Project Details:

Title:
Evaluating resistant soybean varieties and seed treatments to help Iowa farmers maintain high yields on SCN infested fields

Parent Project: Evaluating Resistant Soybean Varieties and Seed Treatments to Help Iowa Farmers Maintain High Yields in SCN Infested Fields
Checkoff Organization:Iowa Soybean Association
Categories:Nematodes
Organization Project Code:021357
Project Year:2020
Lead Principal Investigator:Gregory Tylka (Iowa State University)
Co-Principal Investigators:
Keywords: SCN cyst resistance nematicide seed treatment

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

SCN-resistant soybean varieties vary significantly in effectiveness in suppressing SCN reproduction, and results of greenhouse experiments do not accurately predict nematode control in the field. This project provides field data on yields and effects of SCN-resistant soybean varieties and nematode-protectant seed treatments, a relatively new management option, in Iowa.

Project Objectives

The objectives are to study:
1) the agronomic performance and nematode control provided by SCN-resistant soybean varieties being marketed to Iowa soybean farmers
2) the effects of increasing SCN reproduction on yields of SCN-resistant soybean varieties
3) the effects of nematode-protectant seed treatments on agronomic performance and reproduction of SCN on resistant soybean varieties

Project Deliverables

• list of SCN-resistant soybean varieties for Iowa farmers (ISU Extension publication PM-1649)
• report of results of resistant variety evaluation experiments (ISU Extension publication IPM-52) - printed and distributed as an insert in the Iowa Farmer Today magazine
• research articles published in refereed scientific journals (ex. Plant Health Progress, Plant Disease)
• newsletter articles in the Iowa State University Integrated Crop Management News (online) - see https://crops.extension.iastate.edu/cropnews/2020/01/income-scn-infested-fields-can-be-200-acre-less-pi-88788-peking-resistance

Progress of Work

Updated January 16, 2020:
- Compiled and prepared a publication titled “Soybean cyst nematode-resistant soybean varieties for Iowa,” posted it online - see https://store.extension.iastate.edu/Product/pm1649-pdf. (also uploaded here)
- Harvested research plots in all 9 SCN-resistant variety trial experiments and 27 seed treatment evaluation experiments to determine yields in October 2019. Collected soil samples from every plot in the 9 SCN-resistant variety trial experiments and all 27 seed treatment evaluation experiments to determine final SCN soil population densities in October 2019.
- Extracted SCN cysts, then eggs, from a total of 3,240 soil samples collected from the 9 SCN-resistant variety trial experiments and the 27 seed treatment evaluation experiments at harvest, then counted the eggs to determine final SCN egg population densities in November and December 2019.
- Compiled and analyzed yield and SCN population density data from the SCN-resistant variety trial and seed treatment evaluation experiments in December 2019.
- Prepared a printed report of the SCN-resistant soybean variety evaluation experiment results and distributed the report to 53,250 Iowans as a special insert in the January 11, 2019, issue of the Iowa Farmer Today magazine. The report also is available online - see https://store.extension.iastate.edu/Product/ipm52-pdf. (also uploaded here)
- Revised a manuscript of a research paper that was accepted by the journal Plant Disease that summarizes three years of coordinated ISA On-Farm Network and ISU small-plot experiments evaluating the agronomic benefit and nematode control provided by Ilevo seed treatment (ISA scientists Peter Kyveryga and Tristan Mueller are co-authors). The manuscript includes yield difference graphs (with versus without Ilevo) using Iowa Soybean Association’s online ISOFAST tool.

View uploaded report PDF file

View uploaded report 2 PDF file

Final Project Results

Updated October 13, 2020:
Project progress from 1 April 2020 through 30 September 2020 included:

- Received seed from seed and seed-treatment companies for 2020 field experiments, designed the 2020 field experiments, and packaged and organized the seeds for the various experiments. The variety names and numbers of varieties included in the 2020 SCN-resistant soybean variety trial experiments are from ASGROW (19), Beck’s (15), Cornelius Seed (8), Corteva/Pioneer (12), Dyna-Gro (9), Federal Hybrids (5), Four Star Seeds (4), GROWMARK FS HiSoy (9), Hoegemeyer (12), Jacobsen (5), Kruger (9), Latham (13), Legacy Seeds (3), LG Seeds (13), Merschman (15), NuTech (14), P3 Genetics (3), Stine (17), and Syngenta/NK (18).

- Set up, planted, soil sampled, and maintained nine field experiments located throughout Iowa to evaluate the yield enhancement and nematode control provided by 207 SCN-resistant soybean varieties (21 more than studied in 2019). The first field experiments were planted on April 18, 2020 - the earliest planting date ever for the Tylka field research program.

- Set up, planted, soil sampled, and maintained nine field experiments located throughout Iowa to evaluate the agronomic performance and nematode control provided by four different nematode-protectant seed treatments - namely Aveo (from Valent), Nemasect (from Beck’s), Saltro (from Syngenta), and Trunemco (from NuFarm).

- Extracted SCN cysts (egg-filled dead SCN females), then eggs, from soil samples collected at planting from all 9 resistant variety evaluation experiments and the 36 seed treatment experiments to determine initial SCN egg population densities.

- In early September, began trimming the field research plots at the 45 total field experiments in preparation for harvesting. And 25 experiments at 5 different locations (5 experiments per location) were harvested before the end of September this year.

- In late August, we contacted more than 50 seed companies and gathered information about SCN-resistant soybean varieties to use to update the ISU Extension publication titled “Soybean Cyst Nematode-Resistant Soybean Varieties for Iowa”. This publication will be compiled and released in PDF format by the end of October 2020.

- A research paper summarizing three years of coordinated ISA On-Farm Network and ISU small-plot experiments evaluating the agronomic benefit and nematode control provided by Ilevo seed treatment was published in the journal Plant Disease in September 2020 with ISA scientists Peter Kyveryga and Tristan Mueller are co-authors. The manuscript included yield difference graphs (with Ilevo versus without Ilevo) using Iowa Soybean Association’s online ISOFAST tool.

View uploaded report PDF file

View uploaded report 2 PDF file

Currently there are three options for managing SCN: 1) growing nonhost crops such as corn, 2) growing SCN-resistant soybean varieties, and 3) using nematode-protectant seed treatments on soybean seeds. The results of the experiments conducted in this project help Iowa soybean farmers decide which resistant varieties and seed treatments to purchase for use in fields infested with SCN. The results of the experiments conducted in 2020 are not yet available because not all of the experimental plots have been harvested by the date of this report and none of the end-of-season SCN soil samples have been processed and counted. The report of 2019 variety trial experiment results and the 2019 list of SCN-resistant soybean varieties for Iowa are attached to this final report.

Benefit to Soybean Farmers

There is no legal definition of to what extent soybean varieties must suppress reproduction of SCN in order to be considered “SCN resistant.” And SCN resistance involves numerous genes, so not all SCN-resistant varieties possess the full complement of genes. Therefore, yield and nematode control vary greatly among the hundreds of SCN-resistant soybean varieties from which Iowa soybean farmers have to choose.
In the last decade, nematode-protectant seed treatments (ex. Avicta, Clariva, Ilevo, Votivo) have begun to be sold to Iowa farmers as an additional management tool for SCN. But increased yields and suppression of SCN reproduction by these seed treatments is not guaranteed.
The experiments conducted in this project are farmer-focused applied research that is unique in Iowa and the nation in that SCN-resistant soybean varieties and nematode-protectant seed treatments are intensively evaluated under real Iowa field conditions and nematode data are collected from each individual 4-row research plot at the time of planting and again at the time of harvesting. The intensive-scale information emanating from these experiments is not available anywhere else in the U.S. The research results give Iowa soybean farmers first-hand information generated in their state about the performance that can be expected when these SCN-resistant soybean varieties and the nematode-protectant seed treatments are used.
Furthermore, the experiments with nematode-protectant seed treatments are coordinated closely with the Iowa Soybean Association’s On-Farm Network in order to generate a robust set of data from throughout Iowa to illustrate to Iowa soybean farmers what can be expected in terms of yield increase and SCN reproduction suppression when the seed treatments are used.

Performance Metrics

• number of Iowans receiving report of variety evaluation experiments conducted in 2019 = 53,250
• number of different SCN-resistant varieties evaluated in experiments in 2019 = 193 (11 with Peking SCN resistance); number of brands of seed evaluated in 2019 = 18
• number of variety evaluation field experiments conducted in 2019 = 9; number of seed treatment field experiments conducted in 2019 = 27
• number of plots planted, maintained, soil sampled twice, and harvested in 2019 = 3,240
• number of SCN soil samples processed and counted in 2019 = 6,480
• number of resistant varieties for which information was obtained/compiled in 2019 = 891

Project Years