from the trunk), applied when the soil is moist in early spring, is sufficient. If your trees are prone to iron chlorosis, add iron chelate powder (at the rate given on the package) to the fertilizer before applying it. This will allow the tree to access iron, even in our high Ph (alkaline) soil, and produce needed chlorophyll. You’ll know you are applying the right amount of nutrients if proper growth appears.  Aim for 8 inches to 10 inches of annual growth on apple trees, and 12 inches to 16 inches on peach trees.

Avoid fertilizing late in the year when the tree is preparing to go dormant. The fertilizer will stimulate new growth that is not hardened and ready for the winter. Freezing temperatures will damage this new growth and affect the tree’s physiology negatively. Quite a bit of damage is done to trees in home orchards by lawn mowers and string trimmers. Never mow close to the base of the tree. String trimmers can be especially injurious to your tree. Resist the temptation to trim close to your trees for weeds and grass. If you injure more than 40 to 50 inches of the circumference of the tree by cutting into the cambium layer just under the bark, your tree will never produce well. Trust me, as you read this, you are reading the voice of regret. Let my mistakes be your warning!

To grow fruit well, your tree also needs water. Watering deep and infrequently is superior to frequent and shallow irrigation. Slow growing grasses can be successfully used under the tree for weed suppression without strongly competing with the tree for water and nutrients. Regular grass, however, in the words of Mr. Bitner, is “greedy” and will use up nitrogen quickly that the tree needs. The USU Kaysville experimental farm has its orchards planted in rows with low pressure sprinklers placed in between the trees and spraying out into the alleys between the tree rows. The floor of the orchard is planted with manure crops, legumes or slow-growing grasses. This keeps weeds suppressed, lowers the temperatures, and builds biomass over time. It also puts water farther out from the base of the tree, encouraging wider root growth.

Now on to basic pruning approaches for fruit trees. Orchardists over the years have developed pruning practices for stone and pit type fruits (peaches, nectarines, apricots, cherries), and pome fruits (apples and pears) to maximize sunlight and fruit buds. If you are planting new trees, they should be pruned the day they are put in the ground. The earlier the training begins for these shapes, the better. Young tree tissue is supple and responds readily to your shaping efforts. The most common pome fruits are apples and pears. They are usually pruned to the “central leader” system. Simply stated, a cluster of three to five branches is left in place about 3 feet from the ground level or graft union on the main trunk. These branches should radiate out, perpendicular to the trunk, at very wide angles. In a perfect world, there would be four branches in a vertical space of 8 to 12 inches directed at the points of the compass, but trees don’t know this, so just get as close as you can. Choose or cultivate the widest branch angles you can get. Branches that exit off the main trunk at 90 degrees and have no bark trapped in the angle are much stronger than branches that exit the trunk in “V” shapes and have bark inclusion. As the trunk (central leader) gets taller, and a sufficient amount of buds and side branches develop above the lower branches, allow another cluster of three to five wide-angle side branches develop.  Top (prune off) the central leader just above the last side branch you are keeping in place. This second set of branches (approximately 6 feet up in the tree) should radiate at the sub points of the compass or differently than the set of branches 3 feet or so below. This is to allow both the top and bottom set of branches sufficient exposure to the sun.

Stone fruit trees are typically pruned to the open center shape. This is a goblet or bowl shape. There is no central leader in the central part of the tree canopy. Again, the set of three to five branches originate at wide branch angles about 3 feet above ground level. These branches develop into main scaffold branches, and the center of the tree is kept open to allow sun penetration and new wood growth annually.

No matter what shape system is used, the top of the tree should only be kept to a height that is easily accessible, or as our friend Wade said, “whatever height you are willing to fall!” Short, dense, well cared-for trees are highly productive and easily worked from the ground or short ladders. This includes applying sprays, ongoing pruning, and picking fruit.

There are some general pruning steps to employ, as well, as you work your way through pruning your tree. Pruning is a series of decisions, and once you’ve made the decision, it’s the right one! I work from the bottom of the tree up, starting by removing any suckers that are growing at the soil line. As I move into the main part of the tree, all downward pointing branches are taken off. This maintains the lower horizon line of the tree, keeping adequate space under the tree. Besides, downward pointing limbs don’t produce well. Next, inward pointing branches are removed, as well as parallel and crossing/rubbing branches. Dead, damaged, or broken wood is taken next. Water spouts are pruned flush against the surface of the branches. If the tree is pruned when it should be, early in the season before active growth begins, water spouts can be removed by donning gloves and rubbing the surface of the limbs and popping the water spout buds off.  Water spouts are rapidly growing, mainly vegetative (non-fruiting) growth that the tree produces to fill in the open areas of the tree you have created by careful pruning. Your goal is to produce fruit, not more tree, so get them removed! Lastly, remove top sky-reaching branches just above buds facing the direction that you want new branches to grow. Keep the overall tree size managed, but never remove more than about 1/3 of the tree per year, or you risk causing the tree to skip a year of production. Don’t use tree sealer on the cuts you’ve made. The tree doesn’t need it, and it’s messy and cumbersome. Trees have been healing over cuts and breaks for a long time, and when cuts are flush against trunk growth collars, as well as just above buds, they will heal over just fine.

Have fun, and let me know how it goes!

 

UPCOMING GARDENER EVENTS

Fruit Tree, Grape and Berry Pruning Demonstrations

Saturday, March 8, learn hands on how to prune apple, cherry, peach, pear, grapes, raspberry and blackberries. Session One will be at my home at 984 Ironwood Road, Erda, from 10 a.m. to noon. Session Two will be held at the Bitner home at 140 E. Durfee St. in Grantsville from 2-4 p.m. Bring your pruning tools. Check the weather forecast and dress appropriately!

Saturday Gardening Workshops

Coming Soon at Tooele Valley Nursery at 10 a.m., 425 E. Cimmarron Way and state Route 36. Call 435-843-5959 for more information and topics.

Small Space Gardening Workshop

Taught by Jay Cooper, topics are Self-Watering Containers, Raised and Square Foot Gardening, and Soil Bag Instant Gardens. Hands-on demonstrations, plans, material lists. Saturday, March 22, Tooele Home Depot, 222 E. 2400 North, offered both at 11 a.m. and 1 p.m. Contact Jay Cooper at jay@dirtfarmerjay.com or 435-830-1447.

 

Jay Cooper can be contacted at jay@dirtfarmerjay.com, or you can visit his website at dirtfarmerjay.com for videos and articles on gardening, shop skills, culinary arts and landscaping.

Jay Cooper

Garden Spot Columnist at Tooele Transcript Bulletin
Jay Cooper is a new contributing writer for the Garden Spot column. He replaced Diane Sagers, who retired in November 2013 after writing the column for 27 years. Also known as Dirt Farmer Jay, Cooper and his wife have been residents of Erda since 2001 after moving to Utah from Tucson, AZ. A passionate gardener and avid reader of horticultural topics, for several years he has been a member of Utah State University’s Master Gardeners Program, and served as chapter president in 2013. Cooper says Tooele County has an active and vibrant gardening community, and the Garden Spot column will continue to share a wide range of gardening, landscaping, home skills and rural living themes.

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