Kim Camilli, David N. Appel, and W. Todd Watson Studies on Pruning Cuts and Wound Dressings for Oak Wilt Control ................................................................... 132 Abstract. Ceratocystis fagacearum causes the destructive tree disease called oak wilt. One means of pathogen spread is by insect vectors (Nitid lidae) that transmit spores into fresh wounds on healthy trees. Experiments were conducted in central Texas on native live oaks (Quercus fusiformis) to test pruning methods and paints on disease development. Three treatment combinations were tested on 30 trees (10 trees/treatment): flush cut unpainted, flush cut painted, and unpainted pruning cuts made according to the Shigo method. Unpainted puncture wounds were made on the lower trunks of an additional 20 trees as controls. C. fagacearum spores were applied to the pruning cuts and half of the puncture wounds (positive controls) aſter treatment, whereas the other half of the punctures received distilled water as negative controls. Oak wilt symptoms first appeared in the flush cut unpainted treatment 31 days aſter inoculation. Infection rates, in decreasing order, were; positive control (70%), flush cut unpainted (60%), Shigo pruning method (40%), flush cut painted (20%), and negative control (10%). Pruning wounds, regardless of method, were effective infection courts for the oak wilt pathogen. Fewer trees became infected when pruning cuts were painted, but differences among infection rates for pruning cuts were not statistically significant. Tree diameters and stem aspect ratio had no bearing on infection rates. The Shigo method is recognized as a superior method for pruning, but there is no reason to change current recommendations to paint fresh wounds on susceptible oaks in high-hazard oak wilt areas. Key Words. Branch Protection Zone; Natural Target Pruning; Nitidulid Beetles; Oak Wilt; Pruning Paints; Shigo. Angela Rivenshield and Nina L. Bassuk Using Organic Amendments to Decrease Bulk Density and Increase Macroporosity in Compacted Soils ........................................................................................................... 140 Abstract. Samples of compacted sandy loam and clay loam soil were amended with organic matter: sphagnum peat or food waste compost. Amendments were incorporated into the soil samples at 0%, 10%, 33%, 50%, and 75% on a volume-to-volume basis. Changes in bulk density and macroporosity resulting from amendation were measured. In every permutation but one, macroporosity increased and bulk density decreased to below root-restricting thresholds. These results held true for the half of the samples that were manually recompacted. Differences between the amendments were not significant. Amenda- tion with sufficient amounts of sphagnum peat or food waste compost alleviates compaction, creating an environment more conducive for root growth. Key Words. Aeration Porosity; Amendments; Bulk Density; Compaction; Compost; Macroporosity; Root Growth; Root Restriction; Sphag- num; Woody Plants. Richard H. Yahner, Richard T. Yahner, and Russell J. Hutnik Long-Term Trends in Small Mammals on a Right-of-Way in Pennsylvania, U.S. .................................................. 147 Abstract. The State Game Lands 33 Research and Demonstration Area, Centre County, Pennsylvania, U.S., has been studied since 1953 with the objective of comparing the effectiveness of commonly used mechanical and herbicidal maintenance treatments on vegetation and wildlife on a right-of-way (ROW). Small mammals are important wildlife species on a ROW by consuming tree seeds, thereby reducing invasion of undesi able tree species, and these mammals are important components of a healthy ecosystem. As a follow up to a 2-year study of small mammals conducted 15 years earlier (1989 to 1990) on the State Game Lands 33 ROW, we initiated a 2-year live-trapping study in 2004 on small mammal populations on this ROW. The objectives of our study were to determine relative abundance and species richness (number of species) in six major cover types and in the adjacent forest. One hundred twenty-one individuals of eight species were observed in 2004 and 2005 combined; the most common species was the white-footed mouse (Peromyscus leucopus). One of the most important cover types to small mammals on the ROW was forb-grass, whereas the forest cover type tended to be less diverse in terms of number of mammal species than in cover types on the ROW. Key Words. Herbicides; Pennsylvania; Populations; Right-of-Way; Small Mammals; Vegetation. Henry D. Gerhold Callery Pear Cultivars Tested As Street Trees: Final Report on a 12-year Study ................................................... 153 Abstract. Cooperators in the Municipal Tree Restoration Program planted nine Callery pear (Pyrus calleryana Decne.) cultivars in 11 Pennsylvania, U.S. communities for evaluation as street trees, comparing two cultivars (three in one case) in each community. Cooperators measured them annually with standardized methods for 3 years and then at 3-year intervals until the 12th year. The most noteworthy differences occurred in tree height and crown width. The tallest were Aristocrat™, ‘Cleveland Select’, and ‘Redspire’, attaining more than 8 m (26 ſt) on average by the twelſth year and even 10.3 m (34 ſt) in one community. ‘Autumn Blaze’, evaluated only at one location, was ≈1.5 to 2 m (5 to 6.6 ſt) shorter in the 12th year. Heights of the other cultivars, tested at just one or two locations, were similar to the tallest ones. Crown widths differed more in the first 9 years than at the twelſth when on average most were ≈6.5 m (21.5 ſt) wide. Cleveland Pride®, ‘Cleveland Select’, Valiant®, and ‘Whitehouse’ were narrower than the others until the ninth year, but only ‘Cleveland Select’ at ≈5.6 m (18.5 ſt) remained narrower in the twelſth year and not everwhere. All cultivars were in good health during the whole period, although the foliage of ‘Whitehouse’ exhibited minor injuries in many years. As street trees, the Callery pears were not inva- sive and did not yet experience branch breakage, which can become a serious problem. All of the cultivars are too tall to be planted under utility wires. Key Words. Callery Pear Cultivars; Performance Testing; Pyrus calleryana; Street Tree Evaluation. ©2007 | International Society of Arboriculture | ISSN:1935-5297
March 2007
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