Arborist News

Trees are an important asset in our landscapes, providing many benefits. Yet we must understand that all trees present some level of risk. However, it is important to realize that the benefits trees provide far outweigh the risks. We don’t want to remove trees unnecessarily, but rather should aim to reduce risk and the potential for failure by identifying, analyzing, and evaluating risk and performing the appropriate mitigation. The key component of that process is the ability to identify common defects. (A, U, M, T, L, Bs, Bp)

Urban foresters recognize that species diversification is essential to safeguarding the urban forest and the benefits it provides. However, increasing the diversity of the urban forest does more than just improve resilience to pests. More diverse trees and plants also provide habitat for more diverse bacteria and fungi. This is important, because exposure to these microbes can stimulate the human immune system, leading to surprising health benefits for the people who live among them. (A, U, M, Bm, Bs)

Tree climbing work is hard on the body. Chronic pain and repetitive stress injuries can eventually make climbing too painful or physically difficult to continue, yet daily decisions we make on how we climb can have a direct impact on our futures in this profession. Whether it’s choosing the right tool for the job or practicing techniques that will save time and energy, there are many ways to avoid unnecessary strain and injury. In this article, five tips for climbing smarter to reduce physical effort and improve safety in the tree are discussed. (A, U, M, T, L, Bp)

There are two overarching management pressures influencing urban greening today—and the two forces are seemingly in tension. On the one hand, municipal foresters, arborists, and other professionals managing the urban and peri-urban forest are urged to increase the diversity of street- and park-tree plantings, especially at the genus level. On the other hand, stewards of the urban and peri-urban forest are also urged to only or primarily plant native tree species. There are ways, however, to resolve the tension between favoring natives and promoting diversity—without resorting to nonnatives. (A, U, M, Bp, Bm)

Bacteria, nematodes, viruses, and phytoplasmas can be spread from plant to plant by a variety of methods, including root grafts, wind, raindrop splash, animals, and humans, with insects being one of the more common and efficient methods of disease transmission. Unlike fungi, these pathogens are not capable of directly penetrating plant surfaces, but have to enter through natural plant openings, insect feeding wounds, mechanical damage, storm and flood damage, pruning wounds, or physical damage. Part two of this article series focuses on the role insect vectors play in spreading diseases caused by bacteria, nematodes, viruses, and phytoplasmas, including very brief summaries of disease life cycles and associated symptoms and signs. (A, U, M, Bp, Bs)

The first part of this perspective (published in the August 2020 issue of Arborist News) covered the common arboricultural operation incidents and the development of safety standards. The second part covers the most common event categories and the standards designed to reduce or eliminate these common hazards. (A, U, M, T, L, Bp, Bm)

Arboriculture is a global profession. It is also a profession with exposure to numerous hazards. While there are similarities in arboricultural operation hazards throughout the world, safety practices differ. There is a critical need to understand what safe work practices are required or recommended among the many countries where arboriculture is practiced as a profession. Arboriculture has international certification and climbing competitions, so standardizing safety standards is a natural outgrowth of these processes. In a world with an increasingly interconnected and mobile work force, developing uniform and effective standards can be a valuable contribution to safety. (A, U, M, T, L, Bp, Bm)

The importance of dormant buds is likely to become more significant in many parts of the world as climate warms. They are also important elements in the arboriculture of urban trees, where they can prove to be either valuable assets or the cause of significant problems that can pose both injury and property risks. Lignotubers are modified stem structures that are reservoirs of large numbers of dormant buds and are vital to the environmental stress responses of species which possess them. (A, M, T, L, Bp, Bm)

Sunken, loose bark, or oozing sap on trunks or limbs may indicate a canker, especially if associated with branch dieback. On trees, cankers are areas of localized necrosis of the bark and cambium, caused by a plant pathogen, typically a fungus or bacteria. Some canker-causing pathogens are a minor pest of trees, while others may cause branch failure or even tree death. Management of canker diseases focuses primarily on prevention and sanitation. (A, M, T, Bs, Bp)

An estimated 80 percent of aboveground issues in trees are caused by issues below ground, namely problems related to roots and soil. This has led to an increased interest in the care of belowground features, particularly to overcome soil compaction and fill materials lacking organic matter. Biochar is a form of charcoal added to soil to achieve a desired improvement in soil functions. (A, U, M, T, Bs, Bm)

There are four types of pruning cuts in arboriculture: branch removal cut, reduction cut, heading cut, and shearing cut. Although pruning live branches has a cost, it is essential to forming good structure, maintaining clearances, mitigating risk, and to meeting other objectives, so it is a necessary part of a tree care program. (A, U, M, T, Bp)

Pruning that is well executed results in a variety of benefits, including: reduced likelihood of whole tree, branch, and stem failure; appropriate (or required) clearance for utilities, buildings, vehicles, and pedestrians; improved health and appearance; and enhanced view. When poorly performed, pruning can harm the tree’s health, stability, and appearance. (A, U, M, T, Bp)