Pratylenchus, Gall Nematodes are most commonly found in 2022/2023 Brazilian soybean crop

Difficult to identify, nematodes of the Pratylenchus and root-knot nematode species (RKN, Meloidogyne spp.) are the most commonly found in this 2022/2023 crop year, and have attacked several producing regions in Brazil.

Feared by many farmers, nematodes feed on plant structures, especially roots, tubers and bulbs, and can lead to severe losses in the current soybean crop.

According to the Brazilian Society of Nematology (SBN), these parasites cause losses of BRL35 billion per year to Brazilian farmers, with an average of BRL15 billion in soy crops alone.

With a maximum size of three millimeters, the nematodes are difficult to see, have a life cycle of three to seven weeks, and release toxins that cause necrosis in the tissues of roots.

″Sometimes it is difficult to identify the nematodes in these areas as they can be confused by a lack of nutrition or water,″ said Alan Castro, agronomist and technical coordinator of xarvio, BASF's digital agriculture brand.

Alan Castro, agronomist and technical coordinator of xarvio, BASF's digital agriculture brand

″In addition to causing various types of damage to plants, nematodes act as a gateway for other pathogens and can be the cause of plant diseases,″ Castro added.

″Attacked plants can suffer from chlorosis on their leaves, which is when they do not produce chlorophyll and have a different color than normal, either pale green or yellowish. They can still wither during the hottest hours of the day, the pods are born small or are aborted, and the plants are unable to develop and may even die,″ he explained.

These symptoms are the most common and are usually seen in rolls.

″This year, we are seeing many incidences of root-knot nematodes, which are considered the worst phytopathogenic nematodes, as they have a wide geographic distribution and an enormous range of hosts, causing great damage to crops,″ Castro further said.

Another nematode found was the Soybean cyst nematode, which penetrates the roots of plants and hinders the absorption of water and nutrients, resulting in reduced plant size and chlorosis in the aerial part, causing a disease known as soybean yellow dwarfism, he added.

″There is also the species, Pratylenchus brachyurus, which is known as the ‘Lesions Nematode,’ as it causes root lesions in plants. It has a wide geographical distribution and a large number of host plants,″ he further added.

According to Brazilian Agricultural Research Corporation (Embrapa), to control and manage these parasites, it is necessary to use tolerant varieties, perform crop rotation, clean equipment to prevent their spread, and revolve the soil to expose nematodes to sunlight.

In addition, to manage an area without vegetation for a certain period, it is necessary to use chemical and biological nematicides for control when monitoring indicates this requirement, as well as avoid keeping water available in the soil and excess nitrogen fertilizers, and use satellite maps that can help locate the potential presence if nematode more quickly, Embrapa added.

With the difficulty of identifying the pest, digital technology is an ally to management, Castro stressed.

The use of maps based on satellite images and application maps made using drone images, such as those provided by the xarvio Field Manager, can help locate the potential presence of nematodes more quickly.

(Editing by Leonardo Gottems, reporter for AgroPages)