The cool, wet soils have resulted in some predictable problems with corn emergence, many of which include infection by fungi. Pythium and Rhizoctonia have been prominent this year in fields with emergence problems. As plants move beyond the seedling stage, some of the seedling infections linger and cause more problems. In particular, infection of seedlings by Fusarium species can persist and move into the crown and stalk tissues. Several species of Fusarium commonly can be isolated from crowns of corn plants at any growth stage.
Stalk rot developing from a crown infection.
Normally, the crown tissue of healthy corn plants is slightly darker than surrounding tissue. In these cases, there are usually no other symptoms. In other cases, the discoloration is more severe and the crown tissue can become substantially rotted. These plants can exhibit various symptoms, including stunting, leaf discoloration, wilting, and even death. Stressful growing conditions cause plants to become more susceptible to this type of infection.