2023 National Excellence in Multistate Research Award
NCERA-137: Soybean Diseases
Administrative Advisor: Martin Draper, Kansas State University
Technical Committee Chair: Alyssa Koehler, University of Delaware
(Click to view photos from the NCERA-137 team)
Managing Soybean Diseases
Soybeans are an affordable, protein-rich legume with a wide variety of uses. In the United States, soybeans were planted on 87.2 million acres—about one-third of all croplands—and had a total value of $45.7 billion in 2022. In recent years, yields have been stagnant in several areas largely due to soybean diseases. Some diseases are more prevalent now due to warmer, wetter climate trends and increased use of no-till planting and are difficult to predict and prevent. Soybean diseases can cause losses of up to $45 per acre. Without sufficient disease management strategies, farmers may waste time and money on ineffective or unnecessary options, some of which pose environmental health risks or promote development of fungicide-resistant pathogens.
For more than 30 years, scientists and Extension educators at land-grant universities across the United States have worked together to study soybean disease prevalence and epidemiology; develop detection and management strategies; and share information and tools with farmers, crop consultants, breeders, government agencies, and agricultural companies. With members in more than 20 states, this project provides a forum that facilitates rapid response to soybean diseases.
New tools and products have helped diagnose and manage soybean diseases, increasing yields and saving farmers millions of dollars. For example, Alabama soybean farmers saved an estimated $2.7 million due to reduced yield loss from soybean rust after applying the right fungicide at the right time. Tennessee soybean farmers estimated saving $7 million in 2017 due to lower management costs and yield losses.
Understanding Soybean Diseases
Project scientists studied the biology and epidemiology of soybean diseases. For example, scientists in Alabama, Louisiana, and Mississippi teamed up to understand the fungus causing taproot decline while researchers in Delaware, Iowa, Louisiana, Michigan, Mississippi, North Dakota, Tennessee, and Wisconsin worked together to identify three novel species of Diaporthe fungi that cause seed disease. Other studies determined that soybean vein necrosis virus is spread mostly by soybean thrips, which are more abundant in dry weather.
Project members also looked at how specific farming practices affect soybean diseases. For example, Kansas researchers found that a pre-season mustard cover crop reduces charcoal rot severity. Another study in Kansas found that applying higher rates of phosphorus during corn years lessened the severity of sudden death syndrome in subsequent soybean crops. Michigan and Wisconsin researchers demonstrated that row spacing can dramatically reduce white mold. Studies in Delaware and Maryland showed that double-cropped soybeans may be affected more severely by soybean vein necrosis. Recently, research confirmed that GPS-guided planting of continuous soybeans has contributed to the emergence of taproot decline.
Monitoring Soybean Diseases
Project members designed better tools and methods for detecting soybean diseases, monitoring spread, and estimating risk. For example, researchers in Iowa and Kentucky showed how Twitter can be used to track soybean diseases. Wisconsin scientists developed the free Sporecaster app to help farmers predict white mold severity and determine when to apply fungicide. Since May 2018, the app has had over 3,000 downloads. The newer companion app, Sporebuster, calculates the economic return of deploying a white mold fungicide.
Researchers are also keeping an eye on pathogens that are resistant to fungicides. For example, researchers in Kentucky and New York spearheaded an effort that identified fungicide-resistant strains of Cercospora sojina, which causes frogeye leaf spot, in 22 states. Genomic analysis detected greater frequency of fungicide resistance among the pathogens that cause Septoria leaf spot and target spot. Researchers also developed a tool that tracks fungicide-resistant pathogen populations. With information about fungicide resistance, soybean farmers can avoid wasting time and money on ineffective fungicide applications.
Testing Chemical Control Options
Project members annually test seed treatments and foliar fungicides to determine which are most cost-effective. Fungicide efficacy tables produced by the group reach about 100,000 users in 18 states each year. In addition to decreasing human and environmental health risks, judicious use of chemical pesticides is saving farmers money. For example, in Alabama, researchers showed that a single well-timed fungicide application for soybean rust can increase yield by 15% to 20%. After learning of these findings, farmers treated more acres with fungicide and saved an estimated $2.7 million in potential yield loss from soybean rust (after considering the application cost for the fungicide).
Improving Soybean Varieties
Project members routinely evaluate soybean resistance to disease causing pathogens. For example, in Arkansas, researchers evaluate the susceptibility of soybean varieties to southern root-knot nematode each year. Scientists in North Dakota and South Dakota identified sources of resistance to the fungal pathogen Fusarium graminearum, and scientists in Illinois, Iowa, Minnesota, and Ohio improved the durability of soybean resistance to pest and disease pressure. Researchers also bred numerous soybean varieties with stronger resistance. For example, four varieties with resistance to Sclerotinia sclerotiorum (which causes white mold) will be released in 2024. Soybean variety tests and new disease-resistant varieties help crop consultants and farmers select and plant better soybeans. For example, a farmer in Michigan reported a 20% yield increase after choosing a variety based on trial results.
Increasing Awareness
Providing science-based information to the soybean industry has increased use of effective solutions. Between 2015 and 2023, this committee produced over 725 peer-reviewed publications; 20 books or book chapters; and more than 500 newsletters, videos, webinars, podcasts, news articles, and other extension products. During field days, grower meetings, and other events, thousands of clients improved their knowledge about soybean disease management. In particular, many project members have been involved in training farmers, pesticide applicators, government agencies, and others on how to detect soybean diseases, select and use chemical fungicides, and monitor fungicide resistance. All project members contributed to the Integrated Pest Management Pest Information Platform for Extension and Education, which shows the spread of soybean diseases in real time and helps farmers make decisions. Project members also provided data and materials for the Crop Protection Network. The network’s publications and decision-support tools have over 750,000 page views. North Dakota State University leads the Soybean Cyst Nematode Coalition, which has encouraged farmers to change the way they manage the disease. The coalition’s efforts have saved growers an estimated $100 million. As part of the coalition, project members helped run “Beat the Pest. Take the Test, Version II,” an outreach campaign that encouraged farmers to test for soybean cyst nematode and take appropriate actions.
Project Participation & Funding
NCERA137: Soybean Diseases is funded in part by the Multistate Research Fund through the USDA-NIFA and by grants to project members at the following institutions: Arkansas Cooperative Extension, Auburn University, Cornell University, University of Delaware, University of Florida, University of Georgia, University of Illinois, Illinois Cooperative Extension, Iowa Cooperative Extension, Kansas State University, University of Kentucky, Louisiana State University, Michigan State University, University of Minnesota, Mississippi State University, University of Missouri, University of Nebraska, North Dakota State University, The Ohio State University, Oklahoma State University, Purdue University, Pennsylvania State University, South Dakota State University, University of Tennessee, Virginia Tech, University of Wisconsin-Madison. Other partners include the United Soybean Board and the North Central Soybean Research Program. Industry sponsors include BASF, Bayer, Cibus, Inc., Corteva, FMC, Syngenta, UPL, Valent, Stratton Seed Company, and Progeny Ag Products. Learn more: bit.ly/NCERA-137. This Impact Statement was produced by the Multistate Research Fund Impacts Program. Learn more: mrfimpacts.org/