Planting and Early Care of Deciduous Fruit Trees
The salubrious climate of the southern San Joaquin Valley allows many kinds of deciduous trees fruit to thrive. The typical winter fog is also beneficial for deciduous fruits because fog events increase the number of chilling hours. Mountain locations are also suitable for fruit species, such as apples, which require additional chilling and cooler summer temperatures to develop quality fruit. However, mountain sites may experience an increased risk of late spring frost, an event that can destroy the crop. Desert locations may be suitable for some fruit varieties, and good yields may be obtained in home orchards – again if late frost does not injure the crop.
When planting, choose a location which will receive plenty of sunlight and, if possible, will be protected from wind. Allow plenty of space for the mature trees. For full-size trees, 20 to 24 feet is a typical spacing. Soil amendments in the planting hole are generally not necessary, and may prove deleterious. It’s best to settle the soil with water rather than tamping the soil. Whitewash, or white latex paint diluted 1:1 with water, is recommended for the trunks of young trees to prevent sunburn.
When selecting fruit trees, be sure to obtain a variety suitable for your location. The widest selection is often found in early spring when bareroot trees become available, and bareroot fruit trees are preferable to container stock. Attention to variety selection may also obviate some pest problems. For example, mid-season peaches mature during the annual green fruit beetle flight, whereas later- or earlier-maturing varieties avoid this insect. If cross pollination from another variety is necessary for fruit set, such as for sweet cherries, be sure to get a compatible pollinator, or use a two-in-one or three-in-one grafted tree. It’s a good idea to label varieties so that if a tree dies it can be replaced. Similarly, labeling branches of grafted trees may prevent an inadvertent pruning cut which completely removes the pollinating limb. Nemaguard rootstock is preferred for stone fruits where nematodes may be a problem, which is most locations in Kern County. For apple trees, various rootstocks of the MM series give varying degrees of dwarfing. A list of fruit varieties suggested for home orchards located on the valley floor is available at the UC Cooperative Extension Office, 1031 S. Mt. Vernon, Bakersfield.
Unlike shade trees, deciduous fruit trees should be pruned every year before bud swell for optimum growth and yield. Pruning need not be complicated, but fruit trees are less forgiving than most shade tree species, and with incorrect pruning the yield of fruit will be reduced or eliminated, and the life of the tree will be shortened.
There are three pruning phases in the life of a deciduous fruit tree. The first occurs at planting, when the first cut should be made to foster development of a vase-shaped structure, since an open-center form is preferred for almost all deciduous fruit species on the San Joaquin Valley floor. After a bareroot tree is planted, the trunk should be headed at 24-32 inches above the soil surface. This cut may be emotionally difficult to make, because it may seem $10 of a $15 tree has been summarily removed. In reality, this most-important cut serves to establish low origination points of structural branches, which will allow most pruning, harvesting, and pest management to be performed without a ladder during the life of the tree. When we purchase a tree at the nursery, we are paying for a well-developed root system and the top (scion) variety. The upper structure of the tree may induce purchase by the buyer, but should be removed upon planting. Trees in agricultural fields need higher heads for equipment passage, but at home a low head greatly facilitates tree care.
The second phase of pruning serves to establish structure, and this phase begins the year following establishment. The low heading cut will result in several branches growing outward at various directions and angles, and three or four strong, upwardly growing branches spaced at intervals around the trunk should be selected as scaffolds. Additional branches can be removed. Pruning the next few years emphasizes structural development, including a well-spaced system of scaffolds and laterals.
The third phase of pruning begins with the onset of maturity, which is 5 - 7 years for most fruit trees. At this stage, the tree should be pruned for fruit production, with consideration of the location of fruiting wood. Pruning at this stage serves to invigorate and direct growth of the tree, with a goal of keeping it forever young; that is, annually producing new fruiting wood. Deciduous fruits differ greatly in the amount and location of wood which should be removed. Of trees often found in home orchards, peaches should be pruned the most severely and cherries the least. A detailed discussion is beyond the scope of this article, but principal determinants for pruning are the location and amount of fruiting wood. For example, peaches bear fruit on terminal wood of the previous season, so well-spaced lateral shoots with flower buds are retained. For peaches, it is common to thin (remove) half to two-thirds of the laterals, and to head (shorten) remaining fruiting wood. Apricots, plums and sweet cherries bear fruit laterally on spurs, which live three, five, and ten years, respectively. Therefore, up to 1/3 of the wood may be removed in mature apricots, about 1/5 of the wood in plums, and only light annual pruning is needed for sweet cherries.
If you would like more information, UC Cooperative Extension has an excellent 47-page publication, no. 21171, titled Pruning Fruit and Nut Trees. It is available at the Cooperative Extension Office, 1031 S. Mt. Vernon. UC Cooperative Extension also conducts fruit tree pruning demonstrations annually in December. You may call the office for times and locations, or watch for an announcement in the Bakersfield Californian.