2023
Addressing Management Challenges with Soybean Stem Diseases in Minnesota
Category:
Sustainable Production
Keywords:
Crop protectionDiseaseField management
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Dean Malvick, University of Minnesota
Co-Principal Investigators:
Project Code:
10-15-44-23138
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:
This project focuses on managing stem and root rots and their yield-limiting effects. This project targets management strategies for specific stem diseases, primarily brown stem rot, pod and stem blight. The goals are to identify resistance in varieties adapted to Minnesota and to understand disease management with fungicides and crop rotation. This project also addresses a longer-term goal of understanding the reasons for yield ‘drag’ and the role that disease plays. The researchers aim to understand the distribution of these and other key stem and root diseases through surveys and diagnoses in collected plants.
Key Beneficiaries:
#agronomists, #extension specialists, #farmers, #plant pathologists
Unique Keywords:
#root rot, #soybean diseases, #soybean varieties, #stem rot, #survey
Information And Results
Project Summary

This proposal addresses the priority area of Soybean Pest Management. It focuses on research into managing against yield and quality limiting effects of stem and root rots. Stem diseases are widespread and problematic across Minnesota. They are often clearly damaging to plants and yield, and other times they may be undetected and yet cause yield losses. If we understand when and where stem diseases occur and how to manage them more effectively, yield could increase in many areas. This proposed project targets management strategies for specific stem diseases, primarily brown stem rot (BSR) and pod and stem blight. The goals are to identify resistance to BSR and pod and stem blight in breeding lines and varieties adapted to MN and to understand the challenge and opportunities for disease management with fungicides and crop rotation. This project also addresses a longer-term goal of understanding the reasons for yield ‘drag’ in many fields and the role that disease plays. Changes in the occurrence and types of stem diseases (e.g., BSR, stem canker, pod and stem blight) require that soybean growers and their advisors better understand these risks to plan for and react with appropriate management. Thus, we aim to understand the distribution of these and other key stem and root diseases via surveys and disease diagnosis with plants collected from different areas. This proposed research will address short- and long-term goals to manage key soybean stem diseases.

Project Objectives

1. GOAL: Evaluate tactics to manage brown stem rot (BSR)
OBJECTIVES: Evaluate soybean breeding lines and varieties for resistance to BSR and determine the effects of potential alternative hosts and crop rotation on risk and management of BSR

2. GOAL: Determine methods to manage pod and stem blight (PSB) of soybean.
OBJECTIVE: Determine if there are clear and consistent differences in susceptibility to the pod and stem blight pathogens and determine if seed treatments can reduce severity of pod and stem blight

3. GOAL: Determine distribution and prevalence of important soybean stem and root diseases/pathogens in Minnesota
OBJECTIVE: Conduct survey for soybean stem and root diseases to better understand their current distribution and risk to Minnesota soybean growers

Project Deliverables

• Identify the level of resistance to both prevalent types of the BSR pathogen in soybean breeding lines and varieties from the U of MN soybean-breeding program.
• Determine if new methods to evaluate soybean for resistance to BSR are more consistent and have higher throughput than current methods.
• Determine the effects of crop rotation and alternative hosts of the BSR pathogen on risk and management of BSR
• Identify the level of resistance to the pod and stem blight pathogens in soybean breeding lines from the U of MN soybean-breeding program and select commercial varieties.
• Improve understanding of the distribution and risks of key soybean stem and root diseases to Minnesota soybean growers.
• Develop and extend updated information on the management, distribution, and risks of key soybean stem and root diseases for Minnesota soybean growers.

Progress Of Work

Updated September 1, 2023:
Quarterly Progress Report for 2023-2024 Minnesota Soybean Research and Promotion Council Production Action Team


Project Title: Addressing Management Challenges with Soybean Stem Diseases 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 each part of this project for this reporting period. Please let me know if you would like additional information about this project and the results. Thank you.

Project Objectives

1. Evaluate tactics to manage brown stem rot (BSR) of soybean.
2. Determine methods to manage pod and stem blight (PSB) of soybean.
3. Determine distribution and prevalence of important soybean stem and root diseases/pathogens in Minnesota.

Activity and Progress Report by Objective

Objective 1. Evaluate tactics to manage brown stem rot (BSR) of soybean.
Background. BSR is a common and important soybean disease in Minnesota. Crop rotations and resistant varieties suppress BSR, however, neither method is a complete solution to managing the disease. Because BSR is a continuing threat in Minnesota, more information is needed to understand risk factors and disease management options.

Goal A. Evaluate soybean breeding lines and varieties for resistance to BSR. Advanced breeding lines from the U of MN soybean-breeding program, as well as selected commercial soybean varieties, will be evaluated for resistance to BSR. In addition, because BSR resistance is difficult to evaluate, we also aim to compare different resistance testing methods with the goal of developing a method that is consistent and has higher throughput for breeding and research needs.

Progress and results to date: This research will be conducted in a greenhouse under controlled conditions this fall, winter, and spring when the greenhouse is consistently cool enough to conduct this work.

Goal B. Determine the effects of potential alternative hosts and crop rotation on risk and management of BSR. The BSR pathogen (Cadophora gregata) is thought to only infect soybeans, but this is poorly documented and understood. Thus, we need more information to determine if other plant species can become infected and sustain the BSR pathogen in soil and crop rotations in the absence of soybean.

Progress and results to date; A diverse set of legumes and weed species was tested to determine if they can serve as hosts of BSR pathogen. Twenty-seven different species of weeds and crops were inoculated (via stem injection and root dip) with C. gregata at early growth stage V1 and then grown for approximately 7 weeks before assessing BSR incidence and severity. The preliminary results suggest that some Phaseolus vulgaris cultivars including black bean, pinto bean, and navy pea may be newly discovered hosts of C. gregata. In agreement with one previous report, red kidney and red clover do not appear to be hosts of C. gregata. Further analysis of the plant samples and data is required to confirm these results and fully assess all species tested.



Objective 2. Determine methods to manage pod and stem blight (PSB) of soybean.
Pod and stem blight is a widespread and problematic disease in Minnesota soybean fields. The pod and stem blight pathogens are also common as latent pathogens in asymptomatic plants. Soybean varieties can vary in resistance and crop rotation may be beneficial. but the disease is still widespread and often kills plants. Overall, this disease and how to manage it are poorly understood.

Goal: Evaluate tactics to manage pod and stem blight of soybean. The goals are to determine if there are clear and consistent differences in susceptibility to the pod and stem blight pathogens and to determine if seed treatments can reduce severity of pod and stem blight.

Progress and results to date: Selected commercial soybean varieties are current in a trial in progress and have been inoculated for evaluation for resistance to pod and stem blight. These studies of resistance are being conducted in the greenhouse and field (St. Paul). Disease development and severity have been and are continuing to be monitored. Some of the plants developed clear symptoms, and full results should be available in October.



Objective 3. Determine distribution and prevalence of important soybean stem and root diseases/pathogens in Minnesota.
Increasing and maintaining soybean yields in the presence of new and evolving pathogens and diseases requires continued improvements in soybean varieties, fungicides, and crop management practices. New pathogens and new disease management practices require more information to manage and use them most effectively. Thus, there is a need for increased disease/pathogen survey activity to detect and understand how risks from key soybean diseases are changing and where and when they occur.
Goal: Survey for soybean stem and root diseases to better understand their current distribution and risk to Minnesota soybean growers. Plants samples will be diagnosed in a laboratory to identify symptoms and the presence of key pathogens using pathogen isolation methods and specific DNA diagnostic tests.
Progress and results to date: The dry/drought conditions in Minnesota have been suppressing development of soybean diseases, and so far, we have obtained only a few samples that are useful. Samples with charcoal rot were obtained from one field and broader surveys will be conducted in September to determine the prevalence of key diseases.


Information Dissemination of data/information from this research during this reporting period

During the period from May – July for this report information dissemination has been focused on email and telephone conversations with growers, consultants and others with questions and concerns.



Updated November 8, 2023:
see uploaded file

View uploaded report Word file

Final Project Results

Benefit To Soybean Farmers

This project, as outlined with each of the deliverables, will address the need for improved understanding and management of key soybean diseases that reduce soybean yields across Minnesota. Enhanced understanding of where stem and root diseases occur and managing them more effectively should result in increased soybean yields in many fields. Thus, this research will produce information to improve disease management and reduce risk and yield-loss for soybean. Results will be transferred through newsletters, production meetings and field days, scientific meetings, and news outlets. The ultimate benefit to soybean growers will be increased yields and reduced risk of lost yields due to disease.

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.