Soybean productivity remains stable, but nematodes advance in Mato Grosso

The 2024/25 soybean harvest in Mato Grosso maintained good average productivity, driven by regular rainfall. However, the increased incidence of nematodes, such as cyst nematodes (Heterodera glycines) to gall (Meloidogyne spp.), worries experts. The assessment was made by Rosângela Silva, a nematology researcher at the MT Foundation, during the 25th Soybean Technical Meeting, promoted by the MT Foundation.

According to her, although the visible losses were smaller than in the previous harvest, there was an increase in cases in areas with a high incidence of cyst and root-knot nematodes.

The lack of significant losses in many areas masked the silent growth of nematode populations, which could compromise future harvests. "Many producers did not experience losses, but populations increased. They stopped managing, prioritizing cultivars without resistance," he warns.

This negligence, explains Rosângela, is due to decisions focused only on production ceiling. "For more than three years, producers have opted for the same cultivars. They do not rotate. This favors the growth of nematodes," she says. The lack of agronomic planning, especially in areas with sandy soil, aggravates the problem.

Even on properties with good average productivity, basic care failed. One example cited by the researcher involved a producer who, despite fertilizing correctly and planning the plots well, had been using cultivars without resistance for years. The result: productivity below the regional average.

Farmers' resistance to adopting new cultivars is due to economic and cultural barriers. "Producers want to produce well by doing what they want, not what needs to be done. They want to keep soybeans and cotton in the system, even when both multiply the nematode," says Rosângela.

In the most affected regions, the only solution has been to rotate with corn, even with the price of the grain falling. "Many have had to remove cotton from the harvest due to a lack of prior planning," he points out. Emergency decisions generate high costs and a lasting impact on production.

To reverse the situation, the technical recommendation involves a set of actions. "Know the plots, take samples, choose resistant varieties, apply chemicals and biologicals", he summarizes. Living with the nematode requires continuous actions, without immediate solutions.

Among the available tools, some chemical ones have shown good results. According to Rosângela, biological ones add 3 to 4 bags per hectare, on average. However, alone, they do not significantly reduce the population.

In well-managed areas, the integration of cover crops, such as Brachiaria, and multiple tools has kept the soil productive. Extended rotation helps reduce the nematode before soybeans and cotton return. A current project is testing 13 tools on resistant and susceptible cultivars, seeking to identify which management methods deliver the greatest return.

The next harvest, according to Rosângela, will require extra attention. "This year it rained like clockwork. No one can guarantee what will happen next year. If the weather fails, only those who take care of the basics will have a good harvest."

The researcher's final message is clear: "nematode control does not depend on miracles, but on continuous management, with detailed monitoring of each area and integrated use of tools at the right time."