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Ecology and Epidemiology

Effects of Ozone on Sporulation, Spore Germination, and Growth of Fomes annosus. R. L. James, Plant pathologist, Forest Pest Management, State and Private Forestry, USDA Forest Service, Missoula, MT 59801; F. W. Cobb, Jr.,(2), and J. R. Parmeter, Jr.(3). (2)(3)Associate professor and professor, respectively, University of California, Berkeley 94720. Phytopathology 72:1205-1208. Accepted for publication 2 November 1981. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1982.. DOI: 10.1094/Phyto-72-1205.

Effects of ozone (O₃) on certain cultural characteristics of Fomes annosus were investigated in exposure chamber studies. Growth rates of F. annosus decreased and conidial germ tubes were shorter and had fewer branches as O₃ dosages increased. F. annosus conidial production was very sensitive to O₃; very few conidia were produced when cultures were exposed to relatively low dosages (2,400 μg/m³ -hr). Conidial germination was decreased at the higher O₃ dosages, but spore germination was apparently stimulated at low dosages (184 μg/m³-hr). Colonization of wood disks exposed to O₃ dosages of 16,870 μg/m³-hr and greater was significantly less than that of nonexposed disks. However, O₃ dosages that can be expected under field conditions appear to have little potential effect upon those aspects of pathogen biology that would substantially affect epidemiology of annosus root rot.