Arborist News

The utility industry’s application of tree risk assessment practices differs from that of other commercial arborists working with clients who own individual or small groups of landscape trees. While utility tree risk assessors consider individual trees, risk is assessed and managed across very large populations of trees in proximity to overhead electric lines that compose the utility forest. Likelihood of impact and likelihood of tree failure are assessed independently and then combined to determine the likelihood of the tree or tree part failing and striking the utility target. The combination of likelihood of impact and failure is then used in considering the consequences of the strike failure, which defines the level of risk. 1 CEU (A, U, M, T, L, Bm)

Arborist News quizzes are available free online to members for one year after the date of publication; a maximum of six quizzes are available at any time. CEU quizzes for older articles may be purchased by both members and non-members.

This article reviews best practices for root pruning, including two different styles and how to execute them with minimal harm. Additionally, it will help arborists understand long-term effects of root pruning and how they can negatively affect tree health and stability. Arborists will also learn how to properly care for root-pruned trees to increase a tree’s chance for full recovery. 1 CEU (A, U, M, T, L, Bm, Bp)

Variegated plants possess leaves or petals that have patches or stripes of different colours. These trees and plants have gone in and out of fashion throughout history. When they are in fashion, the cost of purchasing variegated trees can be very high, and their production can be profitable for the nursery industry. Horticulturists have long been interested in the causes of variegation and the processes that may induce variegation because of the high financial value of variegated plants and because of variegations effect on plant health. 1 CEU (A, U, M, T, L, Bs)

Tree injection is an effective way to treat many plant and pest problems. This article, based on the Tree Injection Best Management Practices, provides an overview of administering injections, from tree inspection to treatment application. 1 CEU (A, U, M, T, L, Bp, Bs)

The importance of insects cannot be understated. They are ubiquitous across the planet, playing integral roles in ecosystems on all seven continents. A robust insect community often indicates a healthy ecosystem, including in our urban landscapes. In this article, we will explore the various ecosystem services insects provide, differentiate between “beneficials” and “pests,” and discuss the use of biocontrol for the suppression of urban landscape pests. 1 CEU (A, U, M, T, L, Bs, Bp)

Urban environments and tree species composition affect the species diversity of urban decay fungi. The common and important decay fungi of urban trees in North America have similar characteristics that lend themselves to decaying and fruiting on urban trees. For arborists, this is an important point, as urban conditions potentially reduce the number of important fungi that they are likely to encounter. In this article, the “Big Five” common and important decay fungi of urban trees are reviewed. 1 CEU (A, U, M, T, L, Bs, Bp)

Support systems are installed to mitigate risk associated with certain defects, such as weakly attached and overextended branches. There are four main types of support system: cables, braces, guys, and props. The systems can be used alone or in combination to optimize support for trees while minimizing physiological stress. This article will focus on two support systems: cabling and bracing. It will describe the situations in which cabling and bracing systems may be appropriate; objectives and types of systems; hardware, tools, and techniques used to install them; and their limitations. 1 CEU (A, U, M, T, L, Bp, Bm)

Urban trees often struggle to survive, reducing their ability to provide the shade and ecosystem services needed in our cities. One of the key limitations of tree health is the poor quality of urban soils. While soil compaction is often cited as the primary challenge for urban trees, a wide variety of other factors contribute, including salinity, alkalinity, water scarcity, poor drainage, and altered biological activity. Active soil management both at time of planting and for existing trees is a powerful tool for arborists and urban foresters in their quest to cultivate a healthy urban forest. 1 CEU (A, M, Bs, Bp)

Sonic tomography is an advanced technology used to detect internal defects in trees which cannot be seen from the outside without having to resort to invasive drilling. It produces a two-dimensional image called a tomogram that can be interpreted to estimate the size of defects within the tree. The technology is used in Level 3 Tree Risk Assessments to supplement other observable conditions and to help provide a more complete understanding of the risk associated with a tree, along with better informed options for mitigating risk. 1 CEU (A, M, T, L, Bs, Bm)

IVM control methods include biological, chemical, cultural, prescribed fire and physical. Integrated vegetation management (IVM) best management practices (BMP) are to select the control method best suited to vegetation and site conditions and most often multiple control methods should be integrated for best results. Whenever possible biological methods should be implemented to establish plant communities that will never interfere with management goals and maintenance objectives. 1 CEU (A, U, M, Bp, Bs)