This proposal addresses the priority area of Soybean Pest Management. It addresses a special request from the Research action team to address the increasing problem with the disease frogeye leaf spot (FLS) in Minnesota. It focuses on increasing awareness of FLS as well as increasing our knowledge of its occurrence, distribution, and fungicide resistance in its causal pathogen.

Frogeye leaf spot has long been a common and significant yield- reducing disease of soybean in the southern and central United States. More recently, especially in the past 6 years, FLS has been increasing in incidence and severity in Minnesota. FLS is caused by the fungus Cercospora sojina. Infection and disease development is favored by warm, humid weather, and severe defoliation can occur under these conditions. Frogeye leaf spot can occur at any time during the growing season, but typically occurs after flowering. The pathogen overwinters in soybean residue and seeds. To manage frogeye leaf spot, resistant soybean varieties, fungicides, and rotating to non-host crops can be implemented.

1. Determine the distribution and severity of frogeye leaf spot in Minnesota
2. Determine occurrence and frequency of resistance across the state to QoI's and other common fungicide groups
3. Increase awareness and knowledge of frogeye leaf spot in Minnesota by developing targeted educational materials and events.

• Determine the distribution and severity of FLS across Minnesota and how it’s development in different areas is associated with weather patterns in 2023.
• Identify the distribution and frequency of resistance to fungicides in the FLS pathogen from fields across the state of Minnesota.
• Develop and extend updated information on the management, distribution, and risks of frogeye leaf spot for Minnesota soybean growers.

Update:
Quarterly Progress Report for 2023-2024 Minnesota Soybean Research and Promotion Council Production Action Team


Project Title: Increasing Awareness and Knowledge of Frogeye Leaf Spot in Minnesota
• Principle Investigator: Dean Malvick
• Department/Organization: Department of Plant Pathology, University of Minnesota, St. Paul, MN

• Dates of Reporting: May 1 – July 31, 2023

A summary of activity and progress is summarized below for this project for this reporting period. Please let me know if you would like additional information about this project and the results. Thank you.


Background:
Frogeye leaf spot has long been a common and significant yield- reducing disease of soybean in the southern and central United States. More recently, especially in the past 6 years, FLS has been increasing in incidence and severity in Minnesota during years and areas with average or above average rainfall. FLS is caused by the fungus Cercospora sojina. Infection and disease development is favored by warm, humid weather, and severe defoliation can occur under these conditions. Frogeye leaf spot can occur at any time during the growing season, but typically occurs after flowering. To manage FLS, resistant soybean varieties, fungicides, and rotating to non-host crops can be implemented.

Project Objectives
1. Determine the distribution and severity of frogeye leaf spot in Minnesota
2. Determine occurrence and frequency of resistance across the state to QoI's and other common fungicide groups
3. Increase awareness and knowledge of frogeye leaf spot in Minnesota by developing targeted educational materials and events.

Activity and Progress Report by Objective
The very dry weather and drought conditions for most of the summer in most of Minnesota has not allowed Frogeye Leaf Spot (FLS) to develop in most areas and at only very low levels some areas. Thus, we have been able to collect only a few samples this year so far. Our sampling will continue until the soybeans mature and the leaves senesce. This winter we will produce materials and do presentations to increase awareness of FLS and the risk it poses in Minnesota.

Information Dissemination of data/information from this research during this reporting period. The disease has been absent in most fields in Minnesota this year, and thus there has not been an opportune time (i.e., a good teachable moment) to discuss and disseminate information on this disease this summer.

Update:
Quarterly Progress Report for 2023-2024 Minnesota Soybean Research and Promotion Council Production Action Team

Project Title: Increasing Awareness and Knowledge of Frogeye Leaf Spot in Minnesota

• Principle Investigator: Dean Malvick
• Department/Organization: Dept. of Plant Pathology, University of Minnesota, St. Paul

• Dates of Reporting: August 1 – Oct 31, 2023

Activity and progress for this project are summarized below for this reporting period. Please let me know if you would like additional information about this project and the results. Thank you.

Background: The soybean disease frogeye leaf spot (FLS) has been a common and significant yield- reducing disease in the southern and central United States for many years. However, in the past 6 years, FLS has been increasing in incidence and severity in Minnesota during years and areas with average or above average rainfall. There was very little FLS in Minnesota during the drought years of 2022 and 2023. FLS is caused by the fungus Cercospora sojina. Infection and disease development are favored by warm, humid weather, and severe defoliation can occur under these conditions. Frogeye leaf spot can occur at any time during the growing season, but typically occurs after flowering. To manage FLS, resistant soybean varieties, fungicides, and rotating to non-host crops can be implemented.

Project Objectives
1. Determine the distribution and severity of frogeye leaf spot in Minnesota
2. Determine occurrence and frequency of resistance across the state to QoI's and other common fungicide groups.
3. Increase awareness and knowledge of frogeye leaf spot in Minnesota by developing targeted educational materials and events.

Activity and Progress Report by Objective
The very dry weather and drought conditions during the summer of 2023 did not favor development of frogeye leaf spot (FLS) in Minnesota. In spite of scouting multiple fields in August and September, including irrigated fields, we did not find FLS this year. We had no problem finding this disease in the same fields in multiple years prior to 2021. The absence of FLS this year in the irrigated fields suggests that perhaps the dry weather in 2022 suppressed development of inoculum of the pathogen, thus making it less available to infect soybeans in 2023. We will look for a similar pattern next year. This winter we will produce materials and deliver presentations to increase awareness of FLS and the risk it poses in Minnesota.

Information Dissemination of data/information from this research during this reporting period. The disease has been absent in fields in Minnesota this year, and thus there has not been an opportune time (i.e., a good teachable moment) to discuss and disseminate information on this disease this summer.

Update:
Quarterly Progress Report for 2023-2024 Minnesota Soybean Research and Promotion Council Production Action Team

Project Title: Increasing Awareness and Knowledge of Frogeye Leaf Spot in Minnesota

• Principle Investigator: Dean Malvick
• Department/Organization: Dept. of Plant Pathology, University of Minnesota, St. Paul
• Dates of Reporting: November – February 29, 2024

Activity and progress for this project are summarized below for this reporting period. Please let me know if you would like additional information about this project. Thank you.

Background: Frogeye leaf spot (FLS) has been a common and significant yield- reducing soybean disease in the southern and central United States for many years. In the past 6 years, FLS has been increasing in incidence and severity in Minnesota during years and areas with average or more rainfall. There was very little FLS in Minnesota during the dry years of 2022 and 2023. FLS is caused by the fungus Cercospora sojina. Infection and disease development are favored by warm, humid weather, and severe defoliation can occur. Frogeye leaf spot can occur at any time during the growing season, but typically occurs after flowering. To manage FLS, resistant soybean varieties, fungicides, and rotating to non-host crops can be implemented.

Project Objectives
1. Determine the distribution and severity of frogeye leaf spot in Minnesota
2. Determine occurrence and frequency of resistance across the state to QoI's and other common fungicide groups.
3. Increase awareness and knowledge of frogeye leaf spot in Minnesota by developing targeted educational materials and events.

Activity and Progress Report by Objective: The very dry weather and drought conditions during the summer of 2023 did not favor development of frogeye leaf spot (FLS) in Minnesota. In spite of scouting multiple fields in August and September, including irrigated fields, we did not find FLS this year. We had no problem finding this disease in the same fields in multiple years prior to 2022. The absence of FLS this year in the irrigated fields suggests that perhaps the dry weather in 2022 suppressed development of inoculum of the pathogen, thus making it less available to infect soybeans in 2023. This winter we have given talks to increase awareness of FLS and the risk it poses in Minnesota. But given that this project is primarily field-based and of greatest interest to audiences when it is a problem, the project is essentially no hold now until summer of 2024 when we plan to continue with this project under a no-cost extension.

Information Dissemination of data/information from this research during this reporting period. The disease was absent in fields in Minnesota this year, and thus there have been few opportune times (i.e., a good teachable moments) to discuss and disseminate information on this disease, although we have done some and will continue next summer.

View uploaded report

Updated May 31, 2024:
Quarterly Progress Report for 2023-2024 Minnesota Soybean Research and Promotion Council Production Action Team

Project Title: Increasing Awareness and Knowledge of Frogeye Leaf Spot in Minnesota

• Principle Investigator: Dean Malvick
• Department/Organization: Dept. of Plant Pathology, University of Minnesota, St. Paul

• Dates of Reporting: May 2024

Activity and progress for this project are summarized below. Please let me know if you would like additional information about this project and the results. Thank you.

Background: Frogeye leaf spot (FLS) has been a common and significant yield- reducing soybean disease in the southern and central United States for many years. In the past 6 years, FLS has been increasing in incidence and severity in Minnesota during years and in areas with average or above average rainfall. There was very little FLS in Minnesota during the drought years of 2022 and 2023. FLS is caused by the fungus Cercospora sojina. Infection and disease development are favored by warm, humid weather, and severe defoliation can occur under these conditions. Frogeye leaf spot can occur at any time during the growing season, but typically occurs after flowering. To manage FLS, resistant soybean varieties, fungicides, and rotating to non-host crops can be implemented.

Project Objectives
1. Determine the distribution and severity of frogeye leaf spot in Minnesota.
2. Determine occurrence and frequency of resistance across the state to QoI's and other common fungicide groups.
3. Increase awareness and knowledge of frogeye leaf spot in Minnesota by developing targeted educational materials and events.

Activity and Progress Report by Objective
The very dry weather and drought conditions during the summer of 2023 did not favor development of frogeye leaf spot (FLS) in Minnesota. In spite of scouting multiple fields in August and September, including irrigated fields, we did not find FLS in 2023. We had no problem finding this disease in the same fields in previous years. The absence of FLS this year in irrigated fields also suggested that the dry weather in 2022 suppressed development of inoculum of the pathogen, thus making it less available to infect soybeans in 2023. We will look to determine if a similar pattern occurs next year.

Information Dissemination of data/information from this research during this reporting period.
The disease has been absent in fields in Minnesota this year, and thus there has not been an opportune time (i.e., good teachable moments) to discuss and disseminate information on this disease. This is planned for 2024, as this project has been approved for a no-cost extension.

Updated April 19, 2024:

Updated April 19, 2024:

Updated April 19, 2024:

This project, as outlined above, will address the need for improved understanding and management of frogeye leaf spot in soybean yields across Minnesota. Enhanced understanding of where and when FLS occurs, how to identify this disease, and how to manage it more effectively should result in higher soybean yields. Results will be transferred through newsletters, production meetings and field days, scientific meetings, and news outlets. The ultimate benefit to soybean growers will be higher yields and reduced risk of lost yields due to disease.