BP Singh

216 Arjun Lalcollected or introduced, if they are used carefully. For recovery ofnematodes from infested soil or plant material in large numbersfor identification and further studies, several nematode extractiontechniques are used by the nematologists which require specialequipments.a) To extract nematodes from soil : If the sample size is verysmall (100 g or less), the soil may be placed directly in a funneland processed by the mist extraction or Baermann Funneltechnique. Larger soil samples are first processed by the combinedscreening-funnel technique or the gravity-screening techniquefollowed by mist extraction of the residue.To extract cysts-forming nematodes from soil: The centrifugalflotation tecruuque is most efficient in recovery of cysts from soil.To recover sluggish nematodes from soil: Nematodes havingvery little locomotion power such as Criconemoides, Hemicycliophoraare recovered by centrifugal-flotation methods.b) To extract nematodes from roots: Infected foots are cut intosmall pieces, and processed by mist extraction or Baermann funnel,or gently washed and subjected to jar or plastic bag incubation.Mist extraction is effective in recovering both endoparasitic and~ctoparasitic nematodes. Jar incubation of washed roots recoversendoparasites and migratory endoparasites only.e) To extract nematodes frolP other plant parts: To extractnematodes from tubers, bulbs, rhizomes, leaves etc. the mistextraction method is most effective but Baermann funnel methodcan also be used.Each technique has its own advantages and disadv~ntagesand selection of a method may vary with the purpose of thestudies.Suggested ReadingsCurran, J. and Robinson, M.P. (1993). Molecular aids to nematodediagnosis. In: Plant parasitic Nematodes in Temperate Agriculture(ed. Evans et al.) : 545-564, CAB!, UK.Lal, A. and Mathur, V.K. (1988). Seed health testing for plantparasitic nematodes. In: Proc. Seed Sci. & Tech.( Yadava, T.P.& Chandgi Ram, eds.), pp. 318-320, HAD Press, Hisar.Southey, J.F. (1986). Laboratory methods for work with soil and plantnematodes.· MAFF, HM:SO London: 1-202.