Isolation And Identification Of Nematode Species Found in Fields of Onion Leaf Twister Diseases in The Batticaloa District

Abstract

Leaf Twister Disease (Ll'D) ('Koti kat' in Tamil) appears complex probiem to be a and a major rimitation in the cultivation of onion in the Batticaroa district. It was observed that LTD symptoms usuaily appear under rainy weather ceindition and up to r00% yierd rosses were ::f T:ill li: pjjllh ::fore, rhi s stucly was "ono u"tdJ to iJ""iirrrJ, rL,U,V pnmary cause ofLTD. sii infested fierds in three major oniorrg.o*ing villages namely Karuthavarai, chettiparayam and Thettatheevu were :j:"j*j::11']"llr. !re13a soilsamptes with damaged onion prant materials were colrected at four different Pr4rrr rocations ,.unio*if i, field and examined precisely. Two hundred rnounted srides of nemato"due.sr, were prepared and examined to identi$z the nematodes based on their morphological characteristics. A nurnbe. of different t"y., ."r"r""* collections' taxonomic catalogues and many descriptions *"r" ur"a in the identification. A nematode species Apherenchus avenae was identified from the soir sanrples and damaged onion prant materi ars. Apherenchus ovenae is a cosmopolitan ubiquitous a1d fungivorour r,r*utod" ";;r;;i","' *o decaying plant tissues.