Development of Septoria Nodorum Blotch on Wheat from Infected and Treated Seed. H. H. Luke, USDA, ARS, Plant Pathology Department, University of Florida, Gainesville 32611. R. D. Barnett, Professor of Agronomy, IFAS, North Florida Research and Education Center, Rt. 3, Box 638, Quincy, 32351; and P. L. Pfahler, Professor, IFAS, Agronomy Department, University of Florida, Gainesville 32611. Plant Dis. 70:252-254. Accepted for publication 3 September 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/PD-70-252.

Effects of seed infection on development of Septoria nodorum blotch on the upper leaves and heads of wheat was assessed at two locations over 3 yr. As the incidence of seed infection at planting increased from 1 to 40%, the intensity of subsequent disease increased but the relationship of seed infection to disease was nonlinear. About 10% seed infection supplied sufficient inoculum to cause a severe epidemic. In 1983, disease severity on the head was similar at two widely separated locations but percentages of seed infection at harvest were greatly different. Thus, percent seed infection at harvest seems to be influenced by environmental conditions in the heading phase of crop development. Seed treatments (benomyl or triadimenol) resulted in reduced disease severity on the upper leaves and heads at both locations in all 3 yr.