Wheat Disease Loss Estimates from the United States and Ontario, Canada — 2019

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 29 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 1.8 billion bushels (88.9 percent) of the total wheat produced in the United States and Ontario in 2019 (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 2019. 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. 

2019 Conditions and Production

Farmers in the United States and Ontario planted wheat on 46.2 million acres in 2019. This produced nearly 2 billion bushels of wheat, worth $9.2 billion USD. In the northern Plains of the U.S., temperatures were below average and record precipitation fell. Record precipitation also occurred in other parts of the U.S, making 2019 the second wettest year since observations began. Many regions in the U.S. had above average temperatures.

2019 Disease Losses

In 2019, disease reduced wheat bushels by 9.8 percent across the U.S. states included in this survey and by 2.2 percent in Ontario. Table 1 provides yield loss estimates for all diseases.

Table 1. Estimated wheat yield losses from diseases in 29 wheat producing states in the United States and Ontario, Canada in 2019.

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

Fusarium head blight was the most damaging disease in the northern United States in 2019 — more than 45 million bushels lost (see Table 2). This is nearly 20 million more bushels lost from Fusarium head blight than occurred in 2018. Stripe rust caused the second greatest loss in 2019, but was not in the top five most significant diseases in 2018. Overall, nearly 148 million bushels of wheat were estimated to have been lost due to diseases in the northern United States.

Table 2. Estimated wheat yield losses due to the five most significant diseases in the northernmost U.S. states¹ in 2019.

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

Leaf rust caused the greatest estimated wheat yield losses in the southernmost U.S. states in 2019 (Table 3). Stripe rust was the second greatest cause of yield loss, and did not appear in the top five most significant diseases in 2018. Overall, nearly 39 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 2019.

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

Diseases in Ontario, Canada

Stagonospora leaf and glume blotch, Septoria tritici blotch, and Fusarium root, crown, and foot rot caused the greatest estimated wheat yield loss in Ontario, Canada in 2019 (Table 4). These diseases were followed by Fusarium head blight and leaf rust. Losses were much less in 2019 compared to 2018.

Table 4. Estimated wheat yield losses due to the five most significant diseases in Ontario, Canada in 2019.

Summary

Environmental conditions varied across the United States and Ontario in 2019, which affected the presence of and damage from many diseases. Leaf rust, stripe rust, and Fusarium head blight reduced yield much more in 2019 compared to 2018.

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; Erick DeWolf, Kansas State University; Carl Bradley, University of Kentucky; Paul “Trey” Price III, Louisiana State University; Martin Chilvers, Michigan State University; Jochum Wiersma, University of Minnesota; Tom Allen, Mississippi State University; Kaitlyn Bissonnette, University of Missouri; Mary Burrows, 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; Bob Hunger, Oklahoma State University; Albert Tenuta, Ontario Ministry of Agriculture, Food, and Rural Affairs; Alyssa Collins, Pennsylvania State University; Emmanuel Byamukama, South Dakota State University; Heather Kelly, University of Tennessee; Ken Obasa, Texas A&M University; Hillary Mehl, 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.