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 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.
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.
Pruning is a horticultural, arboricultural, and silvicultural practice involving the selective removal of certain parts of a plant, such as branches, buds, or roots.
Oak wilt is a fungal disease caused by the organism Bretziella fagacearum that threatens Quercus spp. The disease is limited to the Midwestern and Eastern United States; first described in the 1940s in the Upper Mississippi River Valley. The pathogen penetrates xylem tissue, preventing water transport and causing disease symptoms. Symptoms generally consist of leaf discoloration, wilt, defoliation, and death. The disease is dispersed by insect vectors and to adjacent trees through underground root networks. However, human spread is the most consequential dispersal method. Moving firewood long distances can potentially transport diseases and invasive species.
Girdling, also called ring-barking, is the complete removal of the bark from around the entire circumference of either a branch or trunk of a woody plant. Girdling results in the death of the area above the girdle over time. 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. 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.
In trees, heart rot is a fungal disease that causes the decay of wood at the center of the trunk and branches. Fungi enter the tree through wounds in the bark and decay the heartwood. The diseased heartwood softens, making trees structurally weaker and prone to breakage. Heart rot is a major factor in the economics of logging and the natural growth dynamic of many older forests. Heart rot is prevalent throughout the world affecting all hardwood trees and can be very difficult to prevent. A good indication of heart rot is the presence of mushrooms or fungus conks on the tree.
A bridge graft is used to supply nutrients to the rootstock of a woody perennial when the bark, and therefore the conductive tissues, have been removed from part of the trunk. This wound is often caused by rabbits or other rodents, stripping the bark away and girdling the tree. The inability of the plant to transport food manufactured in the leaves down to the root system, causes the root system to die and in the death cycle, the resulting lack of root system causes the upper portions of the plant to die. Where one-quarter or less of the trunk circumference has been girdled, it may not be necessary to use this technique. It is also difficult on small caliper tree trunks. A bridge graft uses scions to 'bridge' the gap. Each scion is taper cut in order to accommodate the need for matching the cambium layers of the scion with those of the tree being repaired. Once in place the graft wounds must be completely sealed to prevent moving of tissues which would inhibit them from joining together and to prevent dissection of the site which would lead to the death of the scions.
The American Elm cultivar Ulmus americana 'Valley Forge' was raised by the Agricultural Research Service in Maryland. The tree was released to wholesale nurseries without patent restrictions by the U. S. National Arboretum in 1995 after proving to have a high resistance to Dutch elm disease. 'Valley Forge' proved only moderately successful in the US National Elm Trial, averaging a survival rate of 66.7% overall, owing largely to environmental factors rather than susceptibility to disease.
The Japanese elm cultivar Ulmus davidianavar.japonica 'Prospector' was originally treated as a cultivar of Wilson's elm U. wilsonianaSchneid., a species sunk as Ulmus davidiana var. japonica by Fu. A U.S. National Arboretum introduction, it was selected in 1975 from a batch of 1965 seedlings in Delaware, Ohio, and released without patent restrictions in 1990. 'Prospector' proved moderately successful in the US National Elm Trial, averaging a survival rate of 76% overall.
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 plant pathogenic fungus Leucostoma kunzei is the causal agent of Leucostoma canker, a disease of spruce trees found in the Northern Hemisphere, predominantly on Norway spruce and Colorado blue spruce. This disease is one of the most common and detrimental stem diseases of Picea species in the northeastern United States, yet it also affects other coniferous species. Rarely does it kill its host tree; however, the disease does disfigure by killing host branches and causing resin exudation from perennial lesions on branches or trunks.
Phellinus pini is a fungal plant pathogen that causes tree disease commonly known as "red ring rot" or "white speck". This disease, extremely common in the conifers of North America, decays tree trunks, rendering them useless for lumber. It is a rot of the heartwood. Signs of the fungus include shelf-shaped conks protruding from the trunks of trees. Spores produced on these conks are blown by the wind and go on to infect other trees. Formal management of this disease is limited, and the disease is controlled primarily by cultural practices. Red ring rot is an important forest disturbance agent and plays a key role in habitat formation for several forest animals.
Fir and spruce forests are greatly affected by slight fluctuations in climate. Temperature is the primary determinate for spatial patterns of fir and spruce. The two dominant trees in this type of forest are Picea engelmannii and Abies lasiocarpa. Although thick-barked trees, such as the Pinus resinosa, frequently survive fire, the thin bark of spruce make them more vulnerable. Trees such as the Douglas fir withstand much of the fire due to the thicker bark they have. The scale of the burn mosaic during a fire, relative to species niche requirements and mobility, can have major impacts on flora and fauna dynamics.
Water sprouts or water shoots are shoots that arise from the trunk of a tree or from branches that are several years old, from latent buds. The latent buds might be visible on the bark of the tree, or submerged under the bark as epicormic buds. They are sometimes called suckers, although that term is more correctly applied to shoots that arise from below ground, from the roots, and a distance from the trunk. Vigorous upright water sprouts often develop in response to damage or pruning.
Frost crack or Southwest canker is a form of tree bark damage sometimes found on thin barked trees, visible as vertical fractures on the southerly facing surfaces of tree trunks. Frost crack is distinct from sun scald and sun crack and physically differs from normal rough-bark characteristics as seen in mature oaks, pines, poplars and other tree species.
Trees can live for a long time but eventually die, either from natural causes or killed by man. Ill-health of trees can be diagnosed, and early treatment, pruning or felling to prevent the spread may result in timber stocks and amenity trees being saved. Tree owners and Arborists/arboriculturists need to be aware of the risk posed by hazardous trees. Construction projects sometimes avoidably damage trees.
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.
Hypoxylon canker of shade trees is a weak ascomycete fungus that negatively affects growth and can eventually lead to the death of already dying or diseased host trees. There are many different species that affect different trees. For example, Hypoxylon atropunctatum, a common species, is found on oak trees, Hypoxylon tinctor affects sycamore trees, and Hypoxylon mammatum infests aspen trees.
Aspen trunk rot is a fungal disease that causes stem decay heart rot of living aspen trees. The pathogen that causes this disease is the fungus Phellinus tremulae. Most of the symptoms of this disease are internal, with the only external signs of a diseased aspen being fruiting bodies called conks. A single conk found on an aspen can indicate advanced decay of up 82% of the tree volume. Internal decayed wood of freshly cut aspens is spongy, yellow/white colored, surrounded by black zones of discoloration, and contains a distinct wintergreen smell. The fungus is spread via airborne spores released from the fruiting body which can infect through dead branches, branch stubs, or wounds in the tree. Although no direct management control is known, harvesting aspen stands that have been damaged or harvesting stands before decay becomes advanced minimizes tree loss. Aspen wood is white, malleable but strong, and heat-tolerant and therefore has many commercial uses including matches, packing paper, lumber, plywood, pulp, and animal beds. Aspen trees diseased with aspen trunk rot decrease the economic value of the lumber.
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.
