Iron-deficiency chlorosis (IDC) in soybean was a major problem early during the 2015 growing season in eastern North Dakota and northwestern Minnesota.
2015 Soybean Iron-Deficiency Chlorosis Ratings Available
Iron-deficiency chlorosis (IDC) in soybean was a major problem early during the 2015 growing season in eastern North Dakota and northwestern Minnesota. IDC symptoms are interveinal yellowing of the leaves with the leaf veins staying a dark green. Chlorosis is caused because the plant cannot take up enough iron (Fe), even if there is sufficient Fe in the soil. The symptoms might be present during the two- to seven-trifoliolate-leaf stages. Plants tend to recover and will turn green at the end of the vegetative and reproductive growth stages. However, IDC during the early vegetative stages can substantially reduce yield potential. Variability in the tolerance level to IDC exists among soybean varieties. On soybean ground with high pH soils with known chlorosis problems, the best way to manage IDC is to select a tolerant variety of suitable maturity that is high yielding. For soybean varieties tested by NDSU in 2015, the Roundup Ready IDC and Conventional / Liberty Link IDC scores are now available at the NDSU variety trials result web site at: https://www.ag.ndsu.edu/varietytrials/soybean.
Data from 2015 is based on field studies which were conducted at three locations with known IDC problems. The resistance to IDC was measured for 257 Roundup Ready soybean varieties and 63 non-Roundup Ready, including Liberty Link varieties. Visual ratings were made on a 1 to 5 scale, with 1 representing no chlorosis and 5 the most severe chlorosis. Ratings were taken at the 2- to 3- and 5- to 6-trifoliolate stages.
Significant differences in IDC scores were observed. Variety selection is the number one management strategy to reduce IDC expression in the field. Farmers are encouraged to pick the most tolerant, high yielding variety for their most severe IDC fields.