By Dan Kaiser and Seth Naeve
Iron deficiency chlorosis (IDC) is a serious yield-limiting factor affecting soybean in western Minnesota. The root cause of IDC is not a deficiency of iron in the soil but rather the poor ability of soybean plant to extract available iron from high pH soils. While we have a general understanding of where IDC occurs, the exact cause is an interaction among both environmental factors and soybean plant genetics, as varieties can vary in their tolerance to IDC. While the exact mechanism of varietal tolerance is not known, variety selection is still considered to be the first line of defense in managing IDC.
We recently updated the U of M guidelines for managing iron deficiency chlorosis in soybean. Here are a few key takeaways from the new guidelines:
1. Variety selection is still the best line of defense for IDC
While some treatment options are available, tolerant varieties still tend to yield as much or more than less IDC-tolerant varieties, even when other mitigation strategies are used. Starting with an IDC-tolerant variety will at least ensure that a complete loss in yield will not occur in some areas of the field if an alternative management strategy is used and doesn’t work.
2. In-furrow ortho-ortho EDDHA chelates can increase soybean yield
The key here is in-furrow. Having these specific chelates near the root is critical for the soybean plant to be able to take up available iron. There are multiple sources of EDDHA chelates but what is critical is the amount of the chelated iron that is in the ortho-ortho form. Other chelates do not provide available iron, so knowing what is in a product is crucial to ensure it will be effective.
3. Manage IDC and soybean cyst nematode separately
Soybean cyst nematode populations can be high in areas of fields affected by IDC. However, research has shown that while IDC and soybean cyst nematodes can reduce soybean yield, their impacts on the soybean plant are separate and the two issues do not interact with each other. If both issues exist in areas of a field, they should be managed separately.
4. Companion crops and increased seeding rates do not work consistently against IDC but may be an option for some growers
Other management strategies such as companion crops and increased seeding rates have not been shown to be consistent across environments. These strategies can help to reduce the impact of IDC but they are not as consistent in reducing IDC severity as variety selection and the use of an ortho-ortho EDDHA iron chelate. Both strategies are an option for growers that may not be able to apply chelates directly on the soybean seed.
If you prefer a printable PDF version of the IDC soy publication, you can email us at nutmgmt@umn.edu.
Source : umn.edu