ARBORICULTURE ARBORICULTU & CONTENTS Kenneth R. James URBAN FORESTRY Volume 40, Issue 3, May 2014 Formerly the Journal of Arboriculture, 1975 – 2005 (Volumes 1 – 31) ® www.isa-arbor.com A Study of Branch Dynamics on an Open-Grown Tree ................................................................125 Abstract. This study investigates the dynamic properties of branches on an open-grown tree, where most of the mass is in the branches rather than in the trunk. When large branches on open-grown trees sway in winds, they individually and collec- tively influence how the whole tree sways. If branches are removed, as in pruning, the effect on tree sway has not yet been stud- ied and the literature is almost nonexistent regarding recommendations for pruning open-grown trees to reduce wind damage. Trees come in many shapes and sizes and in urban areas, usually grow in open spaces and develop many branches. In forests, ® and particularly in closely spaced plantations, trees grow with an upright central trunk and develop significantly less branch mass. Forest conifers have been studied to identify their dynamic properties in winds, but the results may be different for open-grown trees. A 19.7 m tall silver maple (Acer saccharinum) with four codominant branches was tested by pulling and then releasing each branch to determine the dynamic properties. Branches were progressively removed and the tests repeated. The sway response was recorded with strain instruments attached to the trunk and accelerometers attached to each branch. The dynamic properties of frequency and damping were determined for all tests. The tree with all branches attached, in full foliage was difficult to sway because of damping from the branches. Significant changes in oscillating frequency and damping were observed only aſter most of the branches (greater than 80%) were removed. The results sup- port the concept that branches provide damping, which dissipates energy from the wind as a mechanism to help trees survive. Key Words. Acer saccharinum; Branches; Damping; Dynamics; Frequency; Silver Maple. Chanthammavong Noukoun, Gregory Bryant, and Steven D. Frank The Effect of Sticky Bands on Cankerworm Abundance and Defoliation in Urban Trees ...............135 Abstract. Defoliation by insects can reduce tree growth, increase mortality, and increase herbivory of neighboring plants. In North Carolina, U.S., fall cankerworms (Alsophila pometaria) and spring cankerworms (Paleacrita vernata) are important early-season defo- liators and have become more common in recent years. Female fall and spring cankerworm adults are wingless and climb tree trunks to mate and deposit egg masses. Therefore, sticky bands made by wrapping paper bands around trees and covering them with Tangle- Foot™ can intercept female moths as they climb, preventing oviposition and reducing subsequent larval abundance and defoliation. The authors hypothesize that sticky bands reduce cankerworm larvae and defoliation in the canopy when compared to unbanded trees. To test this hypothesis, cankerworm abundance and defoliation were measured on willow oaks with zero, one, and two bands. It was found that trees with two bands captured an average of 38.69% more moths than single banded trees. As a consequence, two-band trees had the least larvae in the canopy. It was found that larval abundance, sampled early in the season with trays of soapy water, was corre- lated with canopy defoliation at the end of the season. However, tree bands did not affect total canopy defoliation. Although many cities use sticky bands as part of cankerworm management, the authors did not find evidence for their efficacy when defoliation is low. Key Words. Alsophila pometaria; Cankerworms; Defoliation; North Carolina; Paleacrita vernata; Tree Mortality; Quercus phellos; Willow Oak. Henrik Sjöman, Johan Östberg, and Johan Nilsson Review of Host Trees for the Wood-Boring Pests Anoplophora glabripennis and Anoplophora chinensis: An Urban Forest Perspective ..............................................................143 Abstract. Two devastating insect pests have been introduced to North America and Europe – the Asian longhorned beetle (ALB) (Ano- plophora glabripennis) and the citrus longhorned beetle (CLB) (Anoplophora chinensis). These two wood-boring beetles are argued to be one of the most serious threats to the tree landscape since they have a large number of host species and genera. With the aim of cre- ating an up-to-date compilation of these hosts, a systematic review was made of the literature for information on tree species attacked and used by ALB and CLB as hosts for complete life cycle or for feeding. This review revealed that a large number of tree species and gen- era are liable to be attacked by ALB and CLB. However, based on the findings, the whole picture is still unclear. One reason for this is the lack of transparency in published studies regarding lists of susceptible tree species for ALB and CLB. Another factor that needs to be reported is whether a tree species supports the complete life cycle of the beetles or just feeding by adult beetles. Without this informa- tion, species possessing moderate host qualities are at risk of being incorrectly labelled as very good hosts and hence excluded as urban trees. Key Words. Anoplophora chinesis; Anoplophora glabripennis; Asian Longhorned Beetle; Citrus Longhorned Beetle; Host; Pests; Review; Tree Selection; Urban Trees; Wood-boring Pests. ©2014 | International Society of Arboriculture | ISSN:1935-5297
May 2014
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
