Damp, Cool Weather Increases Soybean White Mold Risk

Damp weather conditions, dense canopies and a history of white mold can increase soybean white mold risk.

Damp, cool conditions increase the risk of soybean white mold (Sclerotinia stem rot) development, which can develop unseen beneath the canopy. The disease can cut yield by 3.7 bushels per acre for each 10 percent increase in disease incidence, according to Iowa State University estimates.

Infection occurs when splashing rains or irrigation during flowering activates durable fruiting spore bodies called sclerotia. Sclerotia can lie dormant in soil for years or can travel on infested seed. Factors that promote high yield — high plant populations, dense canopies, ample moisture and good soil fertility — also promote spread of white mold.

As soybeans grow and the canopy starts to close, the microenvironment under the canopy becomes much more humid and damp, creating favorable conditions for soybean white mold development.

Factors for Soybean White Mold

  • Field history of white mold
  • Dense canopies, especially narrow-row or drilled soybeans
  • Damp, cool weather
  • Splashing rains or irrigation at flowering
  • High-fertility soils
  • Bin-run soybean seed

Control White Mold

Rapid uptake of DuPont Aproach® fungicide helps prevent white mold within the plant and beneath dense leaf canopies where the disease starts. Watch this video to learn how growers are using Aproach® fungicide to control white mold and protect yield.

For best results, apply 9 fluid ounces per acre of Aproach® at R1 as flowering begins. For fields with a history of soybean white mold or under conditions favorable for development, a second application of Aproach® can be made 14 days later. It is important to protect the soybean crop before infection takes place or the environment becomes conducive for a soybean white mold outbreak.

DuPont Aproach® fungicide are not available in all states.


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