eChapters

Cauliflower, Cabbage and Knol khol
1. Leaf spot
Pathogen
Alternaria brassicae (Berk.) Sacc.
Symptoms
Alternaria leaf spot usually appear in early stage in cauliflower while at later stage symptoms in cabbage appear as circular light brown spot in leaves. Concentric rings are clearly visible on the spots. In older plants on leaves, petioles and stem, brown to black circular to slightly elongated spots appear.

Stem gall

Diagnostic Symptoms

• Symptom appears in the form of tumor-like swellings of leaf veins, leaf stalks, peduncles, stems as well as fruits.

• Infected veins show a swollen hanging appearance to the leaves.

Wilt

Fusarium oxysporum f.sp. vasinfectum

Diagnostic Symptoms

• Disease affects the crop at all stages.

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.

Introduction

Members of the family Brassicaceae, sometimes known as Cruciferae, include cruciferous vegetables, such as cauliflower, cabbage, kale, garden cress, bok choy, broccoli, brussels sprouts, mustard plant, and other related green leafy vegetables. This family comprises several genera, species, and cultivars that are cultivated for food production. While some are shrubs, herbaceous plants make up the great bulk. The leaves are simple (though sometimes deeply incised), without stipules, and grouped in rosettes or alternately on stems. The terminal inflorescences are devoid of bracts. Four longer free stamens and two shorter free stamens are present on. blossoms, as well as four free petals and sepals that alternate.

1. Damping off
Pathogen
Pythium spp
Phytophthora spp
Fusarium spp
Sclerotium spp
Symptoms
It is a term used to describe the damage caused by various fungi to the seed and emerging seedling in the reduced plant stand and sometimes it is so serious that  resowing becomes inevitable. Major symptoms are the failure of the seedlings decay or sudden death of the emerged seedlings roots and lower stems of emerged seedlings become soft and watery and may be reddish brown in colour.

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:

Downy mildew

Pseudoperonospora cubensis

Diagnostic Symptoms

• Yellow, angular spots restricted by veins resembling mosaic mottling appear on upper surface of leaves .

Introduction

Cucurbits, a versatile and economically significant group of plants within the Cucurbitaceae family, encompass a wide array of popular vegetables such as cucumbers, pumpkins, squash, zucchinis, and melons. These cucurbit crops are not only vital components of global diets but also key players in agriculture. Also, cucurbits are used as fibre source and for utensil preparations, decorations, and ceremonial and medicinal purposes (McGrath 2004). However, their productivity and quality are frequently compromised by a range of diseases. In this chapter, we embark on a comprehensive exploration of the diseases that afflict cucurbits, including their names, symptoms, causative agents, etiology, disease cycles, favourable conditions, and strategies for effective management.

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.

Diagnostic Symptoms

• At first pale-green chlorosis, typically appear on lower leaves and extending up the plant.Leaves eventually take on a dull-yellow colour, wilt and the plant collapses and dies.

Downy Mildew

Plasmopara viticola

• Downy mildew of grapes was catastrophic in France in 1878.

Grapevine

One of the fruits that is grown worldwide most commonly, grapes are said to have a longer history of human interaction than either rice or wheat. Apart from their nutritional significance, grapes are today regarded as one of the most lucrative crops. The grapes are farmed for a variety of uses, including the manufacture of raisins, wine, juice, canning, and table grapes. More grapes are produced worldwide than any other fruit crop. Approximately 11 million hectares are devoted to growing grapes, which yield 75 million tonnes yearly. More than half of the world’s supply of grapes was produced in Spain, Italy, and France. Grapes are cultivated in India in both tropical and subtropical climates. In Maharashtra, Karnataka, Andhra Pradesh, and Tamil Nadu, commercial grape production only started in the last 40 years. Grapevine production affect many sever diseases like downy mildew, powdery mildew, Anthracnose, Black rot, Rust, Bacterial canker and abiotic causes.

Introduction

The Myrtaceae family includes the guava (Psidium guajava L.), a significant fruit crop in India (Nakasone and Paull, 1998). It was originated from Mexico or Central America and later spread to Asia, Africa and Europe. Some of the guava cultivars, which are used to produce seeds-free fruits, are triploid (2n=3x=33) while some are diploid (2n=22). It is primarily grown in tropical and subtropical nations including India, China, Thailand, Pakistan, Bangladesh, Mexico, Indonesia, and Thailand. The nutritionally rich, vitamin and mineral-rich guava is referred to as the “poor man’s apple”.

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

Vegetables
Peas
1. Rust
Pathogen
Uromyces fabae (Pers.) de Bary
Symptoms 
The fungus produces characteristics rust pustules on the host. Pustules are mostly found on the leaf blade, though often they may be found on the petiole and stem of pea plants. The sori are small, roundish, open, and powdery as well as brown coloured. In severe infections, the leaf may wither, resulting in considerable damage to the crop. As the plants near maturity, the fungus produces the telial stage on the host.

Diagnostic Symptoms

• Symptoms can occur at both the seedling and plant developmental stages and appear as patches in the field

• It usually occurs near or at the reproductive stages (flowering to podfilling) of crop growth

Okra/Ladies finger/Bhindi
1. Leaf blight/Spot
Pathogen
Cercospora abelmoschi Ell. & Ev.
Symptoms
The fungus grows as shooty to dark olivaceous, ectoparasite covering entire leaf lamina. Pathogen initiates as small isolated fungal growth on lower side of leaf but very soon it spreads on both sides. Pathogen reduces severely the photosynthesis area. Infected leaves fall down very quickly after dropping and rolling. It causes severe loss in seed production crop as well as in the late sown crops.

Mango (Mangifera indica) is a tropical fruit tree that is well-known and cherished for its delicious, sweet, and juicy fruit. It is one of the most widely grown and economically important fruit crops in the world, primarily cultivated in tropical and subtropical regions. Mangoes are not only enjoyed for their taste but also for their nutritional value, as they are rich in vitamins, minerals, and antioxidants.

However, like all agricultural crops, mangoes are susceptible to a range of diseases that can impact their growth, yield, and fruit quality. These diseases can be caused by various pathogens, including fungi, bacteria, viruses, and nematodes.

1. Powdery mildew (caused by Oidium mangiferae) is a fungal disease that affects mango trees, leading to significant losses in fruit production if left unmanaged.

Anthracnose

Colletotrichum gloeosporioides (Glomerella cingulata)

Diagnostic Symptoms

• Disease produces symptoms like leaf spot, blossom blight, withertip, twig blight and fruit rot

• Symptoms on leaves show as gray to brown spots with dark margins and a yellow halo. The spots later enlarge and coaleasce to form sizable necrotic areas.

Botrytis Gray Mould

Diagnostic Symptoms

• Appearance of a gray, fuzzy mold on flowers, leaves or stems of or plants. Also called, “gray mold”.

Introduction

Mulberry is a very hardy and fast growing perennial plant belonging to the genus Morus of the family Moraceae. The leaf of mulberry is used for feeding and rearing of the silkworm, for the production of silk yarn. It is estimated that mulberry silk worm (Bombyx mori) contributes around 90 % of the total global raw silk production and it is a very attractive economic activities mostly to the rural people. In addition to the utilization of mulberry leaves as silkworm feed, it is being used for many other purposes due to its high nutritive value and delicious taste is getting importance as valuable food stuff as well as environmental importance of mulberry taking into account several aspects of its role as animal feed, foodstuff, phyto medicine and remediation of polluted soils and atmosphere etc.

Diagnostic Symptoms

• Intially chlorotic (yellowed) lesions and sometimes galls appeared on the upper leaf surface.

• There are corresponding white blister-like dispersal pustules of sporangia on the underside of the leaf.

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.

Introduction

Okra (Abelmoschus esculentus (L).is a cross pollinated vegetable crop. Okra originated near about Ethiopia& its cultivation became widespread in North Africa and the Middle East (Lamont, 1999; Tindal, 1983). Okra is grown commercially in many nations, such as Ethiopia, Cyprus, India, Bangladesh, Afghanistan, Pakistan, Turkey, Iran, Western Africa, Yugoslavia, Myanmar, Japan, Malaysia, Thailand, Brazil, Southern United States, and Ethiopia (Purseglove, 1987; benjawan et al. 2007; Qhureshi, 2007). It is a widely used, high-valued vegetable crop that is commercially grown for its tender pods during the spring, summer, and kharif seasons. Okra has high moisture content, making it a good source of vitamins, minerals, and mucilage. Okra is cultivated and consumed commercially throughout the year in many different places of India. 

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:

Purple blotch

Alternaria porri

Diagnostic Symptoms

• Disease symptoms occurs on leaf and flower stalks.

Bulbous herb (Onion) that belongs to Alliaceae family and usually called as the “Queen of the Kitchen.” It is an important biennial vegetable crop grown in India with high export value. A crop that thrives in temperate climates where temperatures between 12.8 to 23°C are necessary for vegetative growth and 20 to 25? are required later for proper bulb development. Onion pungency is due to the presence of allyl-propyl-disulphide. The pigment quercetin and anthocyanin is responsible for yellow and red colour of onion. It has medical benefits like lowering disease risk of cardiovascular disease, diabetes and atherosclerosis. It possess antimicrobial, anti-inflammatory and antioxidant properties (Wilson and Demmig-Adams., 2007).The bulb is useful as diuretic and heart stimulant (Ahmad et al., 2016).

Introduction

Carica papaya is a tree-like herb that grows 2 to 10 meters tall and is often unbranched, cylindrical & hollow stem Fruits are large, cylindrical, with fleshy orange pulp. Numerous, small, black, round seed with gelatinous aril. Papaya leaves have historically been used to treat thrombocytopenia brought on by a dengue infection. (Chinnappan et. al. 2016; Sharma et. al. 2019). Papaya fruits have healing capabilities against cancer, antimicrobial anti-malarial, anti-tumor, anti-inflammatory, antioxidant, immune-boosting, blood sugar-lowering, wound healing, gastro-protective, and capable of curing fever, asthma, jaundice, irregular menstruation, and beriberi. The pharmaceutical and wellness industries have seen a steady rise in demand for papaya as a result of researchers’ recent discovery of their therapeutic potential.

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.

Powdery Mildew

Erysiphe polygoni

Diagnostic Symptoms

• At first symptom appears on leaves.

• White floury patches appear on both surface of leaves as well as tendrils, stem and pod.

Leaf Curl

Taphrina deformans

Disease Symptoms

• Initially yellowish to reddish areas appear on leaf blade of young leaves in the spring.

Introduction

Pomegranates are a tasty, juicy, sweet fruit that are rich in nutrients. Punica granatum is its scientific name, and Iran is where it was originally found. Because pomegranates may be cultivated effectively in regions of the nation with dry climates, they hold a distinctive place among the fruits that are grown there. Other names for pomegranates include Dadim in Sanskrit, Bedana in Bengali, Anar in Hindi, and Madulai in Tamil. The states of Maharashtra, Gujarat, Rajasthan, Karnataka, Andhra Pradesh, Tamil Nadu, and Uttar Pradesh are the primary locations for its cultivation. From the perspective of export, this fruit is also highly significant.

Pomegranate is referred to as a “Super Food” because of its many health and nutritional advantages. It is one of the greatest sources of antioxidants and has significant medicinal and nutritional value. Ripe fruit has a pleasant and nutritious juice. Juice from pomegranates in the summer, sherbet is incredibly refreshing. Pomegranates are regarded as a medication for long life and excellent health in the Ayurvedic medical system.

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%)

Late Blight

Phytophthora infestans

• Phytophthora in Greek means “plant destroyer”(phyto=plant, phthora= destroyer).

Introduction

Potato (Solanum tuberosum) is a widely cultivated and essential staple crop globally, known for its versatile culinary applications and nutritional value. With the exception of Kerala, potatoes are grown in practically every state in India under a variety of climatic circumstances. During the brief winter months, which span from October to March, 82% of potatoes are grown in plains. In West Bengal, potatoes are the most widely grown crop after grains (Chakraborty, 2012). Originating from the Andes region of South America, potatoes have become a crucial part of diets worldwide, providing carbohydrates, vitamins, and minerals. With a rich history dating back to ancient civilizations, including the Irish potato famine, this crop has played a significant role in shaping agricultural practices and food security.

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.

Powdery mildew

Sphaerotheca pannosa var. rosae (Sphaerotheca pannosa)

Diagnostic Symptoms

• A white, powdery fungal growth on the upper, lower or both leaves and shoots.

Introduction

Roses, widely cultivated as cut flowers in greenhouses, as entire plants in nurseries, or within home gardens, encounter common issues across these diverse growing environments, including black spot, Botrytis blight, downy mildew, powdery mildew, and rust. Specific challenges like downy mildew and rose rosette gained prominence in the 2010s. The susceptibility of roses to various diseases varies by geographical region; for instance, rose replant disease is a concern in Europe but not in North America. Greenhouses and tropical climates, as seen in Central and South America, face heightened issues with powdery mildew, downy mildew, rust, and Botrytis blight. Disease management proves costly and can constrain rose production, prompting innovations like the adoption of hydroponics in Colombia, leading to improved pest control, enhanced rose quality, and increased productivity.

Tomato
1. Damping off
Pathogen
Pythium aphanidermatum
Fusarium spp.
Sclerotium spp.
Symptoms
Damping off is the most important disease of tomato. Several seed and soil borne fungi can kill before the tender redical and plumule establish in the nursery bed. The pre emergence damping off and seed rotting is the usual cause of poor seedling stand. This type of damping off causes hidden loss but the post emergence damping off is more serious problem. Seedlings get infected near the soil line (collar region) after emergence and give wire stem symptoms. The tissue become soft, water soaked and weak causing the seedlings fall over and later on they die. The entire action is so fast that leaves remain green but they are unable to stand further.

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.

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).

Leaf Spot

(Mycosphaerella fragariae teleomorph, Ramularia brunnea Peck anamorph)?

Disease Symptoms

• Older leaves usually show purple spots (3-6 mm in diameter) on the upper surface, sometimes with a slightly darker halo

Diagnostic Symptoms

• Practically all above ground parts are affected, but stalks are the main targets of stack.

• Spindle leaves (third or fourth) starts drying.

• Further stalks becomes discolored and hollow.

Diagnostic Symptom

• Circular to oval, dark brown to black spots appear on the leaves.The spots enlarge into round to irregular spots with concentric rings and coalesce causing blighting and withering of leaves.

• These are surrounded by chlorotic zone with grey white necrotic center.

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

Tomato scientifically known as Solanum lycopersicum L. is a widely cultivated and consumed fruit that is often mistaken for a vegetable due to its culinary uses. Belonging to the Solanaceae family, tomatoes are native to western South America with their domestication dating back to ancient civilizations in Mesoamerica. Tomatoes are prized for their vibrant red colour, juicy flesh, and rich, slightly sweet f lavour. They are a versatile ingredient used in a wide range of culinary dishes, from salads and sauces to soups and sandwiches. Tomatoes are a significant source of essential nutrients, including vitamin C, vitamin K, potassium, and folate. Additionally, they contain the antioxidant lycopene, which is believed to have various health benefits.

Leaf spot

Colletotrichum capsici

Diagnostic Symptoms

• Initially oblong brown spots having about 4-5 cm in length and 2-3 cm in width with grey centres surrounded with yellow hallo are found on the leaves .

Important diseases of vegetable crops

1. Damping off: (Phytophthora parasitica, Pythium sp. Rhizoctomia solani):This is a disease of the seedlings at the nursery stage. Due to the attack of this fungus seedlings rot at the ground level and collaps.

Rust

The rust of wheat has been studied more than any other disease in the world. In India, K.C Mehta and his associates studied this disease with exemplary zeal. Three rusts of wheat are known. These are Black stem rust, caused by Puccinia graminis tritici, Brown rust (leaf rust), caused by Puccinia recondita, and Yellow rust, caused by P? striiformis. Brown and yellow rusts cause more damage thant the black rust, because of early appearance in the season.