96 Haugen et al.: Efficacy of PBZ Soil Application for Utility Right-of-Way Pruning Previous work indicates that PBZ may signifi- cantly reduce the time required for utility line- clearance pruning operations due to its effect of reducing regrowth. The purpose of this trial was a) to investigate proper timing of PBZ soil applica- tions and pruning events effect on resurgent growth in live oak trees (Quercus virginiana), b) to explore the amount of time crews spent on-site pruning and processing biomass from a pruning event aſter trees were treated with PBZ, and c) to relate biomass reduction due to PBZ application to economic cost. MATERIALS AND METHODS Forty-eight live oak trees were randomly selected from one Entergy Louisiana, LLC. distribution circuit in a mixed residential and commercial neighborhood in Baton Rouge, Louisiana, U.S. All trees are located in urban environments ad- jacent to roadways or commercial structures. Trees were selected in proximity to energized distribution lines and were accessible to a util- ity line-clearance contractor with a hydraulic bucket for pruning. All trees were measured for initial diameter at breast height (dbh) in 2009 and assessed for general tree health. Study trees had a mean 73.66 cm DBH. All trial trees were pruned in a manner consistent with American National Standards Institute (ANSI) A300 and ISA best management practices, and according to Entergy Louisiana, LLC. urban tree care speci- fications of 3.048 m of clearance from all ener- gized lines and other equipment (Entergy 2014). Trees were assigned one of eight a treatment timings using randomized complete block design, with six replications to account for dif- ferences in site conditions. Timings were as fol- lows: PBZ applied at the time of pruning, 180 Plant growth Untreated control 180 days pre-prune 90 days pre-prune 30 days pre-prune At time of pruning 30 days post-prune 90 days post-prune 180 days post-prune regulator application N/A PBZ 22.3% PBZ 22.3% PBZ 22.3% PBZ 22.3% PBZ 22.3% PBZ 22.3% PBZ 22.3% days pre-prune, 90 days pre-prune, 30 days pre-prune, 180 days post-prune, 90 days post- prune, 30 days post-prune, or untreated control (Table 1). Applications of 22.3% PBZ (Cambi- stat 2SC, Rainbow Treecare Scientific Advance- ments, Minnetonka, Minnesota, U.S.) were initiated in July of 2009 with the 180 days pre- prune treatment and concluded in July of 2010 with the 180 days post-prune treatment (Table 1). Treatments were timed to coincide with regularly scheduled pruning that occurred in late January/early February of 2010 (Table 1). PBZ was applied at a rate of 1.81 grams of active ingredient per centimeter diameter at breast height (label rate of PBZ) to the study trees. PBZ was mixed with 11:1 (water: PBZ) ratio to cre- ate a ready-to-use solution. All applications were made using a subsurface soil injection system (HTI 2000 Rainbow Treecare Scientific Advancements, Minnetonka, Minnesota, U.S.). Soil injections were applied below the soil surface at a depth of 10 to 15 cm and 98.4 ml of ready to use solution was applied for every centimeter of trunk diam- eter. Soil injection sites were spaced evenly at the base of the tree within 30.5 centimeters of the root flare, and applications were made by an ISA Certified Arborist® from Edko, LLC, Shreve- port, Louisiana, U.S. (formerly Advanced Appli- cators Inc.). The mixed solution was injected into the soil surface at 1.034 megapascals. In late January and early February of 2013, aſter three growing seasons, all study trees were re-pruned and evaluated by branch length from energized wires, branch re-growth aſter pruning, and pruning and chipping time. To measure branch re-growth, all trees were pruned to a 3.048 m clearing standard using an aerial bucket Table 1. PBZ treatment and application dates for live oak trees (Quercus virginiana) in Baton Rouge, Louisiana, U.S. Treatment # of trees in treatment 6z 6 6 6 6 6 6 6 z One untreated control tree was removed from data-set due to extreme environmental conditions. Application date N/A 07 July 2009 15 October 2009 07 December 2009 15 January 2010 16 February 2010 28 April 2010 14 July 2010 ©2016 International Society of Arboriculture
March 2016
| 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
