crops

Agriculturists are often asked if tree crops such as pine, fruit trees, rubber and oil palm or annual crops such as wheat, maize, rice or soya bean are friendlier for the environment. This article will explore the merits and demerits of planting tree crops or annual crops vis a vis its environmental impact.

One of the major contributors to environmental damage during the planting of annual crops is the heavy usage of machineries in all aspects of cultivation of the crops. There is significant use of mechanisation from seed planting to the harvesting and threshing of the crop. Early in the 19th century, a farmer could produce food for 2.5 people and by 1999 due to advances in agricultural technology, a single farmer could feed over 130 people. Modern harvesters such as combined harvesters and planters are extensively used in the planting of various crops in most parts of the world. While mechanisation increases productivity and lowers the cost of production, it also contributes towards environmental destruction. Most of these machineries are bulky and as they move around the fields, they bring destruction to the top soil causing destruction to the microorganisms found in the soil.

Soil is a favourable habitat for microorganisms and is inhabited by a wide range of microorganisms including bacteria, fungi, algae, viruses and protozoa. Microorganisms are found in large numbers in soil; usually between one and ten million microorganisms are present in each gram of soil and with bacteria and fungi being the most prevalent. Apart from that, soil organisms are very important as almost every chemical action and reaction that takes place in soil involves active contributions from soil microorganisms.

They play an active role in enhancing soil fertility by assisting with the recycling of nutrients such as carbon and nitrogen which is essential for plant growth. Microorganisms also help with the decomposition of organic matter in soil into nutrients. An example would be nitrogen fixing bacteria transforming nitrogen gas present in the soil into soluble nitrate compounds which enrich the soil and is absorbed by the plant. Other soil microorganisms produce hormones that can improve plant health and contribute towards higher yield. Microorganisms are influenced by the nature, properties and arrangement of soil particles. They also modify soil particles and their arrangements. Microbial life in soil is also indirectly influenced by surface interactions. Some microorganisms also burrow into and churn up the soil which improves soil structure and aggregation. Microorganisms have the ability to protect plants from antagonistic pathogens as some can dissolve minerals and provide nutrients in dissolved mineral form to plants. Apart from microorganisms, there are also earthworms that take in dead organic matters from soil, ingest it, excrete the nutrient rich casts in the soil and help to improve aeration, water infiltration, drainage and enhance nutrient availability and cycling. These microorganisms and earthworms which enrich the soil are usually killed by the use of machineries and continued use of machineries in the field do not enable these microorganisms to be re-established.

Another factor to be considered for annual crops is the current practice of double or even triple cropping per year which causes continuous damage to the top soil without providing opportunity for the soil to rejuvenate. Over-tilling and over-ploughing soil destroys natural soil structure with decreased soil pore

size, breakdowns in soil aggregates and decreased pore space which curbs good air and water flow. Continuous use of heavy machinery causes soil compaction which makes it difficult for microorganisms, earthworms and small insects to breed. This also results in poor internal drainage, creates possible run off, inhibits root development and breeds unhealthy plants. Soil compaction also causes water that enters the surface of the soil to be perched on the sub surface of the soil, saturating and ponding the surface of the soil while by right it should have permeated into the soil. Thus soil compaction has a destructive effect on the soil and the environment.

Smoke from these machineries also pollutes the air which is not only detrimental to health but causes chemical pollution of the crops in the form of acid rain. Apart from that, pollution caused by these machineries causes depletion of the ozone layer. In some underdeveloped countries, the stalks of annual crops are burnt after the crop has been harvested, which releases carbon dioxide into the atmosphere. The natural biodiversity of plants, animals and microbes function in many ways to enhance the quality of life enjoyed by the human beings. But in the process of providing food for the human beings, biodiversity has taken a back seat. In the case of rice, vast areas of wetlands have been drained to plant rice which upsets the pre-existing biodiversity. The same goes to vast tracts of land in North and South America where prairies have gradually been converted into field growing crops such as wheat and maize. The conversion of these areas have totally eradicated some indigenous plants and animals. The wild population of the American bisons that inhabited the prairies were practically eradicated in the process of establishing large farms to grow wheat to feed the American population. Historically they ranged across half of North America and numbered in the millions before being reduced to a countable number within a period of two centuries. Their habitat which were the grassland and meadows that were the former prairies have made them an endangered breed of animals. Establishing such farms did not just upset the ecosystems that had been in place there but also caused a gradual extinction of a breed of animal that is part of the American history.

How land is used to produce food can have an enormous effect on the environment and its sustainability. Environmental groups in the United States have mounted attacks on fast food chains such as Kentucky Fried Chicken (KFC) and Pizza Hut because of the adverse effects these organisations have created in the food production chain in the country. Intensive breeding of livestock and poultry for the restaurants have resulted in deforestation in countries such as Brazil, land degradation, and the contamination of water and other natural resources. For every pound of red meat, poultry, eggs and milk produced, farms fields in these countries lose about five pounds of top soil of their field. The water used for meat breeding comes to about 190 gallons per animal per day or ten times of that used by an average family. Overall, animal farms use about 40% of the world’s total production of grain and nearly 50% of the grain production in United States goes towards feeding livestock, not hungry mouths elsewhere in the world. (Source: South End Press, 2000). The demand for these crops are so great that genetically modified (GM) food crops are planted in some developed countries to meet the demand for them. While the peril of genetically modified crops are yet to be seen in the long term, there is already strong resistance from some Western NGOs and protests have been mounted against planting and exporting of GM crops. New concepts such as industrial agriculture have also been mooted so that production of food crops can be enhanced to meet demand for such food products. Planting of food crops is no longer considered essential farming but is increasingly viewed as production of a commodity to meet the demands of customers such KFC and Pizza Hut.

Much of the best agricultural land in the world is used to plant non food crops such as cotton, tobacco, sugar cane, cocoa and food flavour cum oil extractant crops such as soya bean. Soya bean has been found to be the cause of extensive clearing of forest land in South America. Used as a fodder and oil extractant, it requires more than four hectares to produce the same amount of oil extracted from every hectare of oil palm land. In other words for every one hectare of oil palm land you need more than four hectares of land to produce a similar amount of oil from soya bean. So extensive is the use of land and machinery in cultivating this crop in Brazil that vast areas of land in the Matto Grasso and Para districts has been cleared to plant this crop. What was once a thriving ecosystem supporting more than 300 tree species per hectare has been destroyed with the conversion into soya bean farms. The whole process of the cultivation of the soya bean crop from planting to harvesting is fully mechanised and the use of sophisticated machineries causes severe damage to the top soil and the environment. In the past three years nearly 70,000 hectares of primary rainforest has been destroyed to plant the crop. Big earth movers are sent into the jungle to bulldoze the forest trees and then the logs are dumped into pits and burnt. The trunks take weeks to burn and the smoke smoulder for months causing environmental pollution. Brazil produced more than 50 millions of soya in an area of about 23 million hectares and has overtaken the US as the leading producer of soya bean. (Source: Common Dreams. Org. July, 2006)

On the other hand, tree crops cause minimum damage to the environment through the minimal use of machines. Limited usage of mechanical equipments is one of the reasons for tree crops means less pollution to the environment. The most common piece of machinery used is the farm tractor, utilised mainly for the transportation of planting materials and harvested crops. Thus, there is no continuous use of machinery such as those used in annual crops which is heavily utilised through the entire cultivation process.

Another key factor to note is that tree crops have a lifespan ranging from 15 to 25 years thus causing minimum disruption to the soil surface. Once planting has been carried out, the soil is not tilled again until the next planting. In the case of oil palm, replanting is carried out only every 25 years giving the soil ample time to rejuvenate. Within this period, microorganisms that enrich the soil are able to reestablished. Apart from that, minimum disruption to the soil means other organisms such as earthworms and insects are allowed to breed and there is a continuous process of soil enrichment which does not occur with annual crops.

With environmental friendly approaches such as ‘zero burning’, oil palms are felled, mechanically shredded and left to decompose in the soil. By avoiding open burning, there is little disruption to the top soil and microorganisms thus helping to maintain the soil fertility. Oil palms and other tree crops also provide ample space for flora and fauna to flourish during the establishment and subsequent stages of growth of the trees. Compared to other oil producing crops, a hectare of oil palm produces 10 times more oil than other crops and an average yield of between 4- 5 tonnes of crude palm oil per hectare makes oil palms the most efficient oil bearing crop and the most efficient crop in the world.

In conclusion, Deforestation Watch (http://www.deforestationwatch.org) has found that tree crops such as oil palm plantations are 'perrenial’, providing more biodiversity and are more environmentally friendly when compared to annual crops such as soya bean. Thus, agriculturists and environmentalists normally show a predilection for and embrace tree crops and plant these whenever possible. THE END.

I really like the idea of green manure crops. You grow some vegetative crop up to a certain point and then take your tiller and work it all into the soil. This operation probably takes a rear tine tiller like one of the Troy Bilt series tillers. I think it is a wonderful thing for the soil. Years ago, when I was working on this farm, I went to a farmers place over in Eastern Illinois. He was giving a seminar of sorts at his farm about using rye as a green manure crop on his farm. He would plant it in the fall after his crops were out and then in the spring he would work it all into the soil. It was a great idea but the only problem with it that I saw was if you had a wet spring it would take forever to dry out to the point where you could work it in. Then if you had to wait too long your whole crop would be late getting planted. I tried it one year in my own garden. In early spring I had a very nice dense cover of thick rye. But the wait for it to dry out to where it could be worked was interminable.

One of the best things I have used for green manure is buckwheat. You can plant it when it is warm. Just broadcast is and go over it lightly with the tiller. It does not take too much moisture to germinate so it is good to plant in the summer. It grows fast. If you let it go to flowering the bees in the area will really like it. I usually let it flower for a while just to show my appreciation for the bees work and then till it all under. It is a great soil builder. It does not take much seed to cover an area. The best place to find buckwheat is at a health foods store. Or if you live in an area where buckwheat is grown commercially you could probably get some at an elevator.

Another green manure crop that is worthwhile is soy beans. I would broadcast seed them and lightly till them under. Plant them thick. They do not grow as fast as buckwheat but they do fix nitrogen into the soil. You could also get soybeans at a health food store or probably get a bucket full from a local farmer or elevator.

One of the easy green manure crops I use are weeds. In the spring I will usually work the entire garden as early as possible. Each year I try to have part of the garden not raise anything for the whole year. So I let that section begin to grow weeds. When the growth is good and robust I work them into the soil. You have to be careful to not let them go to seed. But as much growth as possible is good. I can usually do this a couple of times a year on the garden section I am working on. I may in the fall plant something in that section or maybe not. During this period I may put some horse manure on or any other fertilizer materials I might have.

Green manure crops are something everyone should try. They improve the soil tilth and generate material for earth worms and soil bacterial and fungi to thrive on.

Blue and green mold are two of the most important post-harvest diseases that can affect a citrus crop.

The infection that occurs the most frequently is green mold and it is caused by the mold Penicillium digitatum. It exists in all citrus fruit growing regions and is a serious threat to the citrus industry.

When the fruit is bruised or punctured while it is being harvested or packed, the mold enters the fruit through these wounds and therefore, this disease can be contracted by fruit on the tree, in the packinghouse where the fruit is prepared for the market, while in transit to the store, in storage, and the retail store.

At first, only a white mold is seen growing on the outside of the fruit and later begins to turn green due to the large amount of spores that are being produced on the surface of the fruit. The fruit begins to decay and become soft. It shrivels up and dies as a result.

Blue mold is caused by the fungus Penicillium italicum and it is different from green mold mainly because of the color. The conditions that the two molds grow in are very similar and tend to grow best at around 75 degrees Fahrenheit.

Their growth is slowed by lowering the temperature and cooling fruits while they are being stored and shipped are a good way to decrease the amount of infections in a shipment. Losses from these molds can also be greatly reduced by taking special care during harvesting and transporting not to bruise or break the skin of the fruits.

Fruits mainly become infected when their outer skin is broken and mold spores make their way inside either from contaminated soil, another infected fruit, or through the air. Fungicides can also be used to reduce the amount of infections. Also, any equipment used to pack the fruit and anywhere they are stored should be sanitized every day to reduce the chance of the fruit becoming infected.

The spores of both of these molds are very easily spread by air currents and any fruits that are contaminated with them should not be exposed to wind or other currents of air near any healthy fruit due to the likelihood of it becoming infected.

Fruits can also become infected due to other physical injuries such as those associated with stem-end rind breakdown and chilling injuries.

Why is it that stupid ideas find so many followers? European Governments, the US Federal Government, and an increasing number of US State Governments have issued legislation that requires the use of ethanol in cars.

Making ethanol from corn was promoted by the US agricultural lobby as the best approach for producing biofuels. None of the decision makers listened to the advice of scientists, who pointed out correctly, that the benefits of ethanol were minute. Ethanol is incapable of reducing consumption of petroleum-derived fuels and of reducing greenhouse gas emissions. Almost all of the food producing acreage in the US must be converted to growing corn before a sizeable reduction in foreign petroleum imports can be expected.

For the agricultural lobby the financial rewards of the ethanol craze have been spectacular. When future prices of corn began to escalate, more and more farmers decided to plant corn in favor of other crops like soybean and wheat. Predictably, food prices started soaring.

Now we must deal with the sorry political mess that the ethanol subsidy of the US Federal Government has left behind. Poor countries have been hit hard with escalating prices for grains and other basic food staples. Protests are growing across the globe demanding price reductions or price controls. Demonstrations are stoking social unrest in many countries. Demands are growing to prohibit the production of biofuels altogether.

What originally began as an effort to reduce greenhouse gas emissions and an attempt to reduce consumption of fossil fuels and petroleum, may instead be perceived as a worldwide failure of renewable biofuels. Such result would be unfortunate and ultimately disastrous.

We know for sure that petroleum reserves are getting scarce and will be depleted soon. We know for sure that global warming is caused by greenhouse gases produced by fossil fuel combustion. We know for sure that economies will begin to fail, when liquid motor fuels become scarce and unaffordable.

We must replace fossil petroleum sources with an alternate source for liquid fuels or world economies are doomed to fail and contract. Only biomass meets the requirements for such a new energy source. However, virtually all the biomass crops, which are being used, have one common shortcoming. Instead of using plants with exceptionally high energy yields, we are converting low-energy food crops into ethanol, a low-energy fuel.

Only high-energy crops can become the savior of our huge transportation sector. The wellbeing of this sector is absolutely vital for the continuing functioning of world economies. Famines will result if we convert instead low-energy food crops into liquid fuels. There are not enough arable lands on this Earth to provide food for an additional three billion people during the next fifty years and grow simultaneously sufficient amounts of low-energy biomass for replacing petroleum as source for liquid motor fuels.

Substitution of petroleum with motor fuels derived from coal or oil shale is not sensible, either. These synthetic fuels will increase greenhouse gas emissions and will accelerate global warming. Therefore, there remains only one single choice for securing the supply of affordable transportation fuels; we must learn to convert high-energy biomass into standard motor fuels.

This will involve the development of new approaches and new technologies for finding, breeding, and growing high-energy crops on fallow and arid lands. We must protect tropical and primal forests and we must assure that arable lands are sustained properly. Arable lands will become scarce and must be protected from exploitation.

The world has huge areas of deserts and arid lands with exceptionally high solar irradiation. We must learn to grow biomass with high-energy yields on these ignored and neglected lands. We must develop new irrigation and cultivating technologies for arid areas and we must learn how to achieve high-energy biomass harvests without excessive water use and without the wasteful and expensive fertilizer runoff.

High-energy plants need plenty of sunshine. We must breed new high-energy plant hybrids and we must develop new agricultural techniques that are effective under these adverse conditions. We must prevent exploitation of forests across the world and we must find ways to protect and preserve tropical and primal forests.

It is mandatory that we bring the recent inflationary wave of food prices under control soon. It is important that we prevent any speculative manipulation of grain prices and that we avoid any irrational reactions to this artificial food crisis.

Above all, we must not blame the concept of renewable biofuels for the artificially created food crisis. Liquid fuels from biomass are our only hope for simultaneously controlling global overheating and preventing hyperinflation of liquid fuel prices.

If we fail to succeed in this crucial and fateful endeavor, we must prepare the world for the collapse of world economies and the disappearance of civilizations.

Companion planting in your vegetable garden is a great way to increase the size of the crop you will have when it comes time to harvest. The right combination of vegetables planted together improves growth, reduces disease, encourages beneficial insects to thrive in the garden, and discourages pests.

But companion planting vegetables does have it's drawbacks, as some vegetables are much more fussy than others about who they are planted next to. This simple guide will help you with a few of the more common combinations you should keep in mind when companion planting vegetables.

Asparagus get on well with most vegetables, but their ideal companions are tomato, parsley and basil.

Bush beans like potatoes, cucumber, corn, strawberries and celery, but hate onions. On the other hand, pole beans are a little more selective – they only like corn and radishes, and hate beets as well as onions.

The cabbage family (broccoli, brussels sprouts, cabbage, cauliflower and kale to name a few) like many companions - beet, celery, cucumber, lettuce, onion, potatoes and spinach. But they have a few hates as well - dill, strawberries, pole beans and tomatoes.

Carrots get on well with a wide variety of vegetables - peas, lettuce, rosemary, onions, sage and tomatoes. Just keep them away from dill.

Celery is also a very accepting vegetable, liking onions, the cabbage family, tomatoes and bush beans. Like asparagus, they don't hate any vegetables.

Keep your corn away from tomatoes, but to keep it happy plant it near potatoes, beans, peas, pumpkins, cucumber and squash.

Cucumber doesn't like being near aromatic herbs or potatoes, but plant it near beans, corn or peas and it will be happy.

Lettuce is an accepting plant, not hating any vegetables but appreciating being planted next to carrots, strawberries and cucumbers.

Onions generally like being planted next to beets, carrots, lettuce and the cabbage family, but keep them away from beans and peas if you want good results.

Peas like being planted next to carrots, turnips, cucumbers, corn and beans, but be sure to not plant them near onions or potatoes.

Speaking of potatoes, you should plant them near beans, corn and members of the cabbage family for best results, and make sure they are away from pumpkins, squash, tomatoes and cucumbers.

Finally the humble tomato - one of the more popular summer vegetables for the gardener to grow. For the best results plant them near onions, asparagus, carrots, parsley or cucumbers, but keep them well away from potatoes or members of the cabbage family.

This isn't a fully comprehensive list – obviously there are many more types of vegetables available for you to plant in your vegetable garden, and this article could easily double or triple in size if we tried to include everything. But this list of the more common vegetables should be a good start in helping you plan the layout of your vegetable garden for the next year.

So give companion planting in your vegetable garden a try. You'll find you'll have happier, healthier plants in your vegetable garden, which in turn will give you tastier vegetables to feed you and your family.

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.
Considering importance of nematodes in the integrated pest management system, following low input plant protection technologies viz. summer ploughing, soil solarization, organic manuring, crop rotation, adjusting dates of sowing, growing resistant varieties, irrigation management, optimum fertilization, hot water treatment, clean cultivation, green manuring, inter/mixed cropping, judicious use of pesticides, integration of two or more above mentioned methods (Gaur &Khan,1995) could be adopted for managing insect pest, diseases including nematodes in the crop production system.
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
The seedlings of many transplanted vegetables crops can be dipped in systemic nematicides like oxamyl, prophos, and dimethoate at 500 to 1000 ppm for six hours to denematize the roots. These practices will further ensure to protect the root system of tender seedlings from early attack of nematodes. The seedlings of transplanted vegetables like brinjal, tomato, chilli and planting materials of pointed gourd treated with carbosulfan (Marshal 25 EC) at 500 ppm for six hours provided effective control against root-knot nematodes. Nursery bed treatment with carbofuran at 0.3g a.i./m2 coupled with seedlings deep with carbosulfan 25 EC at 500pm before transplanting effectively manage M. incognita and enhance crop yield in vegetables.
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) 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
? Scheduling crop rotation with non-host crops as cauliflowers, sesame, groundnut, onion, maize, soybean, cowpea
? Weeding: Rice fields supports a diverse kind of weeds like Echinochloa spp., Eleucine indica, Paspalam scrobiculatum, Cyperus spp. etc.
? Resistant varieties: CR-143-2-2, CR-147-2-1, CR-1009, CT-428, Sudha, Murti
Chemical approaches
? Seed soaking with carbosulfan (Marshal 25 EC) at500ppm or Carbosulfone at 0.1% for 12hrs
? Bare dipping in carbosulfan (Marshal 25 EC) at 500ppm for 20 minutes
? 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 in high temperature of May-June (35-45 0 C) as well as low temperature of December-January (8-12 0 C) in the North Indian conditions (Mathur & Prasad, 1973). Their survival in soil is much longer than in roots in flooded soils. H. oryzae can survive more than 12 months in wet soils. A number of weeds found in rice fields serve as alternative host for this nematode. In West Bengal, the nematode can survive in the months of summer in the absence of any crops under laterite soil conditions (Khan & Mukhopadhyay, 2002). Under rice-wheat cropping system, the nematode maintains a very high population, though wheat is not the host for the nematode. Spread of this nematode occurs mainly through irrigation water, flood water, soil adhering to farm implements, field workers and root of rice seedlings.
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
? Early planting of rice in the month of June or middle of July
? Use of organic amendments such as mustard cake or neem cake at 220-240 kg/ ha
? Balanced NPK fertilization
? Crop rotation with wheat, linseed, potato, cauliflower, mustard and gram in rabi season
? Deep dry summer ploughings
? Weeding during standing rice and in absence of the crop
? Growing resistant varieties/cultivars: TKM-9, CR-142-3-2, CR-52, N-136, W-136
? Sesbania rostrata can be used as trap crop for H. oryzae
Chemical approaches
? 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
? Bare root dip treatment with chlorpyriphos/ carbosulfan 25 EC / monocrotophos 36 EC at 1000-2000ppm for 20 to 30 minutes
? 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
? Destruction of rice stubbles, weeds and wild rice in the rice fields
? Crop rotation with jute, sesame, mustard with rice
? Summer ploughing helps nematode to destroy by desiccation in the scorching heat of sun
Growing early (Padmapani) or resistant (Rayada selection) varieties (Prasad et al., 2001)
Chemical approaches
?
? Spraying with diazinon at 0.01%
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).
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
? Healthy rice seed checks the spread of white tip disease of rice
? Rice stubbles to be burnt or destroyed after harvesting
? 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
? 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
? 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
? Soaking of seeds with phenamiphos at 0.02% for 6 hours
? Soil application of carbofuran or phorate 1kg a.i. /ha at 7 and 50 DAT
? Growing resistant varieties like Lalnakanda, CR143-2-2
? 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 0 C 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
? Nursery raising of seedling should be free from nematode infection
? Previously infested citrus orchard should be either avoided or fumigated to kill any nematode population in soil.
? Preventing run off water from adjacent infested citrus orchard
? 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
? Application of oilcakes of neem, mahua, groundnut etc. at 1kg/plant can reduce nematode populations.
? Combined use of neem cake at 1kg /plant along with carbofuran 3G (Furadan) 1.0 kg a.i./ha is also effective.
? 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).
? 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).
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
? 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.
? 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).
? 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.
? 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.
The symptoms of damage to crops are non-specific on the above ground or even in the below ground parts necessitating a close observation to confirm their presence and damage. It feeds on cortical tissue, phloem and pericycles and its infection may cause formation of necrosis on roots of certain crops. Symptoms appear as root discolouration, shedding of the leaves and formation of malformed fruits and seeds. In addition to causing direct damage to plants roots, the nematode in concert with other pathogens like Fusarium spp., Verticillium spp., Sclerotium rolfsii and Rhizoctonia solani develop diseases complexes. It has also been reported to parasitize the bacterial nodules.
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 moult occurs within eggs and eggs are hatched in water without the influence of root exudates. Juveniles develop to pre-adult stage without any feeding host tissue and quickly completing three superimposed moulting. The young female is the only infective stage. After infection to the roots, young female orient themselves perpendicularly to the longitudinal axis of roots with the posterior part remain outside the root. After establishing the feeding site, it develops into kidney shaped female with posterior portion protrude outside the root. Egg laying starts within 7-10 days after invasion and eggs are laid into a gelatinous matrix secreted by six specialized cells around vagina. Each egg mass contains 30-200 eggs. Total life cycle is completed within 3 to 4 weeks depending upon 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
? Summer ploughing of field reduces nematode populations
? Application of carbofuran (Furadan 3G ) at 1 kg a.i./ha at sowing reduces crop damage caused by soil nematodes
? Growing antagonistic crop like marigold (Tagetes patula) cv. Harmony in autumn after main crop or in between rows of main crop.
? 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 acce