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Ecology and Epidemiology

Effect of Ozone on Parasitism of Corn by Helminthosporium maydis. Allen S. Heagle, Plant Pathologist, Southern Region, Agricultural Research Service, U. S. Department of Agriculture, Plant Pathology Department, North Carolina State University, Raleigh, NC 27607; Phytopathology 67:616-618. Accepted for publication 25 October 1976. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-616.

Corn plants inoculated with Helminthosporium maydis race T were exposed to ozone (O₃) for 6 hr/day on various days before, after, or both before and after inoculation. Lesion length and sporulation were affected by O₃ concentration and timing of the exposures. Lesions were larger on plants exposed to O₃ both before and after inoculation than on nonexposed plants. Sporulation was increased by exposure to 0.12 μliters/liter of O₃ on 6 days before inoculation and decreased by exposures to 0.18 μliters/liter on 6 days after inoculation.