By Greg Tylka
Farmers may be planning to grow soybeans in 2022 in fields cropped to soybeans in 2021 because of high prices and limited availability of inputs for corn production. Doing this in fields infested with the soybean cyst nematode (SCN) is always a risky proposition. But growing beans on beans in SCN-infested fields in 2022 will be especially dicey.
SCN reproduction is greater in hot, dry growing seasons, and many soil samples collected at harvest from field experiments in Iowa in 2021 have very high end-of-season SCN population densities. SCN eggs survive very well in the soil over winter, so high end-of-season SCN numbers in 2021 will affect soybean yields in 2022 and beyond. A recent ICM News article gives details of the very high SCN egg counts and the associated low soybean yields of SCN-resistant soybean varieties in one experiment in southeast Iowa in 2021.
Fields that will have soybeans grown for a second successive year in 2022 need to be sampled for SCN this fall. And a good use of limited inputs to grow corn in 2022 would be in fields with the greatest SCN population densities. Doing this will: 1) eliminate the risk of getting very low soybean yields due to SCN damage from growing beans on beans in 2022, and 2) reduce the SCN egg population density by 5-10% to as much as 50% in just one year, which will pay soybean yield dividends in 2023.