eChapters

Introduction

Citrus (Citrus spp, Fam: Rutaceace, sub-family Aurantioidae) is considered as one of the most remunerative fruit crops in India occupying 953.4 thousand ha with an annual productivity of 11655 thousand tonnes fruit , thereby ranking 4^th at global level (Meena et al., 2018). Citrus is the third most important fruit crop in the world after apple and banana accounting for the production of about 135.76 million tonnes with massive area of cultivation spreading over 9.68 million hectares worldwide (Meena et al., 2018). It is believed that most species under the genus Citrus are originated from tropical and sub-tropical regions of Southeast Asia particularly India, South China, Indonesia and Peninsular Malaysia. The North-eastern states of India is recognized as one of the primary gene centre or natural home and reservoir of 17 Citrus species of which 8 species are indigenous to the region (Bhattacharya and Dutta, 1949).

The crop is commercially cultivated in all the four geographical zones viz. northwest, central, south and northeast, producing different kinds of mandarins (Citrus reticulata), sweet orange (C. sinensis), acid lime (C. aurantifolia), sweet lemon (C. limettoides) and lemon (C. lemon) (Biswas, 2010). They are universally propagated by budding onto seedling rootstocks, seed and propagating materials influencing the chances of pathogen infection, thereby, affecting citrus production nationally and internationally. Citrus production is subjected to variety of diseases caused by various microorganisms’ viz. fungi, bacteria, virus, viroids and nematodes. The present review gives a brief highlight about most important citrus diseases viz. canker, greening, quick decline, gummosis, exocortis, slow decline etc along with their characteristic symptoms, causal organisms, disease cycle, epidemiology as well as integrated management approaches.

Citrus Canker- Xanthomonas citri subsp. citri

Banana (Musa spp.) is one of the most important fruit crops grown in tropical and subtropical regions in the world. The word ‘banana’ is a general term embracing a number of species or hybrids between Musa acuminata and M. balbisiana in the genus Musa and family Musaceae (Perrier et al., 2011). India is known to be one of the origins for bananas and it was grown even before the Vedic period (c.1500 - c.500 BCE). It is referred as “Kalpatharu” (Plant of virtues) due to its multifaceted uses (Mishra et al., 2012). It has been estimated that one medium-sized banana contains about 105 calories (Bjarnadottir, 2017). Raw bananas contain 75% water, 23% carbohydrates, 1% protein, and negligible amount of fat (USDA, 2018). However, carbohydrate, protein and moisture content of banana depend upon the variety, genotype and climatic conditions (Mohapatra et al., 2010). Banana fruits are rich source of antioxidants and vitamins such as vitamin A, B, C, E and P-carotene (Paul and Southgate, 1978; Kanazawa and Sakakibara, 2000; Waller,2005), minerals like potassium and calcium (Mohapatra et al., 2010) and contains a fair amount of fibre (Bjarnadottir, 2017).

Banana is the major staple food crop for millions of people in Central, East and West Africa, Latin America and the Caribbean. In 2016, world production of bananas and plantains was 148 million tonnes, led by India and China with a combined total (only for bananas) of 28% of global production with the adoption of advanced technologies like drip irrigation, use of quality tissue culture plants, fertigation and integrated plant protection technologies lead the country to be number one in area and production. Other major producers were the Philippines, Ecuador, Indonesia, and Brazil, together accounting for 20 per cent of the world total of bananas and plantains. In India, banana ranks first in production followed by mango and third in area among fruit crops after mango and citrus. Banana production accounts about 30.4 M tonnes from an area of 0.86 M ha with an average productivity of 35.4 tonnes/ha (Anon, 2017). Banana crop is a year round food security crop and source of income to a large group of farmers and has tremendous potential as cash and export commodity for most banana growing countries. However diseases and pests constitute major limiting factor for increasing its production and productivity. Banana cultivation is almost evenly spread out across the world and there is a remarkable low genetic variation among plantations, owing to the popularity of a select few cultivars. This exposes monocultures to increasing damage caused by pests and diseases (Ghag et al., 2015).

Introduction

The mango (Mangifera indica L.) is regarded as king of fruits. It is a key fruit crop in the subtropical regions of world including India. Prakash and Srivastava, 1987 reported that mango is attacked by more than 140 fungi (70 diseases), about 12 nematodes and a dozen of phanerogamic parasites and epiphytes. Among these diseases some major diseases of mango having economic important in India are briefly described in this chapter.

Anthracnose

Anthracnose is a severe disease of mango. High disease severity results to heavy loss including post-harvest losses during transit and marketing of produce. Mango anthracnose has been reported to spoil about 29 per cent of Alphanso fruits at Bangalore. Young plantations of Bombay green variety are completely wiped out in Tarai region of Uttar Pradesh as a result of severe wither tip Bose et al., 1973. At Lucknow, 24 per cent loss of fruits of Dashehari variety has been reported by Raoof and Prakash, 1984.

Jackfruit (Artocarpus heterophyllus Lam.) is the largest edible fruit in the world (Naik, 1949; Sturrock, 1977), known as “poor man’s food” belongs to the family Moraceae (Bose, 1985; Haque, 2010). It is an important tree crop in tropical and sub-tropical regions, usually grown in home gardens and commercially in orchards (Elevitch and Manner, 2006; Sangchote et al., 2003). The primary economic product is the fruit, but the tree is also used for timber, fodder, dyes and traditional medicines (Haque, 2006). Jackfruit originally native to Indian subcontinent, is now widely cultivated in the tropics of both hemispheres (Ochas et al., 1981). Incidence of different kinds of diseases of biotic and abiotic origin at different growth stages of Jackfruit have been reported (Haque, 2006; Sangchote et al., 2003). Some of the commonly occurring diseases of jackfruit with symptomatology, causal organism, perpetuation and management approaches have been elucidated below.

LeafSpot

Incidence of leaf spot at different growth stages of jackfruit caused by Chaetopyrena hesperidum (Srivastava, 1974), Cercospora mehra (Rao and Subhendar, 1979) Botryodiplodia theobromae (Rao and Deshmuk, 1986), Corynespora cassiicola (Sangchote et al., 2003), Colletotrichum gloeosporioides (Sirayoi, 1993; Srivastava and Mehra, 2004), Phyllosticta- artocarpi (Annon, 2003) has been reported by various workers from different parts of the world. Some of the common leaf spot diseases have been discussed below.

Economic Importance

Apple (Malus domestica, M. communis, M. pumila and M. sylvestris), the generic name Malus is derived from the Latin word belong to the rose family and include literally hundreds of cultivated varieties. In the apple, the original ancestral species is obscured by so many cultivated variations throughout the centuries that some authors lump them all into one species, Malus domestica. They all originated in western Asia (or Eurasia) and are characterized by fleshy fruits called pomes. In the pome a thick, fleshy hypanthium layer (also called the floral cup or calyx tube) surrounds (and is fused with) the seed bearing ovary or core. The edible part of most fruits is the actual ovary, but in apples and pears only the outer hypanthium layer is eaten (unless you enjoy eating the core). Apple is commercially the most important temperate fruit and is fourth among the most widely produced fruits in the world after banana, orange and grape. China is the largest apple producing country in the world. It is premier table fruit of the world and excels other fruits in having prolonged keeping quality and wide variety of flavour and taste (Sharma, 2000). Apple is a highly remunerative crop and is grown in all temperate regions of the world. In India apple is grown in Jammu and Kashmir, Himachal Pradesh, Uttarakhand and some parts of Arunachal Pradesh. Jammu and Kashmir account for sixty per cent apple in total apple produced in India and is the most important fruit among all the cultivated fruits in the state. The state annually produces 1.31 lakh metric tons apple fruit from an area of 1.28 lakh hectares (Anonymous, 2008). It forms the backbone of the state’s economy and is main cash crop for the small and marginal farmers. However, the production and quality of apple is poor as compared to that of the developed countries because of several factors including diseases and insect-pests (Thakur, 2000). Although a large number of insect pests attacks to apple crops but some of them are very serious and need attention for their control. Besides the insect pests, mites are also associated with apple production and cause significance economic losses to commercial fruit growers (Kerik, 2012).

Aegle marmelos (L.) Corr. is one of the sacred trees of Hindus and is highly popular for its medicinal properties. This tree is commonly known as “Bael” in India and the leaves are used for worshipping Lord Shiva. It has the potential for curing a number of ailments and has been in use since time immemorial. At present bael has become an important source of medicine for curing various human diseases such asdiabetes, liver toxicity, fungal infection, microbial infection, inflammation, pyrexia and to relieve pain. The raw fruits are used to prepare sugar impregnated sweets called murraba and jelly where as juices and shakes are prepared after ripening.

Bael is native to India and found throughout Southeast Asia. In India this fruit is grown in Indo-Gangetic plains and Sub-Himalayan tracts up to a height of 500 m, in North-East India and dry and deciduous forest of central and southern India.

Aegle marmelos is a subtropical plant and grows up to an altitude of 1,200 m altitude from sea level. It grows well in the dry forests on hilly and plain areas. Aegle marmelos is a widely distributed plant and found in India, Ceylon, China, Nepal, Sri Lanka, Myanmar, Pakistan, Bangladesh, Nepal, Vietnam, Laos, Cambodia, Thailand, Indonesia, Malaysia, Tibet, Sri Lanka, Java, Philippines and Fiji. In India it found in Sub-Himalayan tracts from Jhelum eastwards to West Bengal, in central & south India. It found almost in all the states of India.

Bael is a hardy crop and is quite resistant to diseases. However, there are certain fungal and bacterial diseases that have been reported to cause yield reduction in bael. In this chapter, important diseases of beal with causal organism, disease cycle, epidemiology and management practices are described.

Plant diseases comprise a major factor in the culture of papaya. Adequate control measures are necessary to intensify the production of papaya. There are over 17 diseases caused by fungi, viruses, mycoplasma and nematodes, which affect papaya plant all over the world. Of these about 5-6 diseases like collar rot, damping off, anthracnose, mosaic and leaf curl are serious problems in many papaya growing areas of the world. They can reduce yield greatly and impair marketability of fruits. They must be checked and losses due to them must be minimized in order to increase the economics of papaya production.

Anthracnose

Economic Importance

Anthracnose is considered as one of the principle postharvest disease of papaya occurring worldwide and has been noted to cause huge losses in countries like Brazil, Hawaii (USA) and Mexico. It is one ofthe most ubiquitous and destructive disease of papaya, mainly during storage. The fungus infects various parts of the plant but mainly occurs in fruits, which later becomes unfit for commercialization. It is a major limitation to papaya production of about 90% along with the exportation of the fruit to bigger overseas market. The disease can have serious effect on refrigerated fruit for export. The use of inappropriate postharvest methods can result in production of up to 100% diseased fruits from some orchards.

Guava, Psidium guajava L. (Family: Myrtaceae), is native to South America and the West Indies but it is also grown other parts of the tropics and subtropics including India. It is considered to be important hardy crop grown in neglected soil. It is commonly known as ‘Amrood’ or Safed Safari’ in Hindi, which is an important fruit plant of India. It is grown all over the country for its fruits which are nutritive, rich in vitamin C, highly flavoured and delicious. Leading producers are Brazil, India and Mexico. The cultivated varieties of guava are attacked by several pathogens which cause considerable loss in yield and reduce market value.

Wilt

Wilt is one of the most destructive disease of guava in India and there is a significant yield loss. In India, guava wilt was first reported in 1935 from Babakkarpur (Allahabad). Das Gupta and Rai (1947) reported the disease in a severe form in orchards of Lucknow, while Dey (1948) reported it from Allahabad, Kanpur and Lucknow. The work so far done on wilt disease has been reviewed by Prakash and Misra (1993), Misra (1995), Misra and Pandey (1996), Misra (2001) and Negi et al. (2001). Chattopadhyay and Bhattachaijya (1968a) reported up to 80% yield losses due to serious wilt in the commercially grown guava orchards in West Bengal. About 150 and 300 acres of guava orchards in the Punjab and Haryana was forced uprooting during 1979-81 (Jhooty et al., 1984). Wilt infection of 15 to 30% trees in Allahabad, Farrukhabad and Unnao, 5-15% in Kanpur and Jaunpur and less than 5% in Gorakhpur, Balia, Hardoi and Varanasi districts (Mathur, 1956).

Introduction

Mulberry (Morus spp.) is a most important crop which is used as food for silkworm (Bombyx mori L.) belonging to the genus Morus and family Moraceae. In tropical and temperate countries, mulberry is cultivated as shrubs and tree respectively. The total area under cultivation of mulberry in India is around 2,82,244 ha. The largest mulberry producing state is Karnataka (1,66,000 ha) followed by Andra Pradesh (38,084 ha). All over the world there are almost 68 species of Morus genus among 1000 varieties were commercially cultivated (Central silk board, Mysore). The nutritive values of mulberry leaves are affected by many diseases like leaf spot, powdery mildew, rust, root rot and bacterial blight which are causing severe yield loss up to 10-30%. In addition it also affects the growth, development of silkworm and cocoon yield due to feeding ofthose diseased leaves. (Sastry, 1984; Sundareswaran et al. 1998). Occurrence of these diseases based on some factors such as season, temperature, humidity and variety of mulberry (Sukumar, 1996). This chapter will be discussed about the disease causing organism, epidemiology and their management practices.

Cercospora leaf spot

Economic Importance

Cercospora leaf spot is an economically important disease causing abundant damage by reducing the leaf quality of mulberry (Siddaramaiah and Krishnaprasad, 1978). During July-December it causes yield loss of 10-15% and the disease present till January-February.

Introduction

Strawberry (Fragaria vesca) belonging to family Rosaceae is an important fruit crop in India and is commercially produced in temperate and sub- tropical areas of the country. In India, it is mainly cultivated in the states of Himachal Pradesh, Uttar Pradesh, Maharashtra, West Bengal, Delhi, Haryana, Punjab and Rajasthan. Nainital and Dehradun districts of Uttarakhand, Mahabaleshwar (Maharashtra), Kashmir valley, Kalimpong (West Bengal) are the core centers of strawberry cultivation in India. Sub-tropical areas in Jammu also possess tremendous potential to grow the crop in irrigated condition. Strawberry cultivation can boost the income potential of small scale and marginal farmers because its high value creates potential for significant profit. It yields quickest return in shortest time than any other profit. The leaves of strawberry are rich in essential oil. India exports strawberries to countries like Austria, Bangladesh, Germany and Jordan.

Strawberry also possess many health benefits such as flavonoids content lowers the risk of heart diseases. Potassium, Vitamin K and magnesium content of fruit are important for healthy and strong bone. Strawberries are rich in antioxidant ellagic acid, which protects the elastic fibres of skin to prevent sagging. Strawberries lowers blood levels of C- reactive proteins, a signal of inflammation in the body.

The optimum day and night temperature for better growth, development and fruiting of the plant is 22-25°C and 7-13°C respectively. Also, it thrives best on a well drained medium loam and slightly acidic soil with high organic matter content.

Although the strawberry crop is highly remunerative however, its management is intensive and encounters a number of setbacks in form of diseases and pests. A large number of fungal, bacterial and viral diseases are known to infect different parts of plant such as foliage, fruit and root.

Some major diseases of strawberry includes leaf spot, powdery mildew, anthracnose, grey mould, fusarium wilt, crown rot, rhizobus rot, red stele, nematode diseases etc. Few other diseases caused by abiotic factors includes sunburn, frogmouth, albinism.

Introduction

Pineapple is one of the most important commercial fruit crop in India. It occupied an importance in the horticultural wealth and economy of the country. India ranked seventh among the pineapple producing country in the world during 2013-14 (GoI, 2014). It grows well in practically all type of soils with slightly acidic in nature, both in plain and hills. It is affected by several different pathogens wherever it grown and result in substantial crop losses. Some important diseases cause complete loss of the fruit marketableimportance. The major problems faced by pineapple growers in India are discussed below.

Introduction

Pear (Pyrus communis L.) is a temperate fruit that mainly grows in hilly areas at a elevation ranging from 1,500 to 2,500 metres. This temperate fruit is commonly eaten fresh or is canned. It is used to produce an alcoholic beverages and perry. The production of pear is 17 million tons per year in worldwide and the cultivation is expanding throughout the worldwide.

Pear cultivation is affected by many bacterial, fungal and viral diseases due to which it reduces the plant strength and decreases the quality of yield. Besides,pear can be also affected by many disorders and nematodes.

Bacterial Diseases

Fire blight

Fire blight disease is a serious concern to pear producers. It can destroy an entire orchard under optimal conditions in a single growing season.

Introduction

Ber (Zizyphus mauritiana L.) is one of the important fruit crops of arid and semi arid zones of the world. It is known by various other names such as ber, bor, bogori, boroior, kool and ruguin Hindi, Punjabi, Marathi, Assamese, Bengali and Telegu respectively. In America, it is called jujube or Chinese date. Ber is popularly called “poor man’s fruit crop” but now its status in tropical fruit culture has improved considerably. The fruit is palatable and delicious and is known for its high nutritive value. The crop is considered as minor fruit in this country on the basis of its production in restricted area; popularity and awareness but recently itbecame an important cash crop in some areas and its acreage and production have increased. The plant is usually a piny, evergreen shrub or small tree up to 15 m high, with trunk diameter around 40 cm or even more; spreading crown; stipular spines and many drooping branches. The ripe fruits are mostly consumed raw (Bal and Uppal, 1992). In India it is extensively grown in Madhya Pradesh, Bihar, Punjab, Uttar Pradesh, Assam, Gujrat and Maharashtra. The fruits are quite nutritious, rich in vitamin C, second only to aonla and guava and much higher than citrus and apple. The ripe fruits have high nutritive value, having 13-24 per cent total soluble solids and up to 160 mg/100g vitamin C. The dehydrated fruits are kept for a long time and are consumed in the off season.

Due to rapid spread of commercial cultivation, the crop has become a target of different biotic and abiotic factors causing serious losses. So far, little attention to the diseases of ber has been given as the importance of the crop generally continues in a locality or a particular state. So, it overlooked the national importance particularly crop protection measures, leading to limited knowledge for management of different diseases both in pre-harvest as well as post-harvest stage. Ber is affected by many serious diseases like powdery mildew, leaf spots (Alternaria, Cercospora, Septoria, Cladosporium, Pestalotiopsis etc.), sooty mold, anthracnose, fruit rot etc.

Grape is an important fruit crop grown mainly under tropical climatic conditions in India. It has spread on an area of 137 thousand ha with a production of 2951 thousand MTduring 2018-19. Famous Indian medicine scholars, Sasruta and Charaka in their medical treatises entitled ‘Sasruta Samhita’ and ’Charaka Samhita’, respectively, written during 1356-1220 BC, mentioned the medicinal properties of grapes. Native spp. resembling Vitis lanata and Vitis palmata grow wild in the northwestern Himalayan foothills. Indigenous varieties known as ‘Rangspay’, ‘Shonltu White’ and ‘Shonltu Red’ are grown in Himachal Pradesh even today. Cultivated grapes are believed to have been introduced into the north of India by the Persian invaders in 1300 AD, from where they were introduced into the south (Daulatabad in Aurangabad district of Maharashtra) during the historic event of changing the capital from Delhi to Daulatabad by King Mohammed-bin-Tughlak. Currently Mahrashtra, Karnataka, Andhra Pradesh and Tamil Nadu are the major grapes growing states of India.

However, the higher production of grapes is constrained by the incidence of several diseases and pests. The important diseases of grapes causing economic losses have been listed below and discussed in detail in the chapter.

Avocado fruit has become one of the most sought after food sources worldwide. It is a nutritious source of food and is part of the staple diet of many people in third world countries where it is cultivated and where it is native. Production costs are very high owing to the cultural requirements of the avocado tree and the presence of diseases, which can be major limiting factors to production. Phytophthora root rot, caused by Phytophthora cinnamomi, is such a disease. During the developmental stages of hefruit in the orchard and at harvesting, the fruit is also exposed to diseases such as scab (Sphacelomapersea), anthracnose (Colletotrichum gloeosporioides) and Cercospora spot (Pseudocercospora purpurea) Marias (2006).

Major Fungal Diseases of Avocado

Phytophthora root rot

Economic Importance

The causal fungus Phytophthora cinnamomi Rands was first isolated from cinnamon trees in Sumatra in 1922 and has since been reported from over 70 countries. It has an extremely wide host range including 1000 varieties and species of plants. In California alone it has been estimated to affect between 60-75% of the orchards and causes a loss in excess of $40 million annually (Coffey 1992).

Cashew (Anacardium occidentale L.) is an important cash crop and India ranks second to Brazil in production (Shanthi and Vittal, 2012), the incidence of diseases considerable losses in cashew plantations. Cashew nut is a plantation crop that is grown extensively in area along with costal tract of peninsular India. It is the most important export crops and the main source of cash income. Cashews (Anacardium occidentale L.) are a perennial nut crop native to Brazil and belong to the Anacardiaceae family. (Zhongrun and Masawe, 2014). Plans produce numerous pinkish-white flowers and kidney shaped true fruit (nut) in gray-brown shell develops from a fleshy fruit, referred as ‘cashew apple’. The cashew apple is pear shaped and red to yellow in color. The cashew apple is also valued in alcohol fermentation and cashew shell oil for base of paints and water proofing agent. Cashew (Anacardium occidentale L.) is a perennial tree crop, originating from South America from Brazil now widely grown in the tropics. Cashew affected by many biotic and abiotic causes resulting in significant yield losses. Biotic diseases and pests are the most damaging cashew nut yield in terms of quality and quantity. (Freire and Rossetti, 1991; Freire, 1997; Freire and Cardoso, 1995). Many pathogens have now been recorded from seedlings, adult plants and from kernels (Freire, 1996; Freire et al., 1996, 1999).

Major diseases of cashewnut plants are anthracnose (Colletotrichum gloeosporioides), Pestalotia leaf spot (Pestalotia heterocornis), bacterial leaf and nut spot (Xanthomonas citri pv. anacardii), Powdery mildew (Oidium anacardii) Pink Disease or Dieback (Corticium salmonicolor) and gummosis (Lasiodiplodia theobromae) are reported in cashew tree worldwide often considered as the most important diseases causing severe economic damage cashew nut producing countries. According to Sijaona (2013) powdery mildew can cause yield losses ranging from 70 to 100%. In Brazil, anthracnose infection has drastically reduced cashew production by up to 40% in 2000 (Freire et al., 2002).

Introduction

Potato is mostly considered as a vegetable crop in India, whereas it is a staple food crop in Europe, Canada, Australia, U.S.A, South America, Russia, Asia and other countries. In India, it is cultivated extensively in the hilly tracts during December-March or March-June and in the plains during September-January, as it requires cool and moist climate condition. As per FAOSTAT (2015), the potato production in India during 2013 was 45.34 mt from 1.99 mha area with a productivity of 22.76 t/ha. There are several varieties of potato grown in India and many diseases, some of which cause considerable damage to the crop. Potato crop can be affected by diseases caused by fungi, bacteria, virus, viroids and others by non-parasitic.

Late Blight

Economic Importance: Late blight is one of the most devastating diseases of potato throughout the world. It is recorded in area with frequent cool and moist weather. The disease is believed to have been introduced into Europe from South and Central America and spread to other countries which include the East Coast of Canada, Western Europe, Central and Southern China, South Eastern Brazil and the tropical highland. It created history by causing a famine in Ireland known as Irish Famine during 1845-46 resulting in death of many people due to starvation, dysentery and typhus spread among the farmers and subsequent migration of people from Europe especially from Ireland. Late blight has the tremendous potential to cause upto 70% reduction in the yield in a susceptible cultivar. Region wise economic importance of late blight shows that the disease takes highest toll of potato in Sub-Saharan Africa (44% crop losses) followed by Latin America (36%), Caribbean (36%), South-East Asia (35%), South-West Asia (19%)

Tomato (Lycopersicon esculentum Mill.) is one of the most important vegetable crop and is known as protective food due to its wide spread production and special nutritive value. Tomato is referred to be native of tropical America. In the 16^th century, it got spread from America to other parts of the world and became popular in India within the last six decades. It is known as world’s largest vegetable crop after potato and sweet potato. The overall world production of tomato is 1,180,000 tons with a productivity of 65 t/ha. Contribution of USA in tomato production is 13.2 million metric tons to the total world production (FAOSTAT). USA ranks third in position in the total world production of tomato after China and India (FAOSTAT). India produces 22,337MT of tomato from 801ha area.

Fungal Diseases

Fusarium Wilt

Economic Importance

Fusarium wilt caused by Fusarium oxysporum being so widespread, turns out to be a significant problem in many crops. It is one of the most widespread and damaging diseases of tomato wherever tomatoes are grown intensively. The pathogen also causes damage to many other crops likepotato, and pepper of the family Solanaceae. Yield losses of effected crops can goup to 45% in tomato in India.

Introduction

Brinjal, Solanum melongena L. a solanaceous and the native vegetable of India is very favourite among the Indians. It is an economically important vegetable among the small scale farmers and low income consumers of India. It ensures some assured source of income to the resource poor farmers throughout the year due to long fruiting and harvesting period. Brinjal fruits are of a low calorie value and have a mineral composition that is beneficial for human health; these fruits are rich source of minerals (potassium, calcium, phosphorus, sodium, chlorine, iron etc.) and vitamins and have some medicinal importance (Choudhary, 1967). In India, brinjal is grown on the wide range of soils and other variable environmental conditions. In production and productivity, India stands second in the world after China which is mainly grown in the states like West Bengal, Orissa, Bihar, Gujarat, Maharashtra, Karnataka, Uttar Pradesh and Andhra Pradesh. The world production of brinj al in the year 2016 was estimated to be 51.29 million MT in an area of 1.79 million hectare with productivity of 28.59 MT per ha China, the world leader of brinjal production produced 32.03 million tones of brinjal with a productivity of40.96 Mt per ha in an area of 0.78 million ha. The productivity of brinjal as compared to China is very less (18.90 MT/ha) in India although we are the second largest producer ofthis popular vegetable (FAOSTAT Website (http://faostat3.fao.org/home/E).

Chilli is reported to be an inhabitant of South America and widely scattered in all tropical and sub-tropical countries including India. Amongst all the important consumed crops, chilli occupies a dominant position and its economic losses worldwide due to few serious diseases like chilli anthracnose, Phytophthora leaf blight and fruit rot, bacterial leaf spot, bacterial wilt, Cercospora leaf spot, chilli leaf curl virus and so on. Capsicum annuum L., C. frutescens L. are the biological names of chilli. Bird’s eye chilli is grown in Mizoram and some areas of Manipur and Assam. Chilli has got its own regional names. In Hindi, it is popularly known as Lal Mirch, in Gujrat as March, in Marathi as Mirchi and so on. Kanthari White is grown in Kerala and some parts of Tamil Nadu. Kashmir chilli is grown in temperate region such as Himachal Pradesh, Jammu and Kashmir and also in sub-tropical regions of North India. Red chilli held high amount of vitamin C and provitamin A, whereas green chilli too contain a considerable amount of both substances. In addition, peppers are a good quality source of most B vitamins, vitamin B6 in particular. They are very high in Potassium, Magnesium and Iron supplement.

Introduction

Okra (Abelmoschus esculentus L., Family: Malvaceae) also known as lady’s finger has been originated in Africa and introduced to India during early 20^th century. As an economical vegetable crop, it can be grown in tropical as well as sub-tropical parts of the world. During 2018-19, the total area under cultivation of okra was 511 thousand ha while the production stood at 6219 thousand MT in India (Horticulture Statistics Division, 2018). Okra can be grown on wide range of soils, but higher yield can be obtained in well-drained fertile soils with adequate organic matter. It is utilized for various purposes in terms of fresh leaves, buds, flowers, pods and stems providing a rich source of protein, carbohydrates, vitamins, calcium, potassium, enzymes, and total minerals in human diet. The mucilage has medicinal applications when used as a plasma replacement (Nilesh, et al., 2012), and the seeds contain 20 to 40% oil content (Sorapong, 2012).

Okra pods (per 100 g edible portion) are composed of water (88.6 g), energy (36 kcal), protein (2.10 g), carbohydrate (8.20 g), fat (0.20 g), fibre (1.70 g), Ca (84.00 mg), P (90.00 mg), Fe (1.20 mg), p-carotene (185.00 μg), riboflavin (0.08 mg), thiamine (0.04 mg), niacin (0.60 mg) and ascorbic acid (47.00 mg) ((Priya, et al., 2014).). Therefore, okra has been called as “a perfect villager’s vegetable” due to its robust nature, high dietary fibre as well as distinct seed protein with a balance of both lysine and tryptophan amino acids. Okra production is subjected to various diseases caused by fungi, virus and nematodes as a major biotic constraint. The mandates of integrated disease management of okra are to impart knowledge about symptoms, causal organism, disease cycle and epidemiology of major diseases. The present review will give a brief highlight about major diseases of okra viz. yellow vein mosaic, wilt, powdery mildew, cercospora leaf spot, damping off, collar rot and root knot nematode.

Blackrot of Cabbage

Economic Importance

Blackrot is an important bacterial disease of cabbage and other crucifer crops worldwide. The disease was first described in New York on turnips in 1893, and has been a common problem for growers for over 100 years (Smart and Lang, 2013). Blackrot has been given many names such as bacterial blight,black stem, black vein, stem rot or stump rot (Pfeufer and Davis, 2019). These pathogen is particularly damaging to cabbage and cauliflower, but turnip, rutabaga, collard, kohlrabi and Chinese cabbage are also susceptible. Broccoli and radish aregenerally resistant to Blackrot (Flynn,1999).

Cruciferous vegetables are important Kharif vegetable crops, which are grown both for table and seed purposes. This vegetable group constitutes crops like cauliflower, cabbage, radish, turnip and knol-khol. These crops are grown throughout the country and are attacked by number of diseases which not only reduce the quantity but also quality of the produce. Important diseases of Knol Khol are described below:

Major Fungal Diseases of Knol-Khol

Alternaria leaf spot

Economic Importance

It is of concern in north and central India where appreciable seed losses in terms of size, colour and germinability are reported

Introduction

Broccoli (Brassica oleracea L) belonging to family Brassicaceae, is an herbaceous annual or biennial plant which is cultivated for its edible flower heads being are used as vegetable or salads. The broccoli plant has a broad green stalk, or stem, that give produces thick, leathery, oblong gray-blue to green in color leaves. The plant produces large branching green flower heads covered with numerous white or yellow flowers. Broccoli can be annual or biennial depending on the variety. Broccoli is a rich source of vitamins, minerals and antioxidants and has a reputation as super foods (Hatanaka and Ware, 2020).

It is admitted that they are susceptible to a numerous of serious diseases that leads to reduction in yield. Thus, it is the utmost requirement to control such biotic stressors in order to obtain desired quality and decent yields. The most important diseases and its control measures are being portrayed in this chapter for both home gardener and the commercial producers for cruciferous vegetables particularly broccoli (Mani et al., 2020).

Radish (Raphanus sativus) is a cool weather crop and its origin is in Mediterranean, rapid growing annual or biennial plant belongs to family Brassicaceae, grown for its edible taproot. Its edible roots are having different color from as white to red. Radish is generally grown as an annual plant, surviving only one growing season. It is crop of tropical and temperate region. It is growing as herb in West Bengal, Bihar, Uttar Pradesh, Karnataka, Punjab and Assam areas are major radish growing states. Radish is good source of vitamin B6, Calcium, copper, magnesium and riboflavin. Also it is rich in ascorbic acid, folic acid and potassium.

Alternaria Blight

Economic Importance

Alternaria leaf spot diseases occur in every part of the world, in both vegetable crops and seed crops and most important disease of Brassica species, often results in severe yield losses. It is considered as a number one disease of radish affecting both fresh vegetable and seed production. The disease is more severe when the plants are left for seed production in the field and causes significant reduction in seed yield. Alternaria black spot of radish; black pod blotch of radish. A. japonica is a seed-borne pathogen of plants in the Brassicaceae. A. japonica is known to affect most parts of infected plants depending upon growth stage. There are reports of it on the hypocotyls and cotyledons of seedlings and on the leaves, petioles, stem, inflorescence, fruits (siliquae) and seeds of adult plants. A. japonica occurs in all parts of radish (Raphanus sativus) seed. Its presence in the embryo can result in seed death, but in milder infections it will affect seedlings after germination, causing seedling blight both before and after emergence.

Introduction

Elephant foot yam (Amorphophallus paeoniifolius (Dennst.) Nicolson) is an important edible tropical tuber crop since time immemorial in the tropics and sub-tropics (Behera et al., 2009) and regarded as “King of tuber crops” due to its higher biological efficiency as a food producer ). It belongs to the family Araceae. Tender stem and leaves of this tuber crop are used for vegetable purpose. The corms are rich in nutrition and contain 18.0% starch, 1-5% protein and up to 2% fat. Leaves contain 2-3% protein, 3% carbohydrates and 4-7 % crude fibre. It has great scope for commercial exploitation as a medicinal crop in pharmacological industry and widely recommended as a remedy in all three of the major Indian medicinal systems: Ayurveda, Siddha and Unani. The corm is prescribed for bronchitis, asthma, abdominal pain, emesis, dysentery, enlargement of spleen, piles, elephantiasis, diseases due to vitiated blood, and rheumatic swellings. Pharmacological studies have shown a variety of effects, specifically antiprotease activity, analgesic activity, and cytotoxic activity. It has also been found to be a potential inhibitor of bacteria activity when used with antibiotics. In addition, Amorphophallus corm is a good sources of phyto- aestrogens and are effective alternate or complementary to conventional hormone replacement therapy for symptoms associated with menopause and chronic degenerative diseases in women. It is a crop of South-east Asian origin, and grown widely in Philippines, Malaysia, Indonesia and South eastern Asian countries. In India, the crop is popular in the state of West Bengal, Andhra Pradesh, Kerala, Uttar Pradesh, Bihar, Madhya Pradesh, Maharashtra, Orissa, Tamil Nadu and Karnataka. West Bengal is the highest producer of elephant foot yam (293.84 thousand MT in the year 2015-16) followed by Andhra Pradesh (207.52 thousand MT) and Kerala (110.37 thousand MT) (Source: National Horticultural Board). However, the crop is gaining popularity dueto its shade tolerance, easiness in cultivation, high productivity, less incidence of pests and diseases, steady demand and reasonably good price.

Introduction

Colocasia esculenta (L.) Schott, also known as taro, belongs to the family Arecaceae. Taro is believed to have originated in Southern or South-East Asia, and to have been dispersed to Oceania through the Island of New Guinea to many centuries ago but cultivated in Asia for more than 10,000 years. Taro is considered as an important vegetable grown throughout India. Taro is herbaceous perennial plants with a large corm on or just below the ground surface and can be grown in the ground or in large containers. They can be grown in almost any temperate zone as long as the summer is warm.

Taro root contains very significant amount of dietary fibre and carbohydrates, as well as high levels of vitamin A, C, E, B6 and folate, as well as magnesium, iron, zinc, phosphorus, potassium, manganese and copper. Thogh negligible, the plant is also known to provide some protein in our diet. As Taro is a great source of fibre and other nutrients, it offers a variety of potential health benefits, including improved blood sugar management, gut and heart health.

Globally, taro is grown in an area of 1.6 m ha producing 11.66 mt with an average productivity of 7.25 t ha^-1 (FAO, 2009). The plant can be grown in wide range of climatic condition but during growth period taro is prone to attack by at least twenty- three (23) pathogens, of which, only a few causes serious reduction in the potential yield of the crop. Some of the mentionable diseases that commonly occurs and causes yield loss of the plants are as follows:

Introduction

India is the second largest producer of vegetable in the world after China. Every year diseases cause economic losses (8-23%) and also post-harvest losses (20-25 %) in vegetable crops. Bean (Phaseolus vulgaris L.) is a nutritionally important and remunerative crop grown throughout the world and is consumed both as a vegetable, shelled green beans as well as dry beans. It is known commonly known as french bean, common bean, kidney bean, field bean, snapbean, dry bean etc on the basis of its variety and edible purpose. The crop is infected by a number of diseases. Common bacterial blight, Anthracnose, White mold, Bean Common Mosaic, Bean yellow mosaic, Web Blight, Halo blight, Dry root rot and wilt, Bean Rust are some of the major diseases.

Bacterial Blight of Bean

Three types of bacterial blight are found to occur in beans viz. Common bacterial blight or Bacterial blight, Halo blight and Bacterial brown spot. These three diseases affect leaves, pods, stems and seeds in similar manner such that it is usually impossible to distinguish the diseases from one another based on the visual symptoms. While common blight is usually more prevalent in warmer weather, the other two occur more in cool weather.

Introduction

Cowpea (Vigna unguiculata subsp unguiculata) is widely grown in Africa, Asia and Brazil. The crop is grown on about 7 million ha in warm to hot regions of the world (Rachie, 1985). It acts as a major source of protein (20-30%) for Indian vegetarians. Besides, it contains high carbohydrate. Cowpea is generally rich in lysine and limiting in sulphur amino acids and important for human food and animal feed. The crop is also valuable source of dietary fibre as well as vitamins and minerals including folate, thiamin and riboflavin. Besides this, it can fix about 240 kg ha^-1of atmospheric nitrogen and make available about 6070 kg ha^-1nitrogen for succeeding crops grown in rotation with it (Aikins and Afuakwa, 2008).

The crop is prone to several diseases induced by species of pathogens belonging to various pathogenic groups viz., fungi, bacteria, viruses, nematodes, and parasitic flowering plants, and it constitute one of the most important constraints to the profitable Cowpea production in all agroecological zones. Different diseases like anthracnose, fusarium wilt, bacterial blight, Cowpea mosaic virus (and several other less prominent viruses), cercospora leaf spot, rust and powdery mildew etc are reported to be important disease of the crop. In this chapter detail of these diseases and their integrated management approaches are mentioned.

Soyabean (Glycine max L. Merril) belongs to the legume family Fabaceae is one of the world’s most important legume crop and is the second most important cash crop in in India.

Economic Importance

Soyabean contributes to 25% of the global edible oil and about two-thirds of the world’s protein concentrate for livestock feeding (Agarwal, et al., 2013). In many countries such as China, Japan, Korea, Manchuria, Philippines, and Indonesia soyabean is considered to be a source of meat, milk, cheese, bread, and oil and therefore it is called “Cow of the field” or “Gold from soil” (Edwards et al., 2019). Soyabean is a chief source of protein and oil as it contains about 40% protein and 20% oil. Many processed products are made from soyabean such as soy milk, soy flour, soy protein, tofu etc. Due to its amino acids composition, soyabean protein is called a complete protein and is consumed at homes for food purposes. The protein fiber that remains after the oil has been extracted is a good source of animal feed for poultry, pork, cattle, other farm animals and pets. Soyabean is an important foreign exchange earner due to export of soybean defatted oil cake (Agarwal, et al., 2013). Bio diesel is produced from soyabean which is non-toxic, renewable and environmentally friendly and reduces particulate emissions.

Pea (Pisum sativum L.) is considered as the important pulse and popular leguminous vegetable in India. Pea belongs to the genus Pisum, a member of family papilionaceae. Rhizobium bacterium found in root nodules that fixing atmospheric nitrogen and helps in soil fertility. Pea (Pisum sativum L.) originated in the near East and Mediterranean regions. Pea diseases are affect the crop both quantitatively as well as qualitatively. Pea crop diseases caused by the fungal (rust, powdery mildew, downy mildew, aschochyta blight, septoria blight, fusarium root rot, aphanomyces root rot, alternaria blight, wilt, anthracnose, cercospora leaf spot, damping off, seedling rot), bacterial (bacterial blight and brown spot), nematode (root-knot nematode, cyst nematode and lesion nematode) and viral diseases (pea enation mosaic, pea mosaic, pea seed borne mosaic, pea early browning virus, pea streak, pea stunt and cucumber mosaic virus). India is the largest producer, consumer and importer of pulses in the world.

Onion (Allium cepa) and garlic (Allium sativum) are monocots originating from Asia. These are collectively called as Alliums and formerly classified with the Liliaceae (lilies and relatives). But, now they have been classified in their own family the Alliaceae. The plants ofAlliaceae family are mostly used for seasoning and cooking. Some common crops in the family are bulb onion (Allium cepa), spring or salad onion (A. cepa), bunching onion (A. fistulosum), garlic (A. sativum), leek (A. porrum).

Onions and garlic are prone to several different diseases, especially in wet growing seasons. These often get started on their leaves, and if severe, can reduce bulb growth and yield. Another way onion diseases can cause damage is when they infect bulbs later in the season, which may lead to losses in storage. Some important diseases of onion and garlic are being discussed in this chapter:

Introduction

Amaranthus species were grown as the principle grain crop by the Aztecs 5,000 to 7,000 years ago, prior to the disruption ofthe South American civilization by the Spanish Conquistadors. Synonyms such as “mystical grains of the Aztecs,” “super grain of the Aztecs,” and the “golden grain of the Gods” were used to describe the nutritious amaranth grain. Vegetable Amaranthus spp. were and are presently utilized for food from such diverse geographic areas as southwestern United States, China, India, Africa, Nepal, South Pacific Islands, Caribbean, Greece, Italy, and Russia (Stallknecht et. al., 1993). Amaranthus grain is extremely nutritional pseudo-cereal with a higher amount of proteins when compared to true cereals. It is a reasonably well balanced food with functional properties that have been shown to provide medicinal benefits. Amaranth associate underutilized crop and an inexpensive supply of proteins, minerals, vitamin A and C, appears to be a future crop which may substantiate this demand because of its tremendous yield potential and biological process qualities, conjointly recently gained worldwide attention (Topwal, 2019). Amaranth as a unique plant with a long and mysterious history is the obj ect for science and also for business. Its characteristics such as absence of gluten and special composition of oil lead this plant to the position of very important plant for the future. The Advantages of Amaranth for Food Industry: Gluten-free, High-quality protein, Non Food-allergy, Thickening property of amaranth starch. The Advantages of Amaranth oil for Cosmetic Industry: Squalene content has a preserve function for skin and hair against sun and radiation, Available for very sensitive skin, Non- Allergy amaranth oil on skin. Amaranth has a big advantage, because it could be use by two ways-biomass for the bio fuel production and grain for food production (Matusova, 2008). As dyes, the flowers of the ‘Hopi Red Dye’ amaranth were used by the Hopi (a tribe in the western

Introduction

Spine gourd/Teasel gourd (English), (Momordica dioica Roxb.) is popularly known as Kantola or Kakrol in India. It is a perennial, dioecious, cucurbitaceous climbing creeper that belongs to the cucurbitaceae family (Raj et al., 1993). The spine gourd is also called as janglee karela (Harish, 2008). The crop is cultivated for its fruits, which are used as vegetable (Sastri, 1962). Young twigs and leaves of this crop are also used as vegetable (Bandyopadhyay and Mukherjee, 2006). The fruit is rich in ascorbic acid and contain iodine (Rao, 2001). Karnataka and West Bengal are the two main states that cultivate spine gourd commercially. Indira Kankoda I (RMF 37) is a new commercial hybrid variety of spine gourd developed by Indira Gandhi Agricultural University. This hybrid variety is commercially cultivated in the states of Chhattisgarh, Uttar Pradesh, Orissa, Maharashtra and Jharkhand. Spine gourd can also be grown well up to an altitude of 1500 m in Assam and Garo hills of Meghalaya (Ram et al., 2002). This popular vegetable has high demand in market but still remain underutilized and underexploited mainly due to its vegetative mode of propagation and dioecious nature (Bharathi et al., 2010). Adopting improved genotypes and standardized agro- techniques can increased the yield potential of spine gourd (Tiwari and Tigga, 2015).

Cucurbits are major crops of countries having a wide variety of vegetables. Cucurbits include bottle gourd, bitter gourd, pumpkins, squashes, ridge gourd, sponge gourd, and cucumbers. Cucurbits are a large, diverse crop group that are susceptible to over 200 diseases (Zitter et al., 1996). A wide range of pathogens affect the productivity of cucurbits. The diseases may be caused by fungi, bacteria, Cucurbits crops are warm-season large group of crops that are cultivated and harvested over different seasons like spring, summer, and winter. These crops as a group are an important part of a diverse and nutritious diet. Melons are eaten as fruits, whereas summer and winter squashes, cucumber, and pumpkin are eaten as vegetables. In addition, cucurbits are used for fiber, utensils, decoration, ceremonial and medicinal purposes.

A wide range of pathogens affect the productivity of cucurbits, which constitute over 200 diseases (Zitter et al., 1996). The diseases may be caused by fungi, bacteria, viruses, or mycoplasma- like organisms. The disease may be soilborne, seedborne (carried by seed), spread by wind, or transmitted by insect vectors. The moisture content of the seed, storage period, prevailing temperature, and degree of invasion influence the development of seedborne fungi (Anjorin and Mohammed 2009). The pathogen may cause seed abortion and rot, necrosis, reduction, or elimination of germination capacity as well as seedling damage at later stages of plant growth, resulting in the develop- ment of the disease as systemic or local infection (Khanzada et al., 2001). The diseases cause heavy loss in terms of yield and quality. The diseases caused by pathogen are controlled by fungicides against fungal diseases, antibiotics for bacterial diseases, or insecticide in case of viruses transmitted by insect vectors. The diseases of cucurbetaceous crops can be managed by adopting different cultural, biological, and chemical methods of disease management. The following management practices are required to be taken into consideration for raising disease-free cucurbitaceous crops:

Fish as a cheap source of protein, bioavailable minerals, vitamins and essential fatty acids, ensures global nutritional security. India witnessed around 14-fold increment in fish production from 0.7 million tonnes in 1950’s to 10.43 million tonnes in 2014-15. With a contribution of 5.05% to world’s capture production and 6.6% of total aquaculture fish production, India emerged as one among the most progressive fish producing countries in the world. Fisheries as a major agricultural sector, constitutes 0.92% of total GDP and 5.58% of total agricultural GDP of India. With the global fish export value of 148,147 million USD, India ranked seventh position among the top fish exporters of the world. The sector is crucial in securing food supply, job opportunities, nutritional needs and earning foreign exchange for the country, cataloguing it as a sunrise sector of Indian economy.

Technological developments in harvest sector

Introduction of new materials for fishing gears, mechanization of fishing crafts and modern electronic technologies for navigation and fish location, paved way for the significant increase in fish production in India over the years. ICAR-CIFT, Cochin has been involved in the design and optimization of a range of crafts and gears since its inception, which gave a major fillip to the harvest sector of Indian fisheries. Considering the plateauing/decline in catches perceptible since last two decades, ICAR-CIFT has shifted its focus from increasing production to responsible harvest of resources. As a result a large number of technologies for sustainable harvest and green technologies with reduced emissions were developed.

Finfish and aquatic invertebrates are part of Fish Genetic Resources (FiGR) that has actual or potential value for culture and capture fisheries. Fish as a group, have the highest species diversity among all the vertebrate taxa. Out of 62,305 species of vertebrates recognized world over, 32,064 (~ 52%) are valid fish species; of which, the great majority (97%) are bony fishes, mainly teleosts; and the remaining (3%) are cartilaginous fishes (sharks & rays) and jawless fishes (lampreys and hagfishes) (Eschmeyer and Fricke, 2012). India is blessed with vast fishery resources, like exclusive economic zone (2.02 m sq. km), coast line (8,129 km), ponds and tanks (2.254 m ha), beels, ox-bow lakes and swamps (1.3 m ha), reservoirs (2.90 m ha), rivers and canals (173,287 km), brackish water (1.235 m ha) (Ayyappan et al., 2011). The country is fortunate to possess vast and varied fish genetic resources in different aquatic ecosystems and being home to 7.84% of global finfish diversity, with 3535 species of fish, of which 3035 are native species, representing 46 orders, 252 families and 1,018 genera. The 500 exotic fishes are also covered and majority of them are of ornamental fishes. Out of the 3035 native fishes, 1016 are freshwater, 113 are brackish water and 1906 are marine species and at least 258 species are of commercially important (NBFGR, 2016-17). India harbours a rich diversity of fishes and four out of 34 biodiversity hotspot areas of the world. The biodiversity hotspots i.e. the Western Ghats and North East India harbours maximum endemic freshwater fishes. The Western Ghats harboring about 306 finfishes out of which nearly 69% are endemic to the region (Gopalakrishnan and Ponniah, 2000). Likewise North East India, another biodiversity hotspot area, harbors about 240 fin fishes and nearly 40% are endemic to the region (Sarkar et al. 2012). In the past one and half decades more than 50 new species were described from these areas and more than 10 new species were described from the marine environment.

Aquaculture or farming and husbandry of aquatic organisms and plants is the future for increasing aquatic food production. It is the fastest growing food production sector with an annual average growth of >6% in the last two decades. It increased from <1 million tonne in 1950 to 70.2 million tonnes in 2013. An update of aquaculture production (FAO) revealed that the total world aquaculture production continued to grow in 2013, reaching 97.2 million tonnes (live weight) with an estimated value of US$157 billion. A total of 575 aquatic species and species groups are grown in freshwater, seawater and brackish water have been registered in the FAO Global Aquaculture Production Statistics Database. The production of farmed food fish (finfish, crustaceans, molluscs and other aquatic animals) was 70.2 million tonnes in 2013, up by 5.6 % from 66.5 million tonnes in 2012. The production of 27 million tonnes of farmed aquatic plants was a 13.4% jump on the 23.8 million tonnes of 2012. The contribution of aquaculture to the world total fish production reached 43.1%, up from 42.1% in 2012. It was only 30.6% a decade ago in 2003. Meanwhile, world production of aquatic plants, mostly seaweeds, is still overwhelmingly dominated by aquaculture (95.5% in 2013). On a global scale, the production of major non-fed species contributed 30.7% to world food fish aquaculture production in 2013, including 13.9 million tonnes of bivalves and 7.7 million tonnes of filter-feeding carps.

Mariculture involves the cultivation of marine organisms for food and other products in an enclosed section of the sea (cages/pens), or in tanks, recirculating systems, ponds or raceways in seawater..It is a promising sector by which the additional marine fish requirement can be met in the future years. It is also the fastest growing sub-sector of aquaculture. At global level, mariculture produces many high valued finfishes, crustaceans and molluscs viz. oysters, mussels, clams, cockles and scallops. In 2013 mariculture has contributed around 25.5 million tonnes of foodfish globally which formed about 36.3 %of the foodfish aquaculture production(World food fish aquaculture production was 70.2 million tonnes in 2013). Molluscs dominated the global mariculture production (59.7%) followed by finfish (22.7%), crustaceans (16.2%) and others (1.4%). In addition about 26.9 million tonnes of macro algae were also produced by mariculture. The total mariculture production including seaweeds was 52.4 million tonnes in 2013 which constituted 53.9% of the total aquaculture production (The total global aquaculture production including the aquatic plants was 97.2 million tonnes in 2013).

The History of Fish Keeping

Philip Henry Gosse (1810-1888) coined a term “Aquarium” which is now familiar to all of us, in his 1854 book The aquarium: An unveiling of the wonders of the deep sea.

The idea of keeping aquariums can be dated back to 2500 BC and has evolved into a complex hobby that exists today. Ancient Sumerians and Romans kept fish in containers as early as 2500 BC, similar to what we now know as fish tanks. These tanks were designed to keep fish alive long enough to prepare the specimen for food. It is also known that Romans and Babylonians kept ponds filled with fish for ornamental use (History of Fish Keeping as a Hobby).

As time progressed, the art of fish keeping became a “luxury for the rich” (DuHammel 1). Many people consider the Chinese as being the most important contributors to the hobby. “By 1136 AD Emperor Hiau-Tsung started to breed and keep these fish in a more controlled environment. Several new breeds of ornamental fish ornamental emerged.” (DuHammel 1). As more people became involved in the idea of fish keeping, having a goldfish was no longer an indicator of a person’s status. Many common people began to keep goldfish; the fish that they kept represented a good luck charm.

India is situated north of the equator between 8°4' and 37°6' north latitude and 68°7' and 97°25' east longitude, is the largest peninsular country in the world bordered by Arabian Sea in the west, Indian Ocean in the south and the Bay of Bengal in the east. India has a coastline of 8118 km and 0.5 million t sq. km continental shelf endowed with 2.02 million sq. km of Exclusive Economic Zone (EEZ). It has a catchable annual fisheries potential yield of 4.41 million occupying third rank in world marine fish production (Table 1). India’s territorial waters extend into the sea to a distance of 12 nautical miles from the coast baseline. The vital details on marine capture fisheries of India are given in table

Netting yarns for the fabrication of fishing gear are either of textile or non-textile origin. Textile materials compose of netting, twine and rope while non-textile origin materials constitute floats, sinkers, hooks etc. Raw material for fish netting consists of fibres which can be distinguished into two groups: natural fibres and man-made fibres. Different kinds of fibres originating from plant and animal body parts have been used for production of textiles and other products and are termed as natural fibres. Natural fibres such as cotton, manila, sisal, jute and coir were the materials exclusively used in earlier days for fishing gear fabrication.

Later, the invention of polymers resulted in synthetic fibres the use of which revolutionalized the fishing industry. In recent decades advances have taken place in fiber technology, along with the introduction of other modern materials. With the introduction of man-made synthetic fibers in India in the late 1950s, natural fibers used for the fishing gears have been substituted by these synthetic materials due to their high breaking strength, low maintenance cost, long service life and better uniformity in characteristics. Most important synthetic fibres used in fisheries are polyamide (PA), polyester (PES), polyethylene (PE) and polypropylene (PP). Other synthetic fibres, which are less widely used and generally restricted to Japanese fisheries, are polyvinyl alcohol (PVA), polyvinyl chloride (PVC) and polyvinylidene chloride (PVD). Earlier, netting used to be fabricated manually, which is laborious and time consuming while the introduction of synthetic fibres paved way for machine made nettings which are almost exclusively used in fishing net fabrication.

Bottom or demersal trawling continues to be one of the most important fishing methods of the world. In India more than 35,230 trawlers of various sizes ranging from 9 to 30 m L_OA with engine power ranging from 45 to 495 hp @ 2000 rpm are in operation. Trawl is a bag net towed through water to filter out fishes, the mouth of which is kept open horizontally by means of a beam or otter boards and vertically by means of floats and sinkers. Horizontal mouth opening is also effected by dragging the net from two boats known as bull trawling or pair trawling. The principle of trawling is the movement of the net under water filtering the water through the mesh in the netting, without either permitting the fish to escape or gilling them (Fig. 1). Trawl net is fabricated using polyethylene netting after cutting and shaping the panels as per the design

The 20^th century had seen unprecedented increase in fishing capacity; in terms of the vessel number, increase in size of the vessels and advances in the electronic and navigational equipment coupled with easily manufactured and durable fishing nets. The effect of these innovations sequentially, was the burgeoning in the fish production, plateauing of catches and the myth of inexhaustibility of fishery resources in the sea was proven wrong. A large number of stocks world over have declined and the stock status of many are now alarming, but still the trend towards larger, more powerful and faster vessels continues.

Global fisheries production has reached a plateau and is now hovering around 80 million tonnes during the last decade. It is also noted that the status of world’s marine fish stocks have not improved overall. About 31.4% of assessed fish stocks are fished at a biologically unsustainable level and therefore overfished. Fully fished stocks accounted for 58.1% and underfished stocks 10.5%. It is evident that most of the stocks are fully fished with no further potential for increase in production.

The importance of reducing bycatch and minimizing ecological impacts of fishing operations has been emphasized by scientists and fishery managers and recognized by fishermen. Trawl fisheries in different parts of the world are now being required to use bycatch reduction devices as result of pressure from conservation groups and legal regimes introduced by the governments. The Code of Conduct for Responsible Fisheries (FAO, 1995), which gives guidelines for sustainable development of fisheries, stresses the need for developing selective fishing gears in order to conserve resources, protect non-targeted resources and endangered species. Although the problems of using non-legal gears and designs often with smaller mesh sizes are reported. Most of the problems due to generation of bycatch and damage to the ecosystem function, has been implicated due to trawling.

Quality of fish raw material plays an important role for the quality of the end-product. Once the fish raw material freshness and nutrition value is lost, it cannot be recovered in the processing stages. Products that are processed from low quality raw material are not always a safety risk, but the quality (nutrition value) and shelf life is significantly decreased. The quality deterioration can start right away during fishing and it continues all the way to the final user. Time-temperature abuse should be avoided at all stages of handling till landed fish reaches the consumer or the processor. In tropical countries more care in handling is necessary as fishes thrive in high ambient temperature has high body temperature and hastens spoilage.

Fish is highly perishable because of their chemical composition. It has high content of soluble substances in the flesh (many of which contain nitrogen and triglycerides characterized by polyunsaturated fatty acids) and high level of autolytic enzyme. After the death of the fish, spoilage starts due to the action of microbes, enzyme and oxidation. It is therefore, necessary to preserve fish after harvest if not consumed or disposed immediately.

Maintaining the quality of fish begins with harvest and carries through the harvest-to- consumption chain. Careful handling of fish and shellfish while harvesting and during transport to the processing plant is critical if the high quality of the product is to be maintained. There are, however, several constraints on handling the fish; the important among them are the bacteriological, chemical and physical processes that cause degradation of fish. The surface of dead fish is an ideal growth habitat for bacteria and the end result of such activity is spoiled fish. Reduction of temperature can prevent the growth of many bacteria that cause the spoilage. Chemical breakdown due to oxidative and enzymatic reactions can lead to off odours and flavours and rancidity. Digestive enzymes can initiate decomposition in the dead fish. Physical factors can enhance the bacteriological or chemical processes: bruising, tearing, cutting etc. can expose fish muscle to more rapid bacteriological growth, cause internal bleeding which darkens the fillets and expose greater surface area for chemical oxidation.

Since fish is a highly perishable item of food, it has to be immediately processed to various products to preserve the quality and to increase the shelf life. Fish requires proper handling and preservation to increase its shelf life and retain its quality and nutritional attributes. The objective of handling, processing and preservation is to control or reduce the spoilage process so that the final product is wholesome and safe for the consumer. Fish and fishery products brought to market in a well-preserved condition will generally command higher prices, both at wholesale and retail levels, and thus give better returns to the fishing operation.

Low temperature preservation by chilling and freezing methods are widely practiced to maintain the quality and freshness of fish and fish products. Chilled storage method, i.e., keeping the fish in the unfrozen condition has only limited shelf life and it will vary between 4 and 20 days depending on the condition and species of fish. In frozen storage also the shelf life is restricted but it varies from few weeks to years. The various factors that affect the frozen storage shelf lives are condition of fish at the time of catch, handling, processing and product development, packaging and glazing of the product, freezing method adopted, frozen storage temperature, stacking methods and transportation techniques. These factors can be put together and can be termed as ‘Product, Processing and Packaging’ (PPP) and ‘Time Temperature Tolerance’ factors (TTT).

Thermal processing also known as heat processing is commonly used processing method which helps in extending the shelf life of the food productswith high safety level, convenience and a healthy product.Seafood as a whole food is highly nutritious. Benefits to human health associated with the consumption of seafood is well recognized for multiple bodily organs and physiological functions but their high perishable nature is a concern. Seafoodundergoes spoilage due to autolytic, microbial action as well as oxidation of lipid. Proper handling and preservation is essential to maintain quality of fish. Heat processing is an age old preservation method practiced in many countries to extend the shelf life of food products. Heat treatment causes the destruction of microbes which increases the shelf life. There are number of thermal processing operations like- baking, blanching, canning, dehydration, extrusion, frying, pasteurization, sterilization, etc. All these operation serves various purposes and helps in manufacture of different food products.

Thermal processing is of utmost importance to low acid high water activity foods, where there are no hindrances to microbial growth. The proper delivery of heat is essential to cause the destruction of microbes to avoid food spoilage. In seafood’s processing, thermal processing through canning (retort pouch processing) is a common approach. In canning, the food is preserved by application of heat in hermetically sealed cans (pouches). Hermetic sealing means- complete airtight sealing. This prevents contamination from outside. Heating at very high temperature ranging from 110 to 135⁰C for a desirable time helps in killing all the vegetative forms of microorganisms as well as most heat resistant microbial spores. The amount of time needed for processing is different for each food type depends on hurdles present in the food and heat transfer characteristics. In thermal processing of seafood products, heat processing is aimed for the destruction of spores of Clostridium botulinum. A number of thermally processed ready-to-eat (RTE) products are available on market shelf.

Food processing involves the transformation of raw materials into consumer-ready products, with the objective of stabilizing them to prevent negative changes in quality and ensure food safety. To consumers, the most important attributes of a food product are its sensory characteristics like texture, flavour, aroma, shape and colour. The aim of food manufacturers is to develop and employ processing technologies that retain or create desirable sensory qualities or reduce undesirable changes which take place during processing. Alternative or novel food processing technologies are being explored and implemented to provide safe, fresher-tasting, nutritive foods without the use of heat or chemical preservatives. The major non thermal technologies gaining importance are High-pressure processing, Pulsed light technology, Pulsed electric field, Irradiation etc.

High pressure processing

The application of very high pressures (upto 87,000 psi, 6000 bar or 600 MPa) for preservation of food substances in combination with or without heat is known as high pressure processing (HPP). This process is also known as high hydrostatic pressure processing (HHP) or ultra-high pressure processing (UHP). When compared to thermal processing, pressure treated foods have a fresher taste, better appearance, texture and nutritional value. High pressure processing can be conducted at ambient or refrigerated temperatures, thereby eliminating thermal effects and cooked off-flavors. The technology is highly beneficial for heat sensitive products. The first high pressure processing line was introduced in Japan for jam manufacture in 1990’s and has since been upgraded to several food products. A number of HPP products have been commercialized in North America, Europe and in China. Machines are now available with operating pressures in the range 400-700 MPa and capacities ranging up to 900 kg per batch. Since HP processing affect mainly the non-covalent bonds of the food, the quality characteristics of foods such as color, flavor and nutrients generally remain unaffected (Knorr, 1993).

Smoking is an ancient method of food preservation, which is also known as smoke curing, produces products with very high salt content (>10%) and low water activity (~0.85). Smoking is a process of treating fish by exposing it to smoke from smouldering wood or plant materials to introduce flavour, taste, and preservative ingredients into the fish. This process is usually characterised by an integrated combination of salting, drying, heating and smoking steps in a smoking chamber. The drying effects during smoking, together with the antioxidant and bacteriostatic effects of the smoke, allow smoked products to have extended shelf-life. Smoked seafood includes different varieties like, smoked finfish and smoked bivalves. Many of the smoked products are in the form of ready-to-eat.

Developments of modern food preservation technology, such as pasteurization, cooling/refrigeration, deep-freezing, and vacuum packaging, have eclipsed the preserving functions of many traditional methods including smoking. Nowadays, the main purpose of smoking has been shifted for sensory quality rather than for its preservative effect.

Depending upon how the smoke is delivered into the food and smoking temperature, four basic types of smoking can be defined: hot smoking, cold smoking, liquid smoking, and electrostatic smoking. Hot smoking is the traditional smoking method using both heat and smoke, which usually occurs at temperatures above 70 °C. For smoked fish and fishery products, a minimum thermal process of 30 min at or above 145 °F (62.8 °C) is required by FDA (2001). Therefore, after hot smoking, products are fully cooked and ready for consumption.

Pre-processing of fish

Fish is a highly perishable food which requires proper handling and preservation to increase its self life and retain its quality and nutritional aspects. Therefore, fish pre-processing and preservation are become a very important part of commercial fisheries. Preservation means keeping the fish after landing in a condition of wholesome and fit for human consumption for a particular period. This preservation should cover the entire period from the time of capture of fish to its sale at retailer’s counter. The main aim of processing and preservation of fish is to prevent fish from deterioration. Methods which are commonly used to preserve fish and fishery products include the control of temperature using ice, refrigeration or freezing and control of water activity by drying, salting, smoking or freeze-drying etc (FAO, 2011). Fish has to be pre-processed in such a manner that it remains fresh for a long time with a minimum loss of flavour, colour, taste, odour, nutritive value and digestibility. Fish processing can be subdivided into fish handling which is the preliminary processing of raw fish and the manufacture of fish products.

Value addition is the most talked about word in food processing industry, particularly in export oriented fish processing industry because of the increased realization of valuable foreign exchange. Value can be added to fish and fishery products according to the requirements of different markets. These products range from live fish and shellfish to ready to serve convenience products. As far as fish processing industry is concerned value addition is one of the possible approaches to raise profitability since this industry is becoming highly competitive and increasingly expensive.

There is great demand for seafood/seafood based products in ready to eat “convenience” form. A number of such diverse products have already invaded the western markets. One factor responsible for such a situation is more and more women getting educated and taking up employment. Reasonably good expendable income, education, awareness and consciousness towards hygiene and health, increased emphasis on leisure pursuits etc. are some of the other reasons.

Marketing of value added products is completely different from the traditional seafood trade. It is dynamic, sensitive, complex and very expensive. Market surveys, packaging and advertising are a few of the very important areas, which ultimately determine the successful movement of a new product. Most of the market channels currently used is not suitable to trade value added products. A new appropriate channel would be the super market chains which want to procure directly from the source of supply. Appearance, packaging and display are all important factors leading to successful marketing of any new value added product. The retail pack must be clean, crisp and clear and make the contents appear attractive to the consumer. The consumer must be given confidence to experiment with a new product launched in the market. Packaging requirements change with product form, target group, market area, species used and so on. The latest packaging must also keep abreast with the latest technology.