North Dakota State University soybean iron deficiency chlorosis scores available

Date:09-25-2024

This year presented a significant challenge for soybean producers due to cool and wet conditions causing prolonged iron deficiency chlorosis (IDC) symptoms in North Dakota soybean fields, says Ana Carcedo, North Dakota State University Extension broadleaf crops agronomist.

NDSU conducts annual research on soybean varieties to determine their tolerance to IDC. This information is crucial for farmers who deal with IDC in their fields annually. Choosing soybean varieties less susceptible to IDC is the first step in addressing this issue, advises Carcedo.

An iron chlorosis rating scale is used to evaluate IDC tolerance with 1 indicating no chlorosis and 5 indicating the most severe chlorosis. (NDSU photo)

According to Carrie Miranda, NDSU soybean breeder, "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 2025 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."

In the summer of 2024, NDSU's soybean breeding program evaluated 170 Enlist, GT27, Roundup Ready, and Xtend soybean varieties, along with 21 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. NDSU soybean variety trial yield data will also be published at this link.

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.

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