VIEW ARTICLE

Ecology and Epidemiology

Factors Associated with the Epidemiology of Soybean Mosaic Virus in Iowa. J. H. Hill, Associate professor, Department of Plant Pathology, Seed and Weed Sciences, Iowa State University, Ames 50011; B. S. Lucas(2), H. I. Benner(3), H. Tachibana(4), R. B. Hammond(5), and L. P. Pedigo(6). (2)(3)Graduate research assistant, laboratory technician III, Department of Plant Pathology, Seed and Weed Sciences, Iowa State University, Ames 50011; (4)Associate professor and research plant pathologist, U.S. Department of Agriculture, Science and Education Administration, Agricultural Research, Department of Plant Pathology, Seed and Weed Sciences, Iowa State University, Ames 50011; (5)(6)Graduate research associate and professor, Department of Entomology, Iowa State University, Ames 50011. Phytopathology 70:536-540. Accepted for publication 14 November 1979. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-536.

Soybean (Glycine max) grown under fully screened cages, half-screened cages, or without cages were rated for infection with soybean mosaic virus (SMV) by local-lesion indexing and by presence of seed-coat mottling on seeds harvested from the mother plants. Infected plants were detected in the half-screened cages and uncaged treatments but were rare in the fully screened cages. Seed-coat mottling was unreliable as an indicator of virus infection of mother plants and presence of infectious virus in seed. The distribution of SMV in the field suggested plant-to-plant spread from primary inoculum foci. It seems most probable that this primary inoculum consists of infected seedlings derived from SMV-infected seed.