Rye cultivar and herbicide on corn

Title: Effect of winter cereal rye cultivar selection and herbicide choice on seedling disease, pathogen populations, nitrogen dynamics, and growth and yield of corn.
Location: ISU Central Research Farm.
Time Period: 2023 2025.
Research Team: Alison Robertson, Marshal McDaniel, Silvina Arias, Rashelle Matthiesen, Meaghan Anderson, Estaban Gonzalez.
Project Description: The goal of our research has been to improve our understanding of the underlying factors affecting corn yields after a cereal rye (CR) cover crop (CC). CR produces allelopathic compounds (benzoxazinoids (BX)), that are rapidly released following termination of CR and decay to background levels after termination. We demonstrated BX increased corn seedling disease severity. Laboratory and field studies directly measuring soil N cycling show that a CR CC increases N immobilization and decreases plant-available N. We suggest that if there is less available N after a CR CC for corn seedling growth, seedlings may be stressed, less vigorous, and more susceptible to seedling disease. We hypothesize that characteristics of a CR cultivar affect the biological values of CCs as a conservation practice. In this proposal, we plan to investigate if corn seedling disease caused by Pythium species varies among CR cultivars due to differences in allelochemical production by each CR cultivar. Herbicide application, namely glyphosate, is the most popular method used to terminate a CC in Iowa. Glyphosate has been implicated in increased severity and reemergence of several crop diseases (21). We hypothesize that applications of glyphosate used to terminate CR promote the buildup of corn seedling pathogens that results in a “green bridge” between CR and corn. We will compare corn seedling disease, and Pythium and Fusarium populations among CR cultivars terminated with either glyphosate or paraquat+atrazine in experimental field trials.
Publications: Acharya, J., and Robertson, A.E. 2023. Effect of allelochemicals from cereal rye cultivar and Pythium lutarium on corn growth and disease. PhytoFrontiers (in press).
Kaspar, T.C., and Bakker, M. 2015. Biomass production of 12 winter cereal cover crop cultivars and their effect on subsequent no-till corn yield. J. Soil Water Conserv. 70:353-364.
Schlatter, D.C., et al. 2018. Succession of fungal and oomycete communities in glyphosate-killed roots. Phytopathology. 108: 582-594
Funders: INRC
Disclaimer: This is an active research site, please contact Alison Robertson (alisonr@iastate.edu) prior to planning any site visits.