Pythium damping off disease has been showing up on soybean plants this spring throughout various parts of the growing landscape.

Pythium is most active on soybeans that emerge into cool, wet soils. According to Doug Jardine, Kansas State University research and Extension plant pathologist, it’s been “rampant” in eastern and central Kansas, particularly for growers who planted soybeans in mid-May.  

“A lot of soybeans were planted about May 15 to 20 in northeast Kansas; then there was some rain and the soil cooled down, which created ideal conditions for Pythium,” notes Stu Duncan, Kansas State research and Extension crops and soils specialist.

Certain fungicide seed treatments will help protect against Pythium for about 10 to 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,” he explains.

If affected fields are replanted now, seed treatments would not be as necessary as they are for earlier planting dates, Jardine adds.

Where soybeans have been infected with Pythium, the take-home lesson is that soybeans planted no-till before June 1 in Kansas should be treated with a fungicide seed treatment, just to be safe-- and the higher the rate of product used, the better, Jardine says. The seed treatment should contain mefenoxam or metalaxyl.

Source: Kansas State University