2016 Soybean Iron-Deficiency Chlorosis Ratings Available (09/01/16)
2016 Soybean Iron-Deficiency Chlorosis Ratings Available
Early during the 2016 growing season, Iron-deficiency chlorosis (IDC) in soybean, was observed in many fields in the eastern part of North Dakota and northwestern Minnesota. Chlorosis symptoms occur if the plant is unable to take up enough iron (Fe), even if there is sufficient Fe in the soil. The symptoms, yellowing of the leaf tissue, with green veins, might be present during the two- to seven-trifoliolate-leaf stages. Plants may grow out of IDC and will turn green at the end of the vegetative and reproductive growth stages. Yellowing and stunting of the plants during the early vegetative stages may reduce soybean yield. There are genetic differences among soybean varieties for tolerance to IDC. On soybean ground with high pH soils and free bicarbonate and with known chlorosis problems, variety selection is the best way to achieve high yield on areas of the field that have IDC. For soybean varieties tested by NDSU in 2016, the Roundup Ready IDC and Conventional / Liberty Link IDC scores are now available at the NDSU variety trials result web site.
Data from 2016 is based on field studies which were conducted at four locations, with known IDC problems, to measure the resistance of 223 Roundup Ready soybean varieties and 55 non-Roundup Ready, including Liberty Link, varieties to IDC. 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, from 1.4 to 2.7 and 1.3 to 2.6 for the Roundup Ready and non-Roundup varieties, respectively. Variety selection is the number one management strategy to reduce IDC expression in the field. Farmers are encouraged to select the most tolerant, high yielding variety for their most severe IDC fields.
Extension Agronomist Broadleaf Crops