Wheat Disease Loss Estimates from the United States and Ontario, Canada — 2021

Wheat diseases annually reduce yield in the United States and Canada. Diseases of importance vary from year to year, and diseases that affect yield are based on many factors, including weather conditions, crop production practices, and variety selection and susceptibility to disease.

Plant pathologists representing 28 wheat-producing U.S. states and Ontario, Canada, estimated the percent yield loss from wheat disease in their states or province. These reports account for more than 1.5 billion bushels (87.3 percent) of the total wheat produced in the United States and Ontario in 2021 (Figure 1). The yield loss estimates include foliar, root, stem, head, and kernel diseases in the states represented in this survey.

This publication documents the impact of major diseases on wheat production during 2020. The North Central Regional Committee on Management of Small Grain Diseases (NCERA 184) and the Western Wheat Workers (WERA 97) revises disease loss estimates annually. It is important to note that methods for estimat­ing disease loss vary by state or province. The estimates may be based on statewide disease surveys; feedback from university extension, industry, and farmer represen­tatives; and personal experience with disease losses.

Disease loss values are based on yield before estimated losses for each state or province using this formula:

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

Total bushels lost per disease are then formulated using ([percent loss/100] x yield before estimated loss) for each state or province.

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

2021 Conditions and Production

Farmers in the United States and Ontario planted wheat on 47.9 million acres in 2021. This produced nearly 1.8 billion bushels of wheat, worth more than 12.6 billion USD. The continental U.S. experienced above average temperatures in 2021. Many major weather or climate events occurred in 2021 in the U.S., including a derecho, drought, tornadoes, and severe storms. Much of the western U.S. experienced below average precipitation; above average levels of precipitation occurred across many eastern U.S. states.

2021 Disease Losses

In 2021, disease reduced wheat bushels by 8.1 percent across the U.S. states included in this survey and by 2.0 percent in Ontario. Table 1 provides yield loss estimates for all diseases.

Table 1. Estimated wheat yield losses from diseases in 28 wheat producing states in the United States and Ontario, Canada in 2021.

¹Can include needle, root-gall, root-knot, stem, stubby-root, and stunt nematodes; ²Can include pink snow mold, speckled snow mold, and snow rot; ³Can include Alternaria leaf blight, anthracnose, Ascochyta leaf spot, bacterial mosaic, and downy mildew; ⁴Can include Agropyron mosaic and Brome mosaic.

Diseases in the Northern United States

Stripe rust was the most damaging disease in the northern United States in 2021 — 21.1 million bushels lost (see Table 2). Fusarium head blight caused the second greatest losses, followed by High Plains disease, Triticum mosaic, and Wheat streak mosaic. Overall, 108 million bushels of wheat were estimated to have been lost due to diseases in the northern United States in 2021.

Table 2. Estimated wheat yield losses due to the five most significant diseases in the northernmost U.S. states¹ in 2021.

¹U.S. States include Colorado, Idaho, Illinois, Indiana, Kansas, Michigan, Minnesota, Montana, Nebraska, New York, North Dakota, Ohio, Pennsylvania, South Dakota, and Wisconsin.

Diseases in Southern States

As in the northern U.S., stripe rust caused the greatest estimated wheat yield losses in the southernmost U.S. states in 2021 (Table 3). Although not even in the top five diseases in 2020, Barley yellow dwarf virus caused nearly 1 million bushels of estimated yield loss in 2021. Overall, 17.8 million bushels of yield loss occurred in the southernmost United States due to disease.  

Table 3. Estimated wheat yield losses due to the five most significant diseases in the southernmost U.S. states¹ in 2021.

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

Diseases in Ontario, Canada

Powdery mildew caused more than twice as much estimated yield loss than any other disease of wheat in Ontario, Canada in 2021 (Table 4). Powdery mildew has not ranked among the top yield reducing diseases in Ontario since 2018. Septoria tritici blotch and Fusarium head blight ranked second and third, respectively, in terms of estimated yield reductions.

Table 4. Estimated wheat yield losses due to the seven¹ most significant diseases in Ontario, Canada in 2021.

¹Seven diseases were included as three diseases shared the 5th rank in terms of yield losses.

Summary

Environmental conditions varied across the United States and Ontario in 2021, which affected the presence of and damage from many diseases. Overall yield reduction caused by wheat disease was similar in 2021 compared to 2020, but much less than occurred in 2019.

Disclaimer

The disease loss estimates in this publication were provided by members of the North Central Regional Committee on Management of Small Grain Diseases (NCERA 184) and the Western Wheat Workers (WERA 97). This information is only a guide. The values in this publication are not intended to be exact estimates of wheat yield losses due to diseases. The members of NCERA 184 used the most appropriate means available to estimate disease losses and assume no liability resulting from the use of these estimates.

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/.

Acknowledgements

Authors

Andrew Friskop; North Dakota State University; Daren Mueller, Iowa State University; and Adam Sisson, Iowa State University.

Contributors

Kira Bowen, Auburn University; Travis Faske, University of Arkansas; Ron Meyer, Colorado State University; Alyssa Koehler, University of Delaware; Alfredo Martinez Espinoza, University of Georgia; Juliet Marshall, University of Idaho; Nathan Kleczewski, University of Illinois; Darcy Telenko, Purdue University; Kelsey Andersen-Onofre, Kansas State University; Carl Bradley, University of Kentucky; Boyd Padgett and Paul “Trey” Price III, Louisiana State University; Martin Chilvers, Michigan State University; Ruth Dill-Macky and Jochum Wiersma, University of Minnesota; Tom Allen, Mississippi State University; Kaitlyn Bissonnette, University of Missouri; Mary Burrows and Uta McKelvy, Montana State University; Stephen Wegulo, University of Nebraska-Lincoln; Gary Bergstrom, Cornell University; Christina Cowger, North Carolina State University;  Andrew Friskop, North Dakota State University; Pierce Paul, Ohio State University; Meriem Aoun, Oklahoma State University; Albert Tenuta, Ontario Ministry of Agriculture, Food, and Rural Affairs; Alyssa Collins and Paul Esker, Pennsylvania State University; Emmanuel Byamukama, South Dakota State University; Heather Kelly, University of Tennessee; David Langston, Virginia Tech; and Damon Smith, University of Wisconsin-Madison.

Production data from the United States Department of Agriculture-National Agriculture Statistics Service and the Ontario Ministry of Agriculture Food and Rural Affairs. Climate information from the National Oceanic and Atmospheric Administration-National Center for Environmental Information.

In addition to support from United States Department of Agriculture - National Institute of Food and Agriculture, this project was funded in part through the Grain Farmers of Ontario.