Community structure of plant parasitic nematodes in Polyhouse Vegetables in Kerala

An intensive survey was conducted in 53 locations coming under 13 agroecological zones in 12 districts of Kerala. Analysis of soil and root samples from 82 polyhouses revealed the presence of five plant parasitic nematode species belonging to five genera viz Meloidogyne, Rotylenchulus, Helicotylenchus, Hoplolaimus, and Criconema from crops like salad cucumber, yard long bean, tomato, chilli, amaranthus, bittergourd, raddish, beans and cabbage. Among the plant parasitic nematodes, Rotylenchulus reniformis had the highest absolute frequency (88.6%) followed by Helicotylenchus multicinctus (42.9%) and Meloidogyne sp. (36.5%). Absolute density was the highest for Meloidogyne sp. (179.8%) followed by R. reniformis (147.7%) and H. multicinctus (7.02%). Prominence value was highest for R. reniformis (1333.8) followed by Meloidogyne sp. (1087.6). The present investigation revealed that the plant parasitic nematodes (PPN) are inflicting considerable yield loss to the tune of 30–40% in polyhouse. Among the plant parasitic nematode root knot nematode Meloidogyne sp. is rapidly building up in polyhouse due to conducive microclimatic conditions, continuous cropping and improper management under polyhouses conditions.