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It is extremely important to manage the trees in your Forest Garden properly to promote healthy, vigorous growth. Leaving trees unmanaged weakens them, reducing production and increasing the risk of disease damage. Good tree management requires regular pruning. Pruning can be quite technical and labor-intensive, requiring different practices and considerations depending on the species, variety, and climate. However, there are a handful of general guidelines for pruning that you should follow to increase production and reduce risk of disease. The following sections describe best practices for basic pruning of agroforestry, fruit, and timber trees.

Benefits of Pruning

• Promotes healthy, vigorous growth – regular pruning strengthens trees by focusing growth on the root system and the branches you want to grow.
• Encourages production – by improving health and encouraging bud growth, pruning increases the quantity and quality of fruit and nut production.
• Prevents and controls disease – by improving tree health, trees are less susceptible to disease. Identifying and pruning diseased branches early can also prevent disease from spreading to the rest of the tree.

Pruning Do’s and Don’ts

Tools

Be sure you always prune branches with a freshly sharpened, clean tool to ensure clean cuts and reduce damage and exposure to disease pathogens. You can use pruning shears, a knife, or machete for smaller branches. For larger branches it is best to use a saw to ensure a clean cut.

How to prune

You should never pull, twist, or rip branches off, even if you have already cut through the majority of the branch. This can tear the bark on the branch or stem that you are removing it from, leaving a large wound. When removing branches always cut them flush with the branch or stem from which they originate by keeping the flat side of the pruning tool flush against it as you make the cut. Always start by cutting the bark on the underside of the branch to keep it from tearing off the bark below as the large branch falls. If you do not have a saw for larger branches you can use a sharp machete, following the steps outlined in Pruning Figure 3 to avoid damaging or wounding the tree. When large branches are pruned, you should protect the wound from diseases. Most importantly make straight cuts at angles so rain water drains off and does not collect on the wound. On large cuts, you can protect the wound by coating it with a mixture of wet clay and manure and letting it dry. However, this will only protect the wound in the dry season. Diseased branches should be cut 25 – 30 cm below the last diseased section. The branches then should be burned and any fruit buried far from the Forest Garden to prevent spread of the disease.

Pruning Fruit Trees

Pruning entails cutting off certain branches of the tree to thin the number of branches. In doing so you can increase the quality and quantity fruit yields as the tree will put more energy into growing healthy roots and fruits instead of more branches and leaves. It also protects the tree from disease. Fruit trees require periodic pruning to:

• Remove dead, damaged, and diseased branches;
• Decrease the density of the branches to promote air circulation, healthier growth, and productivity, and;
• Train the branches to grow how you want them to grow.

Stages of Pruning Fruit Trees

SEEDLINGS IN THE NURSERY You want to remove any lateral stems growing from the main stem on fruit seedlings in the nursery. You want to have one strong, straight stem on your fruit trees to promote straight and tall stem formation, which will lead to the development of a distinct trunk and crown. If it forks into two or more main stems, the seedling may expend too much energy feeding two strong stems only to have one cut later. This type of pruning starts in the nursery and may go on after outplanting for over a year until the tree attains a height of over one meter and tree shaping can occur. The better pruned your trees are, the quicker they will grow. YOUNG TREES Once trees are grafted and outplanted, or simply outplanted, tree shaping is the next step. Generally any branches lower than one meter should be removed. For all grafted trees it is important to prune away any rootstock suckers that grow below the graft union, as these will maintain the genetic makeup of the rootstock and not the scion. In addition for grafted trees, at any age, branches sprouting from beneath the graft location should be removed. At this point you can begin shaping the tree’s adult crown.  Three to four scaffold (major) branches going in different directions and originating at different heights is the goal of shaping the tree (See left diagram). After the tree is shaped any new branches coming from the trunk should be removed. Also prune secondary branches shooting from too close to the trunk (30 cm) on the scaffold branches. These precautions avoid branch crowding and create a well-shaped tree. MATURING AND ADULT TREES A good rule of thumb in pruning older trees is to periodically remove dead, damaged, diseased, and disruptive branches.   Dead – the dead wood should be removed as it will never flower or fruit again; Damaged – branches that are wounded or damaged can leave the tree more exposed and susceptible to pests and disease; Diseased – any branches, fruit, and leaves which show signs of disease should be removed to prevent the spread of the disease pathogens. Disruptive– small, new growth branches that grow inside the crown will not be exposed to sunlight, will compete for nutrients, and may not even flower and fruit. These branches will lead to overcrowding and cross-over which will disrupt healthy tree growth and productivity.

How to Prune Fruit Trees

As with any pruning, be sure to use a sharp, clean tool. For agroforestry trees that are pruned regularly, the branches are never allowed to grow to thick so pruning shears, a knife, or a machete will work fine. You should never pull, twist, or rip branches off, even if you have already cut through the majority of the branch. This can tear the bark on the branch or stem that you are removing it from, leaving a large wound. When removing branches always cut them flush with the branch or stem from which they originate by keeping the flat side of the pruning tool flush against it as you make the cut. For details refer to the Pruning Do’s and Don’ts section at the start of this article.

When to Prune Fruit Trees

Generally, good times to prune trees at different ages are:

• Seedlings in the nursery – watch them closely and prune as soon as the need, or any problem, arises;
• Young trees – just before the rainy season, when the trees are dormant;
• Mature trees – after harvest.

Notes about pruning  Very few trees require heavy pruning. Removing dead, damaged, and diseased branches periodically will generally suffice. Un-grafted mangos and cashews do not need heavy pruning, as some overcrowding will not affect tree health. Trees like guavas and Sour Sop will grow “leggy”, long spindle-like branches if not pruned but if they are in a protected field and have space there is little danger with that type of tree formation.  Trees unprotected in fields should be pruned to above the reach of livestock.          

Pruning and Managing Living Fences and Green Walls

Regular pruning of the living fence species creates a dense, impenetrable barrier. You should prune your fence at least once per year to ensure that the trees grow bushy and thick.  Pruning should begin early in the life of the tree, before the wood becomes lignified, increasing the chances of new growth low on the stem.

Stages of Pruning Living Fences

IN THE NURSERY The key to an effective living fence is to encourage early and low lateral (sideways) branching, to prevent even smaller animals like chickens and small goats from entering. If you let the trees grow too tall before pruning them, low branching will be less likely. To encourage low, lateral branching, prune the terminal buds (see Figure 2) in the nursery stage, at about two months, and then again after they grow to 75 cm to 1 m.

AFTER PLANTING After you have planted the trees in your living fence or green wall, as the branches grow long enough to reach past the stems of adjacent trees, begin weaving the branches from each tree between the stems the trees next to them. A good time to do this is when the trees are about 50 to 75 cm high. This will train the branches into lattice patterns that produce a dense barrier as the stems and branches grow. At this time, prune the terminal buds of each tree again to further encourage lateral rather than upward growth.

  MATURE TREES Once mature, the trees can be pruned into a hedge at 1.5 to 2 meter height every year. Major pruning is best done during the dry season while trees are still dormant. Light pruning and shaping can be done as often as every 4 to 6 months, or as needed. When pruning, continue to weave lateral branches through the stems of adjacent trees, and prune the remaining branches and leaves for fuelwood, fodder, and green fertilizer. ALLOWING SOME TREES TO GROW Particularly in green walls, you may select species for the inner row that do not need to be pruned as regularly, if at all. Moringa, Gliricidia or Grevillea, for example, may be selected for larger amounts of leaf growth, for timber, or for use as a windbreak. These trees generally do not need regular pruning, other than to remove dead, damaged, or diseased branches as needed, or for harvesting leaves for food in the case of Moringa.

When to Prune Living Fences

In general, the best time to do major yearly pruning of established plants is during dormancy, about a month or two before the rainy season, to inflict as little stress as possible.  To create a thorny hedge, trees should be cut when they reach the height of about 50-75 cm, as this is when they can best withstand the stress.

How to Prune Living Fences

As with any pruning, be sure to use a sharp, clean tool. For agroforestry trees that are pruned regularly, the branches are never allowed to grow to thick so pruning shears, a knife, or a machete will work fine. You should never pull, twist, or rip branches off, even if you have already cut through the majority of the branch. This can tear the bark on the branch or stem that you are removing it from, leaving a large wound. When removing branches always cut them flush with the branch or stem from which they originate by keeping the flat side of the pruning tool flush against it as you make the cut. For details refer to the Pruning Do’s and Don’ts section at the start of this article.

Using the harvest from living fences

You will harvest a large amount of branches, stems, and leaves from the living fence or green wall surrounding your Forest Garden when you prune. Be sure to put this harvest to the best use possible. You can use any larger sticks and poles as stakes or trellises in your garden for example, or for fuel wood. The small stems and branches can be incorporated into the soils in your Forest Garden to increase fertility or used as a mulch around your trees, or even added to your compost as the green, nitrogen ingredient. If you prefer, the leaves and stems can also serve as nutrient-rich fodder for your livestock. Be sure you keep the harvest from different species separate, however, and follow best practice for feeding regimes and restrictions for some species (Leucaena spp. should be fed in varying, limited amounts to most livestock, and not at all to horses and mules) to ensure healthy diets.

Pruning and managing alley cropping, contour, and dispersed trees

Most often, agroforestry trees are pruned for the products they provide, e.g. fuelwood, fodder, and poles, or to provide a service, such as protection from living fences. The agroforestry trees that we recommend for planting in Forest Gardens are selected as much for their ability to resprout quickly after pruning as for the products and services they provide. The agroforestry trees you plant using technologies other than living fences can be pruned in different ways, depending on the technology and your preference. In most cases you will coppice your trees at least once each year for their products and to limit competition for sunlight with the crops growing near them. In the case of dispersed trees, you may choose to prune them when you prune the rest of your trees or, if they are not competing for sunlight with other crops, you can allow them to grow, harvesting them when desired for timber.

When and how to prune

It is not necessary to prune agroforestry trees planted using alley cropping or contour technologies in the nursery. As you should outplant them at the beginning of the rainy season, they will be too small to compete aggressively for sunlight with your crops, so you can allow them to grow until the next cropping season. At the beginning of the next cropping season, at the onset of the rains, the trees should be at least a couple of meters high or more. At this time you want to coppice them to about 50 cm above ground level. You can do this at the beginning of each cropping season, allowing them to grow tall when they are not competing with other crops. As with any pruning, be sure to use a sharp, clean tool. For agroforestry trees that are pruned regularly, the branches are never allowed to grow to thick so pruning shears, a knife, or a machete will work fine. You should never pull, twist, or rip branches off, even if you have already cut through the majority of the branch. This can tear the bark on the branch or stem that you are removing it from, leaving a large wound. When removing branches always cut them flush with the branch or stem from which they originate by keeping the flat side of the pruning tool flush against it as you make the cut. For details refer to the Pruning Do’s and Don’ts section at the start of this article.

Using the harvest

You will harvest a large amount of branches, stems, and leaves from your agroforestry trees when you prune. Be sure to put this harvest to the best use possible. You can use any larger sticks and poles as stakes or trellises in your garden for example, or for fuel wood. The small stems and branches can be incorporated into the soils in your Forest Garden to increase fertility or used as a mulch around your trees, or even added to your compost as the green, nitrogen ingredient. If you prefer, the leaves and stems can also serve as nutrient-rich fodder for your livestock. Be sure you keep the harvest from different species separate, however, and follow best practice for feeding regimes and restrictions for some species (Leucaena spp. should be fed in varying, limited amounts to most livestock, and not at all to horses and mules) to ensure healthy diets.

Pruning and Thinning Timber Trees

Timber trees generally do not need to be pruned as regularly as fruit and agroforestry trees but they will need to be thinned when planted closely together for intensive timber production. Thinning essentially reduces the number of trees planted in an area to allow more growing space for those remaining. The goal is to reach optimal spacing for the mature trees to produce large, straight trunks. The main concern for timber trees is that they grow into tall, straight, single-trunked trees with limited low branching. When you first plant timber trees you can plant them at closer spacing. As the trees start to grow into each other, competing for space, you can thin every other trees for smaller poles, providing the remaining trees with more space to grow taller and thicker. Timber trees do need more care in the first 1 or 2 years after the seedlings have been outplanted, though they will have been hardened off in preparation for leaving the tree nursery. As with any other trees, timber trees may be harmed by frost, drought, wind, browsing animals and poor soil.

Thinning

A good timber tree will give you long, straight logs. When you first outplant your timber seedlings, plant them close together, as close as 1 to 2 meters apart, depending on the species. This keeps branches small so that the tree’s energy goes towards developing a strong, straight trunk that does not taper too much (grow thin at the top). Closely grouped trees will be less exposed to the wind, too. As the trees grow larger, they will begin to compete with each other for water, light and soil nutrients. After 4 to 6 years or more, depending on the species, spacing, and growth, the trees will fill in the canopy. At this time you will want to thin out some of the trees to allow the remaining trees to grow without competition. Thin out trees that are weak, bent, diseased, or that have dead tops. Also cut down those with trunks that lean or have branched into two, and those with many side branches. These can be used for posts, tools, or fuelwood.

Pruning

Pruning timber trees, also called lopping, is generally done when the stand is 6 to 10 years old, depending on the species and growth rate. At this time, you will remove all lower branches to a height as high as you can reach, as well as any secondary branches. Pruning encourages straight growth and creates more clear, knot-free wood, which should add value to the timber logs when sold. It also reduces fire hazard by eliminating fuel sources close to the ground and improving access underneath the trees. A saw is best for cutting larger timber branches. If you do not have a saw, follow the guidelines for cutting branches with a machete (Pruning Do’s and Don’ts, Figure 3). As with any pruning, be sure to use a clean, sharp tool, and cut branches flush with the stem. Pruning of timber trees should take place when the trees are dormant, usually at the end of the dry season. Note that some species may not respond well to pruning as they may require a larger percent of live crown, so be sure you know the growing characteristics of the timber trees you plant. In any case, trees that are pruned must have an adequate percentage of live crown remaining to support the tree. Lopping too much can weaken the tree, thus slowing growth and making it vulnerable to disease or insect attack.

Timber Management

The trees left to grow should be roughly 25 times the diameter of the thickest trunk away from each other. The remaining trees can be left in your Forest Garden to continue growing for years, even decades. As the trees become more valuable as they age, they can serve as a savings account, harvesting (or withdrawing) trees as needed for your own use or for sale. If you (or your children, or grandchildren!) choose to harvest many at once, many years down the line, it is best to do so in sections. You can clear-cut a section of the trees at one time, leaving the other sections to grow. After cutting a section, you can replant it with new timber seedlings and begin the process again. Since the section is cleared, there will be minimal competition for sunlight and other nutrients. These trees will then begin to grow, maturing over time as you cut and replant the other sections, one by one, in a rotational timber management system. This will ensure you always have trees growing at different maturity levels.

Note on Spacing and Design

This section describes a timber system where trees are planted closely together for the primary purpose of timber production. In this scenario, an entire section of your Forest Garden will be set aside for timber and little else. Because timber trees require relatively little care after the first couple of years, it is best to plant your timber trees further from your home, so that other trees and crops that do require more attention are more accessible. Depending on your Forest Garden design and interests, however, you may also choose to plant your timber seedlings further apart. This will decrease the canopy density, allowing for more sunlight to reach understory crops. It is also possible to disperse timber trees throughout your Forest Garden, among fruit trees and other crops, in a more integrated design. In these cases, thinning of your timber trees may not be necessary. References For more information, take a look at the following resources:

1. Forestry Plantation Written by Norman Jones. http://www.agroforestry.net/2014-03-04-10-06-24/forestry-plantation
2. Overstory #217 – Pruning Of Timber Trees Written by Rowan Reid. Posted in The Overstory eJournal http://www.agroforestry.net/overstory-back-issues/40-overstory-217-pruning-of-timber-trees
3. Overstory #182 – Remember To Touch Trees Written by A selection of passages by Alex L. Shigo. Posted in The Overstory eJournal http://www.agroforestry.net/overstory-back-issues/89-overstory-182-remember-to-touch-trees
4. World Agroforestry Centre http://www.worldagroforestry.org/downloads/Publications/PDFS/b15299.pdf