Planting a home orchard is always a challenge, and several decisions must be made in advance.

First, decide whether to plant apples, peaches, apricots or pears.Second, decide on the varieties. Considering that there are more than 10,000 different named apple varieties, as one example, this can be a real challenge.

Third, decide where to plant the trees and whether to plant standard, dwarf or semi-dwarf trees.

Then after the trees are finally in the ground, prune and train them to make them productive.

Trees vary in the severity of pruning needed, according to the following guidelines for different species.

Most severe: Peaches, nectarines, Japanese plums, apples, apricots, sour cherries, European plums.

Least severe: Sweet cherries.

Each tree is different - and these are only general guidelines. Very vigorous trees need substantially more pruning than less vigorous trees.

Decide on a training system for the trees in your orchard. The modified-leader system is best for apples, pears, European plums and sweet cherries. The open-center system is easier to develop and maintain. (These are guidelines for starting new trees not for correcting problems with existing trees.)

Train semi-dwarf or spur-type apple trees to the modified-leader system. Develop one main trunk (8 to 10 feet high for semi-dwarf trees) with tiers of branches coming off the main trunk. Start the lowest branches 24 to 48 inches from the ground, with a branch going out at the four points of the compass. Develop a second tier 18 to 24 inches above the first, with the branches above the second so the tree has a pyramidal shape. Scaffold branches should form 40- to 90-degree angles with the trunk. The overall effect is a tree that is shaped somewhat like a Christmas tree, with broad, spreading branch-es at the bottom. Each higher tier of branches is somewhat shorter to allow maximum penetration of sunlight into the interior areas of the tree.

The number and spacing of scaffold branches and the height of the trunk vary with the type of tree (dwarf, semi-dwarf or standard), and the type of fruit (apple, cherry, pear or plum). Modified-leader trees have low and well-spaced branches, well-distributed fruiting wood and are close enough to the ground to make pruning, spraying and picking easier.

Trees trained to the open-center systems have a single trunk 18 to 30 inches high. Three or four scaffold branches, located 6 to 8 inches apart vertically, are developed near the top of the trunk. Scaffold branches, spaced uniformly around the trunk, form crotch angles of 45 to 90 degrees with the trunk. Properly shaped, open-center (or vase) trees develop into a low-headed tree to facilitate pruning, spraying and picking. The open center allows light to penetrate the interior of the tree.

Trees that have not been properly shaped when young, and trees that have not been pruned for several years, develop several problems. They have too many branch-es, are too tall and the lateral branches are too long. The tree is too dense and sunlight does not penetrate the interior of the tree.

Select five to eight of the better branches as scaffolds. Choose larger branches with wide-angle crotches. Remove other branches rising from the trunk over a three-year period, cutting out about one-third each year. Spreading branch removal over a three-year period reduces the shock to the tree. Excessive pruning upsets normal bearing for several years. Do not fertilize trees during this corrective pruning period. Corrective pruning provides enough growth stimulation.

More information on pruning fruit is outlined in "Pruning the Home Orchard," available from any Utah State University Extension office. These are located in each county in the state. Many also sponsor pruning demonstrations, so call for more information.