The distribution of the paddy nematode, Hirschmanniella oryzae in Sri Lanka

The paddy root nematode, Hirschmanniella oryzae (Van Brcda de Haan) Luc et Goodey, is an important pest of rice, which causes root rot and gradual retardation of plant growth. It was first recorded in Sri Lanka in 1962. 8 Paddy is grown in all the districts of Sri Lanka, occupying 758,940 hectares of land (1985-1986). The occurrence and dispibution of H. oryzae was investigated by collecting samples of paddy roots from 52 locations in 22 districts. Results of this study indicate an islandwide distribution of the nematode. High populations were observed in many locations in the wet zone rather than in the dry zone. Some paddy growing areas were still free of H. oryzae and consequently it is very important to prevent it's spread from infested areas Because of the serious damage it can cause to paddy.