Plant Health Initiative

Iron Deficiency Chlorosis - Management

Soybean varieties differ in their tolerance to IDC. Click on image to view a larger version. Photo credit: R.J. Goos, North Dakota State University

1. Variety selection

The most successful management strategy for IDC is to select a soybean variety with tolerance to IDC. There have been major improvements in soybean varieties that are tolerant to the soil and environmental conditions that lead to iron chlorosis. Most public and private soybean varieties have been rated for IDC tolerance.

2. Minimize the amount of nitrate carry-over from the previous crop

Excess soil nitrates can worsen an IDC problem by furthering inhibiting the plants ability to take up iron.

3. Apply iron as EDDHA iron chelate on the seed at planting.

Iron chelates placed on the seed at planting can be an effective way to get iron into the plant. The type of iron chelate is important: the EDDHAA, or "ortho-ortho" formulation keeps iron available to the plant for a long enough time to prevent IDC from developing. Other less expensive forms of iron chelates do not.

To keep costs down, target areas with a history of moderate to high levels of IDC.

It's important to apply the iron chelates close to the seed. Fortunately, there is little or no risk of seedling injury from these compounds, even though starter fertilizer is not generally recommended for soybean.

Research on coating seeds with iron chelates is ongoing, but so far not enough iron remains on the seed to correct the problem.

Adding iron fertilizer to soil will not correct an IDC problem. Applying an iron chelate to soybean leaves may work, although it is hard to predict when and how much to apply. Research on foliar application of iron is ongoing.

Planting an oat cover crop may be managment intensive, but it can be very effective in preventing IDC in some fields. Photo credit: John Lamb, University of Minnesota.

4. Plant an oats cover crop

Researchers in Minnesota report that planting oats as a competition crop just ahead of planting soybeans, and then killing the cover crop with glyphosate at a height of 10 to 12 inches has proved to be a consistently effective management practice. The oat crop absorbs excess nitrate-nitrogen and soil moisture enough to keep soil iron available to the soybean crop.

Timing is important: killing the cover crop at 10 inches allows enough growth for the cover crop to have an effect on soil conditions, but not too much growth to compete with the soybean stand.

 

Resources

Update on Iron Deficiency Chlorosis, Minnesota Farm Guide, 2008

Iron Deficiency Chlorosis in Soybean, Dan Kaiser, University of Minnesota
Plant Management Network Webcast, September 2011