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Cephalosporium Stripe of Winter Wheat: Infection Processes and Host Response. D. E. Mathre, Professor, Department of Plant Pathology, Montana State University, Bozeman 59715; R. H. Johnston, Research Associate, Department of Plant Pathology, Montana State University, Bozeman 59715. Phytopathology 65:1244-1249. Accepted for publication 3 June 1975. DOI: 10.1094/Phyto-65-1244.

Factors influencing the infection of winter wheat (Triticum aestivum) by Cephalosporium gramineum were examined. Hyphae that could serve as infecting propagules were not observed to develop from infected straw in natural soil. Conidia were able to serve as infecting propagules when roots were severed at depths down to at least 30 cm below the soil surface. Higher infection percentages were noted when conidia contacted wounded root ends immediately after the roots were severed, but infection could take place as long as 16 days after root wounding. When individual severed roots were inoculated with known numbers of conidia there was a linear relationship between the log₁₀ number of conidia and percent plants infected. When individual roots of two genotypes of differing susceptibility were inoculated, there was a difference in the slope of the lines describing the percentage plants infected versus log₁₀ number of conidia used. Inoculation of plants of various genotypes indicated that differences in degree of susceptibility were greatest when single roots were inoculated with 5 × 10⁵ conidia as compared to a massive root slice inoculation or above-ground injection of conidia.