RKN
RKN stands for root-knot nematode, a group of microscopic plant-parasitic roundworms in the genus Meloidogyne. They feed in roots and can cause swellings or galls, reducing effective root function in susceptible plants. Above-ground symptoms such as weak growth are not diagnostic because many root problems look similar. For a mango with suspect roots, use a plant-diagnostic or nematode test and obtain clean nursery material; not every soil nematode is harmful or requires treatment.