Although drought conditions are now at the forefront of many growers’ minds, it may be easy to forget the challenges that marked the beginning of the 2026 growing season.

Cool and wet conditions, particularly across central North Dakota, created favorable conditions for iron deficiency chlorosis (IDC) in soybean. In some areas, prolonged periods of saturated or flooded soils further increased the severity of IDC symptoms in soybean fields.

North Dakota State University conducts annual research on soybean varieties to determine their tolerance to iron deficiency chlorosis.

“This information is crucial for farmers who deal with IDC in their fields annually,” says Ana Carcedo, NDSU Extension broadleaf crops agronomist. “Choosing soybean varieties that are less susceptible to IDC is the first step in addressing this issue.”

Soybean varieties exhibit genetic differences in their tolerance to IDC symptoms. Producers can use the NDSU data to choose an appropriate IDC-tolerant soybean variety for fields known to have IDC issues in the 2027 season.

“Selecting a soybean variety with IDC tolerance is an important management decision that can help producers minimize the negative impact of chlorosis on yield,” says Carcedo.

In the summer of 2026, NDSU's soybean breeding program evaluated 90 Enlist, GT27, Roundup Ready and Xtend soybean varieties, along with conventional varieties, for IDC tolerance.

IDC symptoms include yellowing of plant leaves with green veins, as well as yellowing, browning and stunted growth during the early stages, leading to reduced soybean yields. The test results are based on replicated trials conducted in a location with a history of IDC. Visual ratings were made on a 1 to 5 scale, with 1 indicating no chlorosis and 5 indicating the most severe chlorosis. Ratings were recorded at three different soybean growth stages.

The test results are available at https://vt.ag.ndsu.edu/list/soy.

While IDC tolerance is important, producers are advised to consider the yield potential and other important traits of soybean varieties. Varieties with similar IDC tolerance can differ significantly in their yield potential. NDSU soybean variety trials will be published at the same link.

The North Dakota Soybean Council provided funding for the iron deficiency rating studies.

NDSU Agriculture Communication – Sept. 2, 2026

Source: Ana Carcedo, 701-831-5796, a.carcedo@ndsu.edu

Editor: Dominic Erickson, 701-231-5546, dominic.erickson@ndsu.edu