John R. Pyzner | 2/1/2006 12:24:06 AM
February is the best time to prune most fruit trees in Louisiana. The coldest part of winter is usually over, and trees will soon be growing and can heal pruning injuries.
LSU AgCenter horticulturist Dr. John Pyzner says pruning fruit trees can be beneficial in several ways. It improves tree health by removing dead, injured or diseased limbs. It eases harvesting by shaping and reducing tree height. It increases flower production on trees such as peaches that bloom on new growth. It improves fruit quality by allowing more light penetration, which improves fruit color, and by thinning the fruit crop, which improves fruit size and sugar content.
The basic tools for pruning are lopping shears, hand pruners and pruning saws. Lopping shears can cut wood from ¼ inch up to 1 ½ inches in diameter. The long handles enable limbs to be pruned up to 8 feet away. They also allow extra leverage when cutting larger limbs. Often, no other equipment is needed. A pruning saw is needed, however, for limbs too large for lopping shears.
Hand pruners are very useful on small plants or when a lot of small limbs less than ½ inch in diameter need to be cut. The short handles give more control when doing detail pruning.
The first step in pruning is to remove any dead, broken or diseased branches. Branches should be cut back to a fork or bud. Generally, a ridge or area of wrinkled wood is around the base of the branch. This is called the branch collar.
The collar has the ability to heal nearby wounds and should not be cut. The limb should be cut just outside the collar. The branch collar will then quickly grow over the cut surface. Do not leave a stub sticking out of the collar. The collar will not be able to grow over the cut surface, and the stub will frequently die. This will sometimes lead to a hollow in the tree.
Next, remove branches that grow toward the center of the tree. These branches will often cross other limbs and cause rubbing injury. These limbs also will prevent light penetration and air circulation, which reduces fruit coloring and encourages diseases. Limbs of equal size that form a sharp V will tend to split apart. One of the limbs should be removed before the limbs get very large.
Limb growth can be directed by pruning back to a bud or shoot that is pointing toward the direction where growth is desired. This procedure allows the tree to be shaped or to fill in gaps in tree structure.
Pyzner says different methods of pruning are used on different fruit species. Fruit trees such as peach, nectarine and Japanese plums produce fruit on 1-year-old wood. Because pruning stimulates growth, it is the best means available to assure an annual supply of this essential fruiting wood. Japanese plums also produce fruit on spurs and should not be pruned as much as peaches.
Peaches, nectarines and Japanese plums are typically pruned to a three-limb open center form or sometimes four-limb in Japanese plums. This method allows sunlight into the tree and enables the fruit to develop proper color. The upper shoots can be tipped to keep trees low enough that the fruit can be harvested without the aid of ladders. Failure to control tree height will cause the lower branches to be shaded out and the fruiting wood to be too high to harvest without ladders.
Apple and pear trees produce fruit on short spurs that last 10 to 15 years. Excessive pruning will remove the fruiting spurs and reduce crop size. It will also cause excessive non-spur producing wood to be produced, which is non-productive. Apples and pears are normally trained to a central leader or modified central leader system. Pruning basically consists of thinning out thick areas and removing weak or damaged wood. Excessive pruning can make trees prone to fire blight disease.
Pyzner notes that figs produce fruit on current season wood, although some varieties produce an early crop on the previous season’s growth. Figs do not need heavy pruning to produce fruiting wood. Pruning consists primarily of removing inward growth when necessary to keep the tree open. Dead, diseased or damaged wood along with suckers and water sprouts should be removed.
The horticulturist says citrus trees require little if any pruning except to remove broken or damaged limbs. Freeze-damaged citrus should not be pruned until June. The severity of damage can be properly assessed at that time.
More details on fruit tree pruning can be found in LSU AgCenter publication 1884 "The Louisiana Home Orchard," available online by visiting http://www.lsuagcenter.com/en/communications/
For related horticultural topics, click on the LSU AgCenter Web site, www.lsuagcenter.com.
Source: John Pyzner (318) 644-5865, or Jpyzner@agcenter.lsu.edu