VIEW ARTICLE

Ecology and Epidemiology

The Effect of Visible and Near-Visible Radiation on Sporangium Production by Phytophthora cinnamomi. G. A. Zentmyer, Professor, Department of Plant Pathology, University of California, Riverside, CA 92502; O. K. Ribeiro, Postgraduate Research Associate, Department of Plant Pathology, University of California, Riverside, CA 92502. Phytopathology 67:91-95. Accepted for publication 11 June 1976. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-91.

The effect of light quality and intensity on the production of Phytophthora cinnamomi sporangia was studied using cultures that were grown in a chemically-defined liquid medium. Cultures were irradiated at intensities ranging from 3 μW cm^–2 to 200 μW cm^–2, and at wavelengths between 312 and 1,350 nm. Sporangia were produced at all wavelengths and intensities tested, and in darkness. Sporangium production was stimulated in the near-UV by intensities up to 100 μW cm^–2. At 200 μW cm^–2 there was no significant difference in sporangium production in wavelengths ranging from the near-UV to infrared (312 nm-1,350 nm). These results indicate that sporangium production by P. cinnamomi is light-variable, but not light-dependent.