Plants with symptoms caused by Sclerotinia sclerotiorum, stem rot were found in northeast Ohio. This is unusually early. In a previous article, several fungicides were listed. These were listed for preventative spraying at R1 growth stage. I don’t have any data on spraying fungicides once infections have developed to the point of symptoms.
But we can tell you that Approach (DuPont) is not recommended for these situations. If your fields are at R2, have a susceptible variety and no symptoms, and this field is a historic white mold field, Approach may still be used. If your soybeans are at R2, symptoms are visible then one of the triazole fungicides, Domark (Valent) or Proline (Bayer), are alternative choices; we do not have any data from these situations so leave untreated strips.
If you have a variety that has a good score for resistance to Sclerotinia. It is best to leave it alone, double check with your seed representative to see what they are saying about that varieties genetics.
Photo: Martin Draper, USDA-NIFA, Bugwood.org