eChapters

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: