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.