VIEW ARTICLE

Reaction of Erysiphe graminis f. sp. hordei to Low Levels of Ozone. Allen S. Heagle, Plant Pathologist, Plant Science Research Division, ARS, USDA, National Environmental Research Center, Research Triangle Park, North Carolina 27711; Alice Strickland, Biological Technician, Division of Ecological Research, Environmental Protection Agency, National Environmental Research Center, Research Triangle Park, North Carolina 27711. Phytopathology 62:1144-1148. Accepted for publication 13 April 1972. DOI: 10.1094/Phyto-62-1144.

Barley, Hordeum vulgare, and powdery mildew, Erysiphe graminis f. sp. hordei, were exposed to ozone at concentrations that often occur in polluted ambient air. The effects of ozone on germination of conidia, on plant infection by conidia, on growth of mycelia, and on sporulation were determined. When sporulating colonies were exposed to ozone, the percentage infection by exposed conidia was significantly reduced. Ozone exposures during spore incubation also significantly reduced infection. Germination of conidia was not significantly reduced by the same exposures which inhibited infection. Colony and spore mass length was significantly increased by ozone exposures which caused chlorosis of barley leaves.