2014 Soybean Iron-Deficiency Chlorosis Scores Available (08/28/14)
2014 Soybean Iron-DefIciency Chlorosis Scores Available
Iron-deficiency chlorosis (IDC) in soybean is a major problem in the eastern part of North Dakota and northwestern Minnesota. The IDC symptoms might be present during the two- to seven-trifoliolate-leaf stages. Plants tend to recover and start to turn green again during the flowering and pod-filling stages. However, 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 soybean varieties tested by NDSU in 2014, the Roundup Ready IDC and conventional / Liberty Link IDC scores are now available at the NDSU variety trials result web site at: http://www.ag.ndsu.edu/varietytrials.
Data from 2014 is based on field studies which were conducted at three locations, with known IDC problems, to measure the resistance of 267 Roundup Ready soybean varieties and 51 non-Roundup Ready, including Liberty Link, varieties to IDC. Each plot consisted of a hill. Eight seeds were planted in a hill and the resulting growth was thinned soon after emergence to three plants. The experimental design was a randomized complete block with four replicates at each site. Separate trials were held for Roundup Ready and non-Roundup Ready varieties at each site. 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. Thus, each three-site average shown in the data tables is an average of 24 observations (three sites x four replicates x two ratings per plot). As far as we know, this is the most comprehensive evaluation available to farmers.
In the Roundup Ready trial, three check varieties were included as well as a susceptible reference. In the conventional variety trial, one “standard” variety (Sargent) was entered as well as four RR ready checks, to help in the interpretation of the results.
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.
Extension Agronomist Broadleaf Crops