Soybean Disease Loss Estimates From the United States and Ontario, Canada — 2020

Each year, soybean diseases reduce yield in the United States and Ontario, Canada. The importance of these diseases varies annually, and many factors influence which diseases significantly affect yield. These factors can include environment, production practices, and a variety’s susceptibility to disease.

The current publication provides the estimated annual soybean yield losses due to plant diseases and pathogens in 2020 for the major soybean-producing areas in the United States and Ontario, Canada. Extension, university, USDA plant pathologists and soybean specialists from each state and province provided the estimates. These reports accounted for 99.9 percent of the total soybean production in the United States and Ontario in 2020. The estimated losses include those caused by foliar diseases, stem diseases, nematodes, seedling blights, and diseases of harvested grain.

Disease loss estimates are gathered through various means including disease surveys; interactions with Extension, university, government, industry, and farmer representatives; and personal experience with disease losses. Estimation methods vary by state or province.

For this publication, the authors determined disease loss values based on yield before estimated losses for each state or province using this formula:

(harvested bushels/[{100 – percent estimated disease loss}/100])

The authors then formulated the total number of bushels lost for each disease ([percent loss/100] x yield before estimated loss) for each state or province.

Additional information on yield and economic losses due to soybean diseases can be found at the CPN Field Crop Disease Loss Calculator.

2020 Production

The United States produced more than 4.1 billion bushels of soybean in 2020, an increase of nearly 0.6 billion bushels from 2019. Ontario, Canada, produced 143.6 million bushels in 2020.

2020 Disease Losses

In all, 5.0 percent of the potential estimated soybean production (bushels/acre) in 2020 was lost due to disease in the top 29 soybean-producing states, and 9.1 percent of the total estimated soybean production in 2020 was lost due to disease in Ontario, Canada. Table 1 provides yield loss estimates for the specific diseases included in the survey of plant pathologists throughout the soybean production system in the U.S. and Ontario, Canada. Estimated percent losses in 2020 were less than those reported during either of the preceding two years.

Table 1. Estimated soybean yield losses from diseases in 29 soybean producing states in the United States and Ontario, Canada in 2020, listed in order of most losses to least losses in each disease category.

¹Lance, root lesion, sting, and stubby root. Only root lesion nematode was reported in Ontario, Canada; ²A portion of the estimated yield loss value for purple seed stain in the U.S. is due to dockage from low quality seed reported from New York; ³Bean pod mottle, soybean mosaic, soybean vein necrosis, tobacco ringspot, and tobacco streak. Only soybean mosaic was reported in Ontario, Canada; 4A portion of the estimated yield loss value for Diaporthe (Phomopsis) seed decay in the U.S. is due to dockage from low quality seed reported from North Carolina and New York. The estimated yield loss value for Diaporthe (Phomopsis) seed decay from Ontario is due to dockage from low quality seed; 5Phymatotrichopsis root rot and red crown rot

Diseases in the Northern United States

The northern states in the U.S., which included Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Nebraska, New York, North Dakota, Ohio, Pennsylvania, South Dakota, and Wisconsin, accounted for 66.0 percent of the total estimated yield losses in 2020. Because three-quarters of U.S. soybean production occurs in the northern states, disease losses in these states greatly affect the overall importance of different diseases across the country (see Table 2). However, drought conditions in soybean production areas in 2020 likely resulted in less disease loss than is normal in the northern region.

Table 2. Estimated soybean yield losses due to the seven most significant diseases in the northernmost U.S. states¹ in 2020.

¹Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Nebraska, New York, North Dakota, Ohio, Pennsylvania, South Dakota, and Wisconsin

Diseases in the Southern United States

Soybean cyst nematode, root-knot nematode, and Cercospora leaf blight were the three diseases of greatest importance in 2020 in the southernmost U.S., which included Alabama, Arkansas, Delaware, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, Missouri, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia (see Table 3).

Table 3. Estimated soybean yield losses due to the seven most significant diseases in the southernmost U.S. states¹ in 2020.

¹Alabama, Arkansas, Delaware, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, Missouri, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia

Diseases in Ontario, Canada

Similar to 2019, soybean cyst nematode caused the greatest estimated yield loss in Ontario, Canada, in 2020, followed by sudden death syndrome and seedling diseases (see Table 4). There were no foliar diseases present among the top yield-reducing diseases in Ontario.

Table 4. Estimated soybean yield losses due to the seven most significant diseases in Ontario, Canada in 2020.

Disclaimer

The yield losses estimated in this publication were provided by members of the North Central Research and Extension Activity (NCERA) 137 Soybean Disease Committee and the Southern Soybean Disease Workers. The information contained in the current publication is meant to be used as a guide. The values in this publication are estimates and are not intended to be used as exact measurements of soybean yield losses due to plant diseases. However, these data provide valuable insight into the ranking of importance of a given disease within a production region (north or south) as well as across the entire production system. The most appropriate means available were used to estimate disease losses and no liability resulting from the use of these estimates is assumed.

Values reported in this document were accurate as of publication date and do not reflect corrections or updates occurring since that time. For the most up-to-date values and additional information on yield and economic losses due to diseases, see the Field Crop Disease Loss Calculator at https://loss.cropprotectionnetwork.org/.

Acknowledgments

Authors

Carl Bradley, University of Kentucky; Tom Allen, Mississippi State University; Albert Tenuta, Ontario Ministry of Agriculture, Food and Rural Affairs; Kelsey Mehl, University of Kentucky; and Adam Sisson, Iowa State University.

Contributors

Ed Sikora, Auburn University; Terry Spurlock and Travis Faske, University of Arkansas; Alyssa Koehler, University of Delaware; Nick Dufault, University of Florida; Bob Kemerait, University of Georgia; Nathan Kleczewski, University of Illinois; Darcy Telenko, Purdue University; Daren Mueller, Iowa State University; Rodrigo Onofre, Kansas State University; Carl Bradley, University of Kentucky; Trey Price and Boyd Padgett, Louisiana State University; Marty Chilvers and Fred Warner, Michigan State University; Dean Malvick and James Kurle, University of Minnesota; Tom Allen, Mississippi State University; Kaitlyn Bissonnette, University of Missouri; Tamra Jackson-Ziems, University of Nebraska; Gary Bergstrom, Cornell University; Lindsey Thiessen, North Carolina State University; Samuel Markell and Berlin Nelson, North Dakota State University; Anne Dorrance, The Ohio State University; John Damicone, Oklahoma State University; Albert Tenuta, Ontario Ministry of Agriculture, Food and Rural Affairs; Alyssa Collins and Paul Esker, Pennsylvania State University; John Mueller, Clemson University; Emmanuel Byamukama and Connie Tande, South Dakota State University; Heather Kelly, University of Tennessee; Tom Isakeit, Texas A&M University; Hillary Mehl, Virginia Tech; and Damon Smith, University of Wisconsin-Madison.

Sponsors

The authors thank the United Soybean Board and the Grain Farmers of Ontario for their support. Support also was provided by State and Federal Funds appropriated to the State Land Grant Institutions of cooperating authors and the United States Department of Agriculture - National Institute of Food and Agriculture (USDA-NIFA).