Plant Health Initiative

Charcoal Rot - Risk Assessment

Soybean plants damaged and killed by charcoal rot. Click on image to view a larger version. Photo credit: J.A. Wrather et al. Reaction of Drought-Tolerant Soybean Genotypes to Macrophomina phaseolina. Plant Management Network.

Unlike most soil fungi, which decline in activity when soils become too warm, the charcoal rot fungus is most active when soil temperatures are as high as 80-95° F (27- 35° C).

The disease develops when there is a high level of the pathogen in the soil and when plants are under stress. It's the hot, dry weather that creates much of the stress.