Pythium damping off has been rampant on soybeans this spring throughout eastern and central Kansas. The Plant Diagnostic Laboratory has had many samples of Pythium so far. Pythium is most active on soybeans that have emerged into cool, wet soils. Producers in eastern and central Kansas who planted their soybeans in mid-May ran into this problem in many cases this year. The soybeans in the photos below were planted about May 15-20. Then there was some rain and the soil cooled down, which created ideal conditions for Pythium.
Certain fungicide seed treatments will help protect against Pythium for about 10-14 days. But this may not work in all cases, especially if the lowest labeled rates of the product are used. Even with higher product use rates, if the disease pressure is high enough, Pythium can overwhelm the seed treatment. Evidently there are several cases this year where this has happened.
If affected fields are replanted now, seed treatments would not be as necessary as they are for earlier planting dates. Where soybeans have been infected with Pythium this year, the lesson to learn is that soybeans planted no-till before June 1 should be treated with a fungicide seed treatment, just to be safe -- and the higher the rate of product used, the better. The seed treatment should contain mefenoxam (Apron XL) or metalaxyl (Allegiance).