Management helps to deal with nematodes in the soybean crop 22/23

Feared by many farmers, nematodes could lead to severe losses in this 2022/2023 soybean harvest. According to the Brazilian Society of Nematology (SBN), these parasites cause losses of R$35 billion annually to Brazilian farmers, with an average of R$15 billion in soybean crops alone.

Nematodes are parasites that live in soil and feed on plant structures, especially roots, tubers and bulbs. With a maximum size of three millimeters, nematodes are difficult to see. They have a life cycle of three to seven weeks and release toxins that cause necrosis in root tissues.

“Sometimes it is difficult to identify nematodes in areas because they can be confused with a lack of nutrition or water”, comments Alan Castro (photo below), agronomist and technical coordinator of xarvio, BASF's digital agriculture brand.

Castro adds: “in addition to causing various damages to plants, nematodes act as a gateway for other pathogens and can cause plant diseases.”

“Attacked plants have chlorosis in their leaves, which is when they do not produce chlorophyll and have a different color than normal: pale green or yellowish. It can still wither during the hottest times of the day, the pods are born small or are aborted and the plants are unable to develop and may even die”, explains Alan Castro.

These symptoms are the most common and are generally observed in reboleiras.

“This year we are seeing a lot of incidence of Root Root Nematodes (Meloidogyne spp..), which are considered the most important phytopathogenic nematodes, as they have a wide geographic distribution and enormous host range, causing great damage to crops. Another nematode we found was Soya Cyst, which penetrates the roots of the plant and hinders the absorption of water and nutrients, resulting in reduced plant size and chlorosis in the aerial part, causing the disease known as soybean yellow dwarfism. We also have the species Pratylenchus brachyurus, which is known as the Lesions Nematode, as it causes root lesions in plants. It has a wide geographic distribution and a large number of host plants”, ponders the agronomist.

Tips for control

Some management precautions are important to control these parasites, according to Embrapa:

• use tolerant varieties;

• carry out crop rotation;

• sanitize equipment to prevent the spread of nematodes;

• turn over the soil to expose the nematodes to sunlight, so that the area remains without vegetation for a period;

• use chemical and biological nematicides for control, when monitoring indicates;

• avoid keeping water available in the soil and excess nitrogen fertilizers;

• Using satellite maps can help locate potential nematode presences more quickly.