Nematodes and diseases increase the risk for corn in the Cerrado region

Corn in the Cerrado region faces increasing pressure from pathogens affecting its roots, stalk, and aerial parts. In intensive systems, such as soybean-corn rotation, nematodes, fungi, and oomycetes find hosts, crop residues, and successive windows for multiplication. This combination reduces initial growth, compromises root health, favors stalk rot, and anticipates foliar infections. The result is a loss of vigor, reduced water and nutrient uptake, and difficulty in expressing the productive potential of hybrids.

This is the assessment of Senio Matheus Telles, a seed treatment specialist at BASF, who believes that corn has taken on a greater role in farm profitability, making greater phytosanitary attention to the crop important. This progress has occurred in environments of high production intensity. Producers now make decisions under pressure from pests, diseases, soil fertility, climate, and planting window. "The challenges change over time," he explains. He cites advances in chemical and genetic solutions, as well as hybrid adjustments to the agricultural window. Even so, management requires critical analysis in each harvest.

new problems

In recent years, leafhoppers and stunting diseases have dominated some decisions regarding corn. Genetics has reduced some of this bottleneck. But the system has opened up space for problems previously treated as secondary. Telles cites the leaf spot caused by... Bipolaris maydis For example, the disease gained importance in areas of the Cerrado and began to require attention in the management of susceptible hybrids.

The disease caused by Bipolaris maydis It is commonly called leaf spot or bipolaris leaf spot. The fungus affects leaves and can reduce yield and grain quality in susceptible hybrids under favorable temperature and humidity conditions. The pathogen survives in corn crop residues and releases conidia via wind and rain splash. Infection requires free water on the leaf surface and temperatures between 18°C ​​and 30°C, with an optimum near 25 to 28°C.

Telles also places stalk health among the issues with the highest growing importance. The problem appears at the end of the cycle, when the corn remains in the field until harvest. The longer the period it remains in the field, the greater the exposure to pathogens associated with rot. This point interferes with the plant's structural integrity and the producer's operational flexibility.

Diplodia is included in this group of diseases that impact corn. Stenocarpella maydis, formerly known as Diplodia maydisThis fungus causes white ear rot and stalk rot. It reduces grain weight and quality. It can also cause damping-off, stalk rot, and leaf spots under certain conditions. The pathogen survives as mycelium and pycnidia in corn residues on the surface or partially incorporated into the soil.

The epidemiology of Stenocarpella maydis It depends on crop residues and climate. The primary inoculum comes largely from corn residues from the previous harvest. Prolonged periods of humidity favor the release and dissemination of conidia. Crop rotation with non-host crops, the use of tolerant hybrids, and residue management comprise integrated pest management measures.

Soil pathogens complete the risk picture at the beginning of the crop cycle. Telles points out that the seed faces pressure even before sowing. It can carry pathogens from the production field, become contaminated during storage, and then encounter new organisms in the soil. He cites fungi and oomycetes around the seed and seedling, highlighting... Pythium spp. in early plantings and in environments favorable to the pathogen.

The group Pythium This group includes oomycetes associated with damping-off, seed rot, and root rot. In corn, the problem manifests as root rot and establishment failures. Cold, waterlogged, or poorly drained soils favor the development of the pathogen. The damage affects young tissues and reduces the initial vigor of the crop.

Broad view

According to Telles, producers need to view the disease as a complex issue, not just a problem affecting the aerial parts of the plant. The pressure begins with the seed, continues through storage, reaches the soil, and affects the aerial parts during vegetative stages. "Often we only think about the fungi affecting the aerial parts," he says. In his assessment, the initial phase of the crop deserves attention because it defines the physiological basis for the hybrid's performance.

Greater complexity

Nematodes increase the complexity of pest management. Telles cites, in particular, Pratylenchus brachyurus e Meloidogyne incognitaThese organisms live in the soil, infect roots, and reproduce in weeds and crops such as soybeans, corn, and cotton. In intensive areas of the Cerrado, the population can grow season after season when no intervention occurs.

The expert avoids the idea of ​​eradication. For him, management should seek technical coexistence with the pathogen. Complete elimination is not within the practical horizon, as the system maintains successive crops and hosts throughout the year. Therefore, companies, researchers, and producers treat nematodes as a target for continuous management, and not as a problem solved in a single harvest.

Identifying damage in corn presents an additional challenge. In soybeans, patches of nematode infestation often indicate areas under attack. In corn, this pattern is not always clearly visible. Telles states that the damage can manifest later, in the form of stalk problems. The lesions in the roots created during nematode penetration and feeding act as entry points for opportunistic pathogens. Among these, he cites... Fusarium spp., associated with stalk rot.

Initial Start-up

The impact is also apparent at the initial stage. At planting time, the seed needs to germinate and form roots in an environment already occupied by nematodes. These organisms seek food and attack young roots. Any limitation to root growth hinders establishment. In the off-season crop, this point gains importance, as the producer seeks rapid crop closure and greater resilience in the face of a possible dry spell at the end of the cycle.

Limited root systems reduce the plant's ability to access water and nutrients. This effect can impact the aerial parts of the plant and the stem. Telles associates healthier and deeper roots with plants that have better support capacity and greater stability until harvest. For him, the benefit is not always just immediate in terms of productivity numbers. It also appears in the possibility of keeping the material in the field until the appropriate harvest window.

Seed treatment

In this scenario, seed treatment becomes a strategic step. Telles highlights an operational characteristic: the application occurs only once. After sowing, there is no re-treatment of the seed. The choice of products, the composition of the recipe, and the quality of the operation need to occur before the seeds enter the soil.

The treatment must fulfill several functions in phytosanitary management. It needs to reduce pathogens present in the seed, protect against soil organisms, contribute to the control of early foliar diseases, and assist in nematode management. In practice, the treated seed provides an initial protective barrier during a phase of high physiological vulnerability.

In this context, the product ILEVO® appears as a dual-action tool for maximum crop protection. It is a systemic nematicide and fungicide, effective through contact and ingestion, belonging to the benzamide pyramid chemical group. The active ingredient fluopyram is present at a concentration of 600 grams per liter. The product has a concentrated suspension formulation for seed treatment.

For corn cultivation, the label lists fungal, oomycete, and nematode targets. The list includes Bipolaris maydis, Diplodia maydis (synonym of Stenocarpella maydis), Meloidogyne incognita, Pratylenchus brachyurus, Pythium ultimum e Pythium aphanidermatum.

Telles highlights the mobility of fluopyram within the plant. According to him, after seed treatment, the molecule is able to translocate and reach the foliage. With this, ILEVO® acts as an initial barrier against infections Bipolaris maydis e Diplodia maydisThe goal is to reduce the initial infection and allow the first foliar application to be applied preventively, not curatively.

Importance in practice

This approach gains importance in areas with susceptible hybrids and a history of disease. In many situations, the producer applies foliar fungicide during the vegetative period. When the crop already shows signs of infection, the application becomes curative. Telles states that seed treatment with ILEVO® helps keep the crop "clean" until this first foliar treatment.

No case of Bipolaris maydisIntegrated pest management also involves genetic resistance, cultural practices, and the rational application of fungicides. The disease finds a favorable environment in no-till farming with surface residues, high rainfall, and mild to warm temperatures. Chemical control should occur in situations of high inoculum pressure or in susceptible hybrids, with preventive applications or at the onset of symptoms.

To Diplodia maydis (Stenocarpella maydis)Integrated crop management requires attention to corn residue, crop rotation, and genetic tolerance. The fungus survives in residues and can remain viable for months, especially when straw remains on the surface. Seed treatment with systemic fungicides can reduce damping-off caused by seed transmission.

In nematode management, Telles sees an advantage in including corn in the control program. According to him, part of the investment occurs in soybeans or cotton. Without intervention in the off-season crop, the population can multiply in the corn and return with high pressure in the following cycle. The introduction of a nematicide tool in the corn helps to keep the population below the damage level throughout the system.

One mode, double action

The mechanism of action of ILEVO® explains its dual action. Telles states that the product acts in the same way on fungi, oomycetes, and nematodes. It interferes with the respiratory system and mitochondria by acting on the succinate dehydrogenase enzyme. The active ingredient, fluopyram, is an inhibitor of Complex Two of succinate dehydrogenase, in the C2 group (fungicide) and in the N-3 group (nematicide). Blocking the enzyme reduces energy production, limiting penetration, development, and multiplication.

The expert also highlights the importance of residual effect. According to him, the product needs to remain in the roots for a sufficient period to protect the plant beyond the first few days after sowing. This persistence sustains nematode management during later stages of development. Therefore, initial protection is not limited to the moment of germination.

Telles further explains that the dual action of ILEVO®  It can reduce operating costs by concentrating fungicidal and nematicidal action in a single seed treatment solution.

According to the expert, the main measure does not involve creating productive potential, but protecting the potential already present in the genetics. The hybrid carries a productive ceiling defined in the breeding process. Diseases and nematodes reduce this ceiling by competing for resources with the plant and damaging tissues. The tool's role is to preserve roots, stems, and leaves to allow for greater expression of the material chosen by the producer.

This logic links seed treatment to system management. In the Cerrado region, soybeans, corn, cotton, weeds, and crop residues maintain living organisms between harvests. Nematodes do not disappear with a single application. Fungi and oomycetes find shelter in seeds, soil, straw, and infected tissues. The technical response requires monitoring, tracking the area's history, appropriate hybrids, rotation of mechanisms of action, and integration between seed treatment and subsequent applications.

Attention: This product is dangerous to human and animal health and the environment. For agricultural use. Sold under agronomic prescription. Always consult an agronomist. Get information and carry out integrated pest management. Dispose of packaging and product remains correctly. Read carefully and follow the instructions on the label, package insert and prescription. Use personal protective equipment.