Current Options for Managing Nematodes Pest of Crops in India

Dr. M. R. Khan
Department of Agricultural Entomology
Bidhan Chandra Krishi Viswavidyalaya,
Kalyani, Nadia-741235, West Bengal, India
Email: mrkhanbckv@rediffmail.com

Introduction
Plant parasitic nematode, the hidden enemy of crops is one of the many groups of harmful organism which depend on plants for their survival. Nematode can cause damage to almost all kinds of crops, however, due to their subterranean habit, microscopic size (from 0.3 to 10 mm length), they are invisible to the naked eye. They penetrate and feed on the root of growing plants, stealing nutrients vital for plant growth and exposing the roots to attack by other soil pathogens. It has widely been recognized that plant parasitic nematodes constitute one of the most devastating pests groups and are responsible for insidious disease symptoms in different crops causing huge losses. Estimated annual yield losses in the world’s major crops due to plant parasitic nematodes is about 12.3% and it is about 14% in the developing countries (Sasser & Freckman, 1987). In India, recent estimate showed nematode is responsible for both quantitatively and qualitatively yield losses amounting about Rs.240 billion every year (Sehgal & Gaur 1999). Beside direct damage, plant parasitic nematodes serve as predisposing agents in development of disease complexes with fungi, bacteria and viruses. In many situations, plant varieties resistant to fungi, bacteria are rendered susceptible when parasitized by nematodes. There is no doubt that nematodes either alone or in combination with other pathogens constitute an important constraint to world food production. Intensive and extensive cultivation of crops particularly in irrigated crop production system has seriously aggravated nematode problems in various crops. The hidden nature of nematode causing damage out of sight of farmers, scientists and non specific disease symptoms in the above ground parts of the crops are perhaps main reasons why so little attention has been given to the hidden pest of crops.
Management of plant parasitic nematodes with the use high doses of DD, EDB, DBCP etc. had been found promising, though did not receive much popularity. Moreover, all the effective chemicals have been withdrawn from world market due to their harmful effects on environment. Subsequently, efforts have been made to search for newer chemicals among the group of non-fumigants but failed to achieve the effective control as that of fumigants. In fact, nematodes are comparatively hardy animals require high doses of insecticide having nematicidal property. The growers are still dependent on the limited number of insecticides only because of non-availability of true and effective nematicides. With the increasing concern on environment, various alternative pest control methods like cultural, physical and biological control methods and botanicals are being tried to reduce the nematode damage of crops. However, judicious use of chemical nematicides could be applied for protection of many crops. Integration of various available practices is one of the current approaches for managing pest problems of crops. Cultural practices are known from time immemorial as a multiple pest control strategy. Biopesticides of botanical origin have also been proved as effective alternative of nematicides (Mishra, 2002).
Therefore, current options for nematode management are cultural practices, physical methods, biointensive nematode suppression, botanicals and sensible use of chemical nematicides.
Given the importance of nematodes in integrated pest management system for low-input technologies, namely pesticides. Summer plowing, soil solarization, organic fertilizers, crop rotation, to match the dates of sowing, growing resistant varieties, irrigation management, optimum fertilization, hot water, the clean cultivation, cover crops, inter / mixed cropping, judicious use of pesticides integration of two or more of the above methods (Gaur
Nature of nematode problems
Plant parasitic nematodes can be detrimental to crop growth and development depending on population density and host susceptibility. Generally, they feed on the host tissues with the help of their protrusible stylet causing plants injury and due to feeding and secretion modify the host tissue into specialized nutritive cells as multinucleate giant cell, syncytium or nurse cells for ensuring permanent feeding. Some other nematodes induce gall formation on plant’s root, leaf and seed. While feeding on plant tissues, develop lesion as a result of cell death and subsequent discolourations. Infected plants are easily attacked by various soil pathogens like bacteria, fungi and develop a disease complex/ diseases syndrome. The etiology of those diseases caused by the organisms involved is difficult to determine. Several nematodes serve as vector of plant viruses. Thus nematode functions as plant pathogen, predisposing agent and vector of plant viruses. Plant parasitic nematodes are known to interfere the activity of beneficial nitrogen fixing Rhizobium bacteria in leguminous crops.
In this review, only economically important plant parasitic nematode problems of crops in India and their management options are briefly discussed:
1. Root knot nematodes (Meloidogyne spp.)
Root-knot nematodes (Meloidogyne spp.) are global menace to crop production (Sasser, 1980). It has a very wide distribution and causes serious damage to crops particularly in vegetables. The average yield losses in the world are believed to be about 5% and could be more in the developing countries of tropic and sub-tropic (Taylor & Sasser, 1978). Considering the universal significance of root-knot nematodes, an International Meloidogyne Project (IMP) was operated (1975-1984) with its head quarter at North Carolina State University, USA and its collaborating centres were in many developing countries of the tropics and subtropics. Worldwide more than 97 known species of root-knot nematode have been recorded and only 14 known species of Meloidogyne are recorded in India. Four species of root knot nematodes viz. Meloidogyne indica, M. lucknowica, M. triticooryzae and M. piperi have been described from India. Various insect-pests, diseases and weeds are inflicting damages to vegetable crops. Root-knot nematodes (Meloidogyne spp.) are one of the potential constraints for cultivation of vegetables particularly in the developing countries of tropics and subtropics. Vegetable crops harbour large number of plant parasitic nematodes but root-knot nematode is most damaging one. It affects the crop directly and indirectly by interaction with various soil borne fungi, bacteria and viruses. The most predominant species of root-knot nematodes are Meloidogyne incognita, M. javanica, M. arenaria and M. hapla. All the species of root-knot nematodes produce a characteristic ‘root gall ’or‘knotted root symptom, which could be easily recognized by naked eye. There is hardly any vegetable crop which is not attacked by the root-knot nematodes. Therefore, it has widely been considered as a limiting factor for cultivation of vegetables. The lack of awareness among the farmers about the nematode problems and non-availability of suitable package of practices to extension workers for managing the root knot nematodes are the major hindrance for protecting the vegetable crops from root-knot nematodes. Chemical approach of nematode management is no doubt effective but high doses of nematicides required for managing nematodes are neither economical nor environmentally safe.
The infection of root-knot nematode produces characteristic disease symptoms on the below ground root system popularly known as ‘root gall’ or ‘knotted roots’. Different sizes of galls are induced depending on their host and the species of the nematode involved. On cucurbits, the nematode induces large galls, whereas in chilli small size of galls is produced. Usually the infection of M. hapla produces small galls as compared to M. incognita and M. javanica. The size of galls also differs with the level of infection as in case of heavy infection large size or multiple galls or secondary galls develops. Besides galling, forking of taproot in carrot and tubercle on potato tubers are also noticed. Above ground symptoms are non-specific in nature. Infected plants exhibit symptoms of general mineral deficiency, yellowing, stunting, wilting during hotter part of the day, chlorosis, premature shedding of leaves and poor look of plants resulting in low yield. The nematodes are also involved in interaction with other soil borne fungi, bacteria, and viruses and cause serious damage to crops. The interaction of root-knot nematodes is known in many vegetables, fibre, pulses and plantation crops. However, the most common problem is the breakdown of disease resistance and wilting of healthy plants. The most common interaction of root knot nematode with Ralstonia (=Pseudomonas) solanacearum is causing “Pseudomonas wilt” in tomato, brinjal and potato.
Nematode management options
Root-knot nematodes are polyphagous in nature, having high reproductive potential, and have acquired unique mechanism of survival strategy through laying their eggs in protective gelatinous matrix. Management of root-knot nematode is not easy task under intensive crop cultivation system. Therefore, the idea of keeping the nematode population below the economic damage level by adopting different available tactics is advised to the growers. The young tender seedlings of various crops are very much vulnerable to attack by nematode while the older plants achieve some degree of tolerance. Considering the farmer’s suitability, following hygienic cultivation practices of vegetable crops could be suggested for managing root-knot nematodes:
Cultural practices
Cultural practices are the most effective and economical means of managing insect-pests and disease including nematode problems.
? Two to three summer ploughings (20 cm deep) during the months of May – June at the interval of 15 days expose nematodes, weeds, disease propagules and hibernating stages of insect-pests before the sun and cause their death.

? Inter-cropping with antagonistic plants like marigold (Tagetes spp.) reduces soil population of many soil nematodes including root-knot nematodes. Incorporation of such crop in cropping system either as inter-crop or alternative crop should be considered whenever feasible.

? Crop rotation with resistant varieties or non-host crops like mustard, sesame, maize, wheat etc. are useful to bring down the soil population of nematodes below the damage threshold level.

? Application of organic manure, Farm Yard Manures (FYM) at 18 to 20 t/ha reduces nematode population through their action of released toxic substances, enhanced crop tolerance and encouraging soil microbial antagonists

Resistant varieties
Plant resistance plays an important role in integrated management of root-knot nematodes diseases, however, availability of resistant varieties of vegetable crops are very few in number and many of them are not acceptable to the farmers for their suitability.
Some of the resistance varieties exhibited resistance or tolerance reaction to root-knot nematodes are as given below:
Tomato: SL-120, Hisar Lalit, PNR-7, Hisar N-1, Hisar N-2, Hisar N-3, NT-3, NT-8 NT-12, Ronita, Patriot, PAU-5, Mangla and Karnataka Hybrids.
Chilli: Pusa Jawala, CAP-63, CA-2057, Sindhuri, NP-46 A, Mohini, SP-26, P-6-3, K-235
Brinjal: Giant of Banaras, Black beauty, Gola, Gachha Baigan, Pbr-91-2, IC-95-13, HOE-101, Red Wonder.
Cowpea: Barasati mutant, 82-IB, C-152, IHR-29-5, GAU-1
Pea: B-58, C-50
Potato : Kufri Dewa
Okra: Kanki local green, Harichickni,Vaishali Badher
Pumpkin: Dasna, Jaipuri
Water melon: Shahjanpuri
Ridge gourd: Panipati, Meerut special(modified after Anon. 1988)
Chemical control
Chemical control with the application of nematicides is the most effective means of nematode management. However, most of the effective nematicides have been withdrawn from the world market. At present, a few insecticides having nematicidal property are available to the farmers but because of their high doses required to manage nematode, it becomes cost- ineffective and leaves high pesticide residues to the harvested crops. Despite their inherent drawbacks, chemical nematicides could be applied judiciously so that the doses and cost are reduced drastically. The application of nematicides through bare-root dip treatment, seed treatment and nursery bed treatment has been proved to be effective to protect the young seedlings from nematode attack.
Nursery bed treatment
In most of the cases, the infection is carried through infested seedlings from nursery bed. The damage caused by root-knot nematode to the root system of tender seedlings is more harmful than to older plants. The application of nematicides to nursery bed helps to raise nematode free seedlings. Moreover, it reduces the dose of nematicides and cost substantially. The soil application of carbofuran (Furadan 3G) at 0.3 gm a.i./m2 is sufficient for producing nematode free seedlings of many transplanted vegetables crops. The treatment of nursery bed with sebuphos (Rugby 20 WP) or carbofuran (Furadan 3G) or benfurocarb (Oncol 50 WP) at 0.3 or 0.6 g a.i./m2 at the time of sowing reduced root-knot nematode and in seed yield of tomato by 25-62%.
Bare-root dip treatment
Many vegetable crops, such as seedling transplants can dip Oxamyl, prophos systemic nematicide, and dimethoate 5006 hours to 1000 ppm to denematize roots. These practices will further ensure that the early worm attacks against the tender seedling roots. Like vegetables, transplant seedlings of brinjal, tomatoes, peppers and planting materials, pointed out that the hoist handle 500 parts per million 6 hours, providing an effective control of root-knot nematodes and carbosulfan (Marshal 25 EC). Nursery beds and treatment of carbofuran with the seedlings 500pm and carbosulfan 25 EC deep-added before transplanting the effective management of root-knot nematode, increase vegetable crop yield 0.3 grams ai/m2.
Bare root dip treatment of tomato and brinjal seedlings with Zolone (Phosalone 35 EC) or monocrotophos (Monocil 36 SL) or carbosulfan (Marshal 25 ST or DS) at 0.05% reduces root-knot nematode and increase the yield.
Seed treatment
The practice of seed-soaking and seed-dressing are important prophylactic measures which give adequate initial protection to the young seedlings of tomato, brinjal, okra, chilli, etc. The most commonly used systemic nematicides viz. fenamiphos, isofenphos, carbosulfan etc. are used at 2-3% w/w.
Seed dressing with carbosulfan (Marshal 25 ST) at 3% w/w is quite effective for managing root knot nematode in okra, bottle gourd, pointed gourd, bitter gourd and jute. Seed soaking with dimethoate, carbosulfan (Marshal 25 EC) can also be adopted for providing better crop with early protection against nematode.
Field application
Field application of carbofuran 3G at 2Kg a.i./ha in tomato, brinjal and okra reduces nematode population and increases yields.
Biological control
Despite its several limitations, biological control of root knot nematode is cost effective and eco-friendly method. As a component of integrated nematode management, biological suppression of root-knot nematode is well documented. Several bioagents have been exploited against this but so far only three bioagents viz. Paecilomyces lilacinus (Khan & Goswami, 2002), Psuedomonas fluorescens and Pasteuria penetrans have widely been recognized as effective and promising bioagents. Some formulations of P. lilacinus (Bionematon, Yorker) and Pasteuria penetrans (Pasutsuria 50 WP), Trichoderma viride and T. harzianum(Trichostar, Tricho guard, Bioderma, Ecoderma etc)?are available in the market for checking root knot nematodes.
Integrated Approach for root-knot nematode management
Individual method of nematode control has either proved ineffective or uneconomical approach against root knot nematodes. Therefore integration of various suitable tactics may be an ecofriendly, economically viable and practically feasible approach for managing nematode problems in crops. The adoption of deep summer ploughing during summer period at fortnightly interval along with organic matter application followed by planting with nematode free seedlings is a feasible approach to reduce nematode population. Similarly, farmers with their available resources could follow integration of cultural, biological, chemical methods and resistant varieties in suitable combination for each crop cultivation system. Soil solarization/summer ploughing alone as well as in combination with carbofuran 3 G at 2 Kg a.i./ha has been found effective against nematodes infesting brinjal, chilli and tomato. Seedlings raised in solarized nursery beds treated with carbofuran at 0.3g a.i/m2 integrated with application of neem cake at 5q/ha gives better check against nematodes infesting vegetables and increases yield.
2. Wheat seed gall nematode (Anguina tritici)
This nematode is one of the most serious pests of wheat in the country. It is the oldest known plant parasitic nematode and the nematode alone causes ‘ear cockle’ disease in wheat and in association with the bacterium, Clavibactor tritici produces ‘yellow ear rot’ or ‘tundu’ disease. The host range of this nematode is very few in number and wheat is considered as the most suitable host. Although the control of this nematode is simple and easy as compared to other plant parasitic nematodes, it is still troublesome in many wheat growing parts of Rajasthan, UP, Bihar and Madhya Pradesh particularly in tribal belts where tons of wheat grains are wasted every year (Anon, 1995-2001). Wheat galls are the primary source of dissemination for nematode either as seed mixture of cockle. The juveniles of A. tritici remain viable in anhydrobiotic state inside the cockle for several years. After sowing the galls/cockles come in contact with soil moisture and become soft leading to release of large number of second stage juveniles. These juveniles infect the growing point of seedlings as ectoparasite and are carried to inflorescence due to the natural growth of seedling. The nematode enters the floral primordia and become endoparasite and eventually the floral primordial converted into seed galls.
The initial visible symptom is enlargement of basal stems near the soil surface at the stage of 20 to 25 day-old seedlings. Generally the infested plant exhibits more number of tillers and grows fast as compared to healthy ones. Twisting, curling, crinkling of leaves and stunted growth are common symptoms in the early stage of plants growth the affected ears are typically swollen, broader with or a few awns on the glumes. The cockled ears contain initially green galls later in each spike-let 1 to 5 galls can be seen.
Yellow ear rot or tundu disease
The early stage of plant exhibits similar disease symptoms as that of ear cockle disease. The yellow ear rot disease is primarily caused by a bacterium, Clavibactor tritici only in the presence of nematode, A. tritici. Under humid climatic conditions, the characteristic symptoms are appeared with a production of bright yellowish bacterial slime on the leaf surface which can be seen trickling down the ears. During dry weather, these slimes become hard, diseased spikes are generally distorted, stunted and narrower than healthy ones with the grains partially or completely converted by bacterial mass.
Management options
The nematode is easy to manage as because the gall is the only source of ear-cockle and tundu disease. Both physical and mechanical methods are successful for eradicating this nematode from several developed countries of the world, however, in India this nematode is still becoming problems probably due to poor awareness and failure of national campaign against the dreadful disease of wheat.
Physical methods
? Hot water treatment of wheat seed-lots at 54 to 56 0 C for 10 to 20 minutes.
? Water floatation of seed galls in 5-10% salt solution for 5 to 15 minutes. Seeds containing nematode gall will float in water surface and can be collected and discarded.
Mechanical methods
Fanning or winnowing is an effective method to remove the galls from seed lots. Sieving/ screening is a common practice and most successful method for eradication of seed gall nematode from many countries, though complete removal of gall is not possible with this methods because some large sized galls are retained on the sieves.
3. Cereal cyst nematode (Heterodera avenae)
Heterodera avenae is the causal organism of a serious disease popularly known as ‘molya’ disease of wheat and barley. This disease was first time recorded from Rajasthan in India and subsequently it is known to occur in major wheat growing states viz. Punjab, Haryana, Uttar Pradesh, Delhi, Himachal Pradesh and Madhya Pradesh of India (Kaushal et al., 2001).The nematode is mainly confined to the family gramminae.
The nematode infested fields exhibit patchy growth with stunted and yellowish plant. Infested plants shows thin narrow leaves, reduced tillering, fewer leaves and small size of ear heads with reduced number of grains. The roots of nematode attacked plants appear bushy, bunchy due to emergence of root lets at the site of infection and slight swelling of root tips may be encountered. The above ground symptoms are often confused with the general deficiency symptoms. However, presence of cysts is the only confirmatory evidence for nematode infection.
The second stage juveniles infect the growing tips of roots and upon feeding develop specialized syncytial cells for their growth and development. After three months, the juveniles achieve lemon-shaped sedentary female which is found to attack with roots. Eggs are laid inside the female body and after death of female, the body cuticle transform into brown cyst. During off-season, nematode survives in cysts.
Management options
Cultural practices
? Crop rotation with non-hosts like sarson, toria, raya, taramira, gram, berseem, carrot, coriander etc. with wheat.
? Deep summer ploughing (2-3) at an interval of 10-15 days during hot summer months
? Growing wheat cultivar C-306 as trap crop early in October
? Growing Resistant varieties: Barley cultivar like Rajkiran, C-164, BH-72.
Chemical control
Field application of Carbofuran (FRADAN 3G) at 2kg a.i./ha have been found effective (Kaushal et al., 2001).
Integrated management
Integration of different tactics was found economical against cereal cyst nematode. Early sowing in the month of November along with field application of carbofuran at 2kga.i./ha is quite effective in increasing yield and reduction of cyst population in soil.
4. Potato cyst nematode (Globodera rostochiensis, G. pallida)
It is one of the serious nematode pests of potato in some southern states like Tamil Nadu, Karnataka, and Kerala. The nematode is popularly known as ‘golden nematode’ and has been recognized as one of the major crop protection problems of the world. The nematodes are responsible for average losses of 9% of global potato amounting to about 40 million tons (Krishna Prasad, 1995). In India, potato cyst nematode is known since 1961 when F.G. Jones detected this nematode from a field at Vijayanagaram state farm in Ootacmund of Nilgiri Hills in Tamil Nadu. Considering importance of potato cyst nematode in the country, the Government of Tamil Nadu imposed the Destructive Insect Pest Act 1919(DIP Act 1919) in 1971 to contain the nematode in the Nilgiri Hills.
It is difficult to detect the disease symptoms at low infestation of nematode but the symptoms are prominent only after the build up of population in soil. The disease symptoms appears in small patches of poorly growing plants, temporary wilt of plants in day time, stunted plants, unhealthy yellowish foliage and poor root systems, reduction of number and size of tubers and production of potato yield gradually reduced over the years. The nematode is primarily confined to the family solanaceae and depends on the host root diffusates which induce the hatching of second stage juveniles from eggs. The second stage juveniles infect the root and modify the cells as giant cell for ensuring permanent nourishment to reach adult stage. The adult females are white spherical shape which is found attached with root and after death of female turn into brown cyst. All the eggs laid by the females are retained inside the body. This cyst containing eggs are protected and remain viable for several years in soil even in the absence of potato. The pathotypes RO1 and RO5 of G. rostochiensis and Pa2 and Pa3 of G. pallida of potato cyst nematodes are known to be prevalent in India.
The nematode cyst containing eggs are generally spread through soil particles adhering to tubers, farm implements, gunny bags, farmers’ feet etc. However, irrigation water or rain water running down the hill slope carry the cyst from the infested field to uninfested fields.
Management options
Cultural practices
? Growing non-host solanaceous vegetable crops like cabbage, cauliflower, beet root, carrots, garlic, radish, turnip etc. One of the most useful rotation as potato-cabbage-carrot is commonly practised by the farmers of Nilgiri Hills.
? Resistant Varieties : Kufri Swarna
Chemical control:
Use of carbofuran (FURDAN 3G) at 2kga.i./ha is effective to reduce nematode population as well as increasing potato yield.
Key nematode pests of rice in India
i) Rice root knot nematode, Meloidogyne graminicola
ii) Rice root nematode, Hirschmanniella spp.
iii) Rice stem nematode, Ditylenchus angustus
iv) White tip nematode, Aphelenchoides besseyi
v) Rice cyst nematode, Heterodera oryzicola

5. Rice root knot nematode (Meloidogyne graminicola)
Rice root knot nematode, Meloidogyne graminicola is a well established nematode pest of rainfed upland rice. It poses serious problems in boro and kahrif nursery particularly in sandy loam or recent alluvial soils of West Bengal. It is also becoming problem in transplanted rice grown in waterlogged conditions. The widespread occurrence of M. graminicola has been found in Assam, West Bengal, Gujarat, Orissa, Karnataka and Tripura.
The above ground symptoms are nonspecific in nature as yellowing, stunting of foliage, delayed flowering by 10 to 15 days and reduced number of tillers. The presence of characteristic ‘hook shaped’ or ‘ring-like’ root gall on the root tip of growing rice seedlings is the confirmatory evidence for the association of this nematode. Galls produced by the nematode induce growth of lateral root lets and root hairs. The yield losses due to M. graminicola has been estimated to be between 16 to 32 % in upland rice and in severe cases go up to 64 %( Phukan, 1995). A complete failure of boro rice nursery in ‘simurali’ in the district of Nadia, West Bengal has been noticed (Anon, 2001)
After harvesting of rice, the nematode may survive in egg stage in soil or continue to reproduce on various weeds. Female often remains concealed within root tissue and eggs are laid in cortical tissues and hatched juveniles reinfect the same roots. It completes life cycle within 19 days at 22 to 29 0C in upland rice.
Management options:
Cultural practices
i.Scheduling crop rotation with non-host crops as cauliflowers, sesame, groundnut, onion, maize, soybean, cowpea
ii. Weeding: Rice fields supports a diverse kind of weeds like Echinochloa spp., Eleucine indica, Paspalam scrobiculatum, Cyperus spp. etc.
iii. Resistant varieties: CR-143-2-2, CR-147-2-1, CR-1009, CT-428, Sudha, Murti
Chemical approaches
i.?Seed soaking with carbosulfan (Marshal 25 EC) at500ppm or Carbosulfone at 0.1% for 12hrs
ii.Bare dipping in carbosulfan (Marshal 25 EC) at 500ppm for 20 minutes
iii.?Nursery bed treatment with carbofuran (Furadan 3G) at 1kga.i./ha and similar dose of nematicides at 7 and 50 days after transplanting
6. Rice root nematode (Hirschmanniella spp.)
Rice root nematode is a migratory endoparasite of roots and occurs predominantly in moist habitat. Rice root nematode, Hirschmanniella spp. are unique migratory endoparasites of rice and cause yield losses to the extent of 19% in rice in West Bengal (Ahmad et al., 1984). Hirschmanniella oryzae and H. mucronata are two economically species in rice and occurrence of H. gracilis is doubtful in India (per. Comm. Dr. M. R. Siddiqi). The juveniles and adult stages penetrate through entire length of roots and feed on cortical cells leading to the formation of channels or cavities in the roots. Its feeding sometimes extends to central vascular regions. The infected roots exhibit water-soaked brown lesion which are of mostly spindle shaped. The physiological function of infected plants is disrupted and plants growth reduced. The above ground symptoms are non-specific as stunted growth, leaf chlorosis, reduced tillering and delayed flowering.
The population of Hirschmanniella species was found maximum during active growth phages of rice. The population build up of this nematode increases after transplanting up to 80 days of rice(Singh & Jain,1995) and declines when roots of rice starts degenerating.
Rice root nematode survives better in poorly drained clay and heavy soils. It can survive even at high temperatures in May-June (35-45 0 C), and low temperature in December-January (8-12 0 C) conditions in North India (Mathur
Management options
Direct seeding of rice has been found to be more vulnerable to attack by this nematode compared to transplanted crop (Singh & Jain, 1995).
Cultural practices
i. Early planting of rice in the month of June or middle of July
ii.Use of organic amendments such as mustard cake or neem cake at 220-240 kg/ ha
iii.?Balanced NPK fertilization
iv.?Crop rotation with wheat, linseed, potato, cauliflower, mustard and gram in rabi season
v.?Deep dry summer ploughings
vi.Weeding during standing rice and in absence of the crop
vii.?Growing resistant varieties/cultivars: TKM-9, CR-142-3-2, CR-52, N-136, W-136
viii.?Sesbania rostrata can be used as trap crop for H. oryzae
Chemical approaches
i.?Nursery bed treatment with carbofuran 3G or phorate 10 G at1.0 kg a.i. /ha followed by I.0 kg/ ha at 7 and 50 days after transplanting
ii.?Bare root dip treatment with chlorpyriphos/ carbosulfan 25 EC / monocrotophos 36 EC at 1000-2000ppm for 20 to 30 minutes
iii.?Seed soaking with carbosulfan 25 EC or isofenphos at 0.2% for 6 hours.
7. Rice stem nematode (Ditylenchus angustus)
Rice stem nematode is usually problematic in rice grown in deep water situations. The vernacular name ‘stem nematode’ is derived from the stem inhabiting nature of the nematode. It is an obligate parasite and serious pest of rice causing popular disease symptom referred to as ‘Ufra disease’. In Bangladesh and some areas of India, 100 % yield loss has been recorded due to severe attack of D. angustus. The nematode has been found prevalent in Malda, Murshidabad, Hooghly, 24-Parganas, Jalpaiguri, Coochbehar and West Dinajpur districts of West Bengal and Sibsagar, Jorhat, Morrigaon, Sonitpur, Borbeta and Dhubri in Assam (Phukan, 1995)
The symptom produced by rice stem nematode is popularly known as Ufra or dakpora disease. The Ufra symptoms appear in patches and subsequently spread to the entire field. The nematode attack at vegetative stage results in yellowing or whitish pattern on the leaf sheath and margin becomes corrugated. In due course of time, the splash pattern turns brownish stains and stem and inter node become black. Twisting of leaf and leaf sheath are commonly found symptoms. Sometimes infested nodes give bushy appearance due to branching. The Ufra symptoms may be grouped as:
Swollen or Thor Ufra: Panicle does not come out, it remains enclosed within the leaf sheath and infected portion tending to branch.
Pucca or Ripe Ufra : Panicle emerges partially and panicle bears filled grains at tip only.
The primary sources of infection D. angustus are rice stubbles, straw, wild rice and weeds found in rice fields. The nematode can overwinter through quiescent state (fourth stage juvenile) which remains viable up to 15 months. They live in coiled anhydrobiotic state in grains (Prasad & Varaprasad, 2001); dried plants parts left in the fields and reinfect the crop in the next season.
Management options:
Cultural approaches
i.?Destruction of rice stubbles, weeds and wild rice in the rice fields
ii.?Crop rotation with jute, sesame, mustard with rice
iii.Summer ploughing helps nematode to destroy by desiccation in the scorching heat of sun
iv. Growing early (Padmapani) or resistant (Rayada selection) varieties (Prasad et al., 2001)
Chemical approaches
i.?Spraying with diazinon at 0.01%
ii. Soil application of carbofuran 3G or phorate 10G at 1 kg a.i. /ha at transplanting
8. White tip nematodes (Aphelenchoides besseyi)
A. besseyi is a specialized parasite attacking aerial parts of its natural host, rice. Though rice is the most suitable host of this nematode, it can infect tuberose, onion, soybean, sugarcane, oat, millets, orchids etc. The most characteristic disease symptom is ‘white tip’ in rice leaf produced by this nematode due to which the common name of the nematode is ‘white tip nematode’. It has been recorded in serious form in rice from Gujarat, Tamil Nadu, Madhya Pradesh, Andhra Pradesh and West Bengal. In West Bengal, the nematode is becoming problem in the rice fields adjacent to tuberose fields in different tuberose growing areas of state (Khan, 2001). The nematode is prevalent through out the state of West Bengal (Das?& Khan, 2007).
It is easy to detect the presence of nematode within the rice seeds. In field, the initial appearance of symptoms as the leaf tip up to 5cm becomes pale yellow or whitish at tillering stage and subsequently leaves get dry. These symptoms are found for a short period in the plant. The tip of the flag leaf are often twisted which may obstruct the emergence of panicles. Infested panicles are shorter and lighter in weight as compared to healthy panicles.
A. besseyi survives as pre-adults as well as in adult stages (quiescent state) beneath the hull of rice kernel and does not survive in soil after harvesting rice plants. Infected seeds or presence of other alternative hosts help nematode to survive up to next crop. They usually remain in coiled anhydrobiotic state in rice between lemma and palea up to 3 years. The infected rice seed is the only means for rapid spread of A. besseyi. It also spread through irrigation water or flood water. Female lays eggs on rice plants. All the developmental stages occur on rice plant. The life cycle of A. besseyi is completed within two weeks and, therefore, several generations are completed within a cropping season.
Management options
Prophylactic measures
i.Healthy rice seed checks the spread of white tip disease of rice
ii.?Rice stubbles to be burnt or destroyed after harvesting
iii. Simple spreading the rice seed on the concrete floor on bright sunny days at least 4 hours for 6 consecutive days kills nematodes inside the grain
iv.Seed-soaking in water(1:2 ratio) for overnight followed by adding two volume of boiling water for 10 minutes and then drying of seeds in shade
v.Seed treatment with carbosulfan 25EC at 0.1% for 12 hours.
9. Rice cyst nematode (Heterodera oryzicola)
Heterodera oryzicola has been reported as a serious pest of rice in Kerala. It has also been known to occur in Burdwan and Bankura district of West Bengal (Rao, 1985). This nematode is one of the serious pests of rice and banana in Kerala (Kuriyan, 1995). Its occurrence has been recorded from Karnataka and Goa (Prasad, 2002).
The browning of roots and chlorosis of leaves, retardation in growth, early flowering of plants by 10 to 15 days and partial filling of grains are the typical symptoms of infection of H. oryzicola. No gall developed on rice roots. The presence of brown cyst on rice root is the confirmatory evidence of this nematode infestation. One life cycle is completed in 30 days and 12 generations may occur in a year. Yield losses could be to the extent of 38% due to the attack of nematode (Rao, 1978). The nematode spread through infested seedlings, irrigation water or farm implements.
Management options
i.?Soaking of seeds with phenamiphos at 0.02% for 6 hours
ii.?Soil application of carbofuran or phorate 1kg a.i. /ha at 7 and 50 DAT
iii.?Growing resistant varieties like Lalnakanda, CR143-2-2
iv.Regulatory measures on the movement of banana rhizomes as well as rice seedlings from infested areas have to be adopted.

10. Burring nematode (Radopholus similis)
This nematode is internationally quarantined pest and is capable of parasitizing many fruits, spices and plantation crops. It is known to cause a serious disease of black pepper popularly referred to as ‘pepper yellows’ in Indonesia and ‘slow wilt’ in India and ‘spreading decline’ in Florida. Many economically important crops like banana, citrus, betelvine, coconut, arecanut black pepper, ginger etc. are seriously affected by the nematode. The nematode is mainly problem in Southern states like Kerala, Karnataka, Andhra Pradesh (Parvatha Reddy & Singh,1980). Recently, it has got spread to the state like Orissa, Manipur, Maharastra, Madhya Pradesh and Himachal Pradesh and Gujarat possibly through indiscriminate movement of planting materials of banana, ginger and turmeric rhizomes.
Nematode infested banana plants exhibits ‘toppling disease’ at bearing stage, premature defoliation, poor plant vigour and finally reduction of bunch size and weight. In root, lesion develops on root and subsequent rotting and decaying of tender roots due to the involvement of other soil microorganisms. The coconut plants attacked by R. similis show general decline symptoms like yellowing, stunting and smalling of leaves and button shedding resulted in low yield. In black pepper, slow growth of vines, yellowing of leaves, rapid panicle declines followed by severe die-back and death of vines are common symptoms. The roots of coffee, arecanut, betelvine are seriously attacked and develop characteristic lesions and root decay and rotting. The nematode is a migratory endoparasite of root and feed on the succulent tissues of feeder roots. Due to their intracellular movement, the nematode destroys the cells and forms burrows or cavity inside the root. All the developmental stages are capable of feeding roots. Eggs are laid in root tissues and newly hatched juveniles start feeding and develop inside roots. Therefore, the entire life cycle may be completed within the roots. The total life cycle is completed in 20-25 days. In India, only the banana race of R. similis is prevalent.
Management options
The nematode is difficult to manage due to its endoparasitic nature and wide host range.
Preventive measures
? Planting material/seedlings should be free from nematode
? Any occurrence of discolouration on the rhizome should be removed and treated with Bordeaux mixture or nematicides
? Hot water treatment of rhizomes at 50-55 0C for 20-25 minutes could be done to denematize the planting materials.
? Raising of seedlings of coconut, arecanut, black pepper from nematode free nursery bed
? Before planting, sun drying of banana rhizomes is also effective to reduce nematode population
Curative measures
? Application of carbofuran 6 g a.i. or phorate 3 g a.i./plant 2-3 times in a year is effective to reduce the nematode in coconut and banana.
? Application of neem cake at 400 g/plant once at planting and second dose after 4 months increase bunch weight and the yield of banana
? Avoiding susceptible crops as intercrop
? Intercropping with Crotalaria juncea reduces R. similis population
? Bioagents like P. lilacinus, Glomus fasciculatum, Pasteuria penetrans are promising agents against R. similis
Resistant / Tolerant Varieties:
Banana : Kadali, Pedalimoongil, Kunnan, Pey Kunnan, Pisang Seriby
Arecanut : Resistant: VTL-11x VTL-17( Sundarraju & Koshy, 1988)
Tolerant: Indonesia-6 (VTL-11)
Mahuva-B, Andaman-5 (VTL-29e)
Coconut: Kenthali, Klappawangi, Hybrid Java Giant (JG X Kulasekheram Dwarf Yellow (KDY), KDY X JG, Java Tall X Malayan Yellow dwarf, San ramon X Gangabondan (Sosamma et al.1980)
11. Citrus nematode (Tylenchulus semipenetrans):
Citrus nematode is found in all the citrus growing areas of the country and is widely recognized as economically important pest of citrus. It is one of the causal factors for ‘slow decline’ in citrus’ which is characterized by general reduction of the tree growth, lack of vigour, yellowing of foliage and small size of fruits. The nematode is semi-endoparasite of citrus root. It causes symptoms that are often non-descriptive and difficult to diagnose. The nematode is often unnoticed in the seedlings in nursery which causes widespread distribution. The presence of nematode is best confirmed by microscopic observations of soil and root samples. The female nematodes and their gelatinous matrix containing eggs adhering soil particles and give the roots a dirty appearance which is not easily washed off. The most serious effects of the nematode on the growth and yield of citrus are usually encountered when new seedling are planted on old orchard. This condition is known to as ‘citrus replant problem’. The young tree grows slowly and fruiting is delayed. This condition of infested trees is referred to as ‘slow decline’ which implies general deterioration of citrus trees beginning with production of smaller and fewer fruits. The extent of decline in mature trees is related to their vigour, tolerance to nematode and to the degree of infection.
T. semipenetrans feeds on surface layers of roots causing discolouration and necrosis. A young female penetrate deeper root tissues and establishes a feeding site around the head. The feeding site comprising of 16 cortical cells referred to as ‘nurse cell’. The posterior part of mature female body remains outside and eggs are laid in a gelatinous matrix outside the host tissue. The life cycle of this nematode is completed within 6-8 weeks under optimum temperature at 25 to 31 0C.
Management options:
Prophylactic measures
a.?Nursery raising of seedling should be free from nematode infection
b.?Previously infested citrus orchard should be either avoided or fumigated to kill any nematode population in soil.
c.?Preventing run off water from adjacent infested citrus orchard
d. Use of clean equipment/implements for cultural practices because movement of any adhering soil particles from one place to another in orchard may disseminate the nematode.

It is difficult to eliminate the nematode once it is established in orchard. Therefore, regular monitoring is essential for preventing the nematode to reach above the damage threshold level. Usually the nematode at low population level (500/g of feeding root) are not damaging to the crop but at high population (4000/g root) causes devastating damage to citrus plant (Nickle, 1991).
Curative measures
a.?Application of oilcakes of neem, mahua, groundnut etc. at 1kg/plant can reduce nematode populations.
b.?Combined use of neem cake at 1kg /plant along with carbofuran 3G (Furadan) 1.0 kg a.i./ha is also effective.
c.?Use of biocontrol agent like Paecilomyces lilacinus at 4 g /plant along with carbofuran 3G (Furadan) 1 kg a.i./ha gives good results (Parvatha Reddy et al., 1996).
d.?Use of resistant ‘trifoliate’ citrus stock may be an efficient method to check the nematode.
Cultural practices
Removal of old feeder roots before the start of growth flush followed by application of FYM helps to reduce nematode population in soil.
12. Foliar nematode (Aphelenchoides besseyi) of tuberose
Tuberose is commercially important for loose flower, cut flower and for extraction of essential oils. Its commercial cultivation in West Bengal was started in the second half of 19th century to meet aesthetic need of the English people harboured in Calcutta. At present the total area under tuberose in India is estimated to be about 20,000 ha, out of which 2,110ha is in West Bengal and it is mainly confined in Kolaghat-Panskura, Ranaghat and Haringhata areas. In terms of area and production of tuberose, West Bengal ranked first. Recently, foliar nematode, Aphelenchoides besseyi has been appeared as a serious problem in tuberose in West Bengal. This nematode was first time reported from Hawaii Islands on the leaves of tuberose (Holtzman, 1968). The occurrence of floral malady caused by A. besseyi in tuberose was recorded from Ranaghat areas of Nadia district of West Bengal (Chakraborti & Ghosh, 1993). In India, this nematode is widespread in Eastern and Southern states particularly in rice causing ‘white tip disease’ and estimated to cause yield loss 20 to 30%in rice, though floral disease caused by A. besseyi in tuberose was not encountered any other states except West Bengal. Recently, it has got spread to neighbouring state, Orissa either through movement of bulbs or other means. Recent survey results revealed that A. besseyi is a major limiting factor for cultivation of tuberose in Ranaghat and Haringhata regions of Nadia, Bangaon of 24-Parganas (South) and some pockets of Howrah and Midnapore districts of West Bengal. The high population of A. besseyi was also recorded from fields of Kolaghat-Panskura-II of Midnapore district. The ‘single’ cultivar of tuberose was found to be the most vulnerable to damage caused by A. besseyi as compared to ‘double’ cultivar. Khan et al. (1999, 2001) investigated for severe foliar disease infestation in tuberose and found A. besseyi is the primary causal agent for malformed flowers. The population of A. besseyi causing white tip disease in rice is the same population infecting tuberose and causing floral disease (Khan, 2001). A. besseyi is now recognized as the key nematode pest of tuberose and it was becoming a potential threat for cultivation of tuberose in West Bengal.
The infected flower stalk initially appears rough, stalk become crinkled, stunted and finally distorted and in severe cases flower buds failed to bloom. Brown streaks appear on leaf bracts and petals and subsequently develop rusty brown spots. The severely infected flower stalk becomes rotten and brittle over drying, even get blind. The number of flowers per stalk is also reduced and small crinkled and distorted flowers which are not acceptable in the market. The nematode, A. besseyi remains in masses forming ‘nematode wool’ which could be easily recovered from dark brown spots (Khan & Pal, 2001). The ovary contains large number of nematodes. This nematode is more serious during rainy season generally from July to September and cent percent loss of second year crop particularly in ‘Calcutta single’ cultivar of tuberose was recorded. However, in ‘Calcutta double’ cultivar 30% to 40% flower stalk rendered unsaleable and from individual flower stalk up to 45,000 nematodes were recovered (Khan et al., 2002). In Calcutta single, the nematode could cause 38 to 59% yield loss (Pathak & Khan,2005)
The dissemination of A. besseyi occurs through bulbs collected from infested fields. The nematode survives in coiled anhydrobiotic condition (quiescent pre-adult and adult stages) in the scaly leaves outside the bulbs. The nematode can also survive in the dried scaly leaves, stems and flowers more than 25 months; however, they can not survive in soil for long time (Khan, 2004).
Nematode Management?
a. The planting material (bulbs) should be soaked in neem-seed-kernel-extract (home preparation from locally available neem) for overnight or dipping of bulbs in monocrotophos 36SL at 500ppm for 6 hours.
b. After sprouting of the bulb, three to four sprayings with monocrotophos 36 SL at500ppm at 15 to 20 days interval should be given (Khan et al. 2005).
c.?In the second and third year crop, sprayings with monocrotophos 36 SL at 500ppm at 15 to 20 days interval starting from the month of May onward reduce the nematode infestation.?
d. Clean cultivation of tuberose and any infested parts of plants found in the field should be burnt immediately (Khan, 2006).
13. Reniform nematode (Rotylenchulus reniformis):
The adult female of reniform nematode (Rotylenchulus reniformis) is an obligate, sedentary semi-endoparasite of a wide range of food, fibre, oilseed, oilseed, fruits and plantation crops. The common name ‘reniform’ was derived from the kidney-shaped mature female. It has worldwide distribution and is receiving importance as national pest of crops. At present, there are 10 species of reniform nematode known worldwide but R. reniformis is the most widespread and has economic importance. In West Bengal, R. reniformis has been known to be associated with many vegetable crops, banana, tuberose, tea, pulses, fruits, betelvine etc.
Pairs of non-specific symptoms of damage to crops in the ground, even underground, therefore the need for close observation and to confirm their existence and damaged part in. It breeds in the cortical tissue, phloem and pericycles, the infection may lead to the formation of certain crops, root necrosis. Symptoms appear as the root discoloration, leaves and fruit and seed the formation of abnormal shedding. In addition to causing direct damage to plant roots, in nematodes and other pathogens such as Fusarium concert. , Verticillium dahliae. , Sclerotium damping-off disease and the development of complex diseases. Was also reported that the parasitic nodule bacteria.
The nematode is capable of surviving in air dried soil for a long period of time (Gaur & Perry, 1991). The retention of moulted cuticles of previous stages is a unique adaptation for survival of nematode in soil. Individual young females, males and fourth stages juveniles could survive in a coiled anhydrobiotic state with encrusted cuticles in soil. Survival of this nematode inversely related to the rate of moisture loss in soil. Therefore, alternate drying and wetting of soil resulted in sharpe decline of population density of the nematode in soil.
The first molt occurred in eggs and egg hatching of water without the impact of root exudates. Youth Development is no pre-feeding adult stage of the host tissue, and quickly complete the three superimposed molt. The young woman is the only stage of infection. Source of infection, young women orient themselves with the rear of the vertical axis of the root causes are still not in the root. In establishing a feeding site, it developed into a kidney-shaped roots extending back beyond the women. In 7-10 days after the eggs began to invade and lay eggs about six specific vaginal cells to secrete a gelatinous matrix. Each egg mass contains 30-200 eggs. Throughout the life cycle completed within 3-4 weeks depending on the temperature and host suitability.
Management options:
Cultural methods:
Crop rotation with non hosts crops like mustard, maize, sugarcane, marigold
Growing the susceptible crops in winter seasons in the multiple cropping systems
Organic managements
Application of FYM, oilcakes like neem, karanj, mustard etc. have been found promising.
Summer ploughing:
Two to three summer ploughings during hot months
Irrigation management:
Irrigation between ploughings results in alternate drying and wetting which may stimulate exsheathment of young female of R. reniformis
Crop husbandry:
Good crop cultivation practices like field preparation, fertilizer application and moisture management can improve crop tolerance to nematodes
Resistant Varieties :
Cowpea: Pusa phalguni, C-152, RC-48
Papaya: Solo, Washington, Coorg Honey Dew
Onion: Evergreen
Chickpea: BG-425, BG-426, BG-434, BG-268, BG-273
Blackgram: UG-201, UG-135
Chilli: Pusa Jawala
Chemical Control:
Soil application of carbofuran (Furadan 3G) at 2 kg a. i./ha gives good control but it may not often be economical in many low value crops. However, judicious use of nematicides may be adopted by restricting their use at nursery bed, seed treatments, bare dipping of vine cuttings and pit application particularly for transplanted crops.
14. Lesion nematodes (Pratylenchus spp.)
Pratylenchus spp. are migratory endoparasite of root. The vernacular name of ‘root lesion nematode’ is derived from the discoloured patches (lesion) develop on roots. It has a very wide host range including important crops like wheat, maize, cotton, potato, rice, banana, tea, vegetables, ornamentals and fruits. Some nematode species like Pratylenchus thornei in wheat, soybean, chickpea, sunflower and opium, P. zeae in maize, P. indicus in rice, P. loosi in tea, P. coffeae in coffee and banana, P. pratensis and P.vulnus in fruits are serious problems.
The above ground symptoms caused by the nematode are non-specific in nature. The nematode usually infects in roots, rhizomes or tubers. Having penetrated into roots, they multiply in large numbers. All the stages of this nematode are infective. The attacked plant’s root exhibits dark red brown lesions caused by necrosis of the invaded cells. Root lesion is the most characteristic symptoms. The lesions initially appear as small elongate, water-soaked spots which soon turn brown to black. Loss of primary roots, pruning or decay of roots, reduced size of blossoms, shrinking of grains are also associated with the nematodes. Several secondary soil borne fungi, bacteria are also involved for rotting and decay of roots and thus normal functioning of infested roots are heavily impaired.
Management options
1. Summer ploughing of field reduces nematode populations
2.?Application of carbofuran (Furadan 3G ) at 1 kg a.i./ha at sowing reduces crop damage caused by soil nematodes
3.Growing antagonistic crop like marigold (Tagetes patula) cv. Harmony in autumn after main crop or in between rows of main crop.
4.Hot water treatment of bulbs, corms, tubers and fleshy roots can kill the dormant nematodes inside the root.

15. Pigeon pea cyst nematode (Heterodera cajani)
Heterodera cajani is the only species of cyst nematodes parasitizes a large number of leguminous crops. This nematode is prevalent and gaining importance in almost all pigeon pea growing states. Some populations of this nematode are known to attack sesame also. The species is distinctive for having large egg-sac (almost double of its cyst size). The nematode completes its life cycle in 16 days at 29 0C and in 45-80 day at 10 0C to 24 0C. It can also reproduce parthenogenetically, though it is bisexual species. During a cropping season, it can quickly multiply and build up a huge population. At seedling stage of plant pearl-like or lemon-shaped white female can be found attached with roots. Infected plants show yellowing, stunting, poor vigour and pod formation. Several crops like pigeonpea, cowpea, mungbean, soybean, blackgram and sesame are seriously damaged by the nematode.
Management options:
? Summer ploughing of fields during hot months
? Crop rotation with non host crops for 2-3 years
? Soil application of carbofuran (Furadan 3G) at 1-2 kg a. i / ha
? Bio-agent like Pasteuria penetrans (Pasutsuria 50WP) may be used to suppress soil population.
16. Ectoparasitic nematodes
Several ectoparasitic nematodes are emerging as new problems of crops. In spite of being numerous group in soil and attained much adaptive biological features of survival and multiplication as compared to endoparasites, they are regularly ignored as nematode pest. Many genera like Tylenchorhynchus, Hoplolaimus, Helicotylenchus, Paratylenchus, Hemicriconemoides, Hemicycliophora, Criconemoides, Xiphinema, Longidorus, Trichodorus etc. are prevalent in the rhizosphere of agricultural, horticultural and forest crops and their pathogenic potential have been proved and their damaging nature are well documented. However, ectoparasitic nematodes are given least attention as because of their symptoms induced on plant are not easily convincing, often confused with other soil problems and soil pathogens. The role played by this group of nematode is much more dangerous particularly when they interact with other soil microorganisms and thereby make the plants vulnerable to weak pathogens.
In modern agricultural system, intensive and extensive cultivation of same crops, changes in cultivation practices like high yielding varieties, poor organic nutrition in soil, indiscriminate use of agrochemicals etc. resulted shift in pest status. For instances, Tylenchorhynchus brevilineatus, an polyphagy ectoparasite of diverse crops has appeared as serious problem as ‘kalahasti malady’ disease of groundnut in Andhra Pradesh accounting for 20 to 60% yield losses (Reddy et al.,1984). This nematode is also reported to cause concern in tobacco in Gujarat. There are many instances like T. brassicae in cabbage and cauliflower, Hoplolaimus indicus in rice and jute, Helicotylenchus multicintus in banana, Paratylenchus and Criconemoides in apple and peach, Xiphinema basiri and Hemicriconemoides in citrus and grape and Paralongidorus in sal are emerging nematode problems (Khan & Ganguly, 1995) in the changing agricultural scenario in India.
Management options
? Ectoparasitic nematodes are very much vulnerable to summer ploughing which exposes and break the life cycle of many pathogens including nematodes.
? Crop rotation with poor hosts
Future approaches and conclusion
Plant parasitic nematodes constitute one of the major limiting factors for cultivation of crops. The changes in agricultural situations have tremendous effects on the emergence of new nematode problems in India. The recent outbreak of M. graminicola in the Mandya district of Karnataka, West Bengal, Orissa, Assam, floral malady caused by Aphelenchoides besseyi in tuberose in West Bengal and Orissa, kalahasty malady in groundnut in Andhra Pradesh, Meloidogyne indica in kagzi lime in Gujarat and Pratylenchus zeae in maize are few examples of serious concern. Despite the fact, plant parasitic nematodes are mostly neglected and considered as low priority factor for crop production and protection In India. The economic significance of nematodes in agriculture is very often under estimated and their damage potential is not recognized by the plant protection specialists, scientists and administrators. As an important component of integrated pest management, nematode pathogens cannot be ignored and they could be tackled with the intelligent planning of nematode suppressive crop sequences, summer ploughing, organic manuring, clean cultivation, adjusting sowing time, water and irrigation management and sensible use of nematicides. The increasing concern on the ill effects of chemical pesticides on environment has driven the recent research interests on the use of several alternative strategies like botanicals, biopesticides and cropping system research for management of insect-pests diseases including nematodes. Some of the successes have been obtained for managing plant parasitic nematodes with neem based formulations, fungal formulation of P. lilacinus, bacterial formulations of Pasteuria penetrans and Pseudomonas fluorescens. However, wide application of bioagents in field scale is still limited probably due to their inconsistent efficacy in different agro-ecological situations. Integration of two or more methods can be explored on the basis of their compatibility, economic viability and availability to the farmers. Developing holistic approaches for managing field problems including nematodes inducing disease complexes in concert with other pathogens like fungi, bacteria and viruses will be the major future areas of research thrust.
Shortfalls of Nematology Extension:
1. Inadequate knowledge about nematode to the extension specialists
2. Ignorance of farmers, scientists and administrators about the nematode pathogen
3. Reluctance to give due importance of nematode problems in crops
4. Non acceptance of nematode pathogens as an important component of IPM
5. Lack of nematode specialists and their poor representation in different Government sponsored Training programmes organized by Extension Department/ Government Departments.
6. Non-availability of effective nematicides and a few or no pesticides industries are interested either to develop new molecules or judging their existing product having nematicidal properties.
7. Lack of coordination among the plant protection disciplines to resolve the field problems by developing a comprehensive package of practices.
Suggestions:
1. To create awareness among farmers and convince the authorities concerned about the potentialities of tiny worm to harm the crops.
2. Organizing group meetings of plant protection and production specialists and release a low cost publication for the farmers at least before Rabi and kharif season every year
3. Providing training lectures including practical problems by the Nematology specialist to the extension workers either separately or through routine training programmes organized by the Department,

Selected references

Posted in: java training| Tags: current crops nematodes department disease damage agricultural entomologybidhan nematode plant

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GENERAL KNOWLEDGE Pt. III

• WHY IS AN MP3 FILE CALLED SO?

MP3 is acronym for MPEG audio Layer-3. MPEG is the acronym for Moving Picture Experts Group, which developed compression systems, used for video data like DVD movies and HDTV broadcasts. The MP3 format is a compression system for music. It helps reduce the number of bytes in a song without affecting the quality of the sound. The goal of the MP3 format is to compress a CD-quality song by a factor of 10 to 14 without noticeably affecting the sound quality With MP3, a 32-megabyte (MB) song on a CD compresses to about.

• WHICH FAMOUS BIRD HAS A 'LAUGHING' AND 'BLUE-WINGED' VARIETY?

The famous bird kookaburra has a 'laughing' and a 'blue winged' variety The laughing kookaburra, D novaeguineae, is slightly larger than the blue-winged kookaburra with a slightly longer bill. The blue-winged kookaburra also has a head streaked white, with a white rather than dark eye, and no dark patch behind the eye. The blue-winged kookaburra has a bright-blue wing patch and rump. The call is also quite different.

• WHAT IS GUTTATION?

Guttation is the loss of water in the form of water droplets from hydathodes (small pores) on the leaf margin of a small herbacious plant. Water has the ability to rise up to 2 feet on its own through the xylem of the plant. During the evening or early morning, when the rate of absorption by roots exceeds the rate of transpiration (evaporation) by leaves, a lot of water gets accumulated in the plant body which can damage the cells. Plants have hydathodes at the end of the veins, through which this excess water is lost in the form of droplets. It takes place mostly in small plants like banana, rose, etc.

• WHAT IS GNOTOBLOLOGY?

Gnotobiology is the science of study of animals or other organisms raised in environments free of germs or those which contain only specifically known germs. Scientists compare gnotohiotic animals with ordinary animals whose bodies carry many germs, like bacteria, viruses and parasites. In this way, scientists can determine more precisely how specific germs affect a body.

• WHAT IS BUFFERING IN INTERNET?

Buffering is a situation which occurs when a streaming media player is saving portions of a streaming media file to local storage for playback. Most streaming media players buffer a small percentage of a streaming media presentation before beginning to play it. Buffering also may occur in the middle of a presentation when available bandwidth does not match the presentation's required bandwidth.

• WHAT IS A BIOMETRIC SECURITY SYSTEM?

In security terminology, a biometric security system is an authentication technique that relies on a computer system to electronically validate a measurable biological characteristic which is physically unique and cannot be duplicated. Various types of biometric security systems are being used for real-time identification; the most popular are based on face recognition and fingerprint matching, iris and retinal scan, speech, facial thermograms, and hand geometry.

• WHERE ARE FILES AND WEBSITES ON THE INTERNET STORED?

The internet is a collection of a large number of client-server based systems. So all files and other resources on it are stored on secondary storage devices of the re- spective servers. Servers of websites are termed as web servers. So when you type in a URL of a website in the address bar of your browser, it makes a connection to that web server which in turn fetches the data from the secondary storage device (such as the hard disk) that they must be using and returns it to the respective browser. The same holds true for any other resource (image, MP3 file, zipped file, etc.) that you access on the internet.

• WHY IS THERE NO B DRIVE IN A COMPUTER?

It's not that computers don't have B drives. Initially, (hardly two decades ago), personal computers didn't have hard discs — they were equipped with two floppy drives called drives A and B. Later, a hard disk was introduced and was labelled as the C drive. Other drives like the CD drive, DVD drive, flash drive and others were labelled D, E, etc. If you have a computer having two floppy drives, then they are called A drive and B drive.

• WHAT IS E-WASTE?

All obsolete electronic devices such as computers, servers, printers, monitors, TVs, cellphones, calculators, CDs, floppies, chips, processors, motherboard, PCB etc. end up as e-waste. E-waste contains many hazardous substances like PVC, plastics, heavy metals, Brominated Flame Retardants etc.

• WHAT ARE EFT MONITORS?

Generally all types of monitors are a strain on our eyes. EFT, or Eye Fresh Technology, monitors have a vital coating on the rear that emits anions and far-infrarorf r-o-fresh and ease the strain on the eyes and relax the eyes and body.

• WHY ARE THE FREQUENCY OF FM CHANNELS GENERALLY BETWEEN 90 AND 110 MHZ?

The term FM is slightly misleading because it stands for Frequency Modulation, a technique to broadcast radio waves. The frequencies between 80MHz to 110MHz, generally used to broadcast FM across the world, all fall in the VHP frequency range of 30Mhz to 300Mz. However, the first FM transmission took place in the US in the 1940s in the frequency band 42 to 50MHz. Later in 1945, the Federal Communications Commission allocated bands from 88 to 106MHz for FM broadcasting, citing reasons for its non-interference with other radio bands in and around a city Later, in western Europe, because of the already congested medium wave band, broadcasters preferred to migrate to the usual standard FM bands. In the UK, BBC broadcast for the first time in the FM band in 1955. Since then, FM has almost become an international standard for local broadcasts within city boundaries and the frequency range being used across the globe have been in the 88 to 106 MHz range only.

• WHAT IS THE ORIGIN OF THE WORD 'ROGER' IN TELECOM?

It has its origin from the Morse code in which the end of communication was marked with dih-dahdih (.-.) which incidentally is a code for 'R'. For voice communication, people used an equivalent for every letter (e.g. Omega-Pie-England-Norway for OPEN). For R the equivalent was Roger. Hence, all the communication ended with .-.,i.e. Roger, meaning 'this communication is over'.

• WHAT IS AN ENCODER AND DECODER?

An encoder is a device, which transforms the data into some bits known only to it and the decoder, is a device, which transforms those coded bits to generate the original data again. These two are mainly used in computer technology but the underlying concept can be used anywhere. For example, the name 'Delhi' can be coded as 'ihleD' or '45#1278'. Later, the decoder regenerates the original 'Delhi' from this code as it knows the coding scheme.

• WHAT IS IMEI?

• WHAT IS THE DIFFERENCE BETWEEN A SUBWOOFER AND A WOOFER?

There are no stark differences between these two speaker systems as both are used to reproduce lowfrequency sound notes. Subwoofers are designed to reproduce a band of frequencies below 30Hz level and woofers produce sounds above it. At times, the bands may overlap. The smallest diaphragm of a decent halfway woofer is 8 inches, in a subwoofer it is 12 inches.

• WHAT IS A SIMPUTER?

The word 'Simputer' is an acronym for 'simple, inexpensive and multilingual people's computer'. It is a small, inexpensive, handheld computer, intended to bring computing power to developing countries. It includes text-to-speech software and runs the GNU/ Linux operating systems. The device was designed by the Simputer Trust, a non-profit organisation formed in November 1999. Simputers are generally used in environments where computing devices such as PCs cannot be used.

• WHAT IS BLUE TOOTH TECHNOLOGY?

Bluetooth is a low cost, low power radio interface standard for wireless communication over short distances. It's an open standard for allowing intelligent devices to communicate with each other. This allows any sort of electronic equipment (from computers and cell phones to keyboards and headphones) to make its own connections, without wires, cables or any direct action from a user. It could allow for replacing many propriety cables that connect one device to another with one universal radio link.

• WHAT IS THE DIFFERENCE BETWEEN ELECTRICAL AND ELECTRONIC DEVICES?

• WHEN WAS WINDOWS OPERATING SYSTEM CREATED?

The earliest avtar of Microsoft Windows was Interface Manager, which was being developed in September 1981. The first ever version of Windows operating system was announced on November 10, 1983. It was an extension of MS DOS, and sported a graphic user interface. Windows? 1.0 was finally released into market in November, 1985.

• WHAT IS BETA TESTING?

Typically, software goes through two stages of testing before it is considered finished. Only users within the organization developing the software often perform the first stage, called alpha testing. The second stage, called beta testing, generally involves a limited number of external users. Beta testing is the formal process of soliciting feedback on software still under development. Beta testing is usually the last step a software developer takes before releasing the product to market.

• WHAT IS SPYWARE?

With reference to last week's answer, I'd like to point out that spywares don't come typically named spy ware. exe like spyware32,exe, ispyexe or such. It can be kazaa.exe, msbb.exe, newsupd.exe, dider.exe, etc. Deleting all registry keys is ownright suicidal because the operating system (Windows) would be dead without any registry keys. If the statement is supposed to mean deleting "all infected/ spyware modified" registry keys, that's still a tough call because unless the user is an expert about that particular spyware, it's impossible. More than one anti-spyware software is neededto keep one's PC spyware-free.

• WHY IS IT ADVISED TO SWITCH OFF THE MOBILE PHONE IN PETROL PUMPS?

Cell phones are asked to be switched off at petrol pumps as they are a potential ignition source to the flammable vapours in that atmosphere. This step has been followed after acceptance of the fact that there is risk of fire accidents due to ignition of batteries of cell phones. As a result manufacturers as well as service providers of the cell phones ask users to keep the cell phones in "off" mode.

• WHAT IS SPYWARE?

Spyware is a malicious program which does harm to the computer and invades your privacy. Spyware include Trojans, Adware, Trackware, dialers, Keyloggers and some viruses. Spyware can pluck confidential infor- mation from your computer and slow its performance to a crawl. This threat copies its file(s) to your hard disk, its typical file name is: Spyware.exe. This problem can be solved manually by deleting all registry keys.

• WHAT IS A TFT MONITOR?

Thin Film Transistor (TFT) Liquid Crystal Display technology does away with the traditional bulky Cathode Ray Tube (CRT). LCDs use a strong backlight as the light source and control how much of this light is allowed to reach the dots (pixels) by selectively allowing the light to reach each pixel. LCDs achieve this by taking advantage of a key property of 'twisted' liquid crystal molecules; their ability to naturally block polarised light butthen let it through by degrees when a small electric field is applied. LCD cells are accurately controlled and arranged in a Hat matrix of rows and columns.

• WHAT IS A “FIREWALL” IN COMPUTER TERMINOLOGY?

In computer security, a firewall is a device that blocks unauthorised access to an organisation's local area network. A firewall can reside on the administrative computer, the server that acts as the LAN's gateway to the Internet. The firewall keeps track of every file entering or leaving the local area network in order to detect the source of viruses and other problems that might enter the network.

• WHY IS SPAM IN EMAIL JARGON CALLED SO?

The term spam is derived from the popular Monty Python song 'Spam sketch', set in a cafe where everything on the menu includes Spam luncheon meat. The chorus repeats 'Spam, Spam, Spam' over and over again, drowning out all conversation. Since 'Spam' involves sending identical messages to a large number of recipients without their permission, it has been called so. The correct term for it is Unsolicited Commercial Email (UCE).

• WHAT ARE CHICKEN SWITCHES?

Chicken switches are switches that can disable optimisations on the chip (such as caches) to isolate problems. When we throw all the "chicken switches", we put the processor in "tinkertoymode". If it still isn't working, the problemjsjikely to reside elsewhere, in external memory for example. We do the same sort of thing in software - provide settings to disable caches and other forms of optimisation in order to isolate problems.

• WHAT IS A HANDSHAKE IN COMPUTERS?

Handshake is the process by which two computers initiate communication. A handshake begins when one sends a message to another indicating that it wants to establish a communication channel. The two computers then send several messages back and forth that enable them to agree on a communication protocol. Two modems perform a handshake each time they meet, to help them determine how they will exchange information. If the modem speaker is on, we can actually hear the handshake — the series of squeals and signals.

• WHAT IS CDMA TECHNOLOGY?

CDMA (Code Division Multiple Access) is a digital cellular technology that uses spread-spectrum techniques. Unlike competing systems, such as GSM, that use TDMA, CDMA does not assign a specific frequency to each user. Instead, every channel uses the full available spectrum. Individual conversations are encoded with a pseudo-random digital sequence. CDMA consistently provides better capacity for voice and data communication than other commercial mobile technologies, allowing more subscribers to connect at any given time, and it is the common platform on which 3G technologies are built.

• CAN A COMPUTER HAVE MORE THAN ONE HARD DISK?

There are two main hard disk types used today — IDE (Integrated Drive Electronics) and SCSI (Small Computer System Interface) hard drives. The IDE drives are used in PCs and SCSI in servers. Motherboards usually come with two embedded IDE ports. Each port can have two devices connected to it on the same data cable for a total of four devices. CD and DVD.units are also connected to the IDE ports and counted as one of those four devices. Once you have four devices, then you can add a PCI IDE controller to have more ports to add devices. SCSI hard drives are connected to a PCI SCSI controller that will be able to accept seven devices for standard SCSI and 15 for the newer, wide SCSI.

• HOW DOES A LASER PRINTER WORK?

A laser printer uses the phenomenon of static electricity as a temporary glue. The core component is the photoreceptor, typically, a revolving drum or cylinder. This is made of highly photoconductive material that is'discharged by light photons. The printer coats the drum with a positively' charged toner — a fine, black powder. Since it has a positive charge, the toner clings to the negatively discharged areas of the drum, but not to the positively charged 'background'. With the powder pattern affixed, the drum rolls over a sheet of paper, which moves along a belt below. Before the paper rolls under the drum, it is given a negative charge by the transfer corona wire (charged roller). This charge is stronger than the negative charge of the electrostatic image, so the paper can pull the toner powder away. Since it is moving at -the same speed as the drum, the paper picks up the image pattern exactly To keep the paper from clinging to the drum, it is discharged by the detac corona wire immediately after picking up the toner.

• WHICH COMPANY PRODUCED THE FIRST LAPTOP?

Designed in 1979 by William Moggridge of Britain for Grid Systems Corporation, the Grid Compass was one-fifth the weight of any model equivalent in performance and was used by NASA on the space shuttle programme in the early 1980s. A 340 kilobyte bubble memory laptop computer with die-cast magnesium case and folding electroluminescent graphics display screen, this is probably the first laptop ever produced.

• WHAT IS GREENSTONE DIGITAL LIBRARY SOFTWARE?

Greenstone is a software suite which can serve digital library collections and build new collections. It runs on Windows, UNIX and Mac OS X and provides a new way of organising information and publishing it on the internet or on CD-ROM. Greenstone is produced by the New Zealand Digital Library Project at the University of Waikato, and distributed in cooperation with Unesco and the Human Info NGO. It is a open source software. The New Zealand Digital; Library website contains numerous examA pie collections, all created with the Greenstone software.

• WHICH WAS THE FIRST CELLULAR SERVICE PROVIDER?

On October 13,1983, the first call on a commercial cellular system was made in Chicago, and Cellular One service in the Washington, D.C. / Baltimore area began in 1984.

• WHICH COMPANY PRODUCED THE FIRST LAPTOP?

Designed in 1979 by William Moggridge of Britain for Grid Systems Corporation, the Grid Compass was one-fifth the weight of any model equivalent in performance and was used by NASA on the space shuttle programme in the early 1980s. A 340 kilobyte bubble memory laptop computer with die-cast magnesium case and folding electroluminescent graphics display screen, this is probably the first laptop ever produced.

• WHAT IS THE DIFFERENCE BETWEEN ELECTRICAL AND ELECTRONIC DEVICES?

The distinction between electrical and electronic components/ elements is two-fold. The former, like electric wires/ cables, resistors, etc. are passive i.e. they do not require a power supply for operation. Secondly, the output power of the signals applied to them can never exceed the input power i.e. there is no power amplification. Electronic components like valves, transistors; ICs, etc. are active components. They need their own power supply for operation and also, depending on the design, may or may not provide power amplification.

• WHY DON'T CDMA PHONE HAVE SIM CARDS?

CDMA phones have phone numbers programmed in the handset just as the operator programs numbers in SIM cards. The latest phones have both options. Since all CDMA phones are network locked, there is no necessity for the SIM card provision. As GSM phones are compatible with any operator, who provides the SIM card which enables connectivity to the network. This makes the phone independent of the operator.

• WHAT IS THE DIFFERENCE BETWEEN LINUX AND UNIX?

Unix developed by Ken Thompson is a multi-user multi-tasking operating system that could be exploited remotely, and portable. Thomson and Dennis Ritchie rewrote Unix in the C programming language Linux, developed by Linus Torvalds from Finland, is a variant of Unix. It has all the features of Unix in addition to a few more, such as inclusion of graphical user environments. It is particularly strong in networking and Internet functions and works with a variety of hardware and peripherals that can do something Unix does not on its target of application. The open-source function of Unix has been maintained, everyone can access the Linux source code, regardless of their version.

• WHAT IS GREENSTONE DIGITAL LIBRARY SOFTWARE?

Greenstone is a software suite which can serve digital library collections and build new collections. It runs on Windows, UNIX and Mac OS X and provides a new way of organising information and publishing it an the internet or on CD-ROM. Greenstone is produced by the New Zealand Digital Library Project at the University of Waikato, and distributed in cooperation with Unesco and the Human Info NGO. It is a open source software. The New Zealand Digital Library website contains numerous example collections, all created with the Greenstone software.

• WHAT IS CLICK FRAUD WITH REGARD TO SEARCH ENGINES?

Click fraud is the practice of artificially inflating traffic statistics to defraud advertisers. In the pay-per-click system, advertisers pay a fee for each click on their link. By using automated clicking programs (called hitbots) or employing low-cost workers to click on links, the perpetrators create the illusion that a large number of potential customers are clicking the advertiser's links, when in fact, there is no likelihood that any of the clicks will lead to profit the advertiser. Click fraud scammers often take advantage of the affiliate programs offered by some search engines.

• HOW DOES A GLOBAL POSITIONING SYSTEM WORK (GPS) WORK?

The basic principle of a GPS operation is that any point on Earth can be located if it is monitored from four different locations. For this, the GPS system uses 24 satellites in six different orbits at an altitude of 18,000 kms. So, at any time, any location is monitored by four different satellites. The GPS device sends its signal to the four satellites. These satellites have a database that contains information of all the locations on earth. These four satellites, in turn, send back the latitude, longitude and altitude of that particular location by referring to its database.

• WHAT IS FM?

FM stands for frequency modulation. Attaching it to a carrier wave in radio frequency transmits the sound signal. The frequency of the radio wave is varied or modulated suitably. When the modulated wave is received by a radio set, the radio wave is filtered to reproduce the audio signal. FM are less susceptible to noise compared to AM or amplitude modulation where the mixing is done by varying the amplitude. In TV signals, the sound is frequency modulated while the picture signal is amplitude modulated.

• WHAT IS FUZZY LOGIC?

Fuzzy logic is a process used in computer science to solve problems that involve ambiguous data such as the room temperature is too hot, too cold or just right. It uses multivalued logic to arrive at a more precise and weighted answer. In contrast, binary logic understands only two states: on or off, yes or no, one or zero.

• HOW DO INTERNET SEARCH ENGINES WORK?

Search engines use automated software programs know as spiders or bots to survey the web and build their databases. Web documents are retrieved by these programs and analyzed. Data collected from each web page are then added to the search engine index. When you enter a query at a search engine site, your input is checked against the search engine's index of all web pages it has analyzed. The best uris are then returned to you as hits, ranked in order with the best results at the top.

• HOW DOES A GLOBAL POSITIONING SYSTEM WORK?

The GPS receiver is only a receiver, without any transmitting capability. The satellites does not contain any databases about the locations or anything. They contain highly precise atomic clocks which generates some code which it keeps transmitting to the earth. The GPS receiver gets that code from multiple satellites which are slightly time-shifted due to difference in the distances of satellites. Using this difference the receiver calculates the longitude and latitude.

• WHAT IS THE FULL FORM OF TFT IN COMPUTER AND MOBILE SCREENS?

Thin Film Transistor (TFT) is a type of LCD flat-panel display screen. It's called so because each pixel is controlled by transistors. TFT technology provides the best resolution of all the flat-panel technologies, but it is also the most expensive. TFT displays are usually designed to run at a specific resolution.

• WHAT IS EDGE TECHNOLOGY IN MOBILE PHONES?

EDGE technology is a modulation technique for GSM networks. An Enhanced Data Rates for GSM Evolution (EDGE) is used to increase network capacity and data rates in mobile networks. EDGE provides data rates up to 384 Kbps.

• WHO INVENTED THE QWERTY KEYBOARD?

WERTY keyboard (also known as universal keyboard) is used in modern computers. The name QWERTY comes from the first six letters in the top row. It was invented by C L Sholes in 1872.

• WHAT IS A HOLOGRAPHIC VERSATILE DISC?

A Holographic Versatile Disc is an advanced optical disc technology still in the research stage. It employs a technique known as collinear holography, whereby two lasers —one red and one blue-green are collimated in a single beam. These disks have the capacity to hold up to 3.9 terabytes (TB) of data. The HVD also has a transfer rate of 1 Gbit/s.

• WHAT IS A PICONET?

A piconet is a collection of devices connected via Bluetooth technology in an ad hoc fashion. A piconet starts with two connected devices, such as a portable PC and cellular phone, and may grow to eight connected devices. All Bluetooth devices are peer units and have identical implementations. However, when establishing a piconet, one unit will act as a master and the other as slave for the duration of the piconet connection.

• WHAT IS A MICROCHIP?

• WHAT IS AN E-R DIAGRAM?

The E-R diagram (entity-relation) is a diagrammatical representation of a data model based on a perception of the real world that consists of a collection of basic objects called entities and of relationships among these objects. It is widely used in database design. The E/R diagram was introduced by P P Chen. An entity is a tangible object that exists in the real world, about which some relevant information may be stored. The qualities of an entity which can be stored as information are called the attributes. For example, if teacher is an entity then the teacher's ID, name, etc. are all its attributes. An association among several entities is called a relationship.

• WHAT IS A DEAD PIXEL?

• WHAT DOES VOXML STAND FOR?

The acronym VoxML stands for Voice extended Markup Language. It is a combination of IVR (Interactive Voice Response) technology that deals with digitizing of sound and the Internet technology. Using VoxML, it is possible to hear the contents of a website without using a computer– all you need is a phone.

• HOW BIG IS A VIRUS?

Viruses are called non-living molecules for two reasons; they are parasitic and show no signs of life till they enter a host. They are tiny creatures. The herpes virus measures 100 nanometers or 100 billionth of a meter. In comparison, bacteria are 10 to 100 times bigger than the viruses.

• WHAT IS THE ORIGIN OF THE WORD ALGORITHM?

A formula or a set of steps to carry out arithmetic manipulation is called an algorithm. All computer programmes are based on algorithms. The origin of this word is from the name of an Arabic mathematician — Al Khwpresmi. The actual word is 'algorism. With the influence of the Greek word 'arithmos' which means mathematics, 'algorism' changed to 'algorithm.

WHAT IS WYSIWYG?

WYSIWYG stands for 'What You See is What You Get. This phrase was popularized with the advent of digital typesetting or desktop publishing with the help of the computer. Initially, the print enhancements such as bold type, italics etc. were not visible on the computer monitor but could be reproduced by the printer. The modern word processors display the text as it appears in print.

• HOW IS MUSIC STORED IN A CD?

Sound consists of waves whose intensity varies from zero to a fixed value in a continuous manner. The intensity is converted to an equivalent electrical signal. This signal is sampled at a very fast rate. The instantaneous value of the electrical signal is then digitized and stored in the Compact Disk using a computer-controlled device. A reverse process then reproduces the sound. The faster the sampling rate, the better is the quality of music.

• IS IT POSSIBLE TO HACK A STANDALONE COMPUTER?

It is common knowledge that a computer hooked to a network; a network of networks or the Internet is vulnerable to computer hackers. In other words, information stored in these computers is never safe. Prof Ross Andersen of Cambridge University has, however, illustrated that picking up the radio signals emitted by the video monitor can break into even a standalone computer.

• WHY DO ALL MOBILE NUMBER START WITH THE DIGIT 9.

According to the Telecom Regulatory Authority of India (TRAI), local numbering allowed is in the range of 2-8. While 0 is used for STD access, 1 is used for special numbers. So, the only digit left is 9.

• HOW DOES A COMPUTER KEEP RECORD OF THE TIME EVEN WHEN IT IS SHUT DOWN?

Our computers are not run by a single operating system, but also the BIOS (basic input output system) which resides pernianently in the chips of the motherboard to which virtually every computer hardware is connected. The BIOS is kept powered by a button cell (1.5 V approximately) or any variant. The cell remains present on the board and helps the BIOS remember not only the time but other hardware settings as well; the GUI (graphical user interface) syncs with the BIOS time every the computer is booted up and hence shows the computer shows the correct time.

o??????? WHAT IS BLACK BOX TESTING?

Testing software based on output requirements and without any knowledge of the internal structure or coding in the program is known as black box testing. Black box testing, concrete box or functional testing is used in computer programming, software engineering and software testing to check that the outputs of a program, given certain inputs, conform to the functional specification of the program. A complementary technique, white box testing or structural testing, uses information about the structure of the program to check that it performs correctly.

• WHAT IS MEANT BY INTERNET SURFING?

When you want some information on a subject from your internet connection, you will have the choice to use many search engines and many websites. You open them one by one and gather information on the subject that is of special interest to you. This is referred to as surfing.

• WHAT IS JAVA?

Java is claimed to be the universal computer language that will be used to operate all devices, including those used in households, like toasters, ovens, irons and geysers. The word 'Java' represents coffee, which is exported from the Asian country to the US.

• WHAT IS HTTP?

HTTP stands for 'Hypertext Transfer Protocol'. It is a protocol that governs the pages designed in HTML (Hypertext Markup Language) that allows a user to access information stored in many computers independent of their geographical location. HTTP has revolutionized the field of information technology and is the backbone of the Internet or the information superhighway.WHO COINED THE TERM 'WORLD WIDE WEB'? WWW or the World Wide Web, a synonym for the information superhighway or the Internet, was, surprisingly, coined by a group of nuclear physicists working at the European Centre for Nuclear Research in Geneva.

o??????? WHAT ARE SUPRA-GLACIAL LAKES AND WHERE CAN WE FIND THEM?

Supra-glacial lakes are those found on the ice surface of glaciers early in the melt season. They are found on the surfaces of temperate glaciers.

• HOW DOES CYBERSQUATTING WORK?

Under a 1999 US federal law known as the Anti-Cybersquatting Consumer Protection Act, cybersquatting means registering, trafficking in, or using a domain name with bad-faith intent to profit from the goodwill of a trademark belonging to someone else. It refers to the practice of? buying up domain names reflecting the names of existing businesses, intending to sell the names for a profit back to the businesses when they go to put up their websites.

o??????? HOW DOES A JERK-O-METER WORK?

It is a speech and tone recognition pattern that helps rate how engaged a person is in a conversation. It is rated on a 1 to 100 scale. Researchers at the Massachusetts Institute of Technology (MIT) are developing software for cell phones that analyses speech patterns and voice tones to do this. It is seen as an important tool for improving relationships and has a lot of potential in telemarketing.

o??????? WHAT IS NEALE'S BALL TOKEN INSTRUMENT?

Designed by Neale, an engineer with the GIP Railway (presently Central Railway), it is an electro-mechanical instrument provided at each station on single line railway ections. It ensures safety in train operations by dispensing tokens which are handed over to train drivers as authority to enter a block section. The tokens are spherical steel balls, which are issued in such a manner that only one token can be issued for one direction at a time after ensuring that previous train has already cleared the section and there is no other train between the stations. Each station has one such instrument for each direction, which are electrically connected to similar instruments provided at the adjoining stations on either side. This ensures that only one train can enter the block sections at a time.

• WHO INVENTED THE T9 DICTIONARY USED IN MOBILE PHONES?

The inventors of the predictive T9 dictionary used in cellphones are Svensson Henrik Brun (Denmark) and Williams Stephen (Finland). This predictive text input method helps in efficient typing of SMS messages. It improves on the common multi-tap method since fewer total button taps are needed. It's achieved by using a small, quick-access dictionary to automatically display the word most often desired for a sequence of keystrokes.

• WHAT IS A CRYSTAL RADIO?

A crystal radio is the basic form of a radio, can detect the radio signals with no power. It has very few parts and can be built with popular products in short time. It works best when a station within 40 km from the crowd. Simple crystal radios are often a few hand-made parts such as an antenna wire, tuning coil of copper wire, crystal detector and earphones. A crystal radio receives broadcasts from radio stations that convert sound into radio waves and send the signals everywhere. The crystal radio antenna, a very long wire that takes the signals and passes them through the crowd as the electronic current. It uses a crystal detector to convert the radio waves, electricity, electricity sound. The detector can be made from a special rock of galena in a holder. It uses headphones convert the sound of electricity to the sound you can hear.

• WHATS THE WORLD'S FIRST SOFTWARE?

Ada Lovelace wrote a rudimentary programme for the analytical machine designed by Charles Babbage in 1827, but the machine never became operational, hi 1949, the language short code appeared. It was the first computer language for electronic devices and required the programmer to change its statements into Os and Is by hand.

• HOW IS A SATELLITE PHONE DIFFERENT FROM A CELLULAR PHONE?

Satellite and cellular phones are wireless devices. They almost look alike but the way they work is totally different. A cellular phone functions on the basis of cells, and hence is called cell phones. The whole network area is divided into small areas and an antenna is installed in each area. These are also called towers. When a cellular phone is moving, it enters from one cell to another. When it crosses the border of one cell, the phone sends a signal to the MTSO (Mobile Telephone Switching Office). With the help of control channel the database of the MTSO relocates the phone in a new cell or area. Satellite phones use Low Earth Orbiting (LEO) satellites. When a satellite phone is turned on, a signal goes up to any number of satellites of a group the phone is registered with. When a person makes a call from the handset, a signal goes to the nearest orbiting satellite. The satellite connects to the gateway or ground station. Then the gateway takes the call to the destination.

• WHAT IS THE 3RD SPACE VEST?

These vests help users endure virtual blows, literally An American surgeon has invented a vest that lets computer game users feel physical attacks like shots, stabs, etc. while playing games. The vest uses air pressure and feedback from the computer to simulate thumps on those regions of a person's torso, which would have been hit if the person were actually fighting in a battle. It's designed by Mark Ombrellaro and was originally intended for medical purposes.

• WHY IS THE SYMBOL @ USED IN E-MAIL ADDRESSES?

An e-mail address identifies a location to which e-mail messages can be delivered. The first electronic mail delivery engaging two machines was done in 1971 by Ray Tomlinson, a programmer at Bolt, Beranek and Newman, an engineering company in Cambridge, Massachusetts. He needed a way to separate, in the e-mail address, the name of the user from the machine the user was on. He wanted a character that would not, under any conceivable circumstances, be found in the user's name. He looked down at the keyboard and chose the @ sign among various punctuation marks available on his Model 33 teletype keyboard. He had no idea that he was creating an icon for the wired world. Today, e-mail is the most used application on the internet. Each e-mail account has a unique address. A general format for an e-mail address is: username@computer_name. The part before the @ sign is the local part of the address, the user name of the recipient, and the part after the @ sign is the domain part which is a host computer name.

• WHAT IS INTERPLANETARY INTERET?

If the internet allowed users to get. Information from any corner of the world, then the interplanetary internet will allow users to access information and even control experiments taking place far away from Earth. Vinton Cerf, considered the founding father of the internet and a co-creator of the interplanetary internet, is currently working on standards to guide internet communications in the space era.

• WHAT IS CYBERSLACKING?

It's a slang term used to describe employees who surf the net, write e-mail or indulge in other inter' net-related activities at work that are not related to their jobs. These activities are performed during periods of time when they are being paid by their employer. The individual is called a cyberlacker, while the act is cyberslacking,. It's. also called as cyberloafing.

• WHAT IS CRYOPTOGRAPHY?

It is the practice of enciphering and deciphering messages in secret code in order to render them unintelligible to all but the intended receiver It may also refer to the art of cryptanalysis, through which cryptographic codes are broken. Collectively, the science of secure and secret communication, involving both cryptography and cryptanalysis, is known as cryptology. Today, the principles of cryptography are applied to encryption of fax, TV and computer network communications. The secure exchange of computer data is of great importance to banking, government and commercial communication.

• WHAT IS A ‘VOCAL JOYSTICK’?

The ‘Vocal Joystick’ has been developed by researchers at the University of Washington. It is a computer software which allows the disabled, who can use their voice but not their hands or arms, to control a cursor using sounds. This joy stick detects sounds 100 times a second and converts it into movement on screen.

• WHAT IS AN ELECTRONIC SPIDER?

An electronic spider, also called a web crawler or a web robot, is a programme that can visit the pages, on the world wide web in a methodical automatic manner. They are most commonly employed by search engines for browsing the web and copying new pages so that the indexes of the engine are updated periodically The spiders are also used by some sites for maintaining their pages, to ensure that the hyperlmks are updated and the HTML code is valid. They are also said to be used by spam creators for capturing e-mail addresses contained in web pages.

• WHAT IS WEB 2.0?

— The internet as we know it has been around for over 10 years now. It has principally been used for searching, browsing and reading static information. Now, it is evolving into something quite different. We are now in what is called the Web 2.0 era, where the internet is more about interactivity. The concept began with a brainstorming session between O'Reilly and MediaLive International in 2004. Web 2.0 can be defined as a set of technologies which enable collaboration and sharing between internet users. The tools of Web 2.0 are web pages, web-based communities or hosted services such as social-networking sites, online encylopaedias like Wikipedia, blogs and podcasts, etc.

• WHY IS JUNK MAIL CALLED SPAM?

One possible origin is Monty Python's famous song Spam-loving Vikings sketch which goes 'spam spam spam spam spam spam lovely spam, wonderful spam...' As spam is repeated several times till one tires of hearing it, it's chosen to refer to worthless and repetitive e-mail. Also, canned luncheon meat called spam, made by Hormel, is disliked in America and most Americans consider it nutritionally worthless to be set aside at the first opportunity. A computer group at a university was supposed to have described unsolicited junk mail as spam, as it shares many properties with this meat.

• WHAT IS A 'NANO-FACTORY'?

Researchers in Japan have invented a tiny brain which can act as a remote control for swarms of nano-machines. They simultated eight such nano-machines to create a 'nano factory'. According to experts; nano-machines could also be used to boost the processing power of future computers. They also have high hopes for nano-machines in treating diseases. The machine is made from 17 molecules of the chemical duroquinone. Each one is known as a 'logic device'.

• WHAT IS CYBERSQUATTING?

Cybersquatting is registering a website in the names of popular brands. The word squatting in this context means unauthorised occupation of someone else's property In the internet domain, techsavvy entrepreneurs register websites in the names of popular brands, whose owners do not have websites of their own. This can lead to misrepresentation in the internet media about the products or services the brand sells in the market. The brand owners naturally would like to buy the domain either to give authentic information about products and services or to stem the ill-effects of such misrepresented sites. The person who first registered the brand name sells the site and makes a profit. The ethical and legal aspects of such practice are ambiguous as the intention of the original owner of the site can either be genuine or fraudulent.

• WHAT IS MYSQL?

MySQL (pronounced'my-ess-cueel') is an open source, true multiuser, multi-threaded relational database management system (RDBMS), that uses Structured Query Language (SQL). MySQL was developed by two Swedes and a Finn — David Axmark, Allan Larsson and Michael Widenius. It was written in C, C++, and was first released in 1995. Currently, MySQL has more than 11 million installations. MySQL is fast and flexible enough to allow storing logs and pictures in it. Its main goals are speed, robustness, and ease of use. MySQL is open source, 100% GPL (General Public License) database. This provides a great opportunity for the open source cornmunity and for those who are developing open source software.

• WHAT IS SONET WITH REFERENCE TO AN OPTICAL NETWORK?

Sonet (Synchronous Optical Network) is a high-speed, physical layer network designed to carry large volumes of traffic over relatively long distances on fiber optic cabling using lasers or lightemitting diodes (LEDs). It provides a standard interface for communications carriers to connect networks based on fiber optic cable to handle multiple data types (voice, video, and so on). Sonet defines a technology for carrying many signals of different capacities through a synchronous, flexible, optical hierarchy This is accomplished by means of a byteinterleaved multiplexing scheme. Byte-interleaving simplifies multiplexing and offers end-to-end network management. Sonet was proposed by Bellcore in the mid-'80s arid now an ANSI standard. It is a successor to other wellknown communication technology implemented on fiber optics network called PDH (Plesiochronous Digital Hierarchy). It possesses several characteristics that make it good for the internet today: It defines clear interoperability standards between different vendors' products. It can carry nearly any higher-level protocol (including IP), and includes built-in support for ease of management and maintenance. Sonet has emerged as a powerful protocol which is extensively used for large and high performance networks.

• WHAT IS A SEMAPHORE?

A semaphore (pronounced as sehm uh fawr, invented by Edsger Dijkstra) in computer science is a classic way of protecting shared resources to multi-programming environments like Unix systems, semaphores are a technique for coordinating or synchronising activities in which multiple processes compete for the same operating system resources. A process needing the resource checks the semaphore to determine the resource's status and then decides how to proceed. Depending on the value found, the process can use the resource or will find that it is already in use and must wait for some time before trying again, thus avoiding deadlocks.

• HOW DOES A LASER MOUSE WORK?

A laser mouse is a type of optical mouse. It uses a laser beam which is invisible, or nearly invisible, to the human eye. The beam emitted by the laser mouse moves with the user's hand, triggering an optical sensor system. It works in tandem with a system which tracks how far the mouse has moved by bouncing hundreds of images every second, constantly updating the position of the mouse and the subsequent position of the cursor on the screen.

• WHO INVENTED THE PEN DRIVE?

A pen drive is another term for USB (Universal Serial Bus) flash drive and is basically a data storage device. The pen drive was invented in 1998 by IBM, with the intention of replacing the floppy drive in its ThinkPad line of products. The first flash drive was manufactured by M-systems under contract with IBM and was called the disgo. The disgo came in various sizes: 8 MB, 16 MB, 32 MB and 64 MB. Following the launch of disgo, a number of pen drives of different sizes, types and brands came into the market. Today pen drives are used in a range of devices such as mobile phones, video-game consoles and digital music players.

• WHAT IS THE BEER GOOGLE EFFECT?

The Beer Google effect refers to the tendency to google information on someone we meet for the first time. This generally happens when one consumes alcohol, and under its influence, he looks up the person on the internet. For example, I met Geeta at ABC bar for the first time and she tells me that she works for XYZ Inc. Immediately on returning home, I beer-google her using the search string 'Geeta XYZ Inc’.

• WHICH IS THE EARLIEST SOCIAL NETWORKING SITE?

The earliest social networking site was classmates.com which was established in 1995. It introduced the concept of user profiles and of short messages sent and received by friends on the website. The basic purpose was to keep in touch with old friends. Sixdegrees.com which came in 1997 is considered to be the first social networking website to have all features in one complete package.

• WHAT ARE APPLETS?

An applet is a little application. Prior to the World Wide Web, the built-in writing and drawing programmes that came with Windows were sometimes called applets. On the Web, using Java language, an applet is a small programme that can be sent along with a Web page to a user. Java applets can perform interactive animations, immediate calculations, or other simple tasks without having to send a user request back to the server.

• WHAT DOES BLOATWARE REFER TO?

Bloatware, also called junkware, adware and demoware, refers to pre-installed software and trial software that come with Windows computers. While it's a ploy to get consumers to buy the software, most users regard it as junk and get confused by various icons or toolbars that pop up on their computers. Bloatware can also clog up the system and slow it down.

• WHAT IS THE TIME PREFERENCE THEORY OF INTEREST?

The Time Preference Theory of Interest is also known as The Agio Theory of Interest. It was presented by Bohm Bawerk, who said that interest is an agio (reward) or (premium) for time preference. People prefer present income, present consumption and present satisfaction of wants, which means that people are impatient to spend. To induce them to postpone their consumption, they are to be compensated by paying interest. People prefer present to the future because future is uncertain and wants of today cannot be satisfied tomorrow. Irving Fisher improved upon this, stating, "The rate of time preference measures the rate of interest." The higher the time preference, the higher the impatience to spend, and hence, the higher the rate of interest; the lower the time preference, the lower the rate of interest. According to Fisher, people with low level of income, uncertain about their future and are spendthrifts will demand high rate of interest whereas their opposites will demand low amount of interest.

• WHY IS BLU-RAY DISC BLACK ON TOP?

The Blu-ray disc uses a blue technically violet) laser operating at a wavelength of 405 nanometre (nm) to read and write data. Conventional DVDs and CDs use red and near infrared lasers, at 650 nm and 780 nm respectively. Because the Blu-ray disc data layer is closer to the surface of the disc, compared to the DVD standard, it was at first more vulnerable to scratches. The first discs were housed in cartridges for protection. Now, the rewritable media are spin-coated with a scratch resistant and antistatic coating, which gives the surface of the disc its black colour.

• WHAT IS A GOOGLE BOMB?

A google bomb is an effort to inflate a website's search ranking for a particular term. Google gives importance to pages linking to a particular page for ranking purposes. In case of Google bombing, pranksters use a phrase to link to a particular page from their sites multiple times, to push that page to the top of search results.

• WHAT IS GRID COMPUTING?

Grid computing is a parallel processing architecture in which CPU resources are shared across a network, and all machines function as one large supercomputer. A wellknown example is the ongoing Search for Extraterrestrial Intelligence in which thousands of people share the unused processor cycles of their PCs in the vast search for signs of rational signals from outer space.

• WHAT IS BLUEJACKING?

Bluetooth is a radio wireless technology that allows computers, cell phones, laptops, etc. to talk to each other in a limited range. Bluejacking is the term based on two words — bluetooth and hijack. It refers to sending unnecessary and anonymous messages by using bluetooth enabled devices as a contact.

• WHAT DOES PHARMING REFER TO?

Pharming involves rerouting the traffic of a particular website to a bogus one. This is done by exploiting the weaknesses of the site's Domain Name System server. Pharming poses major concerns to corporates and e-commerce sites.

• HOW MUCH DATA DOES THE INTERNET CONTAIN?

Estimating the data the Internet contains is complicated but there are a few estimates. According to one, the quantity is approximately equal to 500 crore pages. Another assesses the total amount of digital data in the world by 2010 would amount to 12 piles of pages, each of which would be twice as long as the distance between the Sun and Pluto.

• WHAT IS VIRAL MAIL?

A viral email is an online chain letter, which is sent from person to person, almost like ancient talking drums. The term 'viral' comes from virus, meaning pass-along. Viral mails are generally humourous in nature, which a person can forward to friends or they can be used to spread a socially important message that can reach across the world rapidly These mails are also used for commercial purposes — called viral marketing or advertising.

• WHAT IS THE DIFFERENCE BETWEEN A COMPUTER SCREEN AND A GAMING CONSOLE?

The primary device for the PC is a keyboard and mouse, while all console systems come with game pads used to control movement within the game. Technically, a computer game can be thought of as one composed of a computer-controlled virtual universe. A video game is a computer game where a video display is the primary feedback, which is displayed on a television screen.

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