First Symptoms of Corn Red Rot: Signs, Spread, and Risk Factors

Corn red rot is one of the most common diseases in temperate climate regions. It primarily manifests during the milk-wax maturity phase of the grain. It is during this period that a characteristic fungal mycelium appears at the tip of the ear, which can spread quickly and affect a significant portion of the ear.

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Signs of Grain Damage

Grain affected by red rot takes on a brick-red hue, becomes brittle, and is filled with cavities occupied by the fungal mycelium. Under conditions of increased humidity, pink spore deposits form on the surface of the grain, which is an additional sign of disease development.

“Even if the embryo is alive, the sprouts often blacken between the primary and secondary roots and die.”

Sources of Infection and Conditions for Disease Development

The main sources of infection remain corn residues in the field, as this is where the fruiting bodies of the fungus overwinter. In spring, they produce ascospores that can remain active for over two years. In summer, the disease spreads through conidia, which, along with the mycelium, can remain viable in the soil for up to a year.

Favorable conditions for the development of red rot include prolonged wet weather and moderate temperatures during ear maturation. The risk is particularly high in years with abundant rainfall in the second half of summer and autumn, when a favorable microclimate for the spread of infection is created.