This chapter describes how knowledge of epidemiology helps in understanding the seed-transmitted virus disease spread and in framing suitable management measures.Seed infection is epidemiologically important as this is the primary source of inoculum and forms the starting point for the initiation of the disease. The epidemics of the virus diseases in a particular region are the result of complex interactions between various physical, chemical and biological factors, and major epidemics occur when conditions influencing the virus, host and its vector synchronise. The virus disease epidemics depend on the interaction of four components, namely, the pathogen, the vector, the plant and the environment. Among the seed-transmitted viruses, some have limited host range and some others have wide host range. Either annual or perennial or both are affected with virus diseases. Under field conditions, the weed and wild hosts are important as they are the reservoirs for the virus, vector or both. Survival of the virus in the seed for a long period also plays an integral role in virus perpetuation in off seasons. Seed-transmitted viruses are also vector specific, and aphid or beetle or nematodes or fungi play major role in causing epidemics based on the time of emergence, light, humidity, temperature and wind velocity, and abundance of vector population is a significant factor that determines spread of virus diseases both in time and space. Vectors also may have limited host plants or may be polyphagous. The time and number of vectors visiting the crop varies considerably with species over years. Pollen and seed transmission are closely related factors in virus epidemiology. A number of virus diseases spread horizontally through pollen in a number of fruit and vegetable crops. The epidemiology of virus diseases also depends on different pathogen strains which vary in virulence, host range and transmissibility. If the forecasting system is developed against a particular virus disease, it will help to operate an early warning system or to select growing season or areas for crop growing. Examples of how epidemiological information can be used to develop effective integrated disease management strategies for diverse situations are described.K.S. Sastry, Seed-borne Plant Virus Diseases,

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It is a real pleasure to be invited to write a Foreword to this important and timely Encyclopedia as I have been involved in many similar earlier projects whose products are now sadly out of date: the CMI/AAB Descriptions of Plant Viruses, which Bryan Harrison and I started in 1970, and later the VIDE database, which morphed into the ICTVdB under Cornelia Büchen-Osmond. Furthermore, I am the sole survivor of the first committee of the International Committee on Taxonomy of Viruses (ICTV). It was elected at the Moscow Congress in 1966 and initially called the Provisional Committee on Nomenclature of Viruses. So I bring blessings from that august heavenly band! All of these earlier efforts by hundreds of virologists were the antecedents of this magnificent Encyclopedia.The careful collation and presentation of biological information of individual viruses and viroids is as important as ever for a variety of purposes. It is required for identifying novel pathogens and is also required for devising useful names for them. Note that virus and viroid species are man-made groupings, namely, "related strains/isolates, which are so similar that it is most convenient to know them by a single name." Recent advances in molecular biology allow the genomic sequences of all subcellular pathogens to be determined routinely, and although numerical relationships can be calculated from those sequences, and used to form arbitrary categories, phenotypic information is indispensable for interpreting that information to form the most useful groupings to be given single names. This is clearly recognized by the 2018 ICTV Code of Nomenclature which includes the recently modernized Rule 3.20 and states "A species is a monophyletic group of viruses whose properties can be distinguished from those of other species by multiple criteria." Arbitrary boundaries between taxa based on sequence similarity are not enough; biological (phenotypic) attributes are just as important.Up-to-date well-ordered information is also required by field pathologists, researchers, and, especially, those trying to devise control measures that minimize the economic damage caused by plant virus and viroid diseases. Appropriate integrated control programs must be based on accurate scientific information on the biology, mode of spread, etiology, and geography of pathogens. Finally, one must vii recognize the value of this Encyclopedia for the training of students, who are the scientists, pathologists, politicians, and administrators of the future.The plant viruses and viroids listed by the ICTV are only the tip of the iceberg, as the number of identified plant pathogens, including viruses and viroids, is growing at an alarming rate as they "emerge" from wild and local hosts and spread worldwide in the ever-increasing global trade in plants. Primary reports appear in the traditional journals and in metadata, like the CABI Crop Compendium, but a few are also recorded in such open-access databases as Wikipedia. Hence, there is a need for publications of multi-sourced and "di...

Alkali extracted mycelial biomass from Aspergiilus niger, referred to as Biosorb, was found to sequester metal ions (Cd z § Cu z § Zn z § Ni 2 § and Co z § efficiently both from dilute and concentrated solutions upto 10% of its weight (w/w). Sequestration of metal ions from a mixture was also efficient but with attendant antagonisms. The kinetics of metal binding by Biosorb indicated that it is a rapid process and about 70-80% of the metal is removed from solution in 5 min followed by a slower rate. The mechanism of metal binding is shown to be due to exchange of calcium and magnesium ions of the Biosorb during which equimolar concentrations of both the ions were released into the medium. Following this an efficient procedure for the regeneration and reuse of Biosorb was standardized by washing the biosorbent with calcium and magnesium solution (0.1 M). Biosorbents prepared from Neurospora, Fusarium and Penicillium also exhibited similar mechanisms for metal ion binding, though they had a lower metal binding capacity when compared with Biosorb. Chemical modification of carboxylic acid functional groups of the Biosorb resulted in loss of 90% of metal binding capacity which could not be restored even on regeneration. The significance of this finding on the metal sequestration mechanisms of microbial biosorbents is discussed.

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