Use varieties with the highest level of resistance available in a maturity group appropriate for your area.
Charcoal rot field trials. Photo: A. Mengistu, USDA-ARS.
Plant the fullest-season varieties that are practical. Plants are most susceptible to charcoal rot at the beginning at flowering. The longer-season varieties tend to flower later and are in a vegetative growth stage during the early part of the hottest, driest portion of the growing season.
Identifying host resistance to charcoal rot is the goal of several checkoff-funded research projects. A multi-state field screening program is now in place where breedling lines, germplasm, and commercial varieties are tested over different years and environments. As of 2012, 17 lines from MGIII to V have been identified with moderate resistance and four lines with very good resistance. A promising MGII line has also been identified.
Use no-till systems to increase soil microbial activity and conserve soil moisture, which can reduce charcoal rot.
Soybeans direct-seeded in no-till systems typically have lower levels of charcoal rot compared to soybeans under conventional tillage.
Rotate to non-host crops for 1 to 2 years in fields with a history of charcoal rot.
Rotation to non-host crops such as wheat and other small grains for 1 or 2 years should be considered part of a charcoal rot management plan in problematic fields. Also, although corn, sunflowers, and other crops are hosts, research has shown that there are strains of the fungus that have host preferences. For instance, some strains prefer soybeans while others prefer corn or sunflowers. Therefore, rotation with any other crop can be beneficial and the longer the rotation, the better.
Avoid excessive seeding rates to reduce crop stress and minimize loss to charcoal rot.
Consider supplemental irrigation to slow colonization of the plant by the charcoal rot pathogen and reduce symptom severity during drought conditions.
Fungicides do not provide protection
No fungicide seed treatments have been identified that offer consistent control of charcoal rot.