The Effects of Two Winter Rye Cover Crop Seeding Methods on Corn Disease, Growth and Development

Project Overview

Project Type: Graduate Student
Funds awarded in 2018: $11,817.00
Projected End Date: 12/31/2020
Grant Recipient: Iowa State University
Region: North Central
State: Iowa
Graduate Student:
Faculty Advisor:
Alison Robertson
Iowa State University

Information Products


  • Agronomic: corn, rye


  • Crop Production: cover crops
  • Pest Management: cultural control


    Despite numerous environmental benefits associated with cover crops including reducing erosion, improving infiltration, mitigating nutrient loading in surface waters, and improving soil health (Kaspar et al 2001, Kaspar and Singer 2011, Schnepf and Cox 2006), many farmers are reluctant to include cover crops in their production systems because of reported yield declines, especially in corn. There are numerous potential reasons for this yield decline, including seedling disease that reduces stand, and seedling vigor that leads to uneven stands. Cover crops, especially grass cover crops, are hosts of the same pathogens that infect corn seedlings (Bakker et al 2016). Cover crops serve as a 'green bridge' for pathogens by maintaining pathogen populations over the winter between harvest and planting of cash crops, which is normally when pathogen numbers decline on non cover crop fields (Smiley et al 1992; Acharya et al 2017). The goal of this project was to understand the effects of a winter rye cover crop  on corn disease, growth and development, specifically how distance from decomposing rye affect corn.

    To accomplish this we collaborated with the Iowa Soybean Association On-Farm Network who identified two farmers for us to work with over two years. A cover crop of winter rye was seeded in either 30-inch and 15-inch, or 30-inch and 7-inch rows. The corn was planted in 30-inch rows and thus was 15 inches, 7.5 inches, or 3.5 inches from the decomposing winter rye. Both fields were no-till corn-soybean rotations with four replications. At both farms no effect of distance from winter rye treatments were detected on corn growth including yield. At one farm an effect of distance from winter rye was detected on radicle root rot in both years (2019, P = 0.0514; 2020, P = 0.0016). Radicle root rot was reduced when corn was planted further away from winter rye.

    The results of our project were shared at the Department of Plant Pathology and Microbiology weekly seminar ( and an ICM Blog ( Post on social media (Twitter and Facebook) linking to these outputs were done to share the research. Our outreach and output efforts will be evaluated by means of social media, number of citations and surveys over the next year. This project will increase the profitability of farmers by reducing the risk of yield reductions in corn while improving the soil and water quality, and providing a best management practice for farmers.



    Acharya, J., Bakker, M. G., Moorman, T. B., Kaspar, T. C., Lenssen, A. W., & Robertson, A. E. 2017. Time interval between cover crop termination and planting influences corn seedling disease, plant growth, and yield. Plant Dis. 101:591–600.

    Bakker, M. G., Acharya, J., Moorman, T. B., Robertson, A. E., & Kaspar, T. C. 2016. The potential for cereal rye cover crops to host corn seedling pathogens. Phytopathology106: 591-601.

    Kaspar, T. C., Radke, J. K., and Laflen, J. M. 2001. Small grain cover crops and wheel traffic effects on infiltration, runoff, and erosion. J. Soil Water Conserv. 56:160-164.

    Kaspar, T.C., and J.W. Singer. 2011. The use of cover crops to manage soil. In Soil Management: Building a Stable Base for Agriculture, eds. J.L. Hatfield and T.J. Sauer, 321-337. Madison, WI: American Society of Agronomy and Soil Science Society of America.

    Schnepf, M., and C. Cox, eds. 2006. Environmental Benefits of Conservation on Cropland: The Status of Our Knowledge. Ankeny, Iowa: Soil and Water Conservation Society

    Smiley, R. W., Ogg, A. G., & James Cook, R. 1992. Influence of glyphosate on Rhizoctonia root rot, growth, and yield of barley. Plant Dis76:937-942.

    Project objectives:

    The objectives of our proposal were to: (i) understand the impact of spatial planting arrangement of winter rye CC on corn seedling disease, growth, and development, and (ii) determine the Pythium spp. population density in the soil spatially.


    To address our objectives we collaborated with the Iowa Soybean Association On-Farm Network who identified two farmers for us to work with over two years. Both fields were no-till corn-soybean rotations with four replications. One farmer seeded the winter rye cover crop on 30-inch rows and 15-inch rows. The second farmer seeded the winter rye cover crop on 30-inch rows and 7-inch rows and terminated the winter rye early or late. Corn was planted on 30-inch rows resulting in the corn being 15-inches, 7.5 inches or 3.5 inches from the decomposing rye.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.