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Effect of Agar on Inhibition of Spore Germination by Chemicals. W. H. Ko, Associate Professor, Department of Plant Pathology, University of Hawaii, Beaumont Agricultural Research Center, Hilo 96720; J. T. Kliejunas(2) and J. T. Shimooka(3). (2)(3)Assistant Professor, and Technician, respectively, Department of Plant Pathology, University of Hawaii, Beaumont Agricultural Research Center, Hilo 96720. Phytopathology 66:363-366. Accepted for publication 27 August 1975. DOI: 10.1094/Phyto-66-363.

Both agar and nutrients decreased the inhibitory effect of cupric sulfate on spore germination. In general, chemicals were more inhibitory to spore germination in water than in water agar. The agar effect was more profound on cationic inhibition than on that due to anions or weakly dissociated compounds, although there were exceptions. The inhibitory effect of cupric sulfate on spore germination was inversely correlated with the amount of agar present. Agars from various sources and Bacto gelatin were all effective in reducing the fungistatic effect of cupric sulfate. Results suggested that binding of chemicals by agar may slow their rates of diffusion, and may account for the reduced activity of chemicals against spore germination in agar medium.