2021
Survey and rapid diagnostics for fungicide resistant Frogeye Leaf Spot in Nebraska
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Contributor/Checkoff:
Nebraska Soybean Board
Category:
Sustainable Production
Keywords:
Crop protectionDiseaseField management
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Sydney Everhart, University of Nebraska at Lincoln
Co-Principal Investigators:
Project Code:
707
Contributing Organization (Checkoff):
Nebraska Soybean Board
$73,133
Institution Funded:
University of Nebraska at Lincoln
$73,133
Brief Project Summary:
Frogeye leaf spot (FLS) is becoming more common in Nebraska. FLS is caused by a fungal pathogen that overwinters on soybean plant residue and seeds. During the growing season, it spreads through wind and rain. Disease development is encouraged by long periods of wet weather during the growing season. Soybean producers can manage FLS through planting available FLS-resistant varieties, crop rotation with non-host crops, tillage and applying foliar fungicides with different modes of action. Studies on FLS are showing that the pathogen is becoming resistant to QoI fungicides. A survey of soybean farmers found that they’re more focused on fighting sudden death syndrome and white mold over FLS.
Key Beneficiaries:
#local cooperative service providers, #Soybean farmers
Unique Keywords:
# fungicide, #crop rotation, #disease management, #disease management, crop rotation, #foliar fungicide, #frogeye leaf spot, #fungicide application, #fungicide resistance, #leaf samples, #soybean diseases
Information And Results
Project Summary

The proposed study is aimed at developing:
1) a DNA-based method to provide rapid diagnostics to identify FLS-resistance at no direct cost to growers in the next three years;
2) new information on the distribution and spread of fungicide resistant FLS in Nebraska; and
3) educational materials and outreach programs on resistance management practices.

Project Objectives

1. Develop a DNA-based protocol for rapid identification of QoI resistant C. sojina.
2. Solicit FLS samples coming from Nebraska soybean grower fields by contacting crop consultants, commercial agronomists, and Extension educators, and use the DNA-based tool (from Obj. 1) for rapid diagnosis of FLS fungicide resistance at no cost to the grower.
3. Perform targeted follow-up sampling of selected soybean fields to be able to characterize the within-field distribution of fungicide resistance.
4. Characterize the population structure and genetic diversity of C. sojina populations (from Obj. 2 and 3) from soybean to better understand the epidemiology of resistance in Nebraska.
5. Develop/deliver educational materials and outreach programs on resistance management.

Project Deliverables

1. Develop a DNA-based protocol for rapid identification of QoI resistant C. sojina
2. Solicit FLS samples coming from Nebraska soybean grower fields by contacting crop consultants, commercial agronomists, and Extension educators, and use the DNA-based tool (from Obj. 1) for rapid diagnosis of FLS fungicide resistance at no cost to the grower
3. Perform targeted follow-up sampling of selected soybean fields to be able to characterize the within-field distribution of fungicide resistance
4. Characterize the population structure and genetic diversity of C. sojina populations (from Obj. 2 and 3) from soybean to better understand the epidemiology of resistance in Nebraska
5. Develop/deliver educational materials and outreach programs on resistance management.

Progress Of Work

Final Project Results

Updated May 19, 2023:

View uploaded report PDF file

These results will help Nebraska soybean producers select more effective foliar fungicides, especially those with active ingredients from mixed fungicide classes and to use alternative strategies to manage frogeye leaf spot. Knowing that QoI (strobilurin) fungicides are ineffective when used alone, will help producers to select other more effective fungicides for frogeye leaf spot control thereby reducing input costs and reducing selection pressure on other pathogens that can also become resistant to fungicides. Producers may also have samples from their fields tested more rapidly than ever before for fungicide resistance to help them better select more effective fungicide products.

Benefit To Soybean Farmers

In 2019, resistance to QoI fungicides was confirmed in 10 isolates of C. sojina from 10 counties in Nebraska. Fungicide resistance is a serious concern because it threatens the ability to use QoI fungicides, which are some of the most effective and widely used fungicides for managing FLS. A major limitation is that we do not presently have capacity within Nebraska for QoI resistance screening of C. sojina.
The proposed study is aimed at:
1) developing a DNA-based method to provide rapid diagnostics to identify FLS-resistance at no direct cost to growers in the next three years,
2) developing new information on the distribution and spread of fungicide resistant FLS in Nebraska, and
3) develop educational materials and outreach programs on resistance management practices.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.