Tree diseases, hollowing and assessment remain current topics in arboriculture

Abstract

Along with reviews and letters, this first issue of the new year brings four papers and covers a variety of arboricultural topics. With tree diseases very much to the fore at the present time, Copeland et al. (2023) consider the current situation with Dutch Elm Disease in North America. The American elm (Ulmus americana) is a hugely significant tree across wide areas of North America, but as with elms throughout Western Europe, its status has been badly compromised by disease. There are issues in terms of the spread of the infection, of the potential for disease-resistant trees, and of how urban tree managers might deal with the issues that the American elms pose in towns and cities across the continent. With climate change, widespread environmental stresses, and increasing globalisation, problems such as Dutch Elm Disease are certain to grow in the decades to come, and reviews of key issues are therefore especially welcome and timely. Along with diseases, tree-related hazards are another major issue in on-going debates in the arboricultural industry. In urban areas, the risks posed by tree failure are also connected to the amount of traffic on a particular highway, and therefore assessing this in ways that are low cost, effective, and reliable, becomes imperative. Klein et al. (2023) have researched the development of a potential low-cost traffic counter to address these issues. They note the importance of reliable traffic counts (vehicles and pedestrians) in evaluating collisionand failure-related risks, and that the use of automatic counters may be prohibited by cost. Their study presents comparative findings from homemade counters and commercial units, with significant errors from both. The errors for both commercially manufactured and homemade units appear to increase with ambient temperatures. Steel (2023) has evaluated the issues for weaknesses in multi-stemmed trees where weak unions or attachments may generate concerns about structural integrity and possible failure. This becomes particularly important when considering significant specimen trees where interventions to strengthen the structure might be considered but may have longer-term problems. This interesting study assesses the potential of triggering natural support through inducing wound wood growth rather than through physical mechanical interventions alone. The new growth was induced through insertion of a plastic beam into the tree tissue. Manipulating the tree’s natural growth responses may offer effective ways in which to reduce risk. An important question posed is when the time is right to wound a tree to promote growth to reduce failure. Again, connected to assessment of risk and tree failure the study reported by Tong and Slater (2023) researched the impacts on current investigations into tree hollowing and rot, of earlier measures taken to fill tree cavities (such as with foam) to strengthen Arboricultural Journal 2023, VOL. 45, NO. 1, 1–2 https://doi.org/10.1080/03071375.2023.2177429