Maize white mold

The causative agent of maize white mold is the fungal pathogen Sclerotinia sclerotiorum, a member of the Ascomycota division. This highly destructive soil-borne fungus is a widespread polyphage, capable of infecting hundreds of plant species, which complicates effective field management and disease control strategies.

The disease manifests as white, cotton-like mycelial growth on ears, stalks, and roots of corn plants. A characteristic feature of this pathogen is the formation of sclerotia—hard, black survival structures that remain viable in the soil for several years, making the infection persistent even in the absence of a host crop.

The biology of the pathogen is heavily dependent on environmental factors, specifically high moisture and moderate temperatures. The fungus spreads via airborne ascospores or through mycelial contact with the soil. These spores settle on vulnerable tissues, particularly where mechanical damage has occurred, triggering the rapid development of the decay.

The economic impact of white mold is significant, resulting in reduced grain yield and lower seed quality. Furthermore, the infection compromises the integrity of the plant stalk, leading to premature lodging and death. In severe cases, the entire cob can be colonized, making the harvested product unmarketable and prone to secondary storage rots.

Management of the disease requires an integrated approach to minimize soil inoculum levels and prevent secondary spread:

• Implementing diverse crop rotations by avoiding host plants like sunflower and canola.
• Performing deep tillage to bury sclerotia, thereby preventing the formation of apothecia.
• Managing plant density to improve canopy aeration and reduce humidity levels.
• Applying fungicides during critical growth stages when environmental conditions favor the pathogen.