Soybean Disease Loss Estimates From the United States and Ontario, Canada — 2015

Soybean Disease Loss Estimates From the United States and Ontario, Canada — 2015

Each year, soybean diseases reduce yield in the United States and Ontario, Canada. Diseases of importance vary on an annual basis, and diseases that affect yield are based on many factors, including environment, crop production practices, as well as variety selection and susceptibility to disease.

This article provides the annual estimates for soybean losses due to plant diseases and pathogens for the major soybean-producing states in the United States and Ontario, Canada. Extension, university, USDA plant pathologists, and soybean specialists from each state and Ontario provided the estimates used in this report. These reports accounted for 3.9 billion bushels (99.6 percent) of the total soybean produced in the United States and Ontario in 2015. This publication includes seedling blights, foliar diseases, stem diseases, nematodes, and seed diseases in the estimated losses. It is important to note that the methods for estimating disease loss vary by state and province. The estimates may be based on disease surveys; feedback from university, extension, industry, and farmer representatives; and personal experience with disease losses.

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

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

The authors then formulated total bushels lost per disease (percent loss × yield before estimated losses) for each state.

2015 Conditions and Production

The United States produced more than 3.93 billion bushels of soybean in 2015, and many areas reported record yield. Overall, temperatures were mild, and 2015 marked the 19th consecutive year that the average temperature was greater than the 20th century average. Much of the central and southeastern United States had above-average precipitation.

In Ontario, the 2015 growing season overall was moderate and near normal in terms of temperature and rainfall. The total soybean production in Ontario for 2015 was 132,489,900 bushels.

2015 Disease Losses

In all, 11.7 percent of the total estimated soybean bushels in 2015 were lost due to disease in the top 28 soybean-producing states, and 10.4 percent of the total estimated soybean bushels in 2015 were lost due to disease in Ontario, Canada. Table 1 provides yield loss estimates for all diseases.

Diseases in the Northern United States

A total of 81.6 percent of the estimated yield losses for 2015 occurred in northern U.S. states. Disease losses in the northern states greatly influence the overall importance of various diseases across the United States, because the majority (78 percent) of soybean production occurs in these states.

Soybean cyst nematode caused the greatest estimated yield losses in the northern states, with more than 95 million bushels lost (Table 2), which is almost 25 percent of the total amount of disease-related losses. Wet conditions at planting across most of the Midwest contributed to increased loss from soilborne diseases such as seedling diseases and sudden death syndrome.

Diseases in Southern States

In southern states, soybean cyst nematode and root-knot nematode were particularly damaging (Table 3). High relative humidity and warm temperatures contributed to the prevalence of frogeye leaf spot.


Environmental conditions varied across the United States and Ontario in 2015, which affected the presence and impact of many diseases. Wet conditions during planting across the Midwest likely influenced the prevalence of seedling and stem diseases observed.


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. This information is only a guide. The values in this article are estimates and are not intended to be used as exact measurements of soybean yield losses due to diseases. The most appropriate means available were used to estimate disease losses and no liability resulting from the use of these estimates is assumed.

Reference to products in this article is not intended to be an endorsement to the exclusion of others that may be similar. Individuals using such products assume responsibility for their use in accordance with current directions of the manufacturer. 


Carl Bradley, University of Kentucky; Tom Allen, Mississippi State University; Martin Chilvers, Michigan State University; Loren Giesler, University of Nebraska; Kelsey Mehl, University of Kentucky; Daren Mueller, Iowa State University; Albert Tenuta, Ontario Ministry of Agriculture, Food and Rural Affairs; Adam Sisson, Iowa State University; Kiersten Wise, Purdue University


The following individuals contributed to this publication:

Alabama – Ed Sikora; Arkansas – Terry Spurlock, Travis Faske; Delaware – Nathan Kleczewski; Florida – Nick Dufault; Georgia – Bob Kemerait; Illinois – Glen Hartman, Jason Bond, and Carl Bradley; Indiana – Kiersten Wise; Iowa – Daren Mueller; Kansas – Doug Jardine; Kentucky – Carl Bradley; Louisiana – Charlie Overstreet, Trey Price, and Clayton Hollier; Maryland – Nathan Kleczewski; Michigan – Marty Chilvers and Fred Warner; Minnesota – Dean Malvick and James Kurle; Mississippi – Tom Allen; Missouri – Bill Weibold; Nebraska – Loren Giesler; North Carolina – Steve Koennig; North Dakota – Sam Markell and Berlin Nelson; Ohio – Anne Dorrance; Oklahoma – John Damicone; Ontario, Canada – Albert Tenuta; Pennsylvania – Alyssa Collins; South Carolina – John Mueller; South Dakota – Emmanuel Byamukama and Connie Tande; Tennessee – Heather Kelly; Texas – Tom Isakeit; Virginia – Hillary Mehl; Wisconsin – Damon Smith


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