Hirschmanniella oryzae, i.e. the rice root nematode (RRN), belongs to the family Pratylenchidae and is one of the major pests of rice and is the most common plant-parasitic nematode found on rice. In India, Hirschmanniella oryzae and H. mucronata are two nematode species that are widely distributed and are commercially important. It has a global infestation rate of 58% and 10–25% yield loss potential. At high nematode density, infected seedlings exhibit growth retardation, reduction in plant height and weight, and at the same time cause browning of the infected host roots. The nematode infects and multiplies in the roots of the main host rice; however, it penetrates and multiplies in the roots of several selected annual and perennial weeds.