BP Singh

204 V.K. Mathur and Nandini Goktestrawberry causes a condition known as' Crimp, Summer Crimpor Summer Dwarf. Affected plants show crinkled, folded leavesdark brown in colour which are also quite brittle. A. tritici infectionon wheat also results:··l similar crinkled twisted leaves. A. fragariaecauses a condition in strawberry called as' Spring Crimp'. Crinkledleaves are also associated with infestation of Nothotylenchus acrison alfalfa.Leaf galls and spikkles : Galls on leaves are produced by somespecies of Anguina. Small, slightly raised, yellow pimple like areascalled as 'Spikkles' on Narcissus leaves are associated withDitylenchus dipsaci infection.Leaf spots, lesions and discolorations: Spots or lesions on leavesmay be indicative of infection by species of Aphelenchoides. Foliarnematodes enter through stomata causing destruction of leafparenchyma which gets apparent as leaf spots or lesions.A. ritzemabosi and A. fragariae cause leaf spots on Chrysanthemumand Begonia respectively. Spots first appear on undersurface assmall yellow areas whiC;h turn to brown and later black. The spotsspread and coalasce leading to destruction of l~af.A. ritzemabosi causes interveinal discolouration in Strawberryand Chrysanthemum. Discolouration is also evident in Aster leavesinfected with D. dipsaci. White tip disease of rice caused by A.besseyi, is characte:rized by upper 2-5 cm of leaves becoming yellowthen white and ultimately brown and necrotic.Stem galls: Stem galls are produced by many species of Anguina.A. tumajaciens produces greenish or reddish galls on Cyanodontransvaalensis. Similarly, A. pastulicola infection results in pustulelike stem galls on grasses.Necrosis and discolouration of stem: Necrosis and discolourationof stem 4ue to nematode attack may range from light or paleyellowishness to different shades of reddishness or even blackcolour. Rhadinaphelenchus cocophilus causes formation of brown redring in transverse secti-on of stem in coconut. A band of necrotictissue is formed followed by appear~nce of reddish colour due tomortality of cells. Stem discolouration is also evident in pine treesinfected .with Bursaphelenchus xylophilus.Distortion of stem : Stem distortion and twisting are evident ininfestation of Anguina tritici on wheat.