PATH 372 Diseases of Horticultural Crops

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LECTURE 12 DISEASES OF BETELVINE 1) Wilt – (Phytophthora, Sclerotium and Fusarium) Symptoms Sclerotium Collar region is usually infected White mycelial growth over the infected area of stem on which small mustard seed like sclerotia appear Shredding of infected bark Vine wilts and totally dries off Phytophthora parasitica The disease is characterized by darkening of basal stem. Soon the wine wilts accompanied by yellowing of leaves and drooping of vines, starting from tip downwards. Infection from soil level spread upwards reaching 2 nd or 3 rd internode. Roots of affected plants are discoloured, rotted, starting from smaller roots and spreading to the stem Management Destruction of dead vines Long crop rotation with non hosts Deep summer ploughing Green manuring before planting Application of Trichoderma viride, 2kg mixed in 50 kg of FYM Drench the soil with 1% BM 2) Anthracnose/Leaf spot/Marginal blight: Colletotrichum capsici Symptoms Light to dark brown irregular spots on leaves surrounded by diffuse chlorotic halo Marginal leaf tissue becomes black, necrotic and gradually spreads towards the centre Circular, black lesions may girdle the stem culminating in death of the vine Management Spray 1% BM or COC@0.3% at 15 days interval 68
1) Purple blotch – Alternaria porri LECTURE 13 DISEASES OF ONION Symptoms Minute whitish dots on the leaves with irregular chlorotic areas on tip portions Circular to oblong, concentric velvety rings appear in the chlorotic area Sometimes yellow halo is seen around lesions Spots coalesce and leaves die from tip backwards Diseased leaves break at point of infection & hang down Infection also seen on outer scales of bulb, seed stalk and neck Severely infected crop dries up Bulbs become dry and papery Survival and spread P.I: Plant debris and seed bulb S.I: Air-borne conidia Favourable conditions Warm humid weather with rains or heavy dew Management Select disease free bulbs for planting ST with thiram @3g/kg seed Spray mancozeb@0.2% or chlorothalonil@0.2% 2) Smudge – Colletotrichum circinans Symptoms Chiefly a disease of scales of bulb. Red scaled onions are usually resistant to the smudge due to the presence of protocatacheuic acid and catechol Damping off in seed bed under wet and warm conditions Disease appears at all stages and also during storage and transportation Sub-cuticular, dark green to almost black smudge appear on the bulb, neck or green leaves that are clinging to bulb after digging Circular lesions with concentric rings of dark stromata and mycelium appear on leaves Small, sunken and yellow lesions on inner scales Pinkish mass of fungal growth on lesions under humid conditions 69
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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 and 8:
Tristeza affected trees look chloro
Page 9 and 10:
Symptoms: The disease starts with
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Spraying with Karathane 0.1% or cos
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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: Disease cycle P.I: Collateral host
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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