BACKYARD ORCHARD MANAGEMENT: PRUNING PEACH AND OTHER STONE FRUIT TREES
Curtis E. Swift, Ph.D.
Colorado State University
Extension Area Extension (Horticulture)
- Unpruned trees tend to produce weak, short growth and small fruit.
- Pruning should be done as close to bud break as possible.
- Keeps the tree within height and width bounds affording easier management and harvest
- Increases the size and color of the fruit
- Keeps the fruiting wood vigorous and productive
- Helps in insect and disease control
- Pruning is an annual process
- The central leader system is highly recommended
- Pruning stone fruit trees is based on the growth and fruiting habit of the tree.
Pruning is employed to improve both the fruit crop and tree appearance, but is a practice frequently neglected and misunderstood. This publication is designed to assist the home orchardist by providing guidelines on the pruning and training of stone fruit trees from planting time into maturity.
Young trees are pruned (or trained) to establish a strong scaffold (main branch) system of wide-angled, well-spaced branches capable of supporting large crops with a minimum of branch breakage. With older bearing trees pruning is done to:
- Eliminate or reduce those parts/portions of the tree that tend to bear fruit of poor quality.
- Maintain suitable branch spacing to allow penetration of light and spray materials, and
- Maintain desired shape, height and breadth of the tree.
How a fruit tree is pruned should be based on the growth and fruiting habit of the tree. Peaches are borne laterally on shoots that developed the previous year. Plums are borne laterally on current-season shoots and older spurs. The fruiting spurs of sweet cherry may remain productive for 10 to 12 years.
Commercial growers begin the pruning of their orchards in early winter. This allows them adequate time to prune their acreage before spring bud break. Home orchardists, however, because of limited tree numbers, can wait until the arrival of milder weather before pruning. Pruning may be done through the blossoming period but mid March into April is preferred.
Pruning too early can:
- increase the incidence of Cytospora canker,
- increase internal damage, and
- increase sunscald problems.
Cytospora canker is caused by the fungus Cytospora leucostoma. This a severe disease of peach and other stone fruit trees in Colorado. Cytospora gains entrance through wounds, such as pruning wounds. Pruning close to bud break when the tree begins active growth results in rapid healing of pruning wounds and less opportunity for the disease to gain entrance. Pruning too early (e.g. mid-winter) increases the chance of sunscald and additional wounds allowing further entrance of Cytospora.
After pruning a spray is highly recommended to help prevent Cytospora infection. Further information is found in Fact Sheet #2.804.
Trees can be trained to the open vase or the central leader system (Figure 1). The open vase system has serious problems:
- since scaffold branches are attached at the same location to the trunk
- crop size is limited by the strength of that attachment
- breakage of limbs is common
- the trunk is more susceptible to winter damage than if the tree was in a central leader system.
The central leader system, compared to the open vase system, is less likely
to suffer from trunk and branch injury and therefore is the preferred method
of training. This publication explains the steps necessary to achieve a central
FIGURE 1: TRAINING SYSTEMS
Excessive amounts of water and nitrogen fertilizer, like excessive pruning can result in succulent weak growth. Pruning, therefore, must take into consideration the fertilizing and watering practices the tree will be subjected to. This is especially important when fruit trees are planted in turf areas where regular irrigation and applications of fertilizer are made. When possible, fruit trees should be planted in areas where they can be fertilized and watered separate from gardens and lawn areas.
In all cases, suckers (Figure 2) should be removed from the base of the tree.
Some rootstocks are more prone to suckering than others and should be taken
into account when selecting fruit trees.
PRUNING AT PLANTING
The life expectancy of a peach is considerably shorter than that of an apple tree, but the same care should be given to develop a strong framework to help prevent breakage of branches due to heavy fruit loads.
A one-year peach tree may have several side branches. After planting, all branches within 18 to 20 inches of the ground, shoots that are broken, and those with narrow crotch angles should be removed. Three or four branches with wide angles vertically spaced 6 to 12 inches apart should be selected for the main scaffolds. All other branches should be cut off at the trunk being careful to observe the location of the branch bark ridge and branch collar. The leader should be cut back to 30 to 36 inches above the ground. Lateral branches selected as scaffolds should be pruned to 2 to 4 inches long stubs, each having one bud.
FIGURE 3: Peach tree showing cuts made the first year.
Pruning during the remainder of the first season is not recommended. As much leaf tissue needs to be left as possible to establish a healthy root system and increase trunk growth.
PRUNING DURING THE FORMATIVE YEARS
Prune as lightly as possible from the second year to maturity. Excessive pruning delays fruit production. Pruning during these years should consist of increasing the structural strength of the trunk and main scaffolds.
The second year of training consists of selecting permanent scaffolds. These usually are the same ones selected the first summer. However, in instances where previously selected scaffolds have been damaged, another branch may have to be selected.
During the second year:
- Remove branches that tend to grow inward or straight up through the center of the tree
- Remove limbs that grow from one side of the tree across to the other side
- Head back (lightly) permanent scaffolds that exceed 30 inches with few or no side branches
- Remove all but 2 or 3 well-spaced side branches (secondary scaffolds) from the permanent scaffolds. The side branches remaining should be at least 30 inches in length and grow out and slightly up. Those that grow down, straight up, or within 15 inches of the trunk should be removed.
FIGURE 4: The second year showing pruning cuts.
From the second to the fourth year, remove branches with poor crotch angles and included bark, and those that interfere (rub or cross) with scaffold limbs.
PRUNING BEARING (MATURE) TREES
Peaches are borne laterally on shoots that grew the previous year (1-year old shoots). Therefore, pruning must stimulate new shoot growth each year. The number of fruit buds formed is greatest on the longer shoots. Hence, a six inch shoot will have fewer fruit buds than a shoot 18 inches in length.
FIGURE 5: Peach twig showing bud location
On a vigorous one-year shoot, three buds are usually produced at each node (Figure 5). The two plump outside buds are blossom buds and the smaller bud in the center is a leaf bud. A less vigorous shoots may only have one fruit and one leaf bud at each node. Shoots over 18 inches in length shoots may lack fruit buds. The key to fruit production on a peach, therefore, is to prune and fertilize to produce new shoots each year which are 10 to 15 inches in length.
When pruning a fruit-bearing tree, the following branches (secondary scaffolds) should be removed:
- those that are broken, diseased, or insect infested,
- those that are slender and weak - especially on the inside of the tree,
- those that grow toward the center or straight up, and
- those that grow down and interfere with mowing or other equipment.
In addition, it may be necessary to remove a few of the more vigorous branches. Branches which grow out for a considerable distance without branching need to be headed back to induce the development of side branches.
To overcome the peach tree's habit of producing bearing wood further and further from the trunk, retain a few young branches on the inner parts of the tree. These branches should be located to subsequently replace older wood.
Head-back upright branches to outward growing laterals when they reach a distance of about 7 feet above ground. This will permit fruit harvest from the ground.
The majority of the comments made under Pruning Peach Trees
can be followed. A few additional points, however, need to be made.
PRUNING YOUNG TREES
The apricot develops large, heavy branches. Consequently, the central leader system is highly recommended. Heavy pruning, as with the peach, reduces yield and delays fruit bearing.
PRUNING BEARING (MATURE) TREES
The fruit of an apricot is borne on short fruiting spurs as well as toward the tip of last year's shoot growth. After a spur branch has borne fruit for about three (3) years, it usually dies (Figure 6).
Pruning is done to induce new growth for subsequent fruit production. However, mature apricots are not pruned as heavily as peach trees. Pruning every third year is usually adequate.
Figure 7: Almond twig showing buds
- Pruning can be done each year but every second or third year is sufficient,
- Larger and fewer cuts are normally made on almond trees as compared to peach. Cuts should be made where the wood is three-quarters to one and one-half inches in diameter and near a strong outward-growing lateral branch.
Plum trees can have markedly different growing habits. Some are decidedly upright, while others are distinctly spreading. Regardless of growth habit, young trees should be trained to the central leader system.
When developing this central leader system, maintain a minimum vertical distance of 6 inches between main scaffolds. Five or six main scaffold branches should be sufficient.
On upright varieties it may be necessary to head back exceptionally vigorous branches to outward-growing laterals in order to spread the tree. Trees with a spreading habit of growth should be headed back to more upright growing laterals.
PRUNING BEARING TREES
Plums are borne laterally on one-year shoots as well as on fruit-spurs. The bulk of the fruit is borne on spurs.
Pruning helps maintain a supply of young wood on which fruit-spurs are borne. After a plum tree begins bearing, an annual thinning out of water sprouts and branches growing toward the center of the tree is recommended. Heading-back of scaffold branches should be avoided except to suppress those which compete with the leader.
Sweet and sour cherry trees differ markedly in their growth habits.
Sweet cherry trees are typically tall and upright. Sour cherry trees are smaller and more spreading. Both types, however, have whorls of branches (2 or more) which originate at approximately the same level. These whorls should be eliminated by removing one or more of these branches to create a central leader tree. Figure 9: Typical branch whorl seen on a cherry tree.
Train these trees to the central leader system, however, space the main scaffolds
on sweet cherry 8 to 12 inches apart, and sour cherry 6 to 8 inches apart. Only
those branches which form a wide crotch angle should be saved for scaffolds.
Vigorous scaffolds should be headed back.
PRUNING BEARING TREES SWEET CHERRY
Sweet cherry flowers are borne laterally on long-lived spurs as well as on
last season's shoots. A spur may remain productive for 10 to 12 years, consequently
cherry trees require less pruning than the other fruit trees discussed in this
Figure 10: Cherry shoot showing buds
Pruning is done to:
- remove branches that interfere with scaffold development,
- maintain the desired shape and size of the mature tree,
- prevent too tall a tree.
The leader may need to be cut back to a strong-growing lateral 10 to 12 feet above ground.
A light corrective pruning is usually required four or five years after the scaffolds have been developed. The removal of water sprouts, inward-growing branches, and those that cross or interfere with the scaffolds should be removed.
As the sour cherry tree reaches maturity, there is a tendency for it to become dense. At this time, it becomes necessary to thin out branches to keep the tree open. Too much shade in the center of the tree results in the lower and inside wood dying. Pruning to open the tree allows for better application of spray materials.
To maintain annual fruit production, shoot should grow 12 to 15 inches each year. This is maintained by proper pruning and fertilizing practices. Shoot less than 10 inches in length is usually devoid of fruit buds.
Heading-back -- This term refers to the removal of the terminal portion of a shoot (1 year old growth) or branch. This often results in a dense, clustered growth at the cut end, especially when older tissue is cut back to a stub.
Thinning-out -- This cut removes shoots or branches at their base. In general, this is the preferred method of pruning. Always follow the natural-target pruning method.
Placed on the Internet 10/26/00; Updated on August 8, 2009