The risk for white mold infections in the next couple weeks is VERY HIGH.  There is a “perfect storm” of conditions coming together right now for white mold development.  White mold is caused by the fungus Sclerotinia sclerotiorum.  It is a disease that affects soybeans, sunflowers and other broadleaf crops. White mold infects soybeans through dead flower tissue.  There is no true genetic resistance, so all soybeans are potentially susceptible.  Key factors in increasing white mold risk are:
  1. A susceptible crop.  All soybeans are susceptible to some extent.  There are differences in susceptibility, but all soybeans are at least at moderate risk.
  2. Cool temperatures (< 85°F) favor white mold.  Cooler weather is in the forecast for several days here.
  3. Wet or moist conditions.  Recent moisture and future forecasts for more rainfall favor disease development.  Normal or above normal rainfall, soil moisture at or near field capacity, prolonged morning fog and leaf wetness (high canopy humidity) at and following flowering into early pod development are risks.
  4. Closed crop canopy.  Soybeans are at R2 in much of the area and canopies are closing or closed.  Less air movement in the canopy favors spore development, and that means higher white mold risk.
  5. Previous history of the disease. White mold is a disease that is recurrent in fields where it has been present in the past.  Sclerotia survive for several years in soil.
  6. Heavy weed pressure.  High weed pressure, especially with broadleaves, increases the risk for white mold development in the soybean canopy.

Fungicides for white mold are available and can be quite effective.  Applying a fungicide now can protect soybeans for up to two weeks.  If conditions continue to be moist, soybeans can still be at risk as long as soybeans are flowering, so a second application may be needed at around R3-R4 growth stage.  Agtegra has a fleet of ground and aerial application equipment ready to meet your white mold fungicide application needs!

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