Fusarium meridionale

The fungus produces white, pinkish, or salmon-colored mycelium. Laboratory identification relies on morphological features of its macroconidia and advanced DNA analysis techniques.

This pathogen is notorious for its ability to produce various mycotoxins, including fumonisins and trichothecenes, which negatively impact crop quality and safety.

It exists in both asexual and sexual forms (the teleomorph is Gibberella meridionalis), allowing it to survive diverse environmental conditions and spread effectively.

The fungus persists in soil and crop debris as chlamydospores or dormant mycelium, ensuring its long-term survival in agricultural fields.

Corn is the primary host for Fusarium meridionale, where it causes severe diseases such as ear rot and root rot.

Beyond corn, it can infect other cereal crops, entering through natural openings, insect-damaged tissues, or mechanical wounds on the plant surface.

The economic impact involves significant yield losses, reduced seed viability, and grain contamination by mycotoxins, rendering the harvest unsuitable for feed or food.

The pathogen secretes enzymes that break down plant cell walls, leading to tissue necrosis, stunting, and reduced plant vigor throughout the growing season.

Root system infections significantly impair water and nutrient uptake, leading to premature senescence and lodging of the crops before the harvest period.

Pathogen activity peaks during periods of high humidity and moderate temperatures (20°C to 28°C), particularly during the silk-flowering phase of corn.

Spores are dispersed by wind, rain splashes, and insect vectors that feed on corn silks, facilitating the colonization of the developing ears.

Initial soil-borne infections commonly occur in the spring, during seed germination and the early development of the root system in damp soils.

The grain filling stage is critical for the development of ear rot, as sugar accumulation in the kernels provides nutrients for fungal growth.

Late-season rainy weather is particularly dangerous, as it increases the risk of pre-harvest colonization and epidemic development in the field.

Infection on corn ears is characterized by the appearance of a white, pink, or fluffy mycelial growth that often covers groups of kernels or the entire ear.

Affected kernels appear dull, shriveled, and may exhibit discoloration; severe cases result in the total degradation of the ear's structural integrity.

Infected plants may show premature yellowing of the leaves and loss of turgor, indicating systemic issues or root system failure.

Root rot symptoms include browning, rotting of the primary and secondary roots, and an overall lack of plant development compared to healthy stalks.

• Fluffy mycelium on corn ears.
• Shriveled and discolored grain.
• Stunting and premature wilting.
• Root decay and lodging.

Effective crop rotation is the primary management strategy, preventing the build-up of the pathogen in the soil by avoiding continuous corn cultivation.

The use of fungicide-treated seeds is essential to protect young seedlings from early-season root infections and improve initial crop establishment.

Managing insect pests, such as the European corn borer, is vital to minimize entry points for the fungus into the corn ears.

Deep tillage helps bury infested crop residues, promoting their decomposition and reducing the inoculum potential for the next planting season.

Proactive monitoring during the growing season and ensuring rapid drying of the grain after harvest are crucial steps to minimize toxin accumulation.