ARBORICULTURE ARBORICULTU & CONTENTS URBAN FORESTRY Volume 42, Issue 2, March 2016 Formerly the Journal of Arboriculture, 1975 – 2005 (Volumes 1 – 31) ® www.isa-arbor.com Edward F. Gilman, Maria Paz, and Chris Harchick Effect of Container Type and Root Pruning on Growth and Anchorage After Planting Acer rubrum L. into Landscape Soil .............................................................................................73 Abstract. Acer rubrum L. ‘Florida Flame’ were grown in #3 containers of eight types, then shiſted to #15 containers, then finally into #45 con- tainers. Half the trees were root pruned by removing periphery 3 cm of root ball at each shiſt to larger containers. In addition to and simul- taneous with being shiſted into successively larger containers, some trees from each container size were planted directly into soil. Type of container and root pruning had no impact on trunk diameter, tree height, or root cross-sectional area on trees planted into soil from any container size. Type of container influenced architecture of planted root systems evaluated when all trees were five-years-old with lim- ited impact on anchorage. Container type only impacted anchorage of trees planted from #45 containers, and impact was small. In contrast, shaving root balls during production substantially reduced imprint leſt by all containers evaluated when trees were five-years-old. Shav- ing during production also improved anchorage by 20%–25% compared to not root pruning. More roots grew on north than the south side of tree in the nursery and landscape. Bending stress increased with trunk angle and its square while winching trunks to five degrees tilt. Key Words. Lateral Stability; Root Architecture; Root Circling; Root Cross-Sectional Area; Root Defects; Tree Health. ® Stephen A. Wyka, Joseph J. Doccola, Brian L. Strom, Sheri L. Smith, Douglas McPherson, Srđan Aćimović, and Kier D. Klepzig Effects of Grosmannia clavigera and Leptographium longiclavatum on Western White Pine Seedlings and the Fungicidal Activity of Alamo® , Arbotect® , and TREE-äge® .................................84 Abstract. Bark beetles carry a number of associated organisms that are transferred to the host tree upon attack that are thought to play a role in tree decline. To assess the pathogenicity to western white pine (WWP; Pinus monticola) of fungi carried by the mountain pine beetle (MPB; Dendroctonus ponderosae), and to evaluate the potential for systemic prophylactic treatments for reducing fungal impacts, experi- ments were conducted with WWP seedlings to meet three objectives: 1) evaluate pathogenicity of two MPB-associated blue-stain fungi; 2) evaluate phytotoxicity of tree injection products; 3) evaluate the anti-fungal activity of tree injection products, in vitro and in vivo, toward the associated blue-staining fungi. To evaluate pathogenicity, seedlings were inoculated with Grosmannia clavigera or Leptographium lon- giclavatum, common fungal associates of MPB. Seedling mortality at four months aſter inoculation was 50% with L. longiclavatum and 90% with G. clavigera, both significantly higher than controls and thereby demonstrating pathogenicity. Phytotoxic effects of TREE-äge®, Alamo®, and Arbotect® were evaluated by stem injection; no phytotoxic effects were observed. Anti-fungal properties of the same three prod- ucts were evaluated in vitro against G. clavigera, where Alamo was most active. Co-inoculation of G. clavigera and L. longiclavatum into seedlings aſter a stem injection of Alamo showed significantly less mortality and lesion formation than either species alone. Results sup- port the hypothesis that MPB blue-stain associates, particularly G. clavigera, promote death of WWP when attacked by MPB. These findings suggest that the administration of a fungicide with insecticide for tree protection against bark beetles may be advantageous. Key Words. Bark Beetles; Blue-Stain Fungi; Emamectin Benzoate; Grosmannia clavigera; Leptographium longiclavatum; Mountain Pine Beetle; Pinus monticola; Propiconazole; Systemic Fungicide; Systemic Insecticide; Thiabendazole; Tree Injection; Western White Pine. Chris Haugen, Kevin Tucker, Alex Smalling, Emily Bick, Steve Hoover, Grant Ehlen, Todd Watson, and Shawn Bernick The Efficacy of Paclobutrazol Soil Application as it Relates to the Timing of Utility-Right-of-Way Pruning .......................................................................................................................................95 Abstract. The plant growth regulator paclobutrazol’s effect on live oak trees (Quercus virginiana) was evaluated to determine optimum timing of application and pruning time in Louisiana. Variables considered included length of branch regrowth, branch distance to conductor, pruning time and biomass chipping time. Data were evaluated to determine the ideal application timing of paclobutrazol relative to time of pruning. Live oak trees treated with paclobutrazol had significantly reduced branch regrowth, pruning time and chipping time, as compared to control trees regardless of application timing. Paclobutrazol application on live oak trees was idealized within 90 days pre- to 90 days post-prune. Economi- cally, significant gains were found by utilizing this tool ranging from 180 days pre- to 180 days post-prune, allowing for application timing flex- ibility to reduce the growth of trees near power lines. Paclobutrazol treated live oak trees demonstrated significantly less re-growth response. Key Words. Integrated Vegetation Management; Live Oak; Louisiana; Paclobutrazol; PBZ; Plant Growth Regulator; Quercus virginiana; Utility Vegetation Management. ©2016 | International Society of Arboriculture | ISSN:1935-5297
March 2016
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