Topsoil returns strongly to corn in Argentina

Corn top smut has returned to prominence in southeastern Córdoba, Argentina, in recent harvests. The disease, caused by Sporisorium reilianum. The pest infestation caused significant losses and raised concerns among technicians. A survey by the Aapresid Pest Management Network indicates a high incidence in several plots, with yield reductions close to 50% in critical situations.

The impact occurs plant by plant. Each infected individual loses grain production. In areas with high incidence, the effect on total yield becomes direct. Records in the Marcos Juárez department indicate ears of corn completely replaced by carbonaceous structures, with an incidence close to 48% in some cases.

Technicians report a change in the pattern of occurrence. Previously, the disease appeared sporadically. Now, many plots show outbreaks, even with low individual incidence. This scenario increases the regional risk. The repetition of corn and the reduction in the interval between crops favor the maintenance of the inoculum in the system.

Survival on the ground

The pathogen survives for years in the soil in the form of teliospores. This characteristic makes eradication difficult. Infection occurs during germination or emergence. The fungus enters through the roots and colonizes meristematic tissues. Symptoms appear later. Early diagnosis becomes unfeasible during the cycle.

In the field, signs include smaller plants, short internodes, and changes in development. Ears and stalks become deformed or disappear. In many cases, reproductive structures turn into black masses of spores. At harvest, the breaking of these structures releases clouds of dark dust, with the potential to disperse within the plot and to neighboring areas.

Harvesting is a key moment for diagnosis. Before the machine enters, a visual inspection of the field is recommended. During operation, the presence of dark dust indicates the release of spores. After harvesting, cleaning equipment reduces the spread of the pathogen.

curative control

There is no curative control once the disease has taken hold. Management depends on prevention. Crop rotation reduces inoculum pressure. Choosing hybrids with better performance helps limit losses. Balanced nutrition contributes to initial development. Adjusting the sowing time is also part of the strategy, paying attention to cold soils at the beginning of the cycle.