254 Nowak and Peck: Large Oriental Bittersweet Vines and Utility Arboriculture breakage and total collapse. Trees that have eminent risk of collapse (i.e., hazard trees) require arborists, foresters, and other tree care managers to remove them before they degrade, become more hazard- ous, and cause property damage or personal injury. Hazard trees have received heightened atten- tion in the electric utility industry, especially with elevated efforts to maintain safe and reliable trans- mission of electricity (Nowak 2010). Electric trans- mission line rights-of-way (ROWs) commonly pass through forested areas across North America. In New York and the New England area, for example, forests adjoin 60%–80% of powerline corridor edges (Guggenmoos and Sullivan 2007). In the state of Connecticut, off-ROW land uses along 115 kV trans- mission lines were most commonly forest (50%) or residential (38%) (Puolos and Camp 2010). A large portion of the off-ROW forest land has maturing tree communities that present a high and persistent potential for trees to fall into the ROW. The total number of possible danger trees—trees on or off the right-of-way that could contact electric supply lines if they fall (ANSI 2012)—in the northeastern U.S. has been estimated to be well over 4,000,000 trees (Nowak 2010). A small, but important subset of these danger trees are also hazard trees (i.e., trees that are structurally unsound). Little research has been conducted on off-ROW danger and hazard trees for electric transmission lines, and all of that research has been recent (Guggenmoos and Sul- livan 2007; Nowak 2010; Puolos and Camp 2010). Problems with trees and electric outages in electric distribution has slightly longer standing interest and research (Simpson and Van Bossuyt 1996; Guggen- moos 2003). Understanding and management of danger and hazard trees has also been of recent inter- est in other professions and disciplines, including recreation management, arboriculture and urban forestry, and wildlife management (see: Manning et al. 2002; USDA FS 2006; Maruthaveeran and Yaman 2010). Accredited sets of standards and guidelines for managing off-ROW risk trees have been recently developed (UAA 2009; ANSI 2011; ANSI 2012) for the electric utility industry. Guidance on the iden- tification, evaluation, and assessment of off-ROW danger and hazard trees have been developed using tree morphology and other techniques to reduce risk and costs associated with selective cutting and removal of high-risk trees. Identification of hazard ©2016 International Society of Arboriculture trees is based primarily on judging the condition of the tree and its potential for failure. Tree failure can occur with both sound and defective trees, but defec- tive trees are considered more susceptible to failure because of structural weaknesses in stems and roots (Albers et al. 2006). A structurally sound danger tree (low hazard) can fall into a conductor because of high winds. The same tree with defects or other problems (e.g., vines) will have a greater chance of failing in high winds and therefore presents both higher hazard and risk. It is the higher risk trees that may warrant vegetation management treatment. Oriental bittersweet and other vines (e.g., grape, Virginia creeper, poison ivy) can elevate hazard by increasing the chance of tree failure due to increase potential for crown breakage by way of accelerated branch death and increased weight of the crown, which may cause sections of crown breakage or whole trees to fail. Additionally, oriental bittersweet can constrict main stems as it twines and wraps up a tree, causing structural defects along the tree bole. Controlling oriental bittersweet before it can cause trees to become hazardous has become an important part of tree management in natural and human-built environments (Dreyer 1994; Williams and Timmins 2003), but published research specific to cut-stump herbicide effects on oriental bitter- sweet are lacking. Two publications on the use of mechanical and chemical control of oriental bit- tersweet vines were short duration studies as non- refereed Master of Science theses (Lynch 2009; Wooten 2013). Recommendations for using her- bicides and cut-stump methods to control oriental bittersweet are common in the form of information sheets and weed control handbooks (e.g., Dreyer 1994; Williams and Timmins 2003), wherein it is postulated that herbicide treatments are needed to control root suckering and stump sprouting aſter cutting. A notion of sprouting and suckering in bit- tersweet is not surprising given how many other woody plants readily sprout from adventitious buds as a form of vegetative reproduction. The use of her- bicide in conjunction with cutting is well understood as a way to control stump sprouts and root suckers of trees (Abrahamson 1983; Zedaker et al. 1987; Ballard and Nowak 2006; Kochenderfer et al. 2006; Petrice and Haack 2011), but not necessarily with woody vines. In general, various herbicides, and especially those with glyphosate as the active ingredient, can be
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