   Selecting and Orchard Site and Planting Fruit Trees - January 12, 2000 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Seed and nursery catalogs have been steadily appearing in my mailbox to fill my mind with new fruit varieties and grandiose plans. Having recently moved into a home with abundant space, little soil, and lots of rock, I have my work cut out for me. Deciding a site for an orchard often comes down to locating an area with enough soil to dig a hole (at least in my case it does). Choosing a suitable site is especially critical for an orchard where the trees may be there for 40 plus years. First, understand your microclimate. An adequate supply of solar radiation (sunlight) is certainly important. In the Verde Valley, this is rarely lacking unless there is a dense overstory of tree canopies. South and west facing slopes have higher intensities of solar radiation, especially during winter when the sun passes over at its lowest angle on the southern horizon. East and north facing slopes have less solar radiation overall but capture adequate amounts during the growing season (except on the steepest slopes). East and north slopes are more desirable for varieties and species that can break dormancy early and losses due to late spring freezes are a concern. For fruit crops, a north-facing slope is ideal. A building can offer similar effects to a slope (i.e., the north side of the house or barn is similar to a north slope). In addition, slopes affect cold air drainage. Cold air drains downslope and lies still in bottoms and areas where it can be trapped. Houses, sheds, solid fences, and other barriers will trap cold air or slow its movement potentially leading to freeze damage. Ideally, your soil is a loam or silt loam with excellent drainage and water holding capacity. Clay soils have poor drainage and prone to root disease. Sandy soils need more frequent irrigation and nutrients are easily leach away. Both clay and sand can benefit from the incorporation of organic matter. This should be done in a large (12 to 15-foot) radius from the trunk or not at all. Never try to incorporate organic matter into an established orchard. This only damages the roots and stimulates sucker growth. If a caliche layer (calcified hardpan) is present, then it must be penetrated to allow adequate drainage. A digging bar or jackhammer may be needed to break through the caliche. Space must also be considered when planning an orchard. For home orchards, I recommend semi-dwarf rootstocks be used. The following are recommendations for semi-dwarf tree spacing: apples=18 ft; pears=12 ft; and peaches, apricot, plum, and nectarines=16 ft. Aggressive pruning can increase planting density, but if you have the space, it's best to let the trees use it. Some people plant several trees of the same species in one large hole. This helps with pollenization and conserves space. This planting method is easiest to do with bare root stock. The trees are spaced apart at least one foot and angled slightly away from each other. An adequate amount of irrigation water is also crucial to home orchard success. By planning ahead, you can create the ideal situation. Plan for the mature size of the tree when designing irrigation basins or drip systems. Fruit trees draw water and nutrients from the three to four feet depth. One or two drip emitters placed at the trunk will not suffice for a mature fruit tree. Ideally, fruit trees need irrigation at least two feet beyond the drip line of the crown. Drip and microsprinklers are an excellent way to water fruit trees if they are well placed and properly scheduled. Mulching will help conserve water. However, it also prevents the solar radiation from heating up the soil during the day. This is the heat that is re-radiated at night to buffer the effect of cold temperatures. Next week, I'll cover planting methods and suggest some fruit tree varieties: both standbys and some up and coming new stuff. Also, keep watching for our annual fruit tree pruning workshops. We'll have at least two scheduled in the Verde Valley. The University of Arizona Cooperative Extension has publications and information on fruit tree care and varieties. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@kachina.net and be sure to include your address and phone number. |