title: The Potential for Cereal Rye Cover Crops to Host Corn Seedling Pathogens.
abstract: Cover cropping is a prevalent conservation practice that offers substantial benefits to soil and water quality. However, winter cereal cover crops preceding corn may diminish beneficial rotation effects because two grass species are grown in succession. Here, we show that rye cover crops host pathogens capable of causing corn seedling disease. We isolated Fusarium graminearum, F. oxysporum, Pythium sylvaticum, and P. torulosum from roots of rye and demonstrate their pathogenicity on corn seedlings. Over 2 years, we quantified the densities of these organisms in rye roots from several field experiments and at various intervals of time after rye cover crops were terminated. Pathogen load in rye roots differed among fields and among years for particular fields. Each of the four pathogen species increased in density over time on roots of herbicide-terminated rye in at least one field site, suggesting the broad potential for rye cover crops to elevate corn seedling pathogen densities. The radicles of corn seedlings planted following a rye cover crop had higher pathogen densities compared with seedlings following a winter fallow. Management practices that limit seedling disease may be required to allow corn yields to respond positively to improvements in soil quality brought about by cover cropping.
authors.affiliation: First, third, and fifth authors: United States Department of Agriculture-Agricultural Research Service, National Laboratory for Agriculture and the Environment, 1015 N University Blvd, Ames, IA 50011; and second and fourth authors: Iowa State University, Department of Plant Pathology and Microbiology, 351 Bessey Hall, Ames 50011.
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Bakker
authors.affiliation: First, third, and fifth authors: United States Department of Agriculture-Agricultural Research Service, National Laboratory for Agriculture and the Environment, 1015 N University Blvd, Ames, IA 50011; and second and fourth authors: Iowa State University, Department of Plant Pathology and Microbiology, 351 Bessey Hall, Ames 50011.
authors.forename: Jyotsna
authors.initials: J
authors.lastname: Acharya
authors.affiliation: First, third, and fifth authors: United States Department of Agriculture-Agricultural Research Service, National Laboratory for Agriculture and the Environment, 1015 N University Blvd, Ames, IA 50011; and second and fourth authors: Iowa State University, Department of Plant Pathology and Microbiology, 351 Bessey Hall, Ames 50011.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Moorman
authors.affiliation: First, third, and fifth authors: United States Department of Agriculture-Agricultural Research Service, National Laboratory for Agriculture and the Environment, 1015 N University Blvd, Ames, IA 50011; and second and fourth authors: Iowa State University, Department of Plant Pathology and Microbiology, 351 Bessey Hall, Ames 50011.
authors.forename: Alison E
authors.initials: AE
authors.lastname: Robertson
authors.affiliation: First, third, and fifth authors: United States Department of Agriculture-Agricultural Research Service, National Laboratory for Agriculture and the Environment, 1015 N University Blvd, Ames, IA 50011; and second and fourth authors: Iowa State University, Department of Plant Pathology and Microbiology, 351 Bessey Hall, Ames 50011.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Kaspar
mesh_terms: D000383:Agriculture / Q000379:methods; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D005670:Fusarium / Q000302:isolation & purification; D006540:Herbicides; D010935:Plant Diseases / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology; D011775:Pythium / Q000302:isolation & purification; D012434:Secale / Q000382:microbiology* / Q000502:physiology*; D036226:Seedlings / Q000382:microbiology*; D003313:Zea mays / Q000382:microbiology*
chemical_list: D006540:Herbicides; D004247:DNA