Response of Several Eastern Forest Tree Species to Chronic Doses of Ozone and Nitrogen Dioxide. L. W. Kress, Research Associate, Department of Plant Pathology and Physiology, Virginia Polytechnic Institute and State University, Blacksburg 24061. J. M. Skelly, Professor, Department of Plant Pathology and Physiology, Virginia Polytechnic Institute and State University, Blacksburg 24061. Plant Dis. 66:1149-1152. Accepted for publication 24 March 1982. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-1149.

Two- to four-week-old seedlings of 10 eastern forest species were exposed to ozone at 0, 0.05, 0.10, or 0.15 ppm, and 2- to 4-wk-old seedlings of seven tree species were exposed to ozone and/or nitrogen dioxide at 0.10 ppm in 6 hr/day exposures for 28 consecutive days. Loblolly pine and American sycamore exhibited significant growth suppressions, whereas white ash and yellow poplar exhibited significant growth stimulations when exposed to ozone at 0.05 ppm. Yellow poplar and Virginia pine were the only species that failed to show any significant adverse growth effects in response to the ozone treatment at 0.15 ppm. In several instances, significant growth effects were noted in the absence of foliar injury. Nitrogen dioxide alone significantly suppressed root and total dry weight of sweetgum. The only significant interaction effects noted between ozone and nitrogen dioxide were less than additive.

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