eChapters

Calcium is a vital mineral playing an essential role in numerous physiological processes, including bone formation, muscle contraction, nerve impulse transmission, and blood clotting. Proper calcium metabolism in animals is regulated by a complex interplay of dietary intake, hormonal control (mainly by parathyroid hormone; PTH, calcitonin, and vitamin D), and organ systems such as the kidneys, intestines, and bones. Imbalances in calcium homeostasis, whether due to dietary deficiencies, genetic predispositions, hormonal dysfunctions, or systemic diseases, can lead to a wide range of disorders affecting the skeletal system and overall health. Calcium-related disorders in animals can broadly be classified into those resulting from calcium deficiency, excess, or abnormalities in calcium regulation. Among these, skeletal manifestations are the most pronounced, as the bones act as a primary reservoir for calcium in the body. Various diseases related to calcium disorders and their nutritional management are discussed
below:
a) Rickets
Rickets is a skeletal disorder that affects young animals and birds, characterized by improper bone mineralization. This condition occurs primarily due to deficiencies in vitamin D, calcium, and phosphorus, which are essential for proper bone development. Rickets can lead to deformities, pain, and reduced growth rates, and understanding its causes, symptoms, mechanism, and nutritional management is crucial for prevention and treatment.

1. Inflammation of pericardium or pericardial sac is known as

a) Endocarditis b) Pericarditis

c) Myocarditis d) Epicarditis

10.1. Sugarcane

10.1.1. Yellow leaf disease

1. Vector: Melanaphis sacchari , Rhopalosiphum maidis

2. Symptoms

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).

Seedling Blight

Phytophthora parasitica

Economic Importance

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

7.1. Rice

7.1.1. Blast

Magnaporthe oryzae (formerly Magnaporthe grisea) anamorph: (Pyricularia oryzae)

RICE (Oryza sativa)
Fungal diseases
1. Blast
Symptoms: All above ground parts (leaf, leaf sheath, culm) of the plant are affected. There are three type of blasts (leaf blast, node blast, neck blast)
Leaf blast: Eye or spindle shaped spots on leaves (margin is dark brown and centre becomes ashy) and leaf sheath are observed. Several spots appear on the leaves cause blightening.

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

Chili peppers, also spelled chile or chilli, are varieties of the berry-fruit of plants from the genus Capsicum, which are members of the nightshade family Solanaceae, cultivated for their pungency. Chili peppers are widely used in many cuisines as a spice to add "heat" to dishes.

Botanical Name : Capsicum annum

Family : Solanaceae

Chromosome Number (2n) : 24

Diseases of Chilli

 1. Powdery Mildew

The disease was first reported from Morocco in 1937.

Anthracnose or Fruit Rot and Die Back

Colletotrichum capsici

Diagnostic Symptoms

Dieback symptoms

• Small, circular to irregular, brownish black scattered spots appear on leaves .

1. Introduction

Chirata (Swertia chirayita) belongs to the family Gentiniaceae, a potential medicinal plant used as bitter tonic in treatment of fever and for curing various skin diseases, is a perennial herb and distributed throughout the eastern Himalayan region of India. The plant is a native of temperate Himalayas, found at an altitude of 1200-3000 m (4000-10000 ft), from Kashmir to Bhutan and in the Khasi hills at 1200-1500 m (4000 to 5000 ft). It can be grown in sub-temperate regions between 1500 and 2100 m altitudes. It is used in traditional medicine to treat numerous ailments such as liver disorders, malaria, and diabetes and are reported to have a wide spectrum of pharmacological properties. Its medicinal usage is well-documented in Indian pharmaceutical codex, the British, and the American pharmacopeia’s and in different traditional medicine such as the Ayurveda, Unani, Siddha, Horopathy and other conventional medical systems. This ethno medicinal herb is known mostly for its bitter taste caused by the presence of different bioactive compounds that are directly associated with welfare of human health. The increasing high usage of Swertia chirayita, mostly whole plant, as well as the illegal overharvesting combined with habitat destruction resulted in a drastic reduction of its populations and has brought this plant to the verge of extinction. The increasing national and international demand for Swertia chirayita has led to unscrupulous collection from the wild and adulteration of supplies. The bitterness, antihelmintic, hypoglycemic and antipyretic properties are attributed to amarogentin (most bitter compound isolated till date) 1, swerchirin, swertiamarin and other active principles of the herb. Due to the high demand, this plant is being cultivated in many places of Darjeeling district both for domestic use within India and for exporting purpose. During our roving survey (2011-2014), it was observed that this high value medicinal plant facing a number of diseases (like seedling blight, leaf spot, Leaf blight etc.), ultimately, cultivation of Swertia chirayita is getting hampered. The quality of plant is affected due to the occurrences of diseases as whole plants part being used as medicinal purpose and also affects the marketing scenario; the demand of good quality chirata is increasing at a rate of 10% annually. To harvest the benefit of megabiodiversity zone of eastern Himalaya needs urgent attention to combat the upcoming epidemic of diseases of chirata. Here, we are trying to throw some light related to present status of diseases of chirata and standard management practices.

Introduction

Chrysanthemum, commonly known as “mums” or “chrysanths,” is a genus of plants that bloom and belong to the Asteraceae family. These plants are native to Asia and northeastern Europe, with China being the primary centre of diversity for the genus. Chrysanthemums are well-known for their attractive and colorful f lowers, and they are popular ornamental plants in gardens, floral arrangements, and as cut flowers.

Chrysanthemum morifolium is a herbaceous perennial flowering crop. It is the second most popular cut flower worldwide, right behind roses, and a significant decorative plant for commerce (Silva et. al., 2013). Certain species’ flowers, such as those of Chrysanthemum morifolium and Chrysanthemum indicum, are rich in nutrients and biologically active substances and are used to make medicinal tea and cosmetics, respectively (Lin et. al., 2010).

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

Gummosis

Phytophthora spp

Diagnostic Symptoms

• Dark water soaked large patches appear on the basal portions of the stem near the ground level.

Introduction

The innermost layer of the pericarp is the endocarp. The segments are also called “liths”, and the space inside each lith is a locule filled with juice vesicles, or “pulp”. From the endocarp, stringlike “hairs” extend into the locules, which provide nourishment to the fruit as it develops. Citrus fruits are notable for their fragrance, partly due to flavonoids and limonoids (which in turn are terpenes) contained in the rind, and most are juice-laden. The juice contains a high quantity of citric acid giving them their characteristic sharp flavour. The genus is commercially important as many species are cultivated for their fruit which is eaten fresh, pressed for juiceor preserved in marmalades and pickles.

Coconut

 Kingdom: Plantae

 Phylum: Magnoliophyta

 Class: Liliopsida

 Subclass: Arecidae

 Order: Arecales

 Family: Arecaceae

 Genus: Cocos

 Species: Cocos nucifera Linnaeus

 1. Bud Rot

The fungus Phytophthora palmivora is responsible for the ailment known as “bud rot.” Butler first mentioned bud rot in India in 1906. Due to a number of factors, the disease has recently spread to practically every region of the state in a very serious manner.

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.

Common salt, or sodium chloride (NaCl), is an essential mineral that plays a critical role in the health and productivity of livestock and poultry. It is a major source of sodium (Na) and chloride (Cl), both of which are vital for maintaining osmotic balance, acid-base regulation, nerve conduction, and muscle function. However, deficiencies or excesses of common salt can lead to severe health issues, reduced productivity, and even mortality in animals. This chapter discusses common salt disorders, their causes, symptoms, and the nutritional management strategies necessary to prevent and mitigate these
problems.
Importance of common salt in animal health
1. Electrolyte balance: Sodium and chloride maintain osmotic pressure and fluid balance within the body.
2. Acid-base regulation: Sodium and chloride are crucial for maintaining acid-base homeostasis in the blood.
3. Nerve and muscle function: Sodium is essential for nerve impulse transmission and muscle contractions.
4. Digestive health: Chloride is a major component of gastric acid (hydrochloric acid), which aids in digestion.
5. Milk and egg Pproduction: Adequate salt levels are required for optimal production in dairy animals and laying poultry.

1 Condition characterised by bran - like scales on skin surfaces is called

a) Pustule b) Parakeratosis

c) Erythema d) Pityriasis

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

Economic Importance

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

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.

Anthracnose

Colletotrichum lindemuthianum, Glomerella lindemuthiana Shear [teleomorph]

Economic Importance

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

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.

1 True vomiting is seen in

a) Pseudoruminants b) Monogastric animal

c) Ruminants d) All

The primary function of the digestive system include prehension of food material, its digestion, absorption, excretion of undigested material and
maintenance of internal environment. All the these functions are accomplished through the four major functions of the gastrointestinal system.

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.

COTTON (Gossypium spp)
Fungal diseases
1) Damping off
Symptoms: The seeds may rot. Initially the roots and hypocotyls become water soaked and pale green in colour. The hypocotyls become constricted above the soil level and seedlings fall down. Causal organism: Pythium aphanidermatum
Management
i) Seed treatment
ii) Growing of resistant varieties.
2) Root rot
Symptoms: Roots of infected plants rot and show shredding of the bark. The affected plants can be easily pulled out.
Causal organism: Rhizoctonia solani

2.1 Loose Smut of Wheat

The disease is prevalent in all the wheat growing areas in the world. However, it is a serious problem in humid and sub-humid areas. The incidence of the disease is comparatively more in cooler and humid parts of northern India as compared to the drier and tropical parts of the country. Being a simple interest disease epidemiologically, this is a threat to the cultivation of wheat for seeds. The disease is therefore, dreaded by seed growing agencies who have to treat the seeds with costly chemicals.

CEREALS

Rice (Oryza sativa)

1. Rice blast
Pyricularia oryzae

‘Rice blast’ occurs in more than 80 countries across the world. The disease is more prevalent in Thailand, Japan, America, Guyana, Philippines and India. It is particularly serious in places, where rice is irrigated or receives heavy rainfall and where high levels of nitrogenous fertilizers are applied. Rice blast was first reported in China in 1637, in Japan in 1704 and in India in 1913. In India, it is found in all rice growing states, particularly in Telungu Desam, Karnataka, Maharashtra, Uttar Pradesh. Assam, Tripura, West Bengal, Bihar, Orissa, Himachal Pradesh, Punjab, Madhya Pradesh, Gujarat, Kerala, Tamil Nadu and Pondicherry and causes considerable damage to rice crop. In Tamil Nadu, the disease occurs in all rice growing districts and attains epidemic proportions in some seasons. Several rice blast epidemics have occurred in different parts of the world, causing yield losses ranging from 50 to 90 %. In Tamil Nadu, a serious epidemic of the disease occurred in 1919 in the Thanjavur Delta.

Symptoms. The disease, though chiefly a foliage disease, attacks other parts of rice plants, such as leaf sheath, rachis, joints of the culms and even the glumes. On the leaves, the initial symptoms appear as small bluish or grayish specks, which remain circular in older leaves. On young leaves, they enlarge and become eye-shaped, diamond-shaped or spindle-shaped spots, extending over several centimeters in length and about 1.0 cm. in width. The central portion of the lesion appears pale green or grayish green and water-soaked in the beginning. In older spots, the center becomes white to gray with a dark-brown margin surrounded by a yellow hallow. The lesions may coalesce, cover large area of the leaves and eventually the entire leaves are killed. The shape, size and color of the spots vary depending upon the variety, growth stage of the plants and environmental conditions. Similar spots may be formed on the leaf sheath also. During severe incidence, large areas of the leaves dry and die and the entire crop presents a burnt appearance. Hence the disease is known as ‘blast disease’. Leaf blast is more severe during the seedling and maximum tillering stages. In the nursery, the seedlings show numerous spots on the leaves, which wither and die. In case of severe infection, large number of seedlings may die. Blast also affects the leaf collar, which results in the death of the entire leaf.

The disease attacks the stem-nodes at the heading stage leading to production of ‘white panicles’ or the stem may break at the infected node. Rarely the internodes are affected. Further, at heading the fungus also attacks the panicle neck, which is girdled and becomes shining black and shrivelled. This is the most destructive phase of the disease and is known as ‘neck blast’, ‘neck rot’ or ‘panicle blast’. If infection of the panicle neck occurs early, the grains become chaffy and the panicle remains erect. If panicle neck infection occurs late, the grains become partially filled and because of the weight of the grains, the panicle breaks at the neck- node and droops. Sometimes, only parts of the panicle and joints of the culms and some glumes are infected and develop brown to black spots (Fig. 1).

Under conditions highly favorable for the pathogen, even the varieties resistant to the fungus under normal conditions are also attacked and small, round or short elliptical spots develop. However, the spots normally do not enlarge as typical blast spots.

BERSEEM CLOVER (Trifolium alexandrinum)
Fungal diseases
i) Damping-off
Symptoms
Pre-emergence damping-off: Seeds decay inside the soil.
Post-emergence damping-off: Sometimes after germination water-soaked blighted seedlings develop. Seedlings collapse and wilt. Stem and root tissues rot below the soil surface.
Causal organism
i) Pythium spinosum var. spinosum
ii) Rhizoctonia solani
Favourable condition
i) Promoted by high humidity
ii) Poor air circulation.

3.1 Damping-off Disease of Seedlings

The disease is quite common in nurseries or seedbeds all over the world. It is virtually a serious threat to almost all the nursery crops of vegetables and other crops including tomato, chillies, cauliflower, cabbage, brinjal, cucurbits, tobacco and a number of other crops. The economic importance of the disease is more because it takes the toll of precious seedlings in the very initial stages of the crop cultivation. The seed can become infected with a fungus which may cause darkening and softening of the seed leading to its decay. Similarly, seedlings may also be infected while sprouting or even after emergence. The disease is more serious in heavy soils with poor drainage. Abundant soil moisture with 90-100% humidity and temperature around 200C is favourable for the disease.

MANIFESTATIONS OF GASTROINTESTINAL TRACT DISEASES Diseases of gastro-intestinal tract may be acute or chronic. Dehydration and shock are the major effects of acute and hyper acute diseases of gastrointestinal tract respectively. While major effect of chronic dysfunction of gastrointestinal tract is exhaustion from lack of food and water owing to loss of appetite (anorexia,). Other manifestations of gastro-intestinal tract diseases are abnormalities of prehension, mastication and swallowing; salivation; diarrhea: constipation and tenesmus; ileus; vomiting; hemorrhage; abdominal pain; abdominal distension; and shock and dehydration. Abnormal Prehension • Prehension   abnormalities may arise from paralysis of jaw muscles and tongue, dentition defects, mouth pain

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.

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.

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.

Anthracnose

Colletotrichum lindemuthianum

(Sexual stage: Glomerella lindemuthianum)

Diagnostic Symptoms

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

Tikka or Leaf Spot

Cercospora arachidicola/ Phaeoisariopsis personatum

Economic Importance

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

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

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”.

Introduction

Bees belonging to the Apis genus can be found in a wide range of climates worldwide. Among them, the Apis mellifera Linnaeus species is distributed across diverse environments such as sub-Saharan Africa, northern Europe, and Central Asia. This species exhibits remarkable adaptability, thriving in various habitats like the oases of the African desert, the Alps, the edges of the tundra, and the misty regions of the United Kingdom. Additionally, other honey bee species within the Apis genus are predominantly distributed in Asia, specifically in tropical Southeast Asia.Honeybees are good biological indicators.

FRUIT CROPS

Banana (Musa species)

1. Panama disease of banana
Fusarium oxysporum f.sp. cubense

‘Panama disease’, ‘Fusarium wilt’ or ’vascular wilt’ of banana is one of the most serious and destructive diseases of the crop. The disease was first reported from Australia in 1874. Now, it is widely distributed all over the world, including America, Africa, Sri Lanka, Burma, Thailand, Malaysia, Indonesia, Hawai, Fiji, the Philippines, India, Australia and New Zealand. In India, it is prevalent in the states of Assam, Bihar, Karnataka, Kerala, Tamil Nadu, Telungu Desam, Maharashtra and West Bengal.

Symptoms. Usually the symptoms are manifested, when the banana plants are about 5 months old. However, under highly favorable conditions for the pathogen, even 2 - 3 months old plants show wilt symptoms. Initial visible symptoms appear as pale yellow streaks, lengthwise in the petioles of the oldest, lowermost leaves. Two types of symptoms follow this. In the first type, the old leaves turn yellow progressively and finally they break from the petiole and hang down. In the second type, the leaves break from the petiole and hang down, without becoming chlorotic. Gradually, all the leaves collapse and hang down, except the crown, which alone stands upright. The newly formed leaves show yellow blotches and wrinkling of the lamina. Often, the leaf sheaths covering the pseudostem show longitudinal splitting above the ground level. But, sometimes this symptom may not appear. The affected plants may die completely in about 4-6 weeks after the appearance of yellow streaks on the petioles.

The vascular strands show discoloration varying from yellow to dark- brown, which is the characteristic internal symptom of the disease. The discoloration usually appears first in the outer leaf sheaths and extends to the vascular strands of the pseudostem. Vascular discoloration is more pronounced in the corms, but is not common in the roots. When the rhizome of an infected plant is cut transversely, the discoloration of the vascular bundles is distinctly seen as numerous, pin-point like dots all over the cut surface. The roots of affected plants become black and rotten. The suckers growing from the diseased corms are systemically affected and they wilt and die very soon (Fig. 71).

The causal organism. The mycelium of the fungus is hyaline, septate, much branched and mostly intracellular. Few hyphae may also be present in the intercellular spaces. The hyphae are largely confined to the vascular bundles, often filling the cavity of the vessels. The fungus produces three types of spores viz., macroconidia, microconidia and chlamydospores. The sporodochia bearing conidiophores and conidia emerge through the stomata on the petioles and leaves. The conidiophores are vertically branched. Macroconidia are borne at the apical ends of the main and lateral branches and are formed in succession one after another. They are thin-walled, hyaline, pedicellate, sickle-shaped, with both ends somewhat pointed, 2 - 5 septate, mostly 3-septate and measure 22.0 - 36.0 x 4.0 - 5.0µ in size. Microconidia are produced from the branches of conidiophores or from the tips of hyphae in very large numbers. They are single-celled or two-celled, thin-walled, hyaline, ovate or elongated and measure 5.0 - 7.0 x 2.5 - 3.0µ in size. Terminal or intercalary chlamydospores are formed from the hyphae, as well as from the conidial cells. They are oval or spherical, thick-walled and usually occur in pairs. They measure 7.0 - 13.0 x 7.0 - 8.0µ in size (Fig. 71).

The fungus is a facultative parasite. It can invade the host mainly through wounds in the corms or roots. After entry, the fungus develops extensively in the vascular tissue of the corm and then proceeds systemically to the leaf sheaths and pseudostem through the vascular system. The fungus colonizes the vascular bundles and produces masses of mycelium, which bear conidia and chlamydospores, filling the cavity of the vessels. The plugging of vascular elements by the fungus obstructs the translocation of water and nutrients to the aboveground parts of the plant leading to wilting and death of affected plants.

Mode of survival, spread and epidemiology. The fungus is soil-borne in nature. It can survive saprophytically in the diseased corms and other plant parts for prolonged periods and cause fresh infection. The chlamydospores can also remain in a viable state in the soil and diseased plant parts for a long time. The disease can be easily spread through spores present in the infected banana trash and soil, which may be carried in surface flooded water. Suckers used for planting from diseased areas to other places spread the disease easily. Contact of the roots of healthy plants with the roots of diseased plants carrying the spores also leads to fresh infection. The entry of the pathogen is mostly through wounds in the roots or corms, especially deep wounds up to the xylem vessels, caused incidentally during cultural operations or by soil-inhabiting pests, particularly nematodes.

Light textured, sandy loam soils, with acid reaction and low soil moisture of 25 % favor the occurrence and development of the disease. Ratooning of infected banana plants increases the disease incidence to a great extent and leads to continuous accumulation of soil inoculum.

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.

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