PATH 372 Diseases of Horticultural Crops

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Economic importance: Greening disease is known to occur in Andhra Pradesh, Karnataka, Punjab, Uttar Pradesh, Himachal Pradesh, Rajasthan, Maharashtra, Jammu, Bihar, Bengal and Sikkim. The disease is more severe on sweet oranges than on acid lime, mandarin and grapefruits. This disease affects almost all citrus varieties irrespective of root stock. In India Mosambi sweet orange and Darjeeling orange (Citrus reticulata) are good indicator plants for greening. Symptoms: Affected trees are stunted with pronounced leaf and fruit drop. Varied chlorotic patterns on leaves are noticed which are persistent and cannot be corrected by zinc sprays. Reduction in leaf size is common. Many affected leaves show small circular green islands within the chlorotic areas. Heavy leaf fall occurs with the onset of summer. Often new flush may come out and leaves formed are short, upright and chlorotic with green veins or with green blotches on the leaves. Twig die-back occurs. Some branches in a tree exhibit severe symptoms whereas others in the same tree are apparently normal. Fruits show reduction in size, lopsided growth and oblique columella. The rind surface exposed to sun appears yellow whereas the remaining portion remains dull green. Diseased fruits are valueless owing to small size, distortion, low in juice and soluble solids, high in acid and insipid taste. Seeds are poorly developed, dark coloured and aborted. Mode of spread: The disease is transmitted through infected bud wood and citrus psylla, Diaphorina citri. The disease also transmits from citrus to Periwinkle (Catharanthus roseus) through dodder. Management Select certified disease-free seedlings. Control psyllids with insecticides like dimethoate. Use pathogen free bud wood for propagation. Raise virus free plants through shoot tip grafting 500 ppm tetracycline spray though effective, requires fortnightly application which is not economic. 8) Felt disease: Septobasidium pseudopenicillatum 8
Symptoms: The disease starts with onset of monsoon in case of acid lime. A soft felt like fungal growth encircles the twigs and branches. The fungus grows over the bark and does not penetrate the surface. The growth is light brown to grey in colour and colonies of scale insects can be seen underneath it. This results in drying of stems. Management: Spray twice with monochrotophos 0.05% and zineb@0.25% with the onset of monsoon at monthly interval. 9
Page 1 and 2: COURSE MATERIAL FOR PATH 372 DISEAS
Page 3 and 4: Management Preventive measures: Se
Page 5 and 6: Symptoms: The disease attacks leav
Page 7: Tristeza affected trees look chloro
Page 11 and 12: Spraying with Karathane 0.1% or cos
Page 13 and 14: 1. Use of disease free planting mat
Page 15 and 16: The seedling radicle is negatively
Page 17 and 18: The finer roots show black streaks
Page 19 and 20: DISEASES OF PAPAYA Powdery mildew
Page 21 and 22: 4. Leaf curl: Tobacco leaf curl vir
Page 23 and 24: Management Removal and destruction
Page 25 and 26: Disease cycle P.I: Through disease
Page 27 and 28: 6) Banana Mosaic / Infectious chlor
Page 29 and 30: Management Spray carbendazim@0.1% o
Page 31 and 32: Cool dry weather Maximum temperatu
Page 33 and 34: 3. Anthracnose / Birds eye disease:
Page 35 and 36: 6. Rust: Phakopsora vitis GLR is co
Page 37 and 38: • Fruit set - 0.15% captafol 2) P
Page 39 and 40: Symptoms Small outgrowths on stem
Page 41 and 42: Severely infected leaves defoliate
Page 43 and 44: Tomato Spotted Wilt Virus. The dise
Page 45 and 46: 1) Little leaf - Phytoplasma LECTUR
Page 47 and 48: stage produces perithecia in which
Page 49 and 50: LECTURE 9 DISEASES OF POTATO 1) Lat
Page 51 and 52: Infected auxillary bud or the leaf
Page 53 and 54: Favourable conditions High soil te
Page 55 and 56: Also transmitted by pollen and seed
Page 57 and 58: Disease cycle P.I: Mycelium or con
Page 59 and 60:
Management All collateral hosts in
Page 61 and 62:
LECTURE 11 DISEASES OF CRUCIFERS 1)
Page 63 and 64:
The fungus is seed borne and cause
Page 65 and 66:
DISEASES OF CUCURBITS 1) Downy mild
Page 67 and 68:
Disease cycle P.I: Collateral host
Page 69 and 70:
1) Purple blotch - Alternaria porri
Page 71 and 72:
DISEASES OF BEANS 1) Anthracnose -
Page 73 and 74:
Aphis craccivora, Macrosiphum pisi,
Page 75 and 76:
Incorporate green manure crops like
Page 77 and 78:
Provide proper drainage during rain
Page 79 and 80:
As the disease advances the trunk g
Page 81 and 82:
The centers of the spots eventually
Page 83 and 84:
Disease cycle P.I: Infected plant
Page 85 and 86:
Black minute pycnidia develop in th
Page 87 and 88:
On stems, infected areas are blacke
Page 89 and 90:
1) Blotch - Septoria chrysanthemell
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PATH 372 Diseases of Horticultural Crops

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