Determining Whether Cover Crops Affect Soybean Cyst Nematode Population Densities and can be Used for Integrated Pest Management

Project Overview

Project Type: Graduate Student
Funds awarded in 2016: $11,976.00
Projected End Date: 08/31/2019
Grant Recipient: Iowa State University
Region: North Central
State: Iowa
Graduate Student:
Faculty Advisor:
Dr. Greg Tylka
Iowa State University

Information Products


  • Agronomic: soybeans


  • Crop Production: cover crops
  • Education and Training: on-farm/ranch research
  • Pest Management: allelopathy, biological control, cultural control, trap crops
  • Production Systems: holistic management

    Proposal abstract:

    Cover crops are being increasingly implemented in United States cash cropping systems, and there are many unanswered questions regarding how cover crops may affect plant pathogens. The soybean cyst nematode (SCN) is the single, most important plant pathogen to soybean production. There are a handful of unsubstantiated claims that cover crops can reduce SCN population densities. The goal of this proposal is to investigate these claims using rigorous scientific methods. Both small-plot and on-farm field experiments will be conducted to assess effects of cover crops on SCN population densities. On-farm experiments will be conducted in collaboration between the Iowa Soybean Association (ISA) On-Farm Network, five or more Iowa farmers, and one farmer from Illinois. SCN population densities will be monitored in field experiments by collecting soil samples at the time of cover crop seeding, before a killing freeze, and in the spring pre-cash crop planting. Field experiments will be conducted over three years and include corn-soybean rotations under typical agronomic management to best capture the effects of cover crops on SCN population densities in a farmer-managed setting. Greenhouse experiments will complement the field experiments and allow for a closer look at the impact of cover crops on SCN. Experiments will investigate if cover crops decrease SCN survival, and simulated field container experiments will permit testing effects of more species of cover crops on SCN population densities. By collaborating with the ISA On-Farm Network, this research will impact many farmers directly. Results will be presented at the ISA Research Conference, Iowa State University Integrated Crop Management Conference, and at professional scientific meetings, reaching crowds of farmers, consultants, and scientists alike. Additionally, results from these experiments will be published in extension newsletters and peer-reviewed scientific journals. This project will be evaluated biannually for progress, outputs, and outreach. The projected outcome of this proposal will be to know definitively whether cover crops can be used in an integrated pest management approach for suppressing SCN population densities in the soil. The answer to this question is much needed by soybean farmers throughout the Midwest.

    Project objectives from proposal:


    With an increasing interest and implementation of cover crops in the Midwest accompanied by the ever-persistent problem of the soybean cyst nematode (SCN), there is much interest in, speculation about, and even some unsubstantiated claims made about cover crops affecting SCN population densities. The goal of this project is to determine if and how cover crops can affect SCN population densities and if cover crops have potential as an IPM tool for SCN management.


    Results from this research will answer the question to which many soybean growers, crop consultants, and seed companies do not have an answer: Can cover crops reduce the population densities of the soybean cyst nematode (SCN)? There is increasing interest about cover crops among soybean farmers, including whether they can reduce SCN population densities in the soil, yet there are almost no scientific data on the topic. With this research, I intend to not only answer the baseline question of “do cover crops affect SCN populations in the soil?”, I plan to dig deeper into the potential relationship of cover crops and SCN. In addition to field experiments, greenhouse experiments will be conducted to investigate multiple possible modes of SCN suppression that can occur as a result of interactions with cover crops: potential as a biofumigant, trap crop, or hatch-inducing non-host cover crops. Results will be shared in presentations and written publications for both the scientific community and the soybean-producer and crop- consultant communities. Ultimately, this research will determine if cover crops can be utilized as an integrated pest management (IPM) approach for SCN, adding to the other benefits of using cover crops in corn-soybean rotations.


    The expected outputs of this research will be new unbiased information on effects of cover crops on SCN population densities in the Midwest. Results will be published in various outlets including, but not limited to, extension newsletters and refereed scientific journals. The results will also be shared with growers, extension agents, industry personnel, scientists and whomever else may attend or be interested in local, regional, or nationwide extension or scientific society meetings. NCR-SARE will be acknowledged anytime results are presented orally or in print. Results from this study will help shape the way farmers perceive the utility of cover crops beyond their soil-saving and nutrient-scavenging abilities because: (1) methods for managing SCN are losing efficacy; (2) there is lack of scientific data on the effect of various cover crop species on SCN in the soil; and (3) determination of the effects of cover crops on SCN will help growers decide if they can use specific species of cover crops as another method of SCN management.

    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.