eChapters

Safety is a primary concern regarding traditional and complementary therapies. There are two aspects of safety evaluations. First, to ensure that the right quality of material and apt possesses are used from sourcing to marketing; and second, there is no contamination, adulteration or spiking. Few studies have reported adulteration with steroids in some traditional Chinese dermatological preparations. In an analysis of Chinese herbal creams prescribed for dermatological conditions, Keane et al. found that eight of eleven creams analyzed contained steroids194. Spiking with corticostreoinds has been observed in some market preparations claimed to be useful in the treatment of arthritis and asthma195. Recently, Saper et al. from Harvard Medical School have reported heavy metal content of Ayurvedic herbal preparations and have recommended mandatory toxic heavy metal testing196. There have been few reports of heavy metal toxicity following traditional medicine use197,198. Such studies are important and needed, however they are more related to the quality control failures of the mass manufacturing activities. Often they are wrongly used to limit the use of TM. In reality, such a QC failure should not be considered as a general negative notion to create a bias against TM. We certainly need effective QC and regulation of herbal medicines, without limiting public access to these preparations and ensuring public interest and constituting restrictive trade practice.

Despite its existence and continued use over many centuries, and its popularity and extensive use during the last decade, traditional medicine has not been officially recognized in most countries. Consequently, education, training and research in this area have not been accorded due attention and support. The quantity and quality of the safety and efficacy data on traditional medicine are far from sufficient to meet the criteria needed to support its use worldwide. The reasons for the lack of research data are due to not only to health care policies, but also to a lack of adequate or accepted research methodology for evaluating traditional medicine235.

The statement from General Guidelines for Methodologies on Research and Evaluation of Traditional Medicines (World Health Organization, 2000) highlights the need for consensuous in addressing the problems related to the quality of botanical drugs, which ultimately is a critical determinant of safety and efficacy of medicine. Further, the distribution and widespread sale of adulterated, misbranded, spurious botanical drug products and marked increase in misleading health claims of these products demands proper regulations on botanical medicine to protect public health236. Considering these two issues development of parameters for quality control standardization and regulatory norms for controlling the growing business of botanicals is a big task. Various regulatory authorities, research organizations and botanical drug manufacturers are constantly contributing to developing guiding principles addressing issues related to quality, safety and efficacy237. In this chapter we have highlighted problems associated with quality control of the botanicals and tried to guide a way towards a globally acceptable quality standard.

Typically herbal pharmaceutics may include any medicinal or functional food preparations such as phytopharmaceuticals, single or poly herbal formulations, and nutraceuticals made out of botanical materials. This includes two broad categories. First, there are many evidence based formulations and mixures that may or may not be based on traditional knowledge or practices. The second group includes all the traditional or ethnopharmacological preparations. Bringing herbal medications from either group to the market will require a pharmaceutics approach balanced with an understanding of the original context in which the treatment was used.

As an example, Ayurvedic medicines have been used safely for many years on a wide variety of patients. Medications that have not been altered from their original form have de facto gone through a type of safety testing. When a traditional medicine is prepared differently, then it is essential to validate the drug safety to be sure that the effects of the new procedure don’t cause harmful effects. In this same way, the value of animal testing to establish safety and toxicity is not as critical if the botanicals are used in traditional forms. Suitable animal models help in understanding the mechanism of action or pharmacodynamics of medicines. However, it is well known that no good animal models exist for many human diseases, such as asthma, diabetes, and rheumatism. The use of modern technology in making traditional preparations more contemporary and scientific is important but it should not compromise the original basis and principles described in tracditional medicine. The following examples highlight some of the concerns of this approach.

The development of a new drug begins typically in the chemistry laboratory and is followed by a wide range of biological studies in vitro (cells/tissues) and in vivo (animals), which forecast what the agent would do in humans. The focus of these studies moves from evaluating the safety of a drug for use in humans to looking at its clinical relevance. Pharmacodynamics involves a set of biological studies both in vitro and and in vivo to get a better understanding of the mechanism of action of a drug. Preclinical studies mainly include safety and toxicity to ensure its safety for use in humans. Typically, preclinical in vitro, in vivo, and Phase I testing may not be necessary if preliminary data on safety are available. However, preclinical data or clinical observations are still necessary to justify a rationale for use and safety in initial clinical studies.

Three main screening approaches are generally used in drug development. Simple Screening evaluates substances that have a particular property by one or two tests. There is no need for a series of tests in which the interpretation of results of one test may depend on others. Blind Screening is used for a new plant extract where no adequate pharmacological information is available. Blind screening may give clues for potential activity and worthiness to probe further for pharmacological activities. Programmed screening involves a new plant extract or substance with known pharmacological effects and results in more precise information.

This guidance explains when a botanical drug may be marketed under an over-the-counter (OTC) drug monograph and when FDA approval of a new drug application (NDA) is needed. In addition, this document provides guidance to sponsors on submitting investigational new drug applications (INDs) for botanical drug products, including those botanical products (or botanicals) currently lawfully marketed as foods and dietary supplements in the United States. This guidance also discusses several areas in which, because of the unique nature of botanicals, FDA finds it appropriate to apply regulatory policies that differ from those applied to synthetic, semisynthetic, or otherwise highly purified or chemically modified drugs (including antibiotics). In particular, the guidance states that applicants may submit reduced documentation of preclinical safety and of chemistry, manufacturing, and controls (CMC) to support an IND for initial clinical studies of botanicals that have been legally marketed in the United States as dietary supplements or cosmetics without any known safety concerns.

Review of Health Claims

Regulators of different countries have different procedures and views to review health claims of traditional medicine, herbal medicines, botanicals, functional foods, nutraceuticals, health products, diatory supplements and such other natural forms of materials intended to use for health promotion. However, if such products carry any therapeutic or health benefit claims then the regulators may provide general guidance and demand for sufficient evidence base in support of such claims. For instance, U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition (CFSAN) provides general guidance to review of health claims in functional foods and dietary supplements. Ethnopharmacological preparations involving herbal medicine and traditional medicines prepared from natural ingredients also will need similar process. The scientific review process for health claims of such products is comprehensive and mainly focuses on review of individual studies³²⁴

The main purpose of herbal drug technology is to convert botanical materials into medicines with a focus on standardization and quality control with proper integration of modern scientific techniques and traditional knowledge. The use of chromatographic techniques and marker compounds to standardize botanical preparations has limitations because of their variable sources and chemical complexity. DNA-based molecular markers have utility in fields like taxonomy, physiology, embryology, genetics etc. DNA based techniques have widely been used for authentication of plant species of medicinal importance. Pharmacognosy mainly addresses the quality related issues using routine botanical and organoleptic parameters of crude drugs, and chemoprofiling assisted characterization with chromatographic and spectroscopic techniques. The new pharmacognosy includes all the aspects of drug development and discovery where the biotechnology driven applications play an important role. Current focus on chemotype-driven fingerprinting and related techniques require integration with genotype-driven molecular techniques so that an optimal characterization of botanical materials is possible. This review provides a brief account of various DNA based technologies that are useful in genotyping and quick identification of botanicals with suitable examples.

In the area of pharmaceutical discovery, screening methods continue to play a major role in drug discovery. The screening process is simply testing molecular entities (compounds/natural products) for activity to advance those that exhibit the desired activity. This process has evolved over time in both the testing methods and in the degree of testing. Originally, the screening was done entirely by dosing animals and studying their responses. Then came test tube experiments and now, testing is conducted either with cell lines or with purified proteins in miniaturized test tubes called microplate wells. Screening by microplate has allowed the degree of testing to increase from a very small selected set of compounds to libraries, which contain thousands of test substances. Technological improvements in many areas of science and information technology have led to the evolution of screening methods from time consuming, animal dosing studies to high throughput screening (HTS) methods that have the potential to generate very large datasets of information in a very short time. Today, developments in bioinformatics have opened up the possibility of virtual (in silico) screens for targets where there is sufficient knowledge of the target or of its ligand. High throughput screening has become a pivotal part of drug discovery for identifying potential lead molecules for specific disease targets. The success of screening is measured by several factors including the throughput and costs of the assays, but ultimately by how many of the HTS hits progress forward through the drug discovery pipeline. Miniaturization of assays by conversion from 96- to 384- to 1536- wells to well-less platforms, such as microarrays and the utilization of automated equipments are methodologies implemented to increase the throughput and reduce the cost of the screen.

Genetics forms the basis of human life. All individuals have a physical and physiological self, determined by the interactions of genes and environment. Pharmacogenetics is the connotation used to study how heritability affects an individual’s response to drugs.494 The term ‘Pharmacogenomics’ represents systematic identification of all human genes, their products, interindividual variation and intraindividual variation in expression and function over time. It focuses on candidate genes and may include transcriptome and proteome information that affect drug metabolism, pharmacokinetics, and pharmacodynamics. It helps in predicting the patient’s response to a drug and to design new drugs495. Pharmacogenetics is study of single genes and the effects on drug response while pharmacogenomics is related to overall variation in genome. A gene is considered polymorphic when a mutation appears in more than 1% population, which may be present in the form of single nucleotide polymorphism (SNP), simple sequence length polymorphism (SSLP) and nucleotide addition or deletion. After the Human Genome Project, study in this field is accelerated dramatically. It was found that out of 1.4 million SNPs identified in the human genome, over 60,000 are present in the coding region496. These SNPs lead to miscoding of the various proteins that plays crucial role in the biological processes. If a point mutation is present in the gene coding region for various drug-metabolizing enzymes, drug target and drug transporters, it can lead to many non-therapeutic and unpredictable drug responses. In United States, over two million people suffer from severe adverse drug reactions per year and about 100,000 cases are life threatening497.

Very few traditional systems have a fair level of documentations in place. Most of the little traditions, the flow of knowledge is mainly through word of mouth, however, the great traditions such as Ayurveda and Traditional Chinese Medicine do have a good level of documentation. For instance, Ayurveda means science of life in Sanskrit and aims at holistic management of health and disease. It remains one of the most ancient medical systems widely practiced in Indian subcontinent and has a sound philosophical, experiential and experimental basis541. Charak Samhita and Sushrut Samhita (100-500 B.C.) are main Ayurvedic classics, which describe of over 700 botanicals along with their classification, pharmacological and therapeutic properties542,543. A classic diagnostic text Madhav Nidana includes over 5000 signs and symptoms. During the course of evolution and years actual practice, the interpretation of such documents developed different schools of thoughts and resulted in wide variations in understandings. Similar situation also exists in other systems including TCM. These differences often raise issues related to authenticity and correctness of Traditional Knowledge (TK). Thus systematic documentation, interpretations and harmonization of concepts and practices remain a major challenge in most of the systems of TM. Many governments, professional and community organizations have undertaken such documentation and harmonization exercises. Projects like Traditional Medicine Knowledge Digital Library, AyuSoft, Triskandha Kosha and Medicinal Plants Database of FRLHT are attempting systematic documentation of Ayurveda in India544. Other databases such as The NAPRALERT (NAtural PRoducts ALERT) developed by Professor Norman Farnsworth contain bibliographic and factual data on natural products, including information on the pharmacology, biological activity, taxonomic distribution, ethno-medicine and chemistry of plant, microbial, and animal (including marine) extracts. Another project relates to the Global IP, Benefit Sharing and Traditional Medicine Database. It is being developed as a component of the Global Information Hub on Integrated Medicine from the work of the Commonwealth Working Group (CWG) on Traditional and Complementary Health Systems, now directed by the Malaysian Ministry of Health. This Information Hub is planning to create a network of legal centers, scholars and NGOs working together to develop a comprehensive legislative and policy review, information resource and exchange on issues pertaining to IP rights over traditional medical knowledge and the use of medicinal plants545. Other than such efforts, there is limited systematic documentation of TM knowledge and practices.

The traditional medicines are actually used in human for number of years and therefore its clinical existence comes as a presumption. However, for bringing more objectivity and also to confirm traditional claims, systematic clinical trials are necessary. In Ayurvedic medicine research, clinical experiences, observations or available data becomes a starting point. In conventional drug research it comes at the last. Thus, the drug discovery based on Ayurveda follows a ‘Reverse Pharmacology’ path546.

Nevertheless, all the critical Pharmacopoeial tests such as dissolution time, microbial, pesticide and heavy metals contamination etc. must be in accordance with global standards. It is important to ensure that all the Ayurvedic medicine manufacture is in accordance with Current Good Manufacturing Procedures for herbal products547,548. There have been concerns about quality standards and safety issues of herbal medicines549. The need for new regulations for botanical medicines has also been frequently stressed and some such regulations are coming in force in different parts of the world550,551.

Looking forward, it is clear that traditional and western medicine have the potential for rich collaboration that benefits both disciplines. There is growing interest in this partnership, as shown by the number of international journals now dedicated to such research, such as Journal of Ethnopharmacology, Complementary Therapies in Medicine, eCAM, Alternative Therapies in Health and Medicine, and the Journal of Alternative and Complementary Medicine. Even the WHO has taken note of the rich possibilities of the future of TM, having put out such documents as ‘WHO General Guidelines for Methodologies on Research and Evaluation of Traditional Medicine’ and ‘WHO Guidelines on Good Agricultural and Collection Practices (GACP) for Medicinal Plants’. Despite this enthusiasm, there are several areas where the international community will need to focus their attention if the goal of integrating botanical medicines for the good of human health is to be reached.

A. Diseases

1. Bacterial leaf blight

Occurrence & severity status

The disease Bacterial leaf blight, also known as ‘Bacterial leaf spot’, occurs on white jute (Corchorus capsularis) and tossa jute (C. olitorius) in seed crops of jute at the ICARCRIJAF research farm, Barrackpore, West Bengal, India (Biswas et al., 2013, 2014), in Formosa (Elliott, 1951) and Sudan (Sabet, 1957). The incidence of the disease varies from 25% (Borker and Yamlembam, 2017).

Symptoms

The disease initially appears on leaves as small brown circular spots of 25mm diameter (in tossa jute) or angular brown spots (in white jute), In most cases, the spots are surrounded by a yellow halo and the angular spots coalesce at later stage show larger blighted areas on lamina (Borker and Yamlembam, 2017). The lesions on the stems are elongated; sometimes the spots girdle the stem. The disease on the capsules produces small sunken brown spots. Defoliation and death of the plants may result in severe infections. In the later stages of disease, brown sunken spots were found on the green capsules (Sabet, 1957; Biswas et al., 2013, 2014).

A. Mesta diseases

1. Anthracnose

Occurrence & severity status

Mesta (Hibiscus cannabinus) is very much prone to be attacked by anthracnose disease (Singh, 2014). It is very destructive disease in India (Ghosh, 1983). The disease also occurs in South Korea with overall disease incidence of 20%. (Kwon et al., 2015).

Symptoms

Symptoms on kenaf plants include dark brown spots on the leaves, petioles and stems. New leaves and shoots are most susceptible to infection (Kwon et al., 2015). Initially the terminal bud is attacked, where stipules and young leaves are affected and develop necrotic spots and withers (Singh, 2014). Mature lesions on fully expended leaves are dark brown and often irregular in shape, and not vein delimited. Later, the infected leaves fall off; Flowers and seed capsules are also affected by the disease (Singh, 2010). The stems are affected in patches. On stem the lesions are elongated and black, which later form cavities and in severe cases, stem-dieback or wilt occurs (Singh, 2010; Kwon et al., 2015).

A. Diseases

1. Anthracnose

Occurrence & severity status

The Anthracnose [Fig. 14 (A-B)], also called as ‘Stem-break’, is one of the most serious diseases of sunnhemp (Crotalaria juncea ) in India. It occurs in all sunnhemp growing areas of India (Mitra 1934; Kempanna et al., 1960; Kundu, 1964; Kumar et al., 2016). Apart from India, its occurrence in several countries of South Tropical Africa, like, Rhodesia (Whiteside,1955), Zimbabwe, and other tropical countries including Trinidad and Tobago (Damm et al., 2009), was also noticed as a major disease (Purseglove, 1974). In many places, the disease is considered as the second most serious disease of sunnhemp, causing wilt and weakening of the stem.

A. Diseases

1. Alternaria leaf spot

Occurrence & severity status

In the years 2012 and 2013, black leaf spot disease was observed on ramie plants in Hunan and Hubei Provinces, China (Yu et al., 2016). Yu et al. (2016) claimed that their report was the first report of Alternaria leaf spot of ramie in China.

Symptoms

In the field, the symptoms of this disease included dark green to black big spots on leaves (Fig. 20A), often resulting in upwardly curled leaf margins (Yu et al., 2016).

A. Diseases

1. Anthracnose

Hemp anthracnose is caused by two different fungi, viz., Colletotrichum coccodes (=C. atramentarium) and Colletotrichum dematium (Saccardo, 1882; Cavara, 1889).

i) Anthracnose (Colletotrichum coccodes)

Occurrence & severity status

The anthracnose disease occurs on many plants, including hemp (Cannabis sativa). The disease causing fungus is well-studied and it is an important pathogen responsible for black dot disease on potato. The fungus is an unspecialized pathogen, infecting a wide range of host families. It is most common in Canada and commonly regarded as a minor pathogen or secondary invader, but the fungus may seriously affect yield where intensive cropping without rotation occurs. It primarily affects the growth rate of plants and diminishes harvest. Moreover, it becomes fatal occasionally. Hoffman (1958, 1959) reported heavy hemp losses in central Europe. Conversely, Gitman (1968b) considered the pathogen was of little importance in the USSR.

A. Diseases

1. Anthracnose

Occurrence & severity status

Anthracnose has a serious impact on yield and fibre quality of flax (Linum usitatissimum) and is well-known in Europe, Asia and America. Flax anthracnose increased in Germany when flax production was expanding in the 1930s (Rost 1938). The anthracnose pathogen is seed- and soilborne, causes damping off of flax seedlings (Rost 1938), and is one of the causal organisms of so-called flax-sick soils (Bolley & Manns 1932). It has been recorded in nearly every country where the crop is grown either for fibre or oil. It is known to occur in Belgium, the British Isles, Canada, Formosa, France, Germany, Holland, Japan, Latvia, Lithuania, New Zealand, Poland, U.S.A. and the U.S.S.R. (including Siberia), in most of which countries its incidence has resulted in appreciable crop losses (Muskett and Colhoun, 1947). The disease is most common in cool and humid flax-growing areas (Nyvall, 1989). The disease is destructive to the crop, especially when the seed source is contaminated by the fungus. It can spread rapidly under favourable conditions causing severe local epidemics and heavy losses in yield and quality of both fiber and seed (Mercer, 1992c; Rashid, 2003b). The losses of 50% in fibre yield in an epidemic year were reported by Muskett and Colhoun (1947). Ondrej (1985) indicated a considerable loss in fibre strength on attack by anthracnose.

A. Diseases

1. Anthracnose

Occurrence & severity status

Anthracnose of sisal is also called as leaf spot or ring spot disease. The disease is frequently accompanied with sun scorch in Kenya and Tanganyika (Morstatt, 1930). This is considered as a leaf disease of minor importance, occurring on numerous species of Agave as well as the closely related genus Furcraea, including F. macrophylla Baker (wild sisal). The disease is distributed in warm temperate and tropical regions including southern Europe, British Guiana (Bancroft, 1914), the Neotropics, Cyprus (Georghiou and Papadopoulos, 1957), Kenya (Nattrass, 1961) and USA (Parris, 1959). It is also been reported to occur in various countries of Asia, including China (Tai, 1979), Korea (Cho and Shin, 2004), the Philippines (Teodoro, 1937) and Taiwan (Anonymous, 1979). In India, the disease was first reported as leaf spot caused by Colletotrichum agaves Cav. (Butler, 1905). Its occurrence was also reported from Antigua (Bancroft, 1910) and Puerto Rico (Macedo, 1943). Apart from sisal, the disease also occurs on tomato (Lycopersicon esculentum), potato (Solanum tuberosum) and over 35 other hosts, representing 13 families, chiefly in the Cucurbitaceae, Leguminosae and Solanaceae (Chesters and Hornby, 1965). The disease also occurs on onion and strawberry (Mordue, 1967).

A. Diseases

1. Bacterial Disease: Angular leaf Spot

Occurrence & severity status

Angular leaf spot disease, also known as ‘Black arm disease’ or ‘Bacterial blight’ is a disease of cotton potentially destructive in all cotton-growing areas of the world. The disease became prevalent in the USA during the 1950s (Schnathorst et al., 1960) and in India in the 1970s (Verma, 1986). In the USA, losses of between 34 and 59% were reported (Leyendecker, 1950; Bird, 1959). In India, losses of 5-20% were common in crops (Verma and Singh, 1971). Late and very late sowing of crops resulted in more yield reductions (Meshram and Raj, 1992). In general, losses due to bacterial blight in India are ranged between 1% and 27% depending on the cultivar and crop age (Mishra and Krishna, 2001). In Africa, data on crop losses is available for only a few countries. In Sudan, losses of 20% were common from severe infection (Last, 1960). However, nowadays, due to the wide availability of resistant varieties, its importance has been declined, with certain deviations where proliferation of new races has occurred as in Australia (Anonymous, 1980).

Fungal Diseases

Blast

Pyricularia oryzae (Sexual stage: Magnaporthe grisea)

Economic Importance

• Rice blast is the most important disease concerning the rice crop in the world.
• It has been found in over 85 countries across the world.
• The disease was first recorded in China in 1637.
• In India, occurrence of this disease was first reported from the Tanjore district of Tamil Nadu in 1918.
• The disease now occurs in almost all principal rice growing areas of India.
• Every year the amount of crops lost to rice blast could feed 60 million people.
• In severe cases losses amounting to 70-80% of grain yield was recorded.

Loose Smut

Ustilago nuda tritici (Ustilago tritici)

Economic Importance

• Loose smut has been observed and recorded on cultivated wheat from all over the wheat growing regions of the world.
• In India, it is prevalent in areas having cool, humid and semi humid climate during flowering period.
• Loose smut has recently became a more serious problem in the Ladakh region in the Himalayan mountains of India.
• If uncontrolled, loose smut can wipe out entire crops, since it replaces the grain.
• In areas where people depend on their grain crops for survival and don’t have the money or technology resources to control it, the disease can be devastating.
• Not only does it wipe out the crop, growers cannot even try again next year since any seeds they were able to harvest will be infected and will not produce seed the following season.

Rusts

The following three rusts are known to occur on barley

1. Stem black rust: Puccinia graminis tritici f. sp. tritici
2. Leaf rust: Puccinia striiformis
3. Leaf rust: Puccinia hordei

Of these, the first two are described under wheat and the disease symptoms are identical. These two rusts occur commonly on barley and cause severe damage in certain years.

Southern Leaf Blight

Helminthosporium maydis (Syn: H. turcicum)

Economic Importance

• The first epidemics of the Southern corn leaf blight also known as Maydis leaf blight took place in the USA in 1970.
• A highly virulent strain called Race T appeared on maize hybrids with Texas male sterile cytoplasm.
• The disease development was related to the growing of maize with T-cytoplasm on large areas.
• Since 1990 the use of cultivars with T male sterile cytoplasm has been forbidden in selection.
• Presently, the cultivars with M and C types of sterility are used.

Loose Smut/Kernel Smut

Sphacelotheca cruenta

Economic Importance

• Loose smut is distributed in Africa, Europe, Asia and America.
• In India, it occurs in the states of Andhra Pradesh, Maharashtra, Karnataka, Madhya Pradesh and Tamil Nadu.
• It is less common than grain smut.
• The pathogen affects plant growth and development adversely.
• Grain yield losses correlate well with percentage of the disease distribution in fields.

Downy Mildew (Green Ear)

Sclerospora graminicola

Economic Importance

• Downy mildew is reported from temperate and tropical regions of the world.
• In India, the disease is a major stumbling block in the full exploitation of yield potential of hybrids.
• Several epidemics have been observed which resulted in substantial grain yield losses (upto 60 percent) in F₁ hybrids under South Indian conditions.
• Usually the losses in grain yield are directly proportional to disease incidence in the field.

Wilt

Fusarium udum

Economic Importance

• Wilt is widely prevalent throughout the world but more important in India and in eastern Africa.
• Wilt is the worst disease of red gram in India, causing severe damage wherever the crop is grown, especially in Maharashtra, Madhya Pradesh, Uttar Pradesh, Bihar and Tamil Nadu.
• The disease is reported to cause 30-100% loss in grain yield and may cause 100% yield losses in susceptible genotypes.
• The annual losses due to wilt have been estimated at $71 million in India.

Wilt

Fusarium oxysporum f. sp. ciceris

Economic Importance

• Wilt is a serious disease of chickpea in India, Iran, Pakistan, Nepal, Myanmar, Spain, Tunisia, Morocco, Algeria, and Syria.
• Wilt is prevalent in most chickpea growing countries and is a major disease of economic importance in Asian countries.
• It was first reported in India.
• The yield losses encountered was reported to the tune of 60 per cent. However, it causes complete loss in grain yield if the disease occurs in the vegetative and reproductive stage of the crop.
• Seeds harvested from infected plants are lighter and duller than those from healthy plants.

Powdery Mildew

Erysiphe polygoni

Economic Importance

• Powdery mildew can be a serious disease of peas grown in India.
• It appears in epidemic form in the plains almost every year when the pods are formed in January-February.
• Since the disease occurs more frequently and covers a large host surface, it proves much more destructive than the downy mildew disease of the same crop.
• It is worst in dry weather as against the downy mildew, which flourishes in moist weather.
• Severe infections can reduce yield by 10–20%.
• Severe pod infection can lead to poor seed quality.

Anthracnose

Colletotrichum lindemuthianum

(Sexual stage: Glomerella lindemuthianum)

Diagnostic Symptoms

• The pathogen attacks all aerial parts of plants and at any stage of their growth.
• Initial symptoms are circular, black, sunken spots with dark center and bright red orange margins on leaves and pods.
• In severe infections, the affected parts wither off.
• Seedlings get blighted due to infection soon after seed germination.
• The infected pods have discolored seeds.

Anthracnose

Colletotrichum lindemuthianum

(Sexual stage: Glomerella lindemuthianum)

Diagnostic Symptoms

• The pathogen can attack all aerial parts at any stage of plan growth.
• Main symptoms are circular, black, sunken spots with dark center and bright red orange margins on leaves and pods.
• In severe infections the affected parts wither off.
• Seedling get destroyed due to infection soon after seed germination.

Wilt

Fusarium oxysporum f. sp. lentis

Economic Importance

• The disease is present in countries such as India, Jordan, Nepal, Pakistan, Syria, Turkey, Russia, France, Hungary, Ukraine, Egypt, Ethiopia, Morocco, Sudan, Tunisia, Canada, Argentina, Chile and Uruguay etc.
• It may cause 5-10% yield losses but sometimes severe damage may result complete crop failure under favorable conditions.

Anthracnose

Colletotrichum lindemuthianum (Sacc. & Magnus)

Glomerella lindemuthianum Shear

Economic Importance

• Anthracnose warrants a serious attention as it inflicts heavy economic losses to the crop, which may reach up to 100%, under conducive conditions.
• In India disease incidence has been reported to vary between 24.59 to 51.72 per cent.
• In Jammu region of Jammu and Kashmir state disease incidence of 63.46% was recorded.

Anthracnose

Colletotrichum lindemuthianum, Glomerella lindemuthiana Shear [teleomorph]

Economic Importance

• Anthracnose is an important disease in Kenya, Uganda, Brazil, Argentina, Mexico, Guatemala, Costa Rica, Nicaragua, India, Peru, Ecuador, and Colombia .
• The disease causes huge losses in temperate and subtropical zones.
• Yield losses of 95% have been recorded in Colombia and over 92% in Malawi.
• Anthracnose also affects seed quality and marketability of the crop.

Dry Root Rot / Charcoal Rot

Macrophomina phaseolina

Economic Importance

• Dry root rot has been found in most of the soybean-growing areas of the India.
• The disease has been increasing in importance and can result in substantial yield losses.
• In most fields, stand losses range from less than 5% to over 50% in severe cases.
• It is most prevalent on seedling and young plants, causing a root and stem rot.

Tikka or Leaf Spot

Cercospora arachidicola/ Phaeoisariopsis personatum

Economic Importance

• Tikka disease of ground nut is regarded as the most important fungal disease of this crop.
• The infection appears when the plants are one to two month old; one can see this disease in the month of September in the plains of our country.
• Losses due to this disease may go up to 15-50%.

Root Rot or Charcoal Rot

Rhizoctonia bataticola

(Pycnidial stage: Macrophomina phaseolina)

Economic Importance

• Charcoal rot is of great economic importance in the World and has been found to reduce head weight and diameter, stem height and weight and in particular, the stem girth and root weight of sunflower plants.
• The first report of the occurrence of charcoal rot on sunflower was from Sri Lanka by Small (1927).
• Under favourable condition, losses can reach 60-90%.
• Infected plants generally die before seed set is finished.

White Rust

Albugo candida

Economic Importance

• White rust is an important disease affecting mustard crop in world.
• Countries where the disease occurs include the Brazil, Canada, Fiji, Germany, India, Japan, New Zealand, Pakistan, Turkey and UK.
• Up to 60 per cent or more yield losses on B. rapa and B. juncea from this disease have been reported in India.

Seedling Blight

Phytophthora parasitica

Economic Importance

• Seedling blight is wide spread in Africa, India and other Asian countries.
• The average economic loss due to the disease has been 10%.

Wilt

Fusarium oxysporun lini

Economic Importance

• The wilt is very serious disease and occurs in almost all the countries where linseed is grown.
• Continuous cropping in the infected field makes the soil sick.
• Yield losses upto 80 percent has been reported due to this disease. However, in severe cases crop is destroyed completely.

Ozonium Wilt

Ozonium texanum var. parasiticum Thirum / Guizotia abyssinica

Economic Importance

• The disease was reported around Varanasi.
• Heavy losses are incurred as the diseased plants dry.

Wilt

Fusarium oxysporum f.sp. carthami

Economic Importance

• The disease was reported for the first time from America in 1950.
• Wilt is a devastating disease infecting the crop right from seedling to maturity resulting in crop losses to varied degrees depending on the severity of infection.
• The disease incidence has been reported in India to the tune of 80 percent under favorable condition.

Wilt

Fusarium oxysporum f.sp. carthami

Economic Importance

• The disease was reported for the first time from America in 1950.
• Wilt is a devastating disease infecting the crop right from seedling to maturity resulting in crop losses to varied degrees depending on the severity of infection.
• The disease incidence has been reported in India to the tune of 80 percent under favorable condition.

Root Rot or Stem Rot or Charcoal Rot

Macrophomina phaseolina (Sclerotial stage: Rhizoctonia bataticola)

Economic Importance

• Root rot is an important disease of sesame as infection occurs from seed germination and emergence to adult plant stage.
• The losses incurred are even up to 100 per cent, if conditions are favorable.

Red Rot

Colletotrichum falcatum (Perfect stage: Physalospora tucumanensis)

Economic Importance

• The disease is so devastating in nature that it has been referred to as cancer of sugarcane.
• Red rot occurs in all sugarcane growing tracts of India and several epiphytotics have been recorded in the past from states like U.P., Bihar, Haryana, Punjab, Andhra Pradesh and Kerala.
• In U.P and Bihar, the two popular varieties, namely, CO 213 and CO 312 were badly hit by the epidemics of 1938-40 and 1946-47.
• There have been reports of red rot epidemics in many other countries viz., USA, Mauritius, Australia, Hawaii and Myanmar.
• Red rot also causes appreciable damage to canes in Bangladesh, Taiwan and Pakistan.
• The loss in cane yield has been estimated 12 to 44.5% and 35 to 86 % in cane yield of ratoon over preceding plant crops have different levels of disease.

Wilt

Fusarium oxysporum f.sp. vasinfectum

Economic Importance

• Wilt is one of the major diseases of cotton, found wherever this crop is grown like Mexico, African countries, France, Italy, Yugoslavia, India and West Indies.
• In India, the disease was first reported from Nagpur by Evans in 1908.
• It appears in almost every cotton tract of the country. However, it is more or less absent in the loamy soils of Indo Gangetic plains and sandy loams of Maharashtra, Tamil Nadu, Karnataka and other States.
• In affected susceptible varieties yield losses exceed 45-50%.

Damping Off

Pythium aphanidermatum

Economic Importance

• The disease is reported from China, Indonesia, South Africa and the USA.
• It causes extensive damage in the tobacco tracts of Andhra Pradesh, Maharashtra and Gujarat in India.
• The damage in some areas can be hundred percent, in the absence of protective sprays.

Leaf Spot

Colletotrichum capsici

Economic Importance

• The disease is common in many parts of South India, and in recent years has become very severe, causing much damage to the crop.
• The yield losses occur due to leaf spot infection is through the loss of photosynthetic green surface.
• During the period of heavy infestation, yield loss could be as much as 50%.

History and Recent Developments

Richard P. Feynman in 1959 suggested that it should be possible to build machines small enough to manufacture objects with atomic precision. His talk “There is plenty of Room at the Bottom” is widely considered to be the foreshadowing of Nanotechnology. He delivered this talk at the annual meeting of the American Physical Society at California Institute of Technology (Caltech), In 1990, a team of IBM Physicists revealed that they could write (arrange) the letter IBM using 35 individual atoms of Xenon.

In 1992 a book entitled Nanosystems: Molecular Machinery, Manufacturing and Computation was published by Eric Drexler where he outlined a way to manufacture extremely high performance machines out of molecular carbon lattice (diamondoid).

Around year 2000, federal funding for Nanotechnology in the United States began with National Nanotechnology Initiative (NNI). NNI defined nanotechnology as dealing with materials with sizes between 1 and 100 nanometers exhibiting novel properties.

The Government of India, in May 2007 launched a mission on Nano sceince and nano technology (Nano Mission) with an allocation of `1,000 crores.

Solid state materials can exists in various forms namely:

1. Single crystals (preferred for authentic characterization of structure and physical properties)
2. Polycrystalline powders that are agglomerates of large number of crystallites and are used for characterization when single crystal cannot be easily obtained
3. Nanocrystalline or nanostructured materials that posses large surface area
4. Thin films that can be grown in the best crystalline form for many applications
5. Amorphous systems that have no long-range translational order