Fusarium temperatum

Fusarium temperatum is an anamorphic fungus within the Fusarium genus and the Nectriaceae family. It was recently described as a distinct species, having previously been confused with Fusarium verticillioides.

This pathogen is primarily soil-borne and can persist in crop debris and seed material for extended periods as mycelium or resistant spores.

Morphologically, the species is identified by microconidia produced in chains or false heads on monophialides. Macroconidia typically exhibit a slender, sickle-shaped appearance.

The fungus does not produce distinct sclerotia but forms chlamydospores, which enable survival during adverse environmental conditions.

Accurate identification usually requires molecular techniques like PCR analysis, as morphological similarity to other Fusarium species in the fujikuroi complex makes visual differentiation difficult.

Maize is the primary host for Fusarium temperatum. The pathogen is capable of infecting roots, stalks, and reproductive organs, including the ears.

Ear rot is the most significant form of damage caused by this fungus. It penetrates deep into grain tissues, leading to decay and structural degradation of the kernels.

While the pathogen mainly affects maize, it can occasionally be found on other cereal crops, though its ecological niche is highly specialized for corn.

The impact goes beyond yield reduction; the fungus is a known producer of mycotoxins like fumonisins, which pose severe risks to livestock and human health.

Infected plants exhibit reduced vigor and are prone to lodging, which complicates harvesting and further reduces the quality of the harvested grain.

The infection process typically begins during the maize silking period, with spores disseminated by wind or insects landing on the silk.

Secondary infections occur throughout the growing season, favored by high humidity and moderate temperatures, as the name temperatum suggests.

The pathogen remains active until harvest, especially under rainy weather conditions, which promote the rapid colonization of maize ears.

The fungus overwinters as mycelium and spores on crop residues left on the soil surface after harvest.

In the spring, as temperatures rise to 15-25°C, the pathogen reactivates and infects emerging seedlings, starting the cycle anew.

Visible symptoms of ear rot include the development of a fluffy white, pink, or salmon-colored fungal mycelium on the surface of the kernels.

Infection often starts at the ear tip and progresses downward, eventually covering large portions of the cob.

Root system infection leads to discoloration and rotting, which manifests as stunted growth and chlorosis in the lower leaves of the plant.

Internal stalk rot is characterized by a light pink discoloration of the pith, which weakens the stalk and increases susceptibility to breakage.

• Presence of fungal mycelium on kernels.
• Discoloration and rotting of roots and stalks.
• Premature plant senescence and wilting.
• Reduced grain quality and kernel deformities.

Effective crop rotation is the primary management strategy, with a minimum 2-3 year interval before planting maize in the same field again.

Incorporating crop residues into the soil through deep plowing helps accelerate decomposition and reduces the amount of primary inoculum.

The use of genetically resistant maize hybrids is the most sustainable and efficient method for minimizing the impact of Fusarium ear rot.

Seed treatment with high-quality systemic fungicides is mandatory to protect germinating seedlings from soil-borne pathogens.

Integrated pest management, particularly controlling corn borers, is essential to minimize wounding, which serves as a primary entry point for the fungus.