Vegetables are the most important priceless blessings that nature has bestowed upon mankind. They are not only rich in vitamins ‘A’ and ‘C’ and minerals like calcium and iron but also have low calorific values and low in fats. The destructive plant parasitic nematodes are one of the major limiting factor in vegetable production throughout India. Because vegetables are grown throughout the year so they harbor and encourage the build up of nematode population. For centuries, man has been plagued by these microscopic organisms feeding on the roots of crop plants essentials for their survival and well being. Roots damaged by the nematodes are not efficient in the utilization of available moisture and nutrients from the soil resulting in reduced functional metabolism. Visible symptoms of nematode attack often include reduced growth of individual plants. Furthermore, roots weakened and damaged by nematodes are easy prey to many types of fungi and bacteria which invade the roots and accelerate root decay. These deleterious effect on plant growth result in reduced yields and poor quality of crops. Nematode management is therefore, important for high yields and quality that are required through modern crop production. Root-knot nematodes: Meloidogyne spp. The root-knot nematodes are by far the most important pests of vegetable crops. The four most common species viz., M. incognita, M. javanica, M. hapla and M. arenaria are by far most important and leads to formation of conspicuous root galls. M. incognita and M. javanica are most widespread in distribution and have a wide host range among vegetables, whereas M. hapla is encountered and poses problem under temperate conditions and attacks potato and other vegetable crops while M. arenaria infects chillies. Four races in M. incognita, two each in M.javanica and M.arenaria have been reported from India. The most important species of root-knot nematodes (Meloidogyne incognita and M. javanica) attacking vegetable crops are multivoltine. Eggs are laid in a gelatinous matrix surrounding the posterior portion of each female. These eggs undergo embryogenesis, first moult takes place inside the egg and second-stage juveniles emerge out. These pre-parasitic second-stage juveniles move freely in the soil and are attracted towards roots from as far as 75 cm. Physiological races/biotypes are known to be prevalent in a few species of root-knot nematodes. The international Meloidogyne project has identified four races in Meloidogyne incognita and two in M. arenaria. In India, researchers reported four races of M. incognita. In Haryana and Karnataka, existence of four races of M. incognita, i.e., race 1, 2, 3 and 4 has been reported. The prevalence of race 4 that is very rare (2 per cent of 472 world populations) has been reported for the first time from India. The inoculum level varying from 0.5 to 1.0 per g of soil in different vegetable crops, viz., tomato, brinjal, okra, curcurbits, radish, turnip, pea and Chinese cabbage has been found to be pathogenic. Infected plants are stunted with dried peripheral branches bearing smaller chlorotic leaves almost turning to white in later stages. Basically, root-knot nematodes are parasites of roots or underground stem. The disease caused by root-knot nematodes is not of epidemic nature but rather of slow decline in yields spreading very gradually and steadily year after year. Some areas within a field may be severely affected, whereas plants in other parts may not show any sign of disease. The aboveground parts of the diseased plants exhibit symptoms typical of mineral deficiency or drought injury even in the presence of adequate fertilizer and moisture. The other symptoms may include-dieback, yellowing, wilting and premature shedding of the foliage with severe stunting, depending upon the initial nematode population in the field. Chlorosis of the foliage lowers the quality of the crop resulting in severe losses. The belowground symptoms include galls or knots on the roots. These galls vary in size from pinhead to a large size, which in case of heavy infection may coalesce to form large secondary galls. The size of galls also depends upon the host plant and nematode species. The galls produced in curcurbits are much larger than the ones produced on chillies or cotton by the same nematode species. M. hapla usually produces small galls as compared to M. incognita or M. javanica on potato. Besides galling, some other typical symptoms in the form of forking of tap roots as in carrots or beet and pimple-line tubercles on tubers (potato) are also manifested. The root-knot nematodes, Meloidogyne incognita were of the limiting factors in commercial production of vegetables and responsible for 15-60% yield loss (Krishnappa et al., 1992). Various researchers reported a loss of 70 per cent in chillies, brinjal, tomato and okra. In Mahendragarh district of Haryana, in a field naturally infested with M. incognita at 2800-3460 larvae per kg soil, losses in yields of okra, tomato and brinjal were 90.9, 46.2 and 27.3 per cent, respectively. Yield of tomato was reduced by 39.8 per cent in a field at population level of 20 larvae per g of soil. In peas, the avoidable loss in yield was found to be 19-20 per cent. In Tamil Nadu, losses in yields of Capsicum and tomato were 19.7 and 61.0 per cent, respectively, due to M. incognita. In Haryana, in a field having initial M. javanica population of 296±51 per 250 g soil, the avoidable losses in okra yield ranged from 20.2 to 41.2 per cent by using carbofuran and aldicarb @ 2.0 and 4.0 kg a.i. per ha. Per cent avoidable losses in yield of okra, brinjal, French bean and cowpea due to M. icnognita under field conditions at Bangalore were 28.08, 33.68, 43.48 and 28.60, respectively. Yield losses in tomato, brinjal and bittergourd due to M. incognita race 3 under field conditions in Maharashtra were 46.92, 32.73 and 36.72 per cent, respectively. The Reniform Nematode : Rotylenchulus reniformis The reniform nematode infests tomato, brinjal, okra, cowpea, dolichos, French beans, parwal and other vegetables. Two races of this nematode have been reported from India (Dasgupta & Seshadri, 1971). The emergence of cowpea seedlings was delayed by 7 to 9 days and seedling stand was reduced to the tune of 6 to 11 per cent due to R. reniformis at one nematode per g of soil. R. reniformis was observed to cause stunted growth of mint plants, withering of branches with chlorotic leaves at Hessaraghatta near Bangalore. Comprehensive work done by various researchers has established the existence of two biotypes (A and B) in R. reniformis. Biotype A completes its life cycle on all the three differential hosts (cowpea, castor and cotton) while biotype B would not complete its life cycle on castor or cotton. The two races were found to interbreed with each other and the hybrids were fertile and more polyphagous than the parents. Root Lesion Nematodes (Pratylenchus spp.) Nematodes belonging to this genus are designated as lesion nematodes because of the severe necrotic lesions that are produced in the feeding sites in root cortex. De Man described the first species of Pratylenchus in 1880. At present, there are more than 68 species in this genus in the world (Siddiqi, 1986). However, in India, a total of 36 species have been recorded so far (Walia, 1986). Amongst vegetables, tomato is an important host for this nematode. At least five spp. viz., P. brachyurus, P. coffeae, P. penetrans, P. scribneri and P. vulnus have been reported to infect tomato (Jensen, 1972). Of the different species of Pratylenchus present in India, Das described Pratylenchus indicus in 1960 from Hyderabad on tomato and brinjal. It is widespread in the states of Kerala, Gujarat, Orissa and Assam. Pratylenchus species have cosmopolitan distribution with a wide host range including vegetable crops such as peas, pepper, spinach, radish, onion, brinjal and beans etc. P. penetrans is economically most important in North eastern states of USA (Mai et al., 1977). However, it is also present in Canada (Potter & Olthof, 1974) and Europe (Loof, 1978). The life cycle is simple the reproduction is sexual. The eggs are deposited singly mostly in roots. The first moult takes place inside egg and the second stage larva hatches out, which moults three times to become adult. Both larval stages and adult are capable of entering the roots. The nematodes overwinter in the single adults and fourth-stage larvae and eggs in the roots. The time required for completing one life cycle ranges from 90 days depending upon the prevailing soil temperature, host plant and nematode species. Root lesion infected plants show gradual decline or lack of plant vigour with stunting as chlorosis leading to rapid wilting. On the roots, there is formation of lesions and necrosis, which provided site for other micro-organisms to infect, grow and reproduce, thereby leading to other disease complete. Shafiee & Jenkins (1962) noticed that growth of all the plants was retarded due to nematode infection. The phosphorus deficient plants did not exhibit such response. However, marked reduction in plant growth as observed in N-deficient plants. Nematodes belonging to this genus are endoparasitic root feeders which migrate inter and intracellularly and feed in the cortical region leading to cell death and breakdown. Formation of lesion on the roots due to nematode feeding can be seen, which enlarge, coalesce and turn brown and ultimately affected area gets sloughed off. This results in the reduction of proper root development. In pepper, destruction of parenchymatous cells of cortex accompanied by dark and thick cell walls has been observed (Mai et al., 1977). Root cells of many plants contain glycosides (e.g. amygdalin), which are not toxic in glycosidic ion. However, upon hydrolysis they release certain phytotoxic compounds. Mountain and Patrick (1959) reported the P. penetrans hydrolyses amygdalin in peach roots due to the secretion of b-glucosidase, releasing benzaldehyde and hydrogen cyanide, both of which are highly phytotoxic substances. Further, oxidation of these substance in the roots is believed to be responsible for browning of lesions and root necrosis. McKeen & Mountain (1960) observed synergism between Verticillium albo-atrum and P. penetrants brinjal. They found that when present alone, even as high as 4,000 nematodes per plant were unable to the damage. But, in presence of wilt fungus, severe crop damage could be seen. On tomato and pepper, the nematode population was higher in presence of Verticillium than in its absence (Olthof and Reys, 1969). Conroy et al. (1972) found no increase in the susceptibility of tomato to V. albo-altra in the absence of P. penetrans. Mountain and McKeen (1965) reported that reproduction of P. penetrans increased in presence of V. dahliae on tomato and egg plant but not on pepper. Spiral Nematode: Helicotylenchus dihystera H. dihystera causes perceptible reduction in root growth of chillies. Okra. Tomato, brinjal and onion were also found to be good hosts for this nematode. Potato Cyst Nematodes: Globodera spp. The potato cyst nematode (G. rostochiensis and G. pallida) is the most important pests of potato. This nematode has been reported from Nilgiris and Kodai Hills of Tamil Nadu and Munar Hills of Kerala (Ramana and Mohandas, 1988). Out of 9,000 ha under potato, 3,000 ha are infected by this nematode in Nilgiris. In Kodai Hills, about 200 ha are infected (Thangaraju, 1983). Tomato and brinjal are also attacked by this nematode. Total failure of the crop has been reported under severe infestation conditions. Stunt Nematodes : Tylenchorhynchus spp. Nematodes belonging to this genus are widely distributed. These are rot parasites and are found in almost all the areas. The most common species feeding on vegetables in India is Tylenchorhynchus brassicae. The nematode is associated with poor germination and growth of cabbage and cauliflower. Although widely distributed both in temperate and tropical zones, yet only a few species are known to be pathogenic to various vegetable crops. In southeastern USA, T. claytoni has been responsible for stunting of pea and T. marioni in sweet potato. T. brassicae damages cabbage and cauliflower. T. dubius parasitizes cauliflower, pea, radish and turnip in Netherlands (Brezeski, 1971). Besides cauliflower and cabbage, tomato, radish, sugarbeet and lettuce are also good hosts. Stunt nematodes primarily feed ectoparasitically on epidermal cells of roots in the region of root elongation but are sometimes embedded partly or totally in the root tissues. In India, T. brassicae has been observed to penetrate throughout the cortical region. Nematodes remain confined to outer cortical layers with their bodies parallel to the root axis. Populations at and above 1000 per kg soil cause significant damage to cabbage and cauliflower. The nematode feeding results in stubby root condition leading to stunting and reduced plant growth. The optimum temperature for growth and reproduction is around 30oC with 25-30 per cent moisture (Khan, 1969). In the absence of host, the nematodes survive for 90 days and 30 days at 35oC and 45oC, respectively. At low temperatures, the nematode may survive even upto 240 days. Rhizoctonia solani and T. brassicae are often associated with roots of cabbage and cauliflower. R. solani alone suppressed the emergence of cauliflower seedlings by 81% when the two organisms occurred together 97% of the seeds failed to germinate (Khan and Saxena, 1969). The stubby root nematode, Trichodorus allius . T. allius infects onion. The stem and bulb nematode, Ditylenchus destructor. The stem and bulb nematode, D. destructor causes dry rot of potato tubers in Shillong. Management methods Regulatory methods Plant quarantine From the imported germplasm material, economically important nematodes like Heterodera goettingiana, Meloidogyne incognita, Ditylenchus dipsaci, Radopholus similes (Sethi et al., 1972) and Globodera rostochiensis (Renjhen, 1973) have been intercepted. In India, there is a Quarantine Act against the cyst nematode of potato (Globedera rostochiensis) in Nilgiris. Infected seed potatoes from Nilgiris are not allowed to be transported to other parts of India for seed purpose. Seed certification Seed pieces free of the cyst nematode can be produced commercially by seed certification. Physical methods Heat treatment of soil The most important nematode pests controlled by greenhouse steaming are cyst nematode of potato attacking tomatoes and root-knot nematodes on tomatoes, cucumbers and lettuces. Incubation of potato tubers at 45oC for 48 hours has been shown to kill about 98.9 per cent M. incognita without affecting tuber viability (Nirula and Bassi, 1965). Cultural methods Crop rotation Crops, which have been shown to reduce root-knot populations in the soil include varieties of cereals (sorghum, millet, maize, wheat, rice), cruciferous crops (cabbage, cauliflower, kohl rabi, mustard), onion, garlic, groundnut, cotton, Roselle (Hibiscus sabdariffa) and pigeon pea. Continuous cropping with potatoes increases the cyst population of Globodera rostochiensis. More than three-year rotations with wheat, strawberry, cabbage, cauliflower, peas, maize and beans reduces the nematode population to a safe level. Likewise, decrease in root-knot nematode population on tomato, brinjal, okra, chillies and spongegourd occurs following marigold and spinach (Khan et al., 1975). There was sudden decline in population of Tyhlenchorhynchus brassicae when cabbage and cauliflower were rotated with wheat (Siddiqui et al., 1973). The mustard (rabi), radish (summer), sesamum (kharif) sequence considerably reduced the population of Tylenchorhynchus spp. (Haque and Gaur, 1985). A number of crops and other plants are reported resistant to the reniform nematode, Rotylenchulus reniformis which include chillies, Lecaena glauca, Capsicum frutescens, carrot, coriander, Spinacea oleracea, Beta vulgaris and Raphanus sativus (Khan and Khan, 1973). Two successive crops of maize or sorghum preceding susceptible crops are effective in controlling R. reniformis. Rotations with sugarcane and pangola grass are recommended for control of the reniform nematode. Selection of healthy propagating material The potato cyst nematode (Globodera rostochiensis) can be eliminated by selecting nematode-free planting material. Influence of manuring Increased levels of potash have significantly reduced the number of galls by M. javanica in tomato (Gupta and Mukhopadhyaya, 1971). Application of potash in combination with phosphorus or nitrogen or potash alone checks the reniform nematode multiplication on okra to a great extent (Sivakumar and Meerazainuddin, 1974). Trap cropping Cowpea causes the root-knot nematode eggs to hatch, the larvae enter the roots and develop to immobile stage. Then the crop is destroyed before the nematodes mature. Crotolaria is highly susceptible to invasion by the root-knot nematode but is resistant to the development of larvae into adults. Enemy plants Mustard : Potatoes grown with white mustard in a pot of infested soil were less heavily attacked by nematodes than potatoes growing alone. Potato root diffusate was ineffective in the presence of leachings from the roots of mustard seedlings. Mustard oils increased the yield of potatoes by reducing the severity of nematode attack. The active principle involved in mustard is allyl isothiocyanate, which is toxic to the nematodes. Marigold : The root-knot development on tomato and okra was low when interplanted with Tagetes erecta. The population of Tylenchorhynchus, Helicotylenchus, Hoplolaimus, Rotylenchulus and Pratylenchus was also markedly reduced (Khan et al., 1971a; Alam et al., 1977). Alpha-Terthienyl is the active principle in Tagetes spp., which is toxic to these nematodes. Asparagus : Asparagus officinalis would not support populations of Trichodorus chirisitiei for more than 40 to 50 days. Tomato, normally a good host of this nematode, supported only a low population when asparagus was growing in the same pots. A glycoside (asparagiusic acid) is the active principle involved which is toxic to T. christiei and several other nematode species. Sesame : Atwal and Manger (1969) showed that root exudates from sesame (Sesamum orientale) have nematicidal properties against M. incognita. When okra was grown in M. incognita infested soil it was only slightly attacked and there were fewer nematodes compared with when okra was grown in the absence of sesame. Time of planting Planting of potato during third or fourth week of March in Shimla Hills would reduce the damage to M. incognita (Prasad et al., 1983). The yields were maximum, which was concomitant with the lowest tuber infestation and lowest larval population in the soil at harvest Chemical methods Nursery bed treatment Nursery bed treatment with aldicarb and carbofuran both at 2 g a.i. per m2 were effective in increasing seedling growth and reducing root-knot nematode population on tomato, brinjal and chillies (Jain and Bhatti, 1983; Ramakrishnan and Balasubramanian, 1981). In the main field, the above treatments were also effective and increased the fruit yields. DBCP at 50 liters per ha and metham sodium at 250 liters per ha were effective in reducing the reniform nematode population in tomato nursery and in increasing the growth of seedlings (Sivakumar et al., 1977). Seed treatment Fenamiphos, aldicarb and carbofuran all at 1 per cent concentration were effective in controlling the root-knot nematode (M. incognita) infecting cowpea, French bean and peas and in increasing their pod yields (Parvatha Reddy, 1984). Seed treatment with aldirab and carbofuran both at 6 and 12 per cent was effective against the root-knot and reniform nematodes infecting okra (Shivakumar et al., 1976). Aldicarb and carbofuran at 3 per cent were also effective against root-knot nematodes infecting chilli and bottle gourd (Kandasamy and Shivakumar, 1981). Jain and Bhatti (1981) reported effective control of M. javanica on okra by seed treatment with fenamiphos at 2, 4 and 6 per cent. Seedling bare-root dip treatment Carbofuran and oxamyl at 1,000 ppm for 15 to 30 min. (Parvatha Reddy and Singh, 1979); fenamiphos at 250 to 750 ppm for 30 min. (Thakar and Patel, 1985); dimethoate at 500 ppm for 6 hr, phosphamidon and dichlofenthion both at 1000 ppm for 8 hr (Jain and Bhatti, 1978) and thionazin at 500 ppm for 15 min (Reddy and Seshadri, 1975) gave effective control of root-knot nematodes on tomato when used as bare-root dips. Alam et al. (1973) reported that oxamyl was effective for the control of root-knot nematodes infecting brinjal and okra. Bare-root dip treatment of brinjal seedlings with aldicarb, carbofuran and turbofos at 500 to 1000 ppm was effective in reducing the reniform nematode population. Soil treatment in the main field Aldicarb, carbofuran, ethoprophos and fenamiphos each at 1 to 2 kg a.i. per ha were found effective in reducing the root-knot nematode population and in increasing fruit yields of different vegetable crops. (Ahuja, 1983., Singh et al., 1978; Rao and Singh, 1978; Singh and Parvatha Reddy, 1981b, 1982b; Parvatha Reddy, 1985a.,Handa & Mathur, 1981). Aldicarb at 0.5 kg a.i. per ha and carbofuran at 1.5 per ha were effective in reducing Tylenchorhynchus brassicae and T. dubius population and in increasing yields of cabbage (Varma et al., 1978). Reddy and Seshadri (1972) reported that thionazin at 4 kg a.i. per ha proved effective against R. reniformis infecting tomato. Host resistance Screening of germplasm Source of resistance have been identified in certain vegetable crops. Nematode-resistant varieties of a very few vegetable crops have been developed and identified which are given below in Table1.Table 1. Nematode-resistant cultivars of vegetable crops Crop Nematode Resistant cultivars References (s) Tomato Meloidogyne spp. Nematox, SL-120, NTR-1, SL-12, Patriot, VEN-8, VFN Bush, Piersol, Radiant, Nemared, Ronita, Anahu, Bresch, Helani, Campbell-25, Punuui, Arka Vardan, Pelican, Hawaii-7746, Hawaii-7747, Hisar Lalit Patel et al., 1979; Jain et al., 1983; Kanwar and Bhatti, 1990. Brinjal M. incognita Giant of Banaras, Black Beauty, Gola Alam et al., 1974 Chilli M. javanica 579, CAP-63, Pusa Jwala Jain et al., 1983 Potato M. incognita, Glodobera rostochiensis Kufri Dewa, Kufri Swarna Raj and Gill, 1983 Cowpea M. incognita Barsati Mutant, Iron, New Selectin, G-152, 92-1-B, IC 9642-B, TVU 2439-P Sharma and Sethi, 1976a, Darekar and Patil, 1981 French bean M. incognita Banat, Blue Lake, Stringless, Bountiful Flat, Brown Beauty, Cambridge Countess, Gallaroy, Kenya-3, Pinto W5-114, Seafarer, Suttan’s Masterpiece Singh et al., 1981. Ridgefourd M. incognita Pnipati, Meerut Special Khan et al., 1971b Ashgourd M. incognita Jaipuri, Agra Khan et al., 1971b Pumpkin M. incognita Jaipuri, Dasna Khan et al., 1971b Among four species of Solanum tested for their reaction against M. incognita, S. torvum and S. seaforthianum gave resistant reaction, which was reflected in the reduction in number of galls, egg masses and fecundity of females (Shetty and Reddy, 1985b). Biological methods Singh and Sitaramaiah (1966) applied finely divided oil cakes to root-knot infested soil and noted a reduction in disease incidence in okra and tomato. Amendment of soil with oil cakes of neem, groundnut, mustard and castor was effective in reducing the population of Tylenchorhynchus brassicae around the roots of cabbage and cauliflower (Siddiqi et al., 1976). The above cakes were also effective in reducing parasitic nematode population (Hoplolaimus, Tylenchorhynchus, Meloidogyne and Helicotylenchus species) and in increasing yields of tomato, potato, carrot and turnipt. It has been reported that neem and karanj oil cakes at 2 tons per ha were most effective in reducing Rotylenchulus reniformis infecting French bean. Best results in respect of root-knot reduction due to M. javanica and increase in yield of okra and tomato were obtained by amending the soil with saw dust at 2.5 tons per ha 3 weeks before planting and then applying N through urea at 120 kg per ha (Singh and Sitaramaiah, 1971). Rice hull ash at 2.5 tons per ha increased the yield of tomato by 133 to 317 per cent and reduced root-knot incidence by 46 to 100 per cent (Sen and Dasgupta, 1981). Paecilomyces lilacinus is an effective parasite of Meloidogyne eggs. Egg parasites are more dramatic in reducing the nematode population. Nematode eggs of the group Heteroderidae and those deposited in a gelatinous matrix are more vulnerable to attack by these organisms than are those of migratory parasites. Once in contact with the cysts or egg masses, the fungus grows rapidly and eventually parasitizes all the eggs that are in the early embryonic developmental stages. P. lilacinus was found effective against M. incognita on potato and tomato, G. rostochiensis on potato, R. reniformis on tomato and brinjal (Parvatha Reddy and Khan, 1988, 1989). Application of different oil seed-cakes improved the growth of Japanese mint in field conditions coupled with increased oil yield and reduced root-knot nematode population. However, best results were achieved when the soil was treated with neem cake (Haseeb, 1992). Neem cake was also effective against M. incognita infecting basil (Ocimum basilicum) and increased plant growth and oil content (Haseeb et al., 1988a). Isolation of nematicidal plant products Methanol extracts of Catharanthus roseus, onion, Gloriosa superba scented geranium exhibited nematicidal activity against root-knot nematodes. The active nematicidal compounds identified were citronellol, geraniol. and linalool from scented geranium essential oil; colchicine from Gloriosa superba seeds; serpentine from Catharanthus roseus and amino acids (Methionine) from onion seeds. The feasibility of utilisation of serpentine at 5000 ppm for the management of M. incognita in tomato nursery was ascertained (Leela et al., 1992) Integrated methods Integration of a bioagent- Paecilomyces lilacinus and carboflaran at 2 kg a.i. per ha was found to be effective in the management of reniform nematode Rotylenchulus reniformis on tomato (Parvatha Reddy and Khan, 1988). Inoculation of endomycorrhizae Glomus mosseae or G. fasciculatum in the nursery beds amended with neern cake/castor cake/neern leaf/calotropis leaf helped in reducing the infestation of root- knot and reniform nematodes to the maximum extent. Amendment of botanicals in the nursery beds indirectly help in increased multiplication of these endomycorrhizae providing tomato and egg plant seedlings with high colonisation of mycorrhizae which inturn could protect the crop from these nematodes to the maximum extent in the main field resulting in increased yields. Efficacy of these treatments was always compared with carbofruran 2.0 kg a.i./ha) treatments and these treatments have proved as effective as chemical treatment and in some cases better than chemical treatment. Combinations of deep ploughing (up to 20 cm) and nursery bed treatment with aldicarb at 0.4 g per m2 and main field treatment with aldicarb at 1 kg a.i./ha proved effective in the control of root-knot nematodes in tomato which also registered maximum yield (Jain and Bhatti, 1985). In tomato, application of aldicarb and carbofuran each at 1 kg a.i. per ha in combination with neem cake and urea each at 10 kg N per ha, at transplanting, produced maximum yield with lowest gall index (2.5) and nematode population, 90 days after planting (Routaray and Sahoo, 1985). Zaki & Bhatti (1991) also found that integration of P. lilacinus and castor leaves was effective in increasing the growth of tomato and reducing the infestation by root-knot nematodes. Management of M. incognita and R. reniformis in nursery beds to get healthy seedlings was attempted by integrating soil solarization and oil cake (Mahua cake) incorporation. Integrated control. of plant parasitic nematodes on potato was attempted by the combinations of organic amendments, nematicide and mixed cropping with. mustard (Akthar and Alam, 1991). Integration of P. lilacinus and carbofuran at 2 kg a.i. per ha has proved to be effective in the management of reniform nematode, R. renifonnis on brinjal (Parvatha Reddy and Khan, 1989). Inoculation of endomycorrhizae - Glomus mosseael G. jasciculation in the nursery beds and subsequent application of 5% aqueous extracts of neem cake/castor cake/neem leaf/calotropis leaf in the nursery beds resulted in the effective management of root-knot and reniform nematodes in the nursery beds and yielded healthy brinjal seedlings which could withstand the attack of these nematodes after transplanting in the mainfield (Rao et al., 1993). Application of extracts of neem cake/neem leaf with spores of P. lilacinus/V. chlamydosporium in the nursery beds and subsequent root-dip treatment in the above botanicals with the spores of bio-agents protected brinjal in the main field from the attack of root-knot and reniform nematodes. All these treatments significantly increased the yield under field conditions (Rao et al., 1993a). An integrated management of root-knot nematodes, M. incognita infecting okra using neem or karanj oil cake at 0.5 ton per ha along with carbofuran at 1 kg a.i. per ha was achieved. The above treatments gave maximum reduction in root galling with consequent increase in okra fruit yields (Parvatha Reddy and Khan, 1991). Conclusion The nature and magnitude of important diseases of vegetable crops caused by nematodes and their management has been reviewed. Information on historical highlights, economic importance and histopathological aspects has been provided. The role of nematodes in inducing complex plant diseases in association with other pathogens such as fungi, bacteria and viruses has been emphasized. Management of nematode diseases by host resistance and by suppression of nematode populations through physical, cultural, chemical, biological and integrated methods has been thoroughly discussed. The aspects which needs emphasis in future are as follows: Intensive and systematic surveys of vegetable crops should be conducted with the dual objectives of determining the incidence, prevalence and severity of such diseases and the geographical distribution of the nematode involved. This would go a long way in developing an advisory diagnostic service for the farmers. Adequate emphasis should be given to studies on the biology and host-parasite relationship of major nematode pests which may lead to formulation of control methods on sound basis. Studies have to be carried out on biotypes and on intraspecific variation in nematodes already known to be of economic importance in horticultural production in India. Techniques for precise determination of damage thresholds of populations and assessment of crop losses have to be standardised. Work on disease complexes involving nematodes be intensified with adequate collabortion between nematologists and plant pathologists. Research on the use of cultural methods such as deep summer ploughings, use of plastics, intercropping and crop rotations should be intensified. The chemical control measures should be effective and also economical. The use of chemicals should therefore, be explored with a view to get a reasonable cost-benefit ratio. There is a great need to develop varieties, which are resistant or tolerant to nematodes. Varietal screening and subsequent breeding programmes should be intensified. Fundamental investigations in relation to biochemical and physiological basis of resistance may also be taken up. Attempts should also be directed towards biological control. Paecilomyces lilacinus, Verticillium chlamydosporium, Trichoderma harzianum, Pasteurea penetrans and VAM fungi have been identified all over the world as potential biocontrol agents against plant nematodes. The possibility of using these bacteria and fungi as biocontrol agents against nematodes infecting vegetable crops should be explored. Development of integrated nematode management strategies for vegetable crops should be taken up. Research on the use of cultural methods such as deep summer ploughings and minimal use of nematicides by nursery bed treatments, seed treatments, seedlings bare-root dip treatments should be evaluated. References Ahuja, S. 1983. Comparative efficacy of some nematicides against root-knot nematode, Meloidogyne incognita in tomato, okra, brinjal and cauliflower. Third Nematological Symposium. Himachal Pradesh Agricultural University, Solan, p. 43. Akhtar, M. and Alam, M.M. 1991. 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Nematologica, 36 : 114-122. Content Contributed by : Vikas Bamel, Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi – 110 012