Sun rising behind soybean seedling in springThere has been an organized effort to document soybean cyst nematode (SCN) distribution since 2000. Beginning in January 2024, university nematologists, plant pathologists, agronomists and government plant health officials in soybean-producing regions were surveyed about the presence of SCN. The resulting updated SCN distribution maps revealed 31 new counties across 10 U.S. states and 13 areas in Canada reported infestations for the first time between 2020 and 2023.

Iowa State University nematologist Greg Tylka spearheaded the study. He warns that many fields may harbor SCN undetected for years, posing increasing risks to soybean yields. SCN causes more yield loss in U.S. soybeans than any other pathogen. Its ongoing spread predicts further losses.

Genetic resistance has primarily relied on PI 88788 SCN-resistant soybean varieties. However, SCN developed a resistance to PI 88788. New resistance varieties, such as Peking, offer alternatives to farmers. Producers are now encouraged to rotate resistant varieties to combat resistance build-up. Recommendations include testing fields, rotating crops and using nematode-protectant seed treatments.

Farmers have many options to combat the spread, with over 200 Pekin-resistant varieties and 920 SCN-resistant soybean varieties available in Iowa alone. Tools like the SCN Profit Checker available at https://www.thescncoalition.com/profitchecker/ can help quantify losses and guide management strategies.

Read more on the spread of SCN here.