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Pruning is a horticultural, arboricultural, and silvicultural practice involving the selective removal of certain parts of a plant, such as branches, buds, or roots.
The practice entails the targeted removal of diseased, damaged, dead, non-productive, structurally unsound, or otherwise unwanted plant material from crop and landscape plants. In general, the smaller the branch that is cut, the easier it is for a woody plant to compartmentalize the wound and thus limit the potential for pathogen intrusion and decay. It is therefore preferable to make any necessary formative structural pruning cuts to young plants, rather than removing large, poorly placed branches from mature plants.
Woody plants may undergo a process referred to as "self-pruning", where they will drop twigs or branches which are no longer producing more energy than they require. It is theorized that this process can also occur in response to lack of water, in order to reduce the surface area where water can be lost. [1] This natural shedding of branches is called cladoptosis.
Specialized pruning practices may be applied to certain plants, such as roses, fruit trees, and grapevines. Different pruning techniques may be used on herbaceous plants than those used on perennial woody plants.
Reasons to prune plants include deadwood removal, shaping (by controlling or redirecting growth), improving or sustaining health, reducing risk from falling branches, preparing nursery specimens for transplanting, and both harvesting and increasing the yield or quality of flowers and fruits.
Branch wood is an individual stem that grows off of another stem.
Trunk wood is the main stem of a tree which individual stems grow out of.
This refers to the area below the union of where branch wood attaches with the trunk/stem wood. This can often appear raised.
This refers to the junction between branch wood and trunk/stem wood. It usually looks raised. [2]
Pruning in an urban setting is crucial due to the tree being in drastically different conditions than where they naturally grow. [3]
Arborists, orchardists, and gardeners use various garden tools and tree cutting tools designed for the purpose, such as secateurs, loppers, handsaws, or chainsaws. [4] Additionally in forestry, pole pruners and pole saws are commonly used and these are often attached to poles that reach up to 5-6 m, this is a more efficient way of pruning than with ladders. These bush saws on polls have also been motorized as chainsaws which is even more efficient. Older technology used Billhooks, Kaiser blades and pruning knives. Although still used in some coppicing they are not used so much in commercial forestry due to the difficulty of cutting flush with the stem. Flush cuts happen when you cut into the cambium layer of the main trunk which can happen when you are not precise with pruning cuts and remove a portion of the branch collar which can put the tree at risk of entry cords from forest pathogens.
Although there are several different types of pruning they can be simplified into two categories. One of which is cutting the branch back to a specific and intermediate point, called reduction cut, and the other completely removes a branch back to the union where the branch connects which the main trunk, called removal cut. [5]
Reduction cuts is when you remove a portion of a growing stem down to a set of desirable buds or side-branching stems. This is commonly performed in well trained plants for a variety of reasons, for example to stimulate growth of flowers, fruit or branches, as a preventive measure to wind and snow damage on long stems and branches, and finally to encourage growth of the stems in a desirable direction.
In orchards, fruit trees are often lopped to encourage regrowth and to maintain a smaller tree for ease of picking fruit. The pruning regime in orchards is more planned and the productivity of each tree is an important factor.
Branches die off for a number of reasons including sunlight deficiency, pest and disease damage, and root structure damage. A dead branch will at some point decay back to the parent stem and fall off. This is normally a slow process but can be hastened by high winds or extreme temperatures. The main reason deadwooding is performed is safety. Situations that usually demand removal of deadwood include trees that overhang public roads, houses, public areas, power lines, telephone cables and gardens. Trees located in wooded areas are usually assessed as lower risk but assessments consider the number of visitors. Trees adjacent to footpaths and access roads are often considered for deadwood removal. [8]
Another reason for deadwooding is amenity value, i.e. a tree with a large amount of deadwood throughout the crown will look more aesthetically pleasing with the deadwood removed. The physical practice of deadwooding can be carried out most of the year though should be avoided when the tree is coming into leaf. The deadwooding process speeds up the tree's natural abscission process. It also reduces unwanted weight and wind resistance and can help overall balance.
Preventative and structural pruning can be done to mitigate several issues young trees may have in the future. The structural pruning can reduce tree stress, increase the lifespan of trees, and promotes resistance to damage due to natural weather events. Attributes of trees with good structure include excurrent growth by having a single dominant leader, branch unions without included bark, and a balanced canopy. Structural pruning does this by developing or maintaining a dominant leader, identify the lowest branches in the canopy, prevent branches below the permanent canopy from growing too large, keeping all branches less than one half the trunk diameter, space main branches along one dominant trunk, and suppress growth on branches with included bark. [9]
Subordination pruning is done on limbs that will exceed 50% percent of the stem diameter. A reduction cut may be performed while still allowing about 50% of the branch. This is done to help maintain form and deter the formation of co-dominant leaders. Temporary branches may be too large for a removal cut so subordination pruning should be done to slowly reduce a limb by 50% each year to allow the tree to properly heal from the cut. As a tree becomes larger the slower it grows. Reducing the larger limbs for eventual removal will allow for the tree to promote new growth rather than using energy in encouraging unwanted limbs to continue to grow. Removing a large branch increases the likelihood of the cut to not heal properly which also may attract insects, diseases and fungus. [9] [10]
Crown thinning is the removal of live healthy branches which increases light penetration, air circulation and reduces wind resistance which reduces risks from damage and the possibility of pest infestation. [11]
Crown raising involves the removal of the lower branches to a given height. The height is achieved by the removal of whole branches or removing the parts of branches which extend below the desired height. The branches are normally not lifted to more than one third of the tree's total height.
Crown lifting is done for access; these being pedestrian, vehicle or space for buildings and street furniture. Lifting the crown will allow traffic and pedestrians to pass underneath safely. This pruning technique is usually used in the urban environment as it is for public safety and aesthetics rather than tree form and timber value.
Crown lifting introduces light to the lower part of the trunk; this, in some species can encourage epicormic growth from dormant buds. To reduce this sometimes smaller branches are left on the lower part of the trunk. Excessive removal of the lower branches can displace the canopy weight, this will make the tree top heavy, therefore adding stress to the tree. When a branch is removed from the trunk, it creates a large wound. This wound is susceptible to disease and decay, and could lead to reduced trunk stability. Therefore, much time and consideration must be taken when choosing the height the crown is to be lifted to.
This would be an inappropriate operation if the tree species’ form was of a shrubby nature. This would therefore remove most of the foliage and would also largely unbalance the tree. This procedure should not be carried out if the tree is in decline, poor health or dead, dying or dangerous (DDD) as the operation will remove some of the photosynthetic area the tree uses. This will increase the decline rate of the tree and could lead to death.
If the tree is of great importance to an area or town, (i.e. veteran or ancient) then an alternative solution to crown lifting would be to move the target or object so it is not in range. For example, diverting a footpath around a tree's drip line so the crown lift is not needed. Another solution would be to prop up or cable-brace the low hanging branch. This is a non-invasive solution which in some situations may be more economical and environmentally friendly. [12]
Selectively pruning a window of view in a tree.
Reducing the height and or spread of a tree by selectively cutting back to smaller branches and in fruit trees for increasing of light interception and enhancing fruit quality.
A regular form of pruning where certain deciduous species are pruned back to pollard heads every year in the dormant period. This practice is usually commenced on juvenile trees so they can adapt to the harshness of the practice. This practice can be used for tree shaping but is also used in specific species which young branches can be sold for floral arrangements.
Deadheading is the act of removing spent flowers or flowerheads for aesthetics, to prolong bloom for up to several weeks or promote rebloom, or to prevent seeding.
In general, pruning deadwood and small branches can be done at any time of year. Depending on the species, many temperate plants can be pruned either during dormancy in winter, or, for species where winter frost can harm a recently pruned plant, after flowering is completed. In the temperate areas of the northern hemisphere autumn pruning should be avoided, as the spores of disease and decay fungi are abundant at this time of year.
Some woody plants tend to bleed profusely from cuts, such as mesquite and maple. Some callus over slowly, such as magnolia. In this case, they are better pruned during active growth when they can more readily heal. Woody plants that flower early in the season, on spurs that form on wood that has matured the year before, such as apples, should be pruned right after flowering as later pruning will sacrifice flowers the following season. Forsythia, azaleas and lilacs all fall into this category.
A shrub or bush is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple stems and shorter height, less than 6–10 m (20–33 ft) tall. Small shrubs, less than 2 m (6.6 ft) tall are sometimes termed as subshrubs. Many botanical groups have species that are shrubs, and others that are trees and herbaceous plants instead.
Fruit trees are grown in a variety of shapes, sometimes to please the eye but mainly to encourage fruit production. The form or shape of fruit trees can be manipulated by pruning and training. Shaping and promoting a particular tree form is done to establish the plant in a particular situation under certain environmental conditions, to increase fruit yield, and to enhance fruit quality. For example, pruning a tree to a pyramid shape enables trees to be planted closer together. An open bowl or cup form helps sunlight penetrate the canopy, thus encouraging a high fruit yield whilst keeping the tree short and accessible for harvesting. Other shapes such as cordons, espaliers and fans offer opportunities for growing trees two dimensionally against walls or fences, or they can be trained to function as barriers.
Fruit tree pruning is the cutting and removing of selected parts of a fruit tree. It spans a number of horticultural techniques. Pruning often means cutting branches back, sometimes removing smaller limbs entirely. It may also mean removal of young shoots, buds, and leaves.
Pollarding is a pruning system involving the removal of the upper branches of a tree, which promotes the growth of a dense head of foliage and branches. In ancient Rome, Propertius mentioned pollarding during the 1st century BCE. The practice has occurred commonly in Europe since medieval times, and takes place today in urban areas worldwide, primarily to maintain trees at a determined height or to place new shoots out of the reach of grazing animals.
In botany, apical dominance is the phenomenon whereby the main, central stem of the plant is dominant over other side stems; on a branch the main stem of the branch is further dominant over its own side twigs.
Arboriculture is the cultivation, management, and study of individual trees, shrubs, vines, and other perennial woody plants. The science of arboriculture studies how these plants grow and respond to cultural practices and to their environment. The practice of arboriculture includes cultural techniques such as selection, planting, training, fertilization, pest and pathogen control, pruning, shaping, and removal.
An arborist, tree surgeon, or arboriculturist, is a professional in the practice of arboriculture, which is the cultivation, management, and study of individual trees, shrubs, vines, and other perennial woody plants in dendrology and horticulture.
Espalier is the horticultural and ancient agricultural practice of controlling woody plant growth for the production of fruit, by pruning and tying branches to a frame. Plants are frequently shaped in formal patterns, flat against a structure such as a wall, fence, or trellis, and also plants which have been shaped in this way.
Thinning is a term used in agricultural sciences to mean the removal of some plants, or parts of plants, to make room for the growth of others. Selective removal of parts of a plant such as branches, buds, or roots is typically known as pruning.
Girdling, also called ring-barking, is the circumferential removal or injury of the bark of a branch or trunk of a woody plant. Girdling prevents the tree from sending nutrients from its foliage to its roots, resulting in the death of the tree over time, and can also prevent flow of nutrients in the other direction depending on how much of the xylem is removed. A branch completely girdled will fail and when the main trunk of a tree is girdled, the entire tree will die, if it cannot regrow from above to bridge the wound. Human practices of girdling include forestry, horticulture, and vandalism. Foresters use the practice of girdling to thin forests. Extensive cankers caused by certain fungi, bacteria or viruses can girdle a trunk or limb. Animals such as rodents will girdle trees by feeding on outer bark, often during winter under snow. Girdling can also be caused by herbivorous mammals feeding on plant bark and by birds and insects, both of which can effectively girdle a tree by boring rows of adjacent holes.
A branch collar is the "shoulder" between the branch and trunk of woody plants; the inflammation formed at the base of the branch is caused by annually overlapping trunk tissue. The shape of the branch collar is due to two separate growth patterns, initially the branch grows basipetally, followed by seasonal trunk growth which envelops the branch.
The crown of a plant is the total of an individual plant's aboveground parts, including stems, leaves, and reproductive structures. A plant community canopy consists of one or more plant crowns growing in a given area.
A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. In cold climates, woody plants further survive winter or dry season above ground, as opposed to herbaceous plants that die back to the ground until spring.
In viticulture, the canopy of a grapevine includes the parts of the vine visible aboveground - the trunk, cordon, stems, leaves, flowers, and fruit. The canopy plays a key role in light energy capture via photosynthesis, water use as regulated by transpiration, and microclimate of ripening grapes. Canopy management is an important aspect of viticulture due to its effect on grape yields, quality, vigor, and the prevention of grape diseases. Various viticulture problems, such as uneven grape ripening, sunburn, and frost damage, can be addressed by skillful canopy management. In addition to pruning and leaf trim, the canopy is often trained on trellis systems to guide its growth and assist in access for ongoing management and harvest.
A defensible space, in the context of fire control, is a natural and/or landscaped area around a structure that has been maintained and designed to reduce fire danger. The practice is sometimes called firescaping. "Defensible space" is also used in the context of wildfires, especially in the wildland-urban interface (WUI). This defensible space reduces the risk that fire will spread from one area to another, or to a structure, and provides firefighters access and a safer area from which to defend a threatened area. Firefighters sometimes do not attempt to protect structures without adequate defensible space, as it is less safe and less likely to succeed.
The use of vine training systems in viticulture is aimed primarily to assist in canopy management with finding the balance in enough foliage to facilitate photosynthesis without excessive shading that could impede grape ripening or promote grape diseases. Additional benefits of utilizing particular training systems could be to control potential yields and to facilitate mechanization of certain vineyard tasks such as pruning, irrigation, applying pesticide or fertilizing sprays as well as harvesting the grapes.
Bonsai cultivation and care involves the long-term cultivation of small trees in containers, called bonsai in the Japanese tradition of this art form. Similar practices exist in other Japanese art forms and in other cultures, including saikei (Japanese), penjing (Chinese), and hòn non bộ (Vietnamese). Trees are difficult to cultivate in containers, which restrict root growth, nutrition uptake, and resources for transpiration. In addition to the root constraints of containers, bonsai trunks, branches, and foliage are extensively shaped and manipulated to meet aesthetic goals. Specialized tools and techniques are used to protect the health and vigor of the subject tree. Over time, the artistic manipulation of small trees in containers has led to a number of cultivation and care approaches that successfully meet the practical and the artistic requirements of bonsai and similar traditions.
Leucostoma canker is a fungal disease that can kill stone fruit. The disease is caused by the plant pathogens Leucostoma persoonii and Leucostoma cinctum (teleomorph) and Cytospora leucostoma and Cytospora cincta (anamorphs). The disease can have a variety of signs and symptoms depending on the part of the tree infected. One of the most lethal symptoms of the disease are the Leucostoma cankers. The severity of the Leucostoma cankers is dependent on the part of the plant infected. The fungus infects through injured, dying or dead tissues of the trees. Disease management can consist of cultural management practices such as pruning, late season fertilizers or chemical management through measures such as insect control. Leucostoma canker of stone fruit can cause significant economic losses due to reduced fruit production or disease management practices. It is one of the most important diseases of stone fruit tree all over the world.
A branch attachment is where a branch is attached to the trunk of a tree. Three types of branch attachment are recognized due to differences in the anatomical position of buds that form them. Two key components contribute to the mechanical strength and toughness of the attachment: interlocking wood grain at the top of the attachment and an embedded knot that often lies within the attachment. A common malformation of a branch attachment is the inclusion of bark within the join, which can weaken the attachment.