Plant Answers  >  Summer Pruning
Summer Pruning

“If it doesn’t hurt, do it!”

This is the motto that those who practice preventive pruning during the summer months use to justify removing living limbs. Some softhearted people cannot imagine brutalizing actively growing plant life. These same people do not hesitate to even use a chain-saw on their plants during the “dormant” season. Such dormant-season-only pruners actually encourage the major surgical cuts that will be necessary, because they’re unwilling to engage in minor preventive surgery during the tree’s active growth cycle. Most of us have heard such sayings as “nip it in the bud” or a “stitch in time saves nine”. This type of philosophy definitely applies to summer pruning. You have the choice—do a little now, or a lot later!

Any pruning should have a purpose. Reasons to prune include dead wood removal, removal of damaged or rubbing branches, size and shape control, and fruit enhancements.

Fruit enhancement caused by winter pruning occurs due to the removal of excess fruit buds. This prevents overbearing and, consequently, poorly sized fruit the following spring. With summer pruning, the opposite is accomplished. Fruit bud production is enhanced. If not summer-pruned, fruiting wood down in the inside of peach trees can become shaded. Current- season shoot growth that is shaded will be short in length and weak.
In a single season, shade can reduce vigor and even cause death of fruiting wood. As a result, the area of productive, fruiting wood of the tree simply moves higher up and the center remains fruitless.

The appropriate amount of pruning depends on whether trees were pruned the previous winter, the extent of the pruning and tree vigor. The main objective of any summer pruning is to increase light penetration and maintain the vigor of fruiting wood in the major fruiting zone of the tree. In general, this is accomplished by:

1) Reducing the height of trees to permit light penetration within the major fruiting zone.

2) Thinning cuts within the tree to permit light penetration within the major freeze zone.

3) Selective removal of vigorous suckers that develop on the inside of the tree.

The actual amount of pruning must be determined on a tree-to-tree
basis. In general, very vigorous trees would benefit from at least 2 to 3 thinning cuts in each quarter of the tree (1- to 2- inch limbs), and removal of most vigorous watersprouts from the center of the tree, particularly arising from previous pruning cuts within the major fruiting zone. These few but relatively big thinning cuts will go a long way towards increasing light penetration without stimulating excessive re-growth.

As for timing, there is little data to tell us when to summer prune so that fruit wood for the next year is ensured. However, we do know that peach flowers begin initiating in early July. Severe summer pruning late in the season (July through August) results in growth that forms a low percentage of flower buds. This is not an important factor when considering non-fruiting trees. In fact for non-fruiting trees, the month of August is a good time to prune deciduous trees. By this time, most of the terminal and diameter increase (plant growth) has occurred; and, physiologically, it has been shown that there is good wound response at this time. For years, nurserymen removed suckers and unwanted branches during this month. They took advantage of the foliage being on the plant as long as practical, thus adding dimension to the tree trunk, but removing the unwanted growth at a time when the plants calloused over most rapidly.

Summer pruning can be a tremendous benefit when winter-pruning time rolls around the following February. On mature trees, all excessively vigorous shoots should be removed during summer pruning. Suckers and watersprouts will grow extremely fast up through the center of the tree. A mature peach tree should not develop over 12 to 18 inches of terminal growth each year. If you have excessive peach tree growth over this length, cut back on next year’s fertilizer and do not prune as hard during the dormant season.

On young peach trees, small shoots that grow straight down from the main scaffold or sub-scaffolds of trees that are 2- to 4-year old should be removed during summer pruning. One out of every 5 shoots on the scaffold or sub-scaffold limbs of a young tree will grow directly into the center of the tree. These shoots should be removed during summer pruning. Vigorous terminal shoots making excessive upright growth should be headed back by removing the vigorous central shoots. Small side shoots will then develop and produce fruit buds for next year’s crop. Never over-prune the growth in the center of the tree. Enough small shoots should be left to provide shade for the scaffolds and sub-scaffolds. Over-exposure of scaffolds to sun will result in “sunscald”, i.e., death of the upper side of the exposed scaffold.

Many of you have planted peach trees just last spring and are wondering what you should be doing. You definitely need to summer prune!

Within a few weeks after growth begins in the spring, begin the selection of 3 vigorous shoots arising from the top 6 inches on the main stem. They should be evenly spaced 4 to 6 inches apart along the trunk, and one of these should be directed into the prevailing southeast wind. Cut back all other shoots to prevent competition within these 3 scaffold limbs.

The peach trees should make maximum growth during the first and second years. It is extremely important to direct this growth into the permanent scaffold system. In order to properly train these vigorously growing trees, summer pruning is necessary.

At planting time, 3- to 4-foot peach tree nursery stock is pruned to a single trunk and headed back to a height of 24 inches tall. All branches are removed and the lower 18 inches of trunk is wrapped with aluminum foil, felt paper or any other opaque materials. This wrap inhibits suckers along the trunk.

During the first growing season, the peach tree scaffold limbs should be allowed to grow as much as possible. On vigorously growing trees, the aluminum foil should be removed in July to prevent the bark from growing into the wrap. All new shoots should be cut back periodically to 4-inch stubs. This “trashy-trunk” helps reduce sandblast and sunscald. If the major scaffold limbs grow at least 36 inches during the first season, head them back to a length of 32 inches to encourage the sub-scaffold system.
During the first winter, cut off all branches arising from the main stem except the 3 scaffold branches. These limbs should be 32 inches long with sub-scaffolds chosen to develop the horizontal spread of the tree. Watersprouts and suckers arising on the lower parts of these main branches should be removed.

Two sub-scaffolds should be selected on each major branch as soon as possible. These begin approximately 32 inches away from the trunk and develop the horizontal fruit-bearing surface of the tree. Horizontal growth is encouraged during the second growing season. All upright sprouts are removed in the center of the tree to allow horizontal fruit wood to develop for next season. Periodic summer pruning will be needed throughout the season.

Summer pruning has been practiced for many years in Europe to contain trees in hedges and espaliers and to obtain the uniform ripening of fruit. In this country, summer pruning is rather new and is gradually becoming an annual practice to maintain smaller tree size and improve fruit size and color.

Removing leaves by cutting off some current and 1-year-old shoots reduces the growth-manufacturing power of the tree and, therefore, leads to temporary slow-down in tree growth. At the same time, more light penetrates the tree center causing inside leaves to become more efficient, which leads to improved fruit color and quality through the entire tree. By pruning in June, you can see which part (fruit area) of the tree is or is not receiving adequate light. So, by making 1 or 2 minor cuts, you can seed how light reaches the inside. This is most noticeable when pruning is done on a sunny day.

Most people cringe at the thought of cutting on their precious fruit tree “while it’s living”. But just remember—do it now or do it later! Cuts now will be minor surgery compared to the major surgery that will be necessary later to remove larger branches which wouldn’t exist if you had done what you have in the summer months.

 

 

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