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Resistance

Effects of Soluble Silicon on the Parasitic Fitness of Sphaerotheca fuliginea on Cucumis sativus. J. G. Menzies, Research Station, Agriculture Canada, P.O. Box 1000, Agassiz, B.C., Canada, V0M 1A0, and (ADMG) Department of Botany, University of British Columbia, 6270 University Blvd., Vancouver, B.C., Canada V6T 2B1; D. L. Ehret, A. D. M. Glass, T. Helmer, C. Koch, and F. Seywerd. Research Station, Agriculture Canada, P.O. Box 1000, Agassiz, B.C., Canada, V0M 1A0, and (ADMG) Department of Botany, University of British Columbia, 6270 University Blvd., Vancouver, B.C., Canada V6T 2B1. Phytopathology 81:84-88. Accepted for publication 24 August 1990. Copyright 1991. Department of Agriculture, Government of Canada. DOI: 10.1094/Phyto-81-84.

The effects of silicon treatment of cucumber on four components of parasitic fitness of Sphaerotheca fuliginea (a causal agent of powdery mildew of cucumber) were examined. Cucumber plants were treated with nutrient solutions amended with different concentrations of soluble silicon and selected leaves inoculated with known concentrations of conidia of the pathogen. Colony number per leaf, colony area per leaf, and the germination of conidia collected from inoculated leaves were significantly reduced with increasing silicon concentration in the nutrient solutions. The area of individual colonies was also reduced as silicon concentrations in the nutrient solutions increased from 0.05 to 4.10 mM. The decrease in receptivity of plants to mildew infection was apparently due to silicon accumulation in leaves and was not related to cation or ionic strength effects of the silicon treatments.