White Mold: Get Serious About This Disease

white mold collage

“White mold is a serious and significant yield robbing disease,” said Kevin Carlson, Federated’s senior agronomist, and it “has been increasing more every year . . . conditions for the disease have been almost perfect.”

Cool and moist soil conditions have led to large outbreaks throughout Federated’s service areas in recent seasons and, said, Carlson, “it’s time to get serious about controlling the problem with more than just the traditional, marginally effective practices,” which have included:

  1. selecting a soybean variety that has tolerance to white mold (a “must,” said Carlson),
  2. wider row spacing,
  3. lower plant populations.

While these practices offer a good start to controlling white mold, they haven’t proven to be sufficient.

“Even applying foliar fungicides have not been enough to control white mold the last few seasons,” said Carlson. He described the challenge of spraying fungicides on time:

The key to effective application is to layer the fungicide to protect the plants from infection during the flowering period, which keeps the disease from entering the soybean plant. The disease gets into the plant through the flower, and beans flower for a whole month – and therein lies the problem – there’s an entire month when protection is needed. 

Federated agronomists have found Aproach® to be their best recommendation for controlling white mold. At a rate of 9 oz./ac. applied at R-1 flowering, Aproach has shown to be effective – but still not a stand-alone cure.

The longer-term solution, according to Carlson, is to treat the problem at its source by killing the resting spores that germinate and create the infections in the soil. Federated recommends Contans® WG.

“Contans is a soil applied biological fungicide that breaks the cycle of sclerotinia (white mold) disease by destroying the sclerotia (the source of white mold) in the soil. Contans . . . will reduce the sclerotia in the soil and reduce the potential for white mold in future crops” (see Contans FAQs ). Contans:

  1. attacks and destroys the sclerotia fungus that causes white mold;
  2. reduces sclerotia in the soil up to 80-85% each year it is used;
  3. breaks the disease cycle; and should be
  4. soil applied pre-plant, at planting, after cultivation or post-harvest with traditional spray equipment or irrigation (see Contans fact sheet).

Contans is “another effective tool that works,” said Carlson. Contact your Federated Agronomist to discuss options for white mold control early in the season. (Also see this white mold scouting guide .)