[1] Recent modifications in cultivation practices have led to a substantial increase in rice production, which has been accompanied by heightened levels of RRN.
[3] The genus Hirschmanniella is found within the family Pratylenchidae and contains around 35 species, the majority of which are migratory endoparasitic nematodes of plant roots.
RRN has been identified in all of the following Asian countries: Myanmar, India, Pakistan, Bangladesh, Sri Lanka, Nepal, Thailand, Vietnam, Indonesia, the Philippines, China, Korea, and Japan.
The phasmids are located in the posterior third of the tail, which are three to five times as long as the body width at the anus, tapering, and usually terminating in a point or mucron.
[6] While migrating through the cortex, RRN can be found feeding from cortical cells or vascular bundles anywhere inside the root.
[6][8] These below ground symptoms begin by the formation of small brown lesions at points where nematodes have ruptured the surface and entered.
[6] In situ hybridization has shown the activity of esophageal glands in the production of cell wall degrading enzymes such as xylanase and β-mannanase possibly involved in hemicellulose degradation; thaumatin-like protein (TLP) probably involved in protection against bacterial pathogens; late embryogenesis abundant (LEA) proteins possibly involved in the process of anhydrobiosis during survival in dry conditions; and two putative effector proteins that may alter the host defense mechanism: chorismate mutase (CM) and isochorismatase (ICM), thought to be interfering on the salicylic acid pathway and thereby altering the defense mechanisms of the host.
Upon root necrosis, these nematodes can leave and reenter the soil to infect neighboring plants, continuing their destructive migratory force.
Fortunately, nutritional experiments indicate that when plants are given the proper cultural care, they can produce a satisfactory crop though heavily infected, which allows for a level of tolerance of rice to RRN.
Poussin, Neuts, & Mateille (2005) found that nitrogen amendments applied at a rate of 80 kilograms per hectare (71 lb/acre) increased the weight of each rice grain thereby offsetting the damage caused by RRN.