ARBORICULTURE ARBORICULTU URBAN FORESTRY Volume 32, Issue 5, September 2006 & CONTENTS Formerly the Journal of Arboriculture, 1975 – 2005 (Volumes 1 – 31) www.isa-arbor.com Randall James, Ned Tisserat, and Tim Todd Prevention of Pine Wilt of Scots Pine (Pinus sylvestris) with Systemic Abamectin Injections ..................................................................................................................195 Abstract. We examined the efficacy of the insecticide/nematicide abamectin to prevent pine wilt disease caused by the pinewood nematode (Bur- saphelenchus xylophilus) in Scots pine (Pinus sylvestris). Pinewood nematode movement was inhibited (>80% death or paralysis) following a 48 hr exposure to abamectin concentrations as low as 0.1 µL a.i. per L (100 ppb). A commercial formulation of abamectin (Avid™) was injected into Scots pine using a pressurized systemic trunk injection tube (STIT) technique. Fiſteen to 30 mL (0.45 to 0.90 fl oz) of Avid per STIT could be injected into the trees in less than 1 hr. Trees were successfully injected throughout February, March, and April at temperatures above 4.4°C (40°F). Survival aſter 1 year of 10 cm diameter (4 in) at breast height (dbh) Scots pines injected with Avid and subsequently inoculated with pin wood nematode was higher (75%) than in pines injected with water (42%). Similarly, survival aſter 3 years of large Scots pines (30 to 60 cm [12 to 24 in] dbh)] injected with Avid and exposed to a natural epidemic of pine wilt was higher (96%) than in noninjected pines (33%) or those injected with water (71%). These results indicate that preventive injections of Scots pine with Avid are effective in protecting against pine wilt disease. Key Words. Abamectin; Avid; Bursaphelenchus xylophilus; Pine Wilt; Pinewood Nematode; Pinus sylvestris; Scots Pine; Tree Injections. Daniel K. Struve, Petra Sternberg, Nick Drunasky, Kurt Bresko, and Rico Gonzalez Growth and Water Use Characteristics of Six Eastern North American Oak (Quercus) Species and the Implications for Urban Forestry ..........................................202 Abstract. Seedling growth and water use of six North American oak species were studied in a series of four experiments to determine inter- and intraspecies water use characteristics. Xeric-site adapted species (chestnut oak, Q. prinus [L.] and black oak, Q. velutina [Lamb.]) had slower growth (height and dry weight accumulation and lower shoot:root ratios) than mesic-site adapted species (bur oak, Quercus macrocarpus [Michx.]; pin oak, Q. palustris [Muenchh.], northern red oak, Q. rubra [L]; and Shumard oak, Q. shumardii [Buckl.]). Principal component analysis (a statisti- cal technique used to identify correlated variables) using 11 variables found that seedling water use loaded positively with see ling growth factors (taller seedlings tended to have higher dry weights and greater leaf and root areas and used more water than shorter seedlings, which tended to have lower dry weights, smaller leaf, and root areas) in the first principal component. However, in the third experiment, seedling growth factors loaded negatively with seedling water use for Q. prinus. Tall Q. prinus seedlings tended to use less water than short seedlings. However, other measures of water use (g water cm−1 height and cm−2 leaf and root area) loaded negatively on the first principal component. Correlations between seedling heights and seedling waters use were significant and positive, but great within-species and within half-sib family differences in height- adjusted water use (g water cm−1 use seedlings could be identified. Inefficient water use seedlings were shorter and had higher water use cm−1 height) were found. By plotting height-adjusted water use against seedling height, efficient and inefficient water height than efficient water use seed- lings. Inefficient water use seedlings were described as having a xeric-water use habit, whereas tall seedlings had a mesic water use habit. Poten- tially, height-adjusted water use could be used as a method for selecting individual oak seedlings better adapted to stressful urban planting sites. Key Words. Dry Weight; Water Use Efficiency; Xeric- and Mesic-site Adapted Species. Species used in this study. Bur Oak (Quercus macro- carpus (Michx.)); Pin Oak (Q. palustris (Muenchh.)); Chestnut Oak (Q. prinus (L.)); Northern Red Oak (Q. rubra (L)), (Q. shumardii (Buckl.)), (Q. velutina (Lamb.)). Christopher J. Luley and Jerry Bond Evaluation of the Fate of Ice Storm-Damaged Urban Maple (Acer) Trees ........................................................214 Abstract. Annually, ice storms cause millions of dollars of damage to urban trees and infrastructure in the United States and Canada. Ho ever, there is limited information to guide judgments on whether to remove ice-damaged trees. This study followed the response of three maple species that were dam- aged in the 1998 ice storm in northern New York State. Norway (Acer platanoides), silver (A. saccharinum), and sugar maples (A. saccharum) were placed in one of three diameter classes and canopy loss categories and were reevaluated 6 years aſter the initial damage. Over the 5-year study period, 26.8% of trees were removed, and there was no statistical difference among species, crown loss, or diameter class for these removals. Analysis of a variety of tree health and crown parameters showed that tree species was the most important factor in response, whereas diameter class and crown loss were less impor- tant. These results suggest that urban tree managers should consider tree species as an important factor in making removal decisions aſter an ice storm. Key Words. Acer platanoides; Acer saccharinum; Acer saccharum; Canopy Loss; Ice Damage; Maple Species; Norway Maple; Removal Rate; Silver Maple; Sprouting; Tree Response. ©2006 | International Society of Arboriculture | ISSN:1935-5297
September 2006
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