Surveilance of plant parasitic nematodes of different crops in homesteads of Kerala

A multistratified random survey of the nematodes with reference to the cropping patterns in the homesteads of Trivandrum District of Kerala was conducted during 1984. The most widely distributed nematode was Helicotylenchus sp. and it was followed by Meloidogyne incognita, Radopholus similis and Rotylenchulus renifomis. Heterodera oryzicola was observed in three homesteads only. Among these M. incognita, H. oryzicola, R. reniformis, Helicotylenchus sp. and Tylenchorhynchus sp. had reached Economic Threshold Levels (ETL) in 1, 1, 1, 5 and 2 homesteads respectively among 100 homesteads covered in the survey. Population of R. reniformis and Helicotylenchus sp. were significantly higher in homesteads planted with coconut alone than in combination with other crops. The populations of R. renifomis and Helicotylenchus sp. associated with coconut were significantly higher in August than in May and December respectively. August population was the highest in the case of R. similis and Helicotylenchus sp. associated with banana. Populations of Helicotylenchus sp and Tylenchorhynchus sp. associated with coconut were significantly higher in red soil than in sandy soil but the latter was on par with that of laterite soil.