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Tuesday, May 3, 2016

Now Is the Time for Summer Pruning

Q. Back in January you had an article about Apricot trees and you mentioned cutting back excessively long growth over 18-24 inches when it is growing. I planted an apricot a couple of years ago and this year it is growing like crazy with many branches now exceeding 18 inches and still growing.  Would you recommend continuing to cut back excessively long growth and throughout the summer if necessary?

A. When fruit trees are growing like crazy some of it can be part of their genetics and some can be caused by management. Some fruit trees are naturally more vigorous than others. Fruit trees are also affected by the type of rootstock they are grafted to. For example, the variety Katy apricot is much more vigorous than the variety Gold Kist when grown on on the same rootstock. Gold Kist is more restrained in its growth and tends to stay smaller.
Young peach requiring summer pruning
Growth is also be affected by management. Applying too much fertilizer or watering too often can produce excessive growth. Growth is good. Excessive growth is not because it has to be pruned out and that's wasted energy by you and by the tree.

Summer pruning is a dwarfing technique used to help restrain the growth of fruit trees. Fruit trees have stored energy held in reserve through the winter. Trees "invest" this stored energy into new growth in the spring. Vigorous trees invest more of this energy into growth than trees with restrained growth.
Young fruit tree requiring summer pruning because of excessive new growth. Summer pruning only removes some of the new growth, not older wood.
Summer pruning in our climate is done during the months of late March, April and perhaps the beginning of May depending on the weather and the type of tree and its growth. When summer pruning, new growth that is undesirable is removed from the trees after the tree has made its "investment" in this growth. This robs the tree of stored energy that might be used for excessive growth.
Fruit tree restrained after summer pruning
There are two types of pruning cuts. One is total removal of a new shoot (thinning cuts) and the other is cutting excessively long growth, shorter (heading cuts). Total removal of a new shoot opens the canopy of the tree and reduces excessive shading. Cutting long growth shorter creates three new shoots from a single cut. Three shoots created by one cut increases shade created by the canopy.
Upright, vertical growth is usually not desirable in fruit trees. This kind of growth tends to produce lots of leaves and twigs and very little fruit. This type of growth should be totally removed with thinning cuts.
This second type of cut, heading cut, also encourages the development of short shoots along the cut branch. These short shoots begin to flower and produce fruit often times during the next season. These short shoots are called "fruiting spurs". Cutting back excessively long growth to about 18 inches restrains the tree and improves fruit production closer to the trunk.
Heading cuts are made anywhere along a branch just above a bud that is pointed outward.
The result of a heading cut (near my thumb) is seen next year when bud below the cut begin to grow. One cut can result in three to five new shoots. I refer to heading cuts sometimes as "thickening cuts".
What to do? Totally remove (thinning cut) new, long shoots that are 100% vertical. These shoots are sometimes called "water sprouts". Shoots that grow vigorously and vertically upward are not good fruit producers. This type of growth normally produces all shoots and leaves, no flowers.
Undesirable succulent new growth can be pulled from the tree and does not need to be cut if it is done early enough. Pulling new growth from trees, rather than cutting, reduces the amount of regrowth.
New shoots that grow vertically downward are also poor fruit producers. These should be removed as well (thinning cut). The best fruit producers are shoots that grow upward at a 45° angle; halfway between vertical and horizontal. Remove these shoots only if they are crowding or crossing other shoots. If they are excessively long (24 inches or longer) cut them back along the shoot leaving behind about 12 to 18 inches of new growth. This single cut of an excessively long shoot restrains the size of the tree and helps produce side shoots or spurs that will eventually flower and fruit.

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