This is an excerpt from the Book called “The Backyard Orchardist “ by Stella Otto. Continue reading to learn more about Pruning Basics, thanks to the author.
Pruning fruit trees is one area of horticulture that often seems mysterious or scary for most people, but it really need not be so. Once you understand a few basic principles and follow a step-by-step system, the pruning process and its results really become quite simple and predictable. Also, remember that it is hard to harm a tree with a light pruning, but neglecting pruning can eventually lead to a poorly-shaped tree that may be too overgrown to produce a good crop. There are a number of reasons why annual pruning is important to maintaining a healthy tree. Pruning can:
- establish and maintain a strong branch structure that can support the weight of a heavy crop
- renew fruiting wood or spurs.
- allow sunlight penetration, which is critical for fruit bud formation, into the central portion of the tree.
- increase air circulation that reduces the spread of fungal diseases and minimizes the need for fungicide sprays.
- enable full penetration and coverage of sprays, when they are needed, to make them most effective in controlling pests and diseases.
- confine a tree to its allotted space.
The need for pruning can be looked at from several directions, such as the time period in a tree’s life and how pruning affects it, or specific desired effect and how pruning can accomplish it. Let’s look first at the various stages of a fruit tree’s life and why pruning might be needed at any given stage.
Pruning Systems to Match the Tree’s Growth Habit
Pruning young fruit trees in the years before they start bearing is mostly aimed at helping the tree to establish a strong framework of branches that will be capable of supporting the weight of the future fruit crops. For freestanding trees (those that are not supported by tying to some type of trellis system or post), there are three major choices of pruning system. Which one you choose will normally be dictated by the tree’s growth habit, or natural way of growing. These three systems are known as the central leader system, the modified leader system, and the open center or vase system.
The Central Leader System. The central leader system is most commonly chosen for trees which naturally grow with one central trunk that has a strong tendency to grow upright. This system is most frequently used for apples. Usually, 3 or 4 layers of fairly horizontally growing branches, radiating out from the trunk, are left to grow. That eventually become the major bearing surface for the fruit. These individual, horizontally growing branches are often called scaffold branches because they make up the framework or “scaffold” of the tree.
Each of the layers of scaffold branches normally has 3 to 4 branches radiating out from the trunk and spaced fairly equally around it. If you were to look at the ideal central leader tree from the top looking down at the roots, the scaffold branches would radiate out in four compass directions, ideally, north, south, east, and west.
Each of these groups of branches is often referred to as a whorl. Within each whorl, you may leave 6 to 9 inches between the individual branches. In a tree of 10 to 12 feet tall (which is a typical and manageable height for a fruit tree in the home garden), the first whorl of scaffold branches would occur about two and a half to three feet off the ground. The second whorl would be about three feet above it, with two and a half to three feet between each subsequent layer of scaffold branches. When viewed from the side, a central leader tree will have a cone, or Christmas tree shape, wide at the bottom, tapering to the top.
Most fruit trees in the home garden are best kept to a maximum of 10 to 12 feet in height and three whorls of branches. Once the desired height is reached, the tree is contained by pruning the leader off to a weakly growing vertical branch or by allowing the leader to bend over under the weight of load of fruit.
Modified Central Leader. As its name implies, the modified central leader system is a variation of the central leader training system. This system is used most often with fruit trees whose initial structure starts with one upright growing trunk and a layer of scaffold branches, much like the central leader. Usually 5 or 6 scaffold branches are grown more or less in a continuous whorl spiraling up the trunk. When the scaffolds have reached about six feet from the ground, the central trunk or leader is headed back or cut off to a strong outward-growing scaffold branch. The tree is now maintained with an open center (discussed below) from the point of the heading-back cut.
This pruning technique is often used to contain a tree at a desired height when its natural tendency is to grow considerably taller. Pears are often trained to a modified leader system. Tart and sweet cherries are also trained this way. Some upright-growing plum varieties and some of the more open-growing apple varieties also lend themselves to the modified leader system.
Open Center. The open center training system is used for fruit trees whose natural growth habit is more like a bowl-shaped vase than dominated by a single, upright, central trunk. With the open center system, 3 to 5 scaffold branches are developed in a bowl-shaped whorl about 3 to 4 feet off the ground. Any leader that may develop out of this point is headed back to the whorl of scaffolds.
Lateral side branches of the main scaffolds continue to provide additional growth and fruit bearing surface while they grow out and upward in a vase or bowl shape that leaves the center of the tree open for sunlight to reach inside. This system is commonly used with peaches and plum varieties that have a naturally open, vase-shaped growth habit.
Pruning shears. These will be one of the first pruning tools you will use. They are compact and handy for trimming the fruit tree in the first years of its life. Pruning shears come in two basic types, bypass shears and anvil-head cutters. Anvil head shears cut by pressing the sharp blade against the flat anvil portion of the head. Unless kept very sharp, anvil cutters have a tendency to crush the branch tissue but are able to cut larger stock than a bypass shear.
With bypass shears, the cutting blade works like a scissor. The general rule for bypass shears is they will cut wood up to the diameter of a thumb. (Do be careful to keep those thumbs and fingers out of the way as a sharp bypass shear won’t discriminate!) Bypass shears will cut more cleanly than an anvil shear, but are more likely to be damaged if you try to cut something they aren’t meant to cut. If you are going to buy only one pruning shear as a beginning orchardist, your best bet would be a high-quality bypass shear.
Then, take care of it as you would with any treasured tool and don’t allow it to be used for anything other than its intended purpose. It will serve you well for many years.
There are many styles and sizes of hand grips for pruning shears. Look at several. Try them out and see what feels best in your hand. If you are left-handed, there are few styles made for you, too, and it is worth investing in one to avoid hand fatigue if you are doing a lot of pruning.
Also consider a pruning shear that allows you to remove the blade and sharpen it periodically or replace it if necessary. This will help both in keeping your pruning cuts nice and clean and in not tiring your hand when doing an extensive amount of pruning.
Limb Loppers. For cutting branches larger than what pruning shears can handle, limb loppers are the next step up. Loppers normally have handles 12 to 30 inches long to give more leverage when cutting branches up to an inch and a half in diameter;
Loppers are used by holding them with both hands are often similar in style to pruning shears, being of either the anvil head or, more commonly, the bypass type. Choose your lopper for the same reasons as you would shears; they should be sharp, sturdy, and comfortable in your hands. When choosing loppers, be sure that the handle are good and solid, since they can be under considerable stress when cutting thick branches and you do not want them to give way suddenly. Also, if you are doing much cold winter or dormant pruning, metal handles tend to be colder than wood.
Pruning saws. Pruning saws come in a number of sizes and shapes, but all do essentially the same work. They are most suitable for cutting medium to large wood that loppers can’t handle or reach. A pruning saw may be a small blade that folds into the handle, a bow-type saw with a thin blade for tricky places, or a pole saw on a long handle to reach the tops of tall trees.
Most pruning saw blades have coarse teeth that are offset with teeth alternately bending to the right and left down the saw blade. The teeth are often sharpened in only one direction so that they cut while being pulled, but do not bind up when being pushed back for the next stroke. Due to the offset teeth, most blades will make a fairly wide cut, which helps shed wet, sticky sawdust from their path. Many of the blades themselves are narrow or curved on the end in order to reach into tight places between branches. Most pruning saw blades can be removed and sharpened for just a few dollars when dull or easily replaced when worn out.
In choosing a saw, consider what type of pruning you will be doing most. If you have all dwarf trees that you can reach from the ground, if your space is very compact, or your tree is planted close to a building, a hand saw will be most convenient. A pole saw is the best choice if you need to reach the tops of larger trees.
Once you get used to them, pole saws are very handy because you can stand back from the tree and get a complete overview of the tree while you prune. Many commercial fruit growers do all the pruning of their mature trees with pole saws as they are fast, lightweight, convenient, and relatively inexpensive. If you are doing much dormant pruning, consider a saw that you can hold comfortably with your work gloves or mittens.
One word of caution on saws; the one saw to avoid is the type with a string attached to each end of the blade and meant to be thrown over an out-of-reach branch. (In most home gardens your trees will not be so large that you would even think about needing to use this type of saw). Since there is no way to make a bottom cut with these, they will often cause considerable bark tearing if cutting a big branch. Use a pole saw for those hard-to-reach spots or, if safely possible, climb into the tree and use a hand saw. For smaller diameter wood, the next tool may do the trick for you.
Pole Pruners. A pole pruner is somewhat of a hybrid instrument, a cross between a pruning shear and a pole saw. Normally the cutting assembly consists of a spring-loaded bypass blade that is operated by pulling a string or metal rod attached to it. The whole assembly is attached to a pole, much like a pole saw. A handle around the pole often secures the other end of the string or metal rod that operates the cutting blade.
A pole pruner can be very handy if you have small diameter wood that is too far away to climb to safely, but small enough to cut with a snip of the pruner. If you have large, vigorous-growing pear, sweet cherry, or apricot trees, consider investing in a pole pruner.
As with most tools that you expect to use skillfully and often, it is wise to invest in good pruning tools even if the better ones cost a little more. They will pay you back many times over by making pruning easier. Do remember, too, that they will serve you just as well on the other shrubs and trees in your yard as they will on your fruit trees, so you will probably use them more than you originally anticipated.
Proper Pruning Cuts
Most people who are concerned about pruning a valued tree or shrub are afraid of damaging the plant beyond repair. In most cases this is unlikely to occur, but proper attention to how the cut is made can help the tree heal faster after pruning.
In pruning, you will likely be making one of two types of cuts. You will either be cutting shoots and young branches with diameters of less than an inch or you will be cutting more substantial-sized wood. Cuts on most small diameter wood can be made with hand clippers, limb loppers, or a small hand saw. Larger wood will need to be cut with a saw of some sort.
The basic point to remember in all pruning is that the cut should be as close to the collar of the branch as possible without cutting into it. As much as possible, you should also avoid leaving branch stubs sticking out. If you look closely where a branch grows out of the trunk, you will notice an area at the base of branch that is somewhat thinker than the branch itself.
This area is the collar. It contains a natural chemical barrier that stops decay and has cells that will rapidly grow scar tissue to heal the area where the branch is removed. The scar tissue will heal most easily when it has a clean, smooth surface to grow over. Consequently, it is important to try to make clean, flush pruning cuts that do not leave stubs behind.
Making the nice, smooth cuts mentioned above is easy. Just work with good, sharp tools. For small cuts, one firm clip of the shears should do it. If you are cutting large, heavy branches, though, the weight of the limb can sometimes cause the bark to tear as a branch breaks before being fully cut. To avoid this unnecessary injury to your tree, large branches should be cut with a three-part cut. First, make a cut on the bottom side of the branch to be removed.
The cut should be about 2 to 3 inches away from the collar and about one third of the diameter into the branch (or until the weight of the branch starts to pinch your saw). Then, from the top of the branch, complete the cut. The branch should cut away clean in most cases, but if it does not, any bark tearing will most likely stop at the cut you made on the bottom side of the branch and avoid tearing a big strip of bark down the trunk of the tree. A third cut, if needed, can remove the remaining stub.
Most pruning cuts fall into one of two types: thinning out cuts or heading back cuts. Thinning-out cuts are what their name implies. They are used to remove unwanted branches and are made by cutting a branch back to its base. In the case of a scaffold branch, this would mean removing it back to the tree trunk. Lateral branches are thinned out by cutting them back to the scaffold branch from which they originated. Thinning-out cuts usually have the effect of encouraging other neighboring buds to begin growing.
Heading back cuts involve cutting the tips of branches back to a given point, not necessarily to a main trunk or scaffold. Heading back cuts are commonly used to contain a tree that may be growing too large for its allotted space. A heading back cut tends to temporarily stop further growth of the branch that was cut back and has little effect on the growth of other neighboring buds or branches. In most cases it is preferable to thin out rather than head back a branch.
Pruning Young Nonbearing Fruit Trees
In the early years of a fruit tree’s life, it is best to prune sparingly. The major goal is to help develop the shape into one of the three systems discussed earlier. Fruit spurs and smaller branches that will be the first to fruit should be allowed to grow. Ideally, the scaffold branches that are left to grow should have about a forty five degree angle or greater from where they attach to the tree trunk. Only those branches that have poor crotch angles or compete with the desired branches are removed.
The key to pruning in the tree’s early years is to form a desirable branch structure in the beginning so that severe pruning can be avoided later. Generally, the more you prune, the more vigorous, vegetative growth will be stimulated. Your goal in the first three year should be:
Year 1: Prune as lightly as possible to form scaffolds
Year 2: Encourage balanced growth of scaffold branches
Year 3 and beyond: Keep the tree canopy open for air circulation that minimizes fungus disease development. This will also allow sunlight penetration that encourages even distribution and renewal of fruiting wood.
Pruning the Bearing Fruit Tree
Once the major scaffolds of the fruit tree have been developed and it starts bearing fruit, you will want to shift the focus of your pruning. Now the goal will to be maintain the established tree shape and height while allowing enough sunlight into the interior of the tree. You will also want to open up some avenues so that you can easily access the interior of the tree canopy to pick the fruit.
Sunlight is necessary for photosynthesis and fruit bud development. For this reason, much of the pruning that is done on mature, bearing trees is done to allow sunlight into the tree. Another reason for pruning the bearing tree is to stimulate a modest amount of new vegetative growth to replace older wood whose fruit production is decreasing. Which of these effects you seek will dictate at what time of the season you will want to do your main pruning.
If you are pruning primarily to open the tree up to allow sunlight in, you will want to prune sometime during the early to middle part of the active growing season on all but the most fireblight-susceptible varieties. This will normally be from May through August, varying somewhat with the growing season in your area. You may hear this referred to as “summer pruning”. By pruning once growth has started, you avoid stimulating growth of excess “watersprouts” or suckers that often occur if the tree is pruned aggressively during the dormant season.
When your main goal is to invigorate the tree and encourage new vegetative growth, you should prune during the dormant period. Typically, the winter months from December to March to April, depending on your location, are a suitable time. Trees should have shed their leaves, active shoot growth should be finished for the season, and green tissue should be sufficiently hardened down before starting dormant pruning.
Otherwise, since pruning stimulates growth, the tree may be prompted to grow again, leaving tissue susceptible to winter cold injury. More hardy trees, such as apple or pear can be pruned almost any time during this dormant period. More cold-sensitive trees, such as cherries or plums are best pruned closer to the end of winter so that they may begin growing again soon and avoid cold injury and drying of the pruning cuts. Peaches are often pruned just after they bloom, especially in cold climates.
When pruning the mature bearing tree, it is often easiest to have a simpler system in mind. When selecting branches to prune, remove them in this order:
- Cracked, broken, or diseased branches
- Low hanging branches that drag on the ground or hang below horizontal should be cut out. The same goes for water sprouts and double leaders.
- If two branches are rubbing on each other, remove the weakest.
- Where two scaffold branches are crowding each other, remove one. Generally thus should be the lower one, but common sense will tell you if one is noticeably better than the other. Your goal is to allow about four feet vertically between parallel branches.
- Lastly, create holes for sunlight by cutting out several large lateral branches in the main canopy of the tree. Removing them will give you holes that also allow you to reach inside the tree canopy and pick the fruit.
- On a central leader tree, you may also want to head back the higher scaffolds by 20% to 50% of their length to maintain the Christmas tree shape.
If these steps are kept in mind, pruning a fruit tree can be as simple as 1-2-3. For most people, the first cut is the hardest, but with a little bit of practice, you’ll be moving right along. Common sense and increasing experience will show you which branches to prune. A regular annual pruning will make the job easiest and will also be best for the tree, but don’t worry too much; many fruit trees get along fine being pruned only once every 2 or 3 years.
Rejuvenating The Neglected Overgrown Tree
Most questions on rejuvenating an old, overgrown tree come from people who have acquired a “gentleman’s farm” in the country. Often these are old farmsteads that include a neglected fruit tree or two. The trees are likely to be apples or pears, since they are the most inclined to survive in spite of neglect.
With some patience and hard work, it is often possible to rejuvenate the forgotten tree. Several factors should be evaluated first, however:
- Is the tree still reasonably alive? Assuming it is rather large, if the main trunk and at least one-third of the major branches are still healthy, the possibility of rejuvenation exists.
- If available, sample some fruit. Your personal taste will have to serve as the judge of whether it is indeed worthy of many hours of sweat and attention.
- Ask yourself why you are saving this tree. Is it to preserve something special or is it “just because it’s there?” You will need to put more time and effort into slowly bringing an old tree back than will be required of a newly planted tree. The actual long-term cost of a newly planted tree is no more and often less than the care of a large old tree. Also, if your major goal is to preserve a variety you fear will otherwise be lost, you could gather scion wood from the old tree and propagate new trees using the normal grafting procedures.
All that said and done, if you have decided you want to pursue renovating the old trees, forge ahead! Remember that there is no need to be afraid that your pruning will do great damage to the tree. Those first cuts are always scary, but they will be a benefit to the tree if it is not already on its last leg. Should your renovation be unsuccessful, it is probable that the tree was already beyond hope, not that you did anything incorrect.
Begin renovating by cutting out all obvious dead wood. (This could involve using a chainsaw.) When cutting large limbs, remember to use the techniques illustrated earlier in this chapter. Of the live wood that remains, one-third to one-half can safely be removed. Concentrate on those limbs whose structure is the poorest. That is, broken branches, limbs growing across or rubbing on others, limbs growing too low to the ground, and limbs growing straight up.
Continue this process each year until you have obtained a desirable tree shape. You may find winter the easiest time to prune. The leaves are not on the tree and your view of the branches will be clearest then. Annually, during midsummer, remove the abundance of suckers that will appear at many of your large pruning cuts. If done when the suckers are 8 to 12 inches long, they can often just be bent downward by hand and will pop of easily.
Continue to systematically prune the tree annually for 3 to 4 years. You can remove one-third to one-half of the overgrowth each season. In several years, you should have a manageable tree. From that point on, prune it as you would any mature tree of its type.
One major caution to observe; by removing so much wood, you may fool the tree into thinking that it is being well-fed, now that the roots have fewer branches to feed. The tree may respond by growing very lush, soft green shoots. Especially on pears and apples, these shoots can be very susceptible to fiber light.
Do not encourage additional shoot growth by also feeding the tree large doses of fertilizer. Prudently feed only a very small dose in the first year or two after major renovation. Later, you can increase the dose based on the tree’s growth.
