Purple seed stain
Area of impact: Seeds
Description: Seeds develop purple or pink spots and patches. However, infected seeds do not always show symptoms. Also, look for symptoms of Cercospora leaf blight as the same fungus causes both diseases.
Pathogen involved: Cercospora kikuchii (a fungus)
Timing/Conditions: Infection occurs between flowering and maturity during warm very humid weather.
Contributing factors: The fungus overwinters in soybean tissue and infected seeds.
Management practices: Plant pathogen-free seeds and rotate out of soybeans. Using foliar and seed treatment fungicides may help.