Project Details:

Title:
Assessing nematode control and yield of SCN-resistant soybean varieties in response to different SCN populations (Hg types)

Parent Project: Assessing nematode control and yield of SCN-resistant soybean varieties in response to different SCN populations (Hg types)
Checkoff Organization:Iowa Soybean Association
Categories:Insects and pests, Nematodes, Education
Organization Project Code:
Project Year:2015
Lead Principal Investigator:Gregory Tylka (Iowa State University)
Co-Principal Investigators:
Keywords: Soybean Cyst Nematode (SCN), Soybean Variety Testing

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

SCN-resistant soybean varieties are critical for managing SCN. The scientific definition of an SCN-resistant soybean variety is one that allows 10 percent or less SCN reproduction relative to a standard susceptible variety in greenhouse testing. Not all soybean varieties described as resistant to SCN are truly resistant to the pathogen. In fact, some "SCN-resistant" varieties are completely susceptible, allowing unchecked SCN reproduction. This project provides comprehensive information about how well "SCN-resistant" soybean varieties suppress nematode population densities and how well the varieties yield in SCN-infested fields in Iowa. The project also is revealing the relationship between SCN population HG types (formerly called SCN races) and yield loss on SCN-resistant soybean varieties with the different sources of resistance.

Overview of Accomplishments: In October 2013, we compiled and distributed an Iowa State University Extension publication that lists soybean varieties in maturity groups 1, 2, and 3 that are marketed as resistant to SCN that are available to Iowa farmers. Additionally, we conduct field and 30-day-long greenhouse experiments each year to assess SCN reproduction on resistant soybean varieties and to also assess soybean yields (for field experiments).

Results of greenhouse experiments reveal that some varieties that are described as resistant to SCN allow as much nematode reproduction as susceptible soybean varieties, or more. Results of field experiments reveal a wide range of magnitude of season-long changes in SCN soil population densities as well as a wide range of soybean yields among the SCN-resistant soybean varieties. The field experiment results were compiled into a report published in December 2013 and distributed to 70,000 Iowa farmers in January 2104.

Project Objectives

1. Compile information each year about soybean varieties marketed as resistant to SCN that are available to Iowa farmers.
2. Assess each year the amount of SCN reproduction on the roots of SCN-resistant soybean varieties using SCN populations from Iowa fields in short-term greenhouse experiments under controlled environmental conditions.
3. Assess the agronomic performance each year of SCN-resistant soybean varieties in experiments conducted in fields infested with different SCN HG types at various locations throughout Iowa.
4. Measure each year the control of SCN population densities provided by SCN-resistant soybean varieties in experiments conducted in fields infested with different SCN HG types at various locations throughout Iowa.

Project Deliverables

1. An annually updated list of SCN-resistant soybean varieties marketed to Iowa soybean farmers in maturity groups 0, 1, 2, and 3 will be compiled and published in PDF format as ISU Extension publication Pm-1649 “Soybean cyst nematode-resistant soybeans for Iowa” in October.

2. Nine field experiments will be conducted annually in which the agronomic performance and SCN control provided by 50 to 60 SCN-resistant soybean varieties will be assessed. The results of these experiments will be compiled annually into a report titled “Evaluation of soybean varieties resistant to soybean cyst nematode in Iowa” (ISU Extension publication IPM-52) that will be printed and direct mailed to 70,000 Iowa farmers and agribusiness personnel as an insert in the Iowa Farmer Today magazine.

3. SCN reproduction on the SCN-resistant soybean varieties studied in the field experiments will be measured and compared in 30-day-long greenhouse experiments to obtain basic information about the reproduction of the different SCN populations on the soybean varieties.

Progress of Work

Update:
In October 2014, the list of SCN-resistant soybean varieties was completed and posted online on the ISU Extension and Outreach Online Store. And the publication was announced in an article titled “More Choices of SCN-Resistant Soybean Varieties for Iowa for 2015” on October 21, 2014, in the online ISU Integrated Crop Management News (www.extension.iastate.edu/cropnews/).

Also, on October 22, 2014, Greg Tylka tweeted “Newly updated ISU Extension publication Pm1649 has info on >800 SCN-resistant soybean varieties. Wow–so many choices! #resistthecyst” to his 60 Twitter followers. The tweet was re-tweeted by three ISU Extension field agronomists who follow Tylka on Twitter to their 1,004 Twitter followers.

The other primary deliverable of the project is the annual report of the ISU SCN-resistant Soybean Variety Trials, which is an official ISU Extension publication titled “Evaluation of soybean varieties resistant to soybean cyst nematode in Iowa” (publication IPM-52). A report with agronomic and SCN data for the soybean varieties in each experiment from 2014 was made available in January 2015, with color-coded graphs and data tables. The publication was direct mailed to approximately 70,000 Iowa farmers and agronomists as a special insert in the January 18, 2015, issue of Iowa Farmer Today.

Update:
Soybean varieties to be studied in 2014 were selected by Tylka laboratory personnel, and seed companies were contacted to obtain seed of the varieties selected for testing. Final selections were made for the nine field locations at which experiments were established in 2014. The towns nearest to the experimental locations were Ames, Arlington, Fruitland, Leighton, Mason City, Moorhead, Newell, Pacific Junction, and Urbana, Iowa.
Preemergence herbicides were applied to each field experiment location, the 4-row field plots were planted and soil samples were collected from each plot at the nine locations to determine the initial SCN egg population density that was present at the time of planting. Weed control was monitored and glyphosate was applied to supplement preemergence weed control at the nine experimental locations. We also collected stand emergence data from each plot and began processing soil samples to determine the initial SCN egg population densities. Approximately half of the soil samples collected at the time of planting have been processed and the SCN eggs have been counted and the data recorded. The field experiments were also monitored for foliar diseases and insect pests.

Final Project Results

Benefit to Soybean Farmers

Performance Metrics

Project Years

YearProject Title (each year)
2015Assessing nematode control and yield of SCN-resistant soybean varieties in response to different SCN populations (Hg types)
2014Assessing nematode control and yield of SCN-resistant soybean varieties in response to different soybean cyst nematode populations (Hg types)
2013Assessing nematode control and yield of SCN-resistant soybean varieties in response to different soybean cyst nematode populations (Hg types)
2012Assessing nematode control and yield of SCN-resistant soybean varieties in response to different soybean cyst nematode populations (Hg types)
2011Assessing nematode control and yield of SCN-resistant soybean varieties in response to different SCN populations (Hg types)
2010Assessing nematode control and yield of SCN-resistant soybean varieties in response to different SCN populations (Hg types)