Susceptibility of Tree and Shrub Species and Response of Black Cherry Foliage to Ozone. D. D. Davis, Associate Professor, Department of Plant Pathology, Pennsylvania State University, University Park 16802. D. M. Umbach, Graduate Student, and J. B. Coppolino, Project Coordinator, Department of Plant Pathology, Pennsylvania State University, University Park 16802. Plant Dis. 65:904-907. Accepted for publication 2 February 1981. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-904.

Plants of 12 species were exposed to 0.20 ppm of ozone for 5 hr periodically throughout the growing season of 1976. Species exhibiting symptoms, in approximate descending order of susceptibility, were Hinodegiri azalea (Rhododendron obtusum 'Hinodegiri'), black cherry (Prunus serotina), American sycamore (Platanus occidentalis), hybrid poplar (Populus maximowiczii × trichocarpa 'USDA Forest Service clone NE-388'), yellow poplar (Liriodendron tulipifera), black walnut (Juglans nigra), Delaware Valley white azalea (Rhododendron mucronatum), black elder (Sambucus nigra), and spreading cotoneaster (Cotoneaster divaricata). Species failing to show symptoms were Austrian pine (Pinus nigra), eastern white pine (P. strobus), and Virginia pine (P. virginiana). During the summer of 1977, black cherry seedlings were exposed for 2, 4, 6, and 8 hr to 0.10 and 0.19 ppm of ozone. Visible foliar injury followed exposure for 4 hr at 0.10 ppm and for 2 hr at 0.19 ppm. The Larsen-Heck dose-response equation was used to model the effects of different concentrations and times of exposure. The predicted response of black cherry to the dosage used in the 1976 study was in good agreement with what had been observed.