Ring nematode

The ring nematode Hemicriconemoides pseudobrachyurus belongs to the order Tylenchida, family Criconematidae. It is a small ectoparasite characterized by pronounced cuticular rings on its body, which gives this group its common name.

Adult individuals possess a stylet—a specialized piercing-sucking apparatus that allows them to feed on the contents of root cells. Females of this species often have a protective cuticular sheath that helps them survive in the soil environment.

The biology of the species is closely linked to the rhizosphere, where nematodes move through soil pores. They prefer light, well-aerated soils where their mobility and ability to locate a host are significantly improved.

The life cycle includes an egg, four larval stages, and an adult stage. Development occurs without changing hosts, and larval survival depends on substrate moisture and the presence of suitable host roots.

Unlike many endoparasites, ring nematodes rarely penetrate deep into the roots, preferring to remain in the rhizosphere, which makes their visual detection extremely difficult.

This pest affects a wide range of crops, including fruit trees, citrus, ornamental shrubs, and some field crops. The nematode poses a particular threat to young seedlings in nurseries.

Feeding by Hemicriconemoides pseudobrachyurus leads to the destruction of epidermis and root cortex cells. Necrotic spots often appear at the stylet puncture sites, hindering the normal absorption of water and minerals.

As a result of nematode activity, the root system loses its ability to regenerate. Lateral roots die off, and the main root stops growing, leading to overall suppression of the above-ground part of the plant.

Affected plants show reduced photosynthesis intensity, leaf chlorosis, and delayed flowering. Under conditions of heavy infestation, young plants may die completely due to the inability to take up nutrients.

Root damage by nematodes opens the door for secondary infections caused by soil-borne fungi and bacteria, which significantly exacerbates the overall damage to the crop.

The first sign of infestation is uneven plant development in the field—the appearance of "stunted" patches. Affected crops lag in growth and show symptoms of nutrient deficiency despite adequate fertilization.

Plant leaves often lose turgor during hot hours, even with sufficient watering, which indicates damage to the root vascular system. Over time, lower leaves turn yellow and drop prematurely.

When plants are uprooted, a significant reduction in the volume of the root system can be observed. Roots appear "stunted" or thinned and often darken due to secondary rots.

Diagnosis requires laboratory analysis of soil and root fragments. In the laboratory, nematodes are extracted using centrifugation or filtration methods via Baermann funnels.

An indirect sign is the deterioration of crop quality: smaller fruit sizes, loss of market appearance, and reduced resistance to environmental stress factors.

The primary control method is the use of certified, healthy planting material, which prevents the introduction of nematodes to clean fields. Quarantine control is the first line of defense.

Agronomic measures include deep plowing and crop rotation with nematode-suppressive or non-susceptible species. The application of organic fertilizers is also beneficial, as it stimulates the development of beneficial soil microflora.

The use of chemical nematicides is justified only under high soil infestation levels. It is essential to follow application protocols to minimize negative impacts on beneficial soil invertebrates.

Modern biological methods include the use of preparations based on antagonistic fungi and specific bacteria that parasitize nematodes.

To prevent the spread of the pest, it is crucial to disinfect agricultural equipment after working on infested fields to eliminate the transfer of invasive larvae with soil particles.