The book is intended as a text book for undergraduate students of agriculture and post graduates specializing on Nematology, Plant Pathology and Agricultural Entomology.
This book covers all aspects of Plant Nematology which includes an introduction covering the importance of nematodes in Agriculture and Horticulture, estimated loss due to the damage of nematodes.
The book provides a brief account of historical background including the developments in India and abroad. Morphology and taxonomy are dealt in detail covering general morphology, structural and functional aspects of nematode morphology with vivid diagrams. Nematological techniques are dealt in detail with suitable diagrams.
Anatomy and Physiology of plant parasitic nematodes have been elaborately covered with details of digestive, reproductive, excretory and nervous system with appropriate diagrams.
The nematode classification based on their feeding habits and interactions of nematodes with microorganisms viz., fungus, bacteria and virus has been provided. Nematode management in important agricultural and horticultural crops with photographs of root and foliar symptoms are dealt in detail.
Exclusive chapter on all the methods of management like regulatory, physical, chemical, cultural, biological and host plant resistance are provided. The book also provides a brief account of Entamopathogenic nematode and also on the nematode Caenorhabitis elegans which is being used as a biological model in most of the biological research as on today.
Appropriate examples schematic diagrams, pictorial keys and glossary are used to describe nematode taxonomy, biology and life cycle. In this revised edition all the information have been updated with appropriate information with suitable pictures.
Nematodes are a complex, diverse group of round worms that occur worldwide in essentially all the environments. Plant parasitic nematodes are recognized as serious pests of crop plants in recent years. The world-wide annual crop loss due to these obligate parasites have been estimated as $ 78 billion. The damage caused by nematodes are often overlooked. They are hidden enemies and the associated symptoms can also be attributed to nutritional and water related disorders. The epidemics of sugarbeet sickness due to cyst nematode, yellow disease of black pepper, molya disease on wheat and barley, the ar-cockle disease on wheat and others have led to the recognition of the science Plant Nematology as an important branch of Agricultural Sciences. The recognition of nematodes as serious detevrrents to crop productivity was felt in India only in the 1961, when Dr. Jones from Germany reported the menace of potato cyst problems were identified in important crop plants. Compared to other disciplines of crop protection, Plant Nematology is the youngest deserving tremendous support to strengthen the discipline.
Agricultural crops are being affected by a wide range of organisms such as insects, mites, fungi, bacteria etc. Another important and unseen enemy is known as plant parasitic nematodes. The study on nematodes is known as Nematology.
In light of the high population of nematodes, N.A. Cobb (1915) who is considered to be the father of American Nematology, provided a dramatic description of the abundance of nematodes. He stated, “if all the matter in the universe except the nematodes were swept away, our world still would be dimly recognisable.
Eventhough nematodes occupy nearly every habitat on earth, they are remarkably similar in morphology and life stages. Despite their structural complexity, certain basic principles are common to all nematodes. Nematodes are triploblastic, bilaterally symmetrical, unsegmented, pseudocoelomate, vermiform and colourless animals.
Life cycle of nematode has six stages. The egg stage, first stage juvenile (J1), second stage juvenile (J2), third stage juvenile (J3), fourth stage juvenile (J4) and the adult stage.
Plant parasitic nematodes cause serious problems in sustained crop production. For a successful management of nematodes, their morphology, biology and host - parasitic relationship should be thoroughly studied. A thorough study is achieved only when its taxonomical position is known. Thus, in a simple way taxonomy can be defined as the theroretical study of classification of an organism.
Sampling for nematode communities has been the basis for the development of appropriate control strategy. The major purposes of sampling for nematodes include population estimation for general detection, advisory or predictive programme, disease diagnosis and also for research purposes.
The nematode feeding on plant can be divided into above ground feeders and below ground feeders.
Most of the plant parasitic nematodes affect the root portion of plants except Anguina spp., Aphelenchus spp., Aphelenchoides spp., Ditylenchus spp., Bursaphelenchus cocophilus and B. xylophilus. Nematodes suck the sap of the plants with the help of stylet and causes leaf discolouration, stunted growth, reduced leaf size and fruits, lesions on roots, galls, reduced root system and finally wilting.
Plant parasitic nematodes favour the establishment of secondary pathogens viz., fungi, bacteria, virus etc. The nematodes alter the host in such a way that the host tissue becomes suitable for colonization by the secondary pathogens. Even though the nematodes themselves are capable of causing considerable damage to the crops, their association with other organisms aggravate the disease.
Plant parasitic nematodes cause serious damage to rice crop. Thirty two species belonging to 13 genera were observed in association with the crop. Among them few are considered to be important. They are the rice white - tip nematode (Aphelenchoides besseyi), rice stem nematode (Ditylenchus angustus), rice root nematode (Hirschmanniella oryzae), root-knot nematode (Meloidogyne graminicola) and the cyst nematode (Heterodera oryzicola).
Citrus is an important fruit crop and ranks third in area which is followed by mango and banana. They are grown in 105,396 hectares in India. Among the oranges, mandarin oranges, limes and sweet oranges are very popular while lemons, grape fruits, pummelos, sour and bitter oranges are of minor importance. The Citrus spp. are grown in larger extent in the states of Maharashtra, Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Punjab, Haryana, Rajasthan, Assam, Orissa and Bihar.
Potato is one of the most important vegetable crop grown in India. It thrives best in cool climate. Therefore it is a summer crop in the hills and a winter crop in plains.
Crossandra (Crossandra undulaefolia) is one of the important commercially grown flower crop in Tamil Nadu. In recent years there is a marked decline in the cultivation of this crop in Madurai, Dindigul, Coimbatore, Salem, Thiruvannamalai and Tiruchirappalli districts. The common problem with the crop is death of plants in patches during the second and third year. This is due to the nematode-fungal complex disease in the crop.
Black pepper (Piper nigrum) is indigenous to the tropical forests of Western Ghats of South India. The crop is grown in Kerala, Karnataka, Tamil Nadu, Andra Pradesh and Assam.
Plant parasitic nematodes can be controlled by several methods. The nematode control aims to improve growth, quality and yield by keeping the nematode population below the economical threshold level. The control measures to be adopted should be profitable and cost effective. It is essential to calculate the cost benefit ratio before adopting control measures.
Nematode associated with insects are referred as entomophilic, entomogenous and entomophagous nematodes. Generally they belong to the superfamilies Tylenchoidea, Rhadbitoidea, Oxyuroidea and Mermithoidea of the phylum Nematoda.
Model organisms are widely used in biological researches to describe basic biological processes. When selecting living organisms as models to work with, a wide range of characteristics are used which include: 1) rapid development with short life cycles, 2) small adult size, 3) ready availability and 4) tractability.
Andersen, S. 1956. Collection of cysts of Heterodera major and estimation of the cyst content. Nematologica, 1: 303-306. Anon, 1971. Estimated crop losses due to plant – parasitic nematodes in the United States. Special Publ. No.1, Suppl. J. Nematol., 7 p.
1. Who is considered as the father of American Nematology? 2. The first record of plant parasitic nematode was made by _________ in the year __________. 3. Mention the contribution of the following Nematologists. - de Man - Carter - Atkinson - Christie - Goodey- Triantophyllou
