The Phytonematode populations associated with Allium cepa were screened to analyse the density buildup and the study revealed that the Tylenchid genera buildup on Allium cepa were Psilenchus, Helicotylenchus, Pratylenchus, Aglenchus and Filenchus with their absolute frequency of 100%, 90%, 96.6%, 83.3% and 73.3% respectively. The effect of organic amendments including poultry manure, pigeon manure and saw dust was looked into in order to calculate their effects on Filenchus cylindricaudus (Wu, 1969) Siddiqi, 1986. Population densities reduced to a considerable extent on the application of organic amendments in the order of pigeon manure > Poultry manure > saw dust.