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The Relationship Between Structure and Fungicidal Activity of Pyridine Alkane and Carbinol Compounds as Turf Fungicides. J. W. Whaley, Senior Plant Pathologist, Eli Lilly and Co., Greenfield, Indiana 46140; H. M. Taylor, Research Scientist, Eli Lilly and Co., Greenfield, Indiana 46140. Phytopathology 60:771-778. Accepted for publication 28 October 1969. DOI: 10.1094/Phyto-60-771.

The fungicidal activity of a number of pyridine alkane and carbinol compounds related to α,α- diphenyl-3-pyridinemethanol was studied. Laboratory, greenhouse, and field experiments demonstrated control of several turf pathogens with cycloalkyl substitution on the carbinol carbon. Substitution on the 3 position of pyridine resulted in maximum activity against all pathogens tested. Another moiety on the pyridine ring in addition to an active substitution at the 3 position eliminated activity. Poor fungicidal activity resulted when the hydrogen or hydroxyl on the alpha carbon was replaced with chloro, amino, or methoxyl groups. No significant increase in activity resulted when substitutions were made on phenyls attached to the alpha carbon. The greatest increase in activity was noted when certain cycloaliphatic groups were substituted for one or both phenyl moieties on alpha carbon. Determinations of ed₅₀ and ed₉₅, values for the most active cyclohexyl-pyridine compounds indicated that dosages required were considerably less than those for Daconil 2787 and Dyrene. Field studies indicated that dosages of the effective fungicides increased exponentially with the increase of time between applications in the control of Sclerotinia homoeocarpa on Astoria bentgrass (Agrostis tenuis).