BP Singh

Symptoms of Nematode Damage 203adverse conditions (as lack of moisture, temperature extremes,nutrient deficiency), reduced tillering and general weakening 'ofplant. There may also be reduction in quality as well as quantityof flowers, seeds and fruits. In standing crop, patches of unthriftyplants are usually indicative of nematode problem. These symptomsresult from inadequate supply of water and nutrients to aerial partsdue to improper functioning of root systems.Specific symptoms of nematode damageSpecific symptbms of nematode damage may be evident onabove ground parts and! or on subterranean parts. The expressionof symptoms varies .with nematode species and host plantinvolved. Most often the infested plants exhibit a combination ofsymptoms. The follO"~ing description can serve to familiarisegermplasm collectors of symptoms of nematode attack so thatcollection and exchange of nematode infected germplasm materi~lcan be avoided.Symptoms on above ground partsDead or devitalised buds : Growing point or buds of plants mayget killed due to infestation by nematodes as Aphelenchoidesparietinus, Abesseyi and A fragariae. The term 'blind' denotes thiscondition. Abesseyi on strawberry causes dropping off of flower'buds.Seed galls : Seed galls formed by Anguina trifici offers the mostoutstanding example. Nematode larvae invade flower primordiawhich instead of developing into seed gets transformed intorounded nematode gall. Nematode galls are green initially butwith crop maturity turn brown black. Gall formed on Festuca grassby A. agrostis are fatal to animals due to association of bacteria withgalls.Distorted, shrunken, discolored seeds: Seed borne nematodes asAphelenchoides besseyi and Ditylenchus dipsaci attack inflorescence ofplants and result in formation of withered, shrivelled andmalformed seeds. Seeds showing such symptoms may harbourheavy population of nematodes as usually no symptoms areexpressed at low levels of nematode infection.Crinkling of leaves : Crinkled, folded leaves usually result fromattack by Anguina spp. and Aphelenchoides spp. A.besseyi on