As the US soybean harvest progresses, independent reports of seed quality problems are rising across the country. Specific problems vary by region and sample, though multiple issues are co-occurring in certain areas (Figure 1). Although the Federal Grain Inspection Service (FGIS) maintains standard definitions for soybean classes (yellow or mixed)1 and grades them on specific factors,2 reports indicate significant variation in how soybeans are currently being classified, graded, and docked in 2026.
It is important to understand which problems are present, their associated implications (if any), and how they fit into FGIS standards for soybean. Some examples of seed quality problems arising in 2026 include purple seed stain, Diaporthe seed decay, soybeans of other colors (SBOC), and more (Figure 2).
FGIS Definitions
FGIS maintains definitions for two classes of soybeans, yellow and mixed.2 Samples are classified as mixed if they do not meet the definition for yellow soybeans.1 Current FGIS standards define yellow soybeans as
“Soybeans that have yellow or green seed coats and which, in cross section, are yellow or have a yellow tinge, and may include not more than 10.0 percent of soybeans of other colors.”1
Current FGIS standards further define soybeans of other colors as
“Soybeans of other colors are soybeans that have black or bicolored seedcoats, as well as soybeans that have green seedcoats and are green in cross section. Bicolored soybeans will have seed coats of two colors, one of which is brown or black, and the brown or black color covers 50 percent of the seed coats. The hilum of a soybean is not considered a part of the seed coat for this determination.”1
After classification, soybean is then split into four grades based on a maximum percentage of damaged kernels, foreign material, and splits.2 Current FGIS standards define damaged kernels as
“Soybeans and pieces of soybeans that are badly ground- damaged, badly weather-damaged, diseased, frost-damaged, germ-damaged, heat- damaged, insect-bored, mold-damaged, sprout-damaged, stinkbug-stung, or otherwise materially damaged. Stinkbug-stung kernels are considered damaged kernels at the rate of one-fourth of the actual percentage of the stung kernels.”1
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