White Mold Fungicide Application Considerations

Wilted, dead leaves remain attached to stems of white mold infected plants. Image: A. Sisson. Crop Protection Network. White, fluffy growth and sclerotia on soybean stem characteristic of white mold. Image: D. Mueller. Crop Protection Network.

Wet and cool conditions during flowering are ideal for development of the fungus Sclerotinia sclerotiorum.

No variety is completely resistant to white mold, particularly under severe disease pressure, but differences in tolerance exist among varieties.

Crop rotation, weed management, and tillage are helpful in management of White mold. Multiple products are labeled for white mold control and suppression including both synthetic and biological fungicides. Applications must be made prior to infection because they have little activity on the established pathogen.

Optimal timing for fungicide application is typically at the R1 growth stage when blooms are vulnerable to the initial infection and canopies are still open. Later fungicide applications may be inhibited from ideal canopy penetration especially in narrow-row soybeans. Less penetration means less efficacy.

Growers should carefully monitor growth stage of the crop when investing in a fungicide treatment.