by Carl Cantaluppi
When working as an Extension Agent, people would inquire about growing fruit trees. I would tell them that it is hard work and a person should have the time to devote to their proper care.
Proper pruning is needed in order to get maximum fruit production. Spraying insecticides and fungicides at the right time are crucial in order to harvest sound fruit. Vegetation has to be managed under the tree to discourage weed growth and rodents.
Fruit trees should not be planted in areas shaded by houses, buildings or trees. Planting next to fences and hedges keeps cold air trapped around young trees. They should be planted in open areas, staying at least 50 feet away from wooded areas to have good air circulation. Never plant fruit trees in low lying areas, as these serve as frost pockets to kill open blossoms in the spring.
Before planting an orchard, people wonder if it is better to grow trees under sod cover or in bare soil. Here are some advantages and disadvantages of growing fruit trees in permanent sod:
- Provides good organic matter
- Protects the roots
- Legumes, such as clover, can supply nutrients to the tree
- Minimizes soil temperature fluctuations
- Will harbor insects
- Competition of nutrients between tree and grass
- Promotes shallow rooting
- No soil erosion
- No leaching of nutrients
Some advantages and disadvantages of growing in bare soil with cultivation to control weeds are:
- Promotes deep rooting of trees
- Doesn’t harbor insects
- Organic matter can be easily incorporated into the soil
- No competition of nutrients to the tree from existing sod
- Facilitates soil erosion
- Nutrient leaching is faster but they are more available to the tree
Growers need to know fruit tree bearing and flowering habits as follows: Apples and pears bear terminally on spurs (short, stout twigs that bear the fruit buds), terminally on twigs (annual growth) and laterally on twigs (annual growth). Apples and pears have mixed buds, containing both rudimentary flowers and leaves in the same bud. Apple and pear buds have five to eight flowers and 10 leaves in the same bud.
All stone fruits (peach, nectarine, plum, cherry and apricot) produce their buds laterally on twigs or spurs, never terminally. Stone fruits have pure (simple) buds, either containing flowers or leaves – not both. A peach or nectarine flower bud is a simple bud, containing one flower per bud. A cherry flower bud contains one to three flowers per bud. A plum flower bud contains three to five flowers per bud.
Stone fruits have a co-lateral arrangement of buds on the twig. This means that a flower bud can be next to a leaf bud, or a leaf bud can be sandwiched between two flower buds. The buds can be easily distinguished between each other; flower buds are plump and leaf buds are always smaller and slender.
Excess fruit has to be thinned or removed to allow the remaining fruits on the tree to reach desirable size and color. Ideally, fruits should be thinned to have four to six inches of space between fruits. If they’re not thinned, fruit size will remain small and can overload tree branches, which can cause limb breakage. Thinning also prevents fruit from rubbing against each other and will enhance fruit bud formation the following year.
Growers need to buy fruit trees from a reputable nursery that certify their trees are inspected and free from insects and diseases. Dormant, bare-rooted trees should be planted in the spring, as soon as the soil can be worked. Soil samples should be taken as far in advance as possible and the necessary fertilizer and lime recommendations should be added to the soil. For a spring planting, add the lime and fertilizer during the previous autumn if possible.
When planting, dig a hole large enough to contain the root system when spread out. Limit root pruning only to roots that are broken. Use the existing soil to fill the holes so the roots can adapt to the soil and establish quickly. Do not remove the existing soil and replace with a peat-lite mix or other soil amendment, as this will cause initial rapid root growth but when the roots come in contact with the edge of the hole, it will be difficult for them to penetrate.
Fruit trees of the variety desired are grafted or budded on a rootstock. The known variety is called the scion. These rootstocks are grown by fruit tree nurseries. They may have resistance to certain diseases, or can impart a degree of dwarfness to the scion.
When back filling the planting hole with soil, remember to leave the bud crook a few inches above the soil. The bud crook is a point on the trunk where the known variety was grafted onto the rootstock. If the bud crook is buried below the soil, the rootstock will send out shoots that will grow and will not be of the desired variety.
Most dwarfing rootstock work has been done with apples. With other fruits, most of the rootstocks that are used for grafting are non-dwarfing. With judicious annual pruning, the tree height can be easily maintained, with all pruning, spraying and harvesting operations being done from the ground.
Fruit trees to be planted should be “whips” – unbranched trees with no side branches. Do not buy trees that are taller than five feet because they will be pruned back at planting. Apple and pear tree whips should be pruned back to a height of three feet. Start training the first branch (called a scaffold branch) at about two feet from the ground and arrange the branches in a “spiral staircase” pattern up the tree with about six inches between branches. Do not let scaffold branches emerge that are opposite each other. Let the central trunk or “leader” continue to grow.
Stone fruit trees should be trained to the “open-center” system. When planting, cut the whips back to 30 inches. Let scaffold branches emerge on the trunk at about 20 inches from the ground. Instead of a spiral staircase fashion, let branches emerge at close to the same height from the ground in a “spokes of a wheel” pattern. As the tree grows, select three to five scaffold branches to keep. The central trunk or “leader” should be pruned back at a height of about 20 inches. The central leader is not allowed to grow any further. Instead, the three to five scaffold branches that were selected early in the life of the tree are the only branches that will be retained. All other branches are removed. The open-center training system maximizes sunlight penetration into the tree to enhance coloration of the fruit. Remember that shade is your enemy. All parts of the tree should receive adequate sunlight.