By the time symptoms of sudden death syndrome (SDS) appear in a soybean field, it’s likely already to cost farmers about 6 bushels per acre in yield potential, says Jennifer Riggs, product development manager for Bayer CropScience.

Significant levels of SDS are showing up in Iowa fields for the second year in a row, a result of wet conditions at planting along with plentiful August moisture. Researchers say SDS is most severe when soybeans are planted early into cool, wet soils and when heavy mid-summer rains saturate the soil.

The tough conditions are proving the effectiveness of Bayer’s new Ilevo soybean seed treatment in protecting soybean plants from SDS in side-by-side trials,...