MAJOR ROOT-PARASITIC NEMATODES ASSOCIATED WITH IRRIGATED RICE IN THE PHILIPPINES

Two surveys were conducted in five regions representative of most of the irrigated rice ecosystems in the Philippines. Six genera of plant parasitic nematodes were detected : Criconemella, Helicotylenchus, Hemicriconemoides, Hirschmanniella, Meloidogyne, and Tylenchorhynchus. The prevalent species was Hirschmanniella oryzae, observed in high population densities in 90% of the fields. Meloidogyne graminicola was detected in 26% of the fields surveyed and in more than 50% of the fields in two regions including Central Luzon, the major rice producing area in the country. M. graminicola was mostly observed in non-permanently flooded fields, light soil areas and where farmers are practising intermittent irrigation. Hirschmanniella mucronata was observed in low population densities in 10% of the fields. The other nematode genera were detected in a few fields with very low population densities.