Soybean iron deficiency chlorosis (IDC) is a major problem in the eastern part of North Dakota and northwest Minnesota, says Hans Kandel, North Dakota State University Extension Service agronomist.
The IDC symptoms might be present during the two- to seven-trifolioate leaf stages. Plants tend to recover and start to turn green again during the flowering and pod-filling stages.
But IDC during the early vegetative stages can reduce yield potential severely. Some varieties are more tolerant to IDC than others. For high pH soils with known IDC problems, select an iron chlorosis-tolerant variety of suitable maturity that is high yielding.
For the soybean varieties tested by NDSU in 2014, the Roundup Ready IDC and conventional Liberty Link IDC scores are available at the NDSU variety trials result website, www.ag.ndsu.edu/varietytrials .
"Seed companies already are offering soybean seed for sale for the 2015 growing season, so this new IDC information is important in making the right soybean variety selection decisions," Kandel says.
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Data from the 2014 trials is based on field studies conducted at three locations that had known IDC problems. The IDC resistance of 246 Roundup Ready and 51 non-Roundup Ready, including Liberty Link, soybean varieties were measured.
For the research, eight seeds were planted near each other. Soon after emergence, the number of plants were thinned to three.
Visual IDC ratings were made of the plants on a one to five scale, with one representing no chlorosis and five the most severe chlorosis. Ratings were taken at the two to three and five to six trifoliolate stages.
"Significant differences in IDC scores were observed during the testing," says Ted Helms, who conducted the research and is the NDSU soybean breeder. "As far as we know, this is the most comprehensive evaluation available to farmers."
"Variety selection is the number one management strategy to reduce IDC expression in the field," Kandel says. "Farmers are encouraged to pick the most tolerant, high yielding variety for their most severe IDC fields."
