Radopholus similis is a species of nematode known commonly as the burrowing nematode. It is a parasite of plants, and it is a pest of many agricultural crops. It is an especially important pest of bananas, and it can be found on coconut, avocado, coffee, sugarcane, other grasses, and ornamentals. It is a migratory endoparasite of roots, causing lesions that form cankers. Infected plants experience malnutrition.

History and distribution

The nematode was first described from necrotic tissue in a species of Musa, the banana genus, in 1891. It is one of the most important root pathogens of banana crops, causing yield losses of up to 30 to 60% in many countries. It is known in temperate regions worldwide. R. similis prefers warmer environments, hence the tropical habitats. R. similis is an obligate parasite, and therefore must have hosts to survive. Due to the inability to live without a host, they are found in environments where susceptible hosts flourish.

Hosts and symptoms

Radopholus similis parasites can be found in tropical climates, and therefore infect a lot of plants native to tropical areas. Common hosts that are economically important include: banana, coconut, coffee, ginger, sugarcane, ornamentals, and tea. Although R. similis has not been found to infect citrus plants, it is closely related to another variety of burrowing nematodes, Radopholus citrophilus, that is a prominent pathogen to citrus plants. They are migratory endoparasites, and therefore can cause many localized necrotic patches throughout an infected root system.

The nematode completes its life cycle in about 21 days at 25 °C. Females and juveniles feed inside roots, especially near the tips. Males with their weak stylets do not feed. Females lay two to six eggs per day.

The nematode causes a disease condition called toppling or blackhead disease in plants.

Management

The nematode load in the soil can be reduced with fumigation and crop rotation. Cover crops that are not susceptible to the nematode, such as Crotalaria or Tagetes, can be sown. Disease-free sprouts raised from clean tissue cultures can be used.

There are a few notable management strategies used to control R. similis today. There are some nematicides available, although the use of these to control infections continuously declines. Resistant hosts cause the nematodes to be unable to survive and reproduce, decreasing the population. There is also continued research regarding fungus (biological) controls for nematodes like R. similis. There is evidence that mutualistic relationships with mycorrhizal fungi may reduce the susceptibility of plant hosts. However, there are some conflicting results regarding this technique of nematode control, so it is not currently widely used. Since R. similis is an obligate parasite, they cannot survive without an available host. Planting individuals grown in vitro and guaranteed nematode free prevents any presence of nematodes being inoculated into a crop field. Applying environmental controls such as hot water or increased sun exposure to saplings before planting to desiccate any nematodes present. of the alternative flatworm mitochondrial code.

References

  • Radopholus similis. Musapedia.