Root rot disease has become more alarming because of its epidemic nature and propensity to kill the plant completely. M. phaseolinais a soil borne pathogen was isolated from various root rot disease affected samples collected from the mulberry gardens ofTamil Nadu , South India. The affected plants show sudden withering of leaves followed by death of plants along with decaying and rotting of roots and stem cuttings. The disease is soil borne in nature and spreads fast primarily through contaminated soil, irrigation, diseased saplings farm implements etc. The population of nematodes in soil was assessed at the time of termination of the experiment by drawing a composite sample of 250g soil from each pot. The root system of the plants was carefully removed and dipped in a bucket of water for assessing adult nematode population in the root. the incidence of major nematodes namely, Meloidogyne incognita, Rotylenchus reniformis and Helicotylenchus ulcinctus populations varied from place to place, soil to soil and depends upon season to season.the maximum nematode population in mulberry garden viz., M. incognita in 58 (No./200cc soil), R. reniformis 34 (No./200cc soil) and H. ulcinctus 29 (No./200cc soil) in Erode district, where as low population of M. incognita (07 No./200cc soil) in Dharmapuri district, R. reniformis (13 No./200cc soil) in Tirunelveli District and (12 No./200cc soil) H. ulcinctus in Krishnagiri District, respectively.