ARBORICULTURE ARBORICULTU URBAN FORESTRY Volume 32, Issue 3, May 2006 & CONTENTS japonicum. Glynn C. Percival, Ian P. Keary, and Kelly Marshall The Use of Film-Forming Polymers to Control Guignardia Leaf Blotch and Powdery Mildew on Aesculus hippocastanum L. and Quercus robur L. ...............................100 Abstract. The effects of four commercially available film-forming polymers (Bond, Designer, Spray Gard, Nu-Film-P) on disease severity of po dery mildew (Microsphaera alphitoides Griffon and Maubl.) on English oak (Quercus robur L.) and Guignardia leaf blotch (Guignardia aesculi (Peck) Stewart) on horsechestnut (Aesculus hippocastanum L.) were examined in a field experiment. In addition, a comparative evaluation of the fungicide penconazole, commercially used for powdery mildew control, was conducted. Effects on tree vitality were also assessed by measuring leaf chloro- phyll fluorescence and chlorophyll concentrations. Irrespective of tree species, Nu-Film-P and Spray Gard did not significantly infl ence disease severity of powdery mildew and Guignardia leaf blotch. Likewise, no significant effects of these two film-forming polymers on chlorophyll fluores- cence and chlorophyll content were recorded. Reduction in disease severity following spray applications of the film-forming polymers Bond and Designer was statistically comparable with penconazole. None of the film-forming polymers and fungicide evaluated was phytotoxic to the test trees. Results suggest that application of an appropriate film-forming polymer may provide a useful addition to existing methods of plant disease control. Key Words. Disease Control; Foliar Pathogens; Fungicides; Integrated Disease Management; Urban Trees. Paul Thomas Tiddens and Raymond A. Cloyd Susceptibility of Three Rose Genotypes to Japanese Beetle (Coleoptera: Scarabaeidae) Adult Feeding ............................................................................. 108 Abstract. Japanese beetle (Popillia japonica) adults are a major insect pest of cultivated roses, causing extensive feeding damage to both foli- age and flowers. Insecticides are primarily used to minimize adult injury to roses; however, insecticides may be harmful to natural enemies and their use may be restricted, particularly in public gardens. An alternative management strategy is the use of rose genotypes that express some level of herbivore tolerance. However, there is little information on rose genotypes that are tolerant or less susceptible to adult Japanese bee- tle leaf feeding. This study evaluated the susceptibility of three new rose genotypes introduced into the Crasberg Rose Garden at the Chicago Botanic Garden, Glencoe, Illinois, U.S. The genotypes were Rosa ‘Radrazz’ Knock Out™, Rosa ‘Crimson Bouquet,’ and Rosa ‘Love and Peace.’ Two laboratory experiments, a no-choice and multiple-choice leaf-feeding assay, were conducted in 2002 and 2003 to assess susceptibility of the new rose and two established genotypes to Japanese beetle adult feeding. Although there were significant statistical differences between the rose genotypes, in almost all cases the mean percentage damage rating exceeded 50%. Mean percentage damage ratings for the 2002 and 2003 no-choice experiments ranged from 15% to 78% and 60% to 75%, respectively. Mean percentage da age ratings for the 2002 and 2003 multiple- choice experiments ranged from 34% to 58% and 47% to 53%, respectively. These results indicate that all the rose genotypes tested are sus- ceptible to Japanese beetle adult feeding and may not be appropriate selections for use in areas with established Japanese beetle populations. Key Words. Host Plant Resistance; Integrated Pest Management; Japanese Beetle; Plant Health; Popillia japonica; Rosa spp. Formerly the Journal of Arboriculture, 1975 – 2005 (Volumes 1 – 31) www.isa-arbor.com F. Ferrini and M. Baietto Response to Fertilization of Different Tree Species in the Urban Environment .................................................93 Abstract. The influence of fertilization on shoot growth, leaf gas exchange, leaf chlorophyll content, and mineral content was monitored on sweetgum (Liquidambar stryraciflua L.), Japanese pagoda tree (Styphnolobium japonicum Schott), and European ash (Fraxinus excel- sior L.) over a 3-year period aſter planting in the urban environment. The research was carried out on newly planted trees that were placed in different urban sites and fertilized aſter planting. Fertilization was repeated for 2 years aſter planting at the beginning of the spring. There were contrasting results according to the species and the year of measurements. Fertilization was to a limited extent effective in the first year aſter planting but failed to provide better results in the following years. Thus, the results of this research do not support the util- ity of fertilizer application as a method to improve plant establishment, growth, or physiology aſter transplanting in the urban environment. Key Words. Fraxinus excelsior; Leaf Gas Exchanges; Leaf Mineral Content; Liquidambar styraciflua; Plant Nutrients; Plant Physiology; Styphnolobium ©2006 | International Society of Arboriculture | ISSN:1935-5297
May 2006
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