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Factors Affecting the Overwintering of Trichometasphaeria turcica on Maize. R. R. Nelson, Professor, Department of Plant Pathology, The Pennsylvania State University, University Park 16802; G. L. Scheifele, Former Research Assistant, Department of Plant Pathology, The Pennsylvania State University, University Park 16802, Junior author is now associated with PAG, Champaign Research Station, Champaign, Illinois, as Associate Plant Pathologist and Assistant Plant Breeder. Phytopathology 60:369-370. Accepted for publication 26 September 1969. DOI: 10.1094/Phyto-60-369.

The ability of Trichometasphaeria turcica (Helminthosporium turcicum) to overwinter saprophytically on maize is influenced in part by the genotype of the host on which the pathogen overwinters. Races of the pathogen have differing abilities to survive per se in the overwintering stage, and have differing abilities to survive on different host genotypes. Although van der Plank states that the saprophytic medium is the factor operative in stabilizing selection in nonobligate parasites in favor of simple races, the apparent greater survival ability of the complex race used in these studies suggests that the rationale for stabilizing selection may not be appropriate. If the saprophytic medium serves as a stabilizing factor, it may be more appropriate to state that the nature of the saprophytic medium may determine whether stabilizing selection is operative.