Prune your trees at planting time and yearly thereafter. If you train your fruit trees properly you will need to perform only moderate pruning in later years to keep tree growth from becoming too thick and to correct minor structural weaknesses. In addition, a properly trained tree should not require large pruning cuts, which provide an entrance for disease organisms. In early training, keep an ideal tree in mind, and do the best you can to attain that ideal.
Why prune a fruit tree?
Fruit trees should be pruned for several reasons:
- To develop desired tree shape;
- To maintain the tree at the desired size;
- To allow sunlight and spray materials to enter the center of the tree;
- To improve tree strength and encourage new shoots;
- To improve air circulation within the tree and reduce the potential for disease; and
- To remove dead or broken branches.
Pruning principles
- Do your pruning in late winter (February or March);
- Prune young trees (up to 10 years of age) lightly;
- Excessive pruning encourages excessive shoot growth, delays fruiting, and reduces the quality of the fruit on young trees;
- Tipping, or pinching off, the terminal one-half inch of new shoot growth in mid-June will encourage lateral branching. Trees from 1- to 4-years-old are best suited to this practice;
- Older trees (25 years and older) will produce higher-quality fruit following a vigorous pruning;
- Make your thinning cuts back to the branch collar—do not leave stubs;
- Thinning-out cuts (entire limb or shoot removal) are associated with increased flowerbud production on apples;
- Heading-back cuts (shortening the ends of branches) encourage shoot growth; and
- Remove and dispose of prunings away from the orchard area. Deadwood will harbor disease organisms that can spread back into the tree.
Terms used in fruit-tree pruning
Fire blight control - apple and pear
Most apple and pear cultivars are subject to fire blight, a bacterial disease that can kill limbs or entire trees. Fire blight infections are more likely to be severe following heavy pruning.
You should prune out shoots blighted by fire blight infection as soon as possible. However, new cankers form around pruning cuts so removing the infected branch or limb to the next healthy limb junction can cause the pathogen to move into large healthy limbs or the main trunk. The “ugly stub” pruning method is a two-step process that prevents the bacterium from moving into healthy wood during the growing season. Prune infected limbs well below the visible blight symptoms leaving at least a 4- to 5-inch naked stub below the pruning cut. Fire blight bacteria will then colonize and form small cankers around the cut. Then you can locate the “ugly stubs” during the dormant season (when temperatures are below 40°F and the bacteria cannot multiply) and cut them back to the branch collar.
Reasons for thinning fruit trees
The practice of fruit thinning (removing some of the fruits) will contribute to your tree’s success. Reasons for thinning are slightly different than those for pruning:
- A portion of the fruit is removed so that the remainder will develop an adequate size;
- Thinning increases the plant’s ability to form flower buds for the next year provided the thinning is done early enough. Failure to thin can lead to biennial bearing problems i.e., over-production in one year followed by a year of extremely low yields;
- Thinning reduces the weight of the fruit load on the branches, thus reducing breakage: and
- Insects and diseases are more difficult to control when fruits hang in clusters.
How to thin fruits
- It is recommended to thin the apples, pears, nectarines, plums, or peach tree fruits.
- Hand thinning is the easiest and safest method for removing excess fruit.
- Begin hand thinning when the fruits are about ½ inch in diameter. Start at one end of a branch and systematically remove fruit, leaving one fruit every 6 to 8 inches.
- Keep in mind that only 5% to 10% of the tree’s flowers are needed to set a full crop of fruit.