PATH 372 Diseases of Horticultural Crops

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7) Root knot nematode – Meloidogyne sp. Root knot is the most important group of phytonematodes and was first recorded in green house vegetables in England in the year 1855. Of the four predominant species of Meloidogyne, M. incognita and M. javanica are commonly found in the tropics, whereas M. arenaria is more common in the sub-tropics. M. hapla is common in the temperate region and can occasionally found in the cooler uplands of tropics. Symptoms Formation of galls on host root system is the primary symptom Roots branch profusely starting from the gall tissue causing a ‘beard root’ symptom In severely infected plants the root system is reduced and the rootlets are almost completely absent. The roots are seriously hampered in their function of uptake and transport of water and nutrients Plants wilt during the hot part of day, especially under dry conditions and are often stunted. Seedlings infected in nursery do not normally survive transplanting and those surviving have reduced flowering and fruit production Mode of spread and Survival Juveniles and eggs survive periods of moisture stress in a state of anhydrobiosis Irrigation water and soil adhering to animal feet and implements help in dissemination of juveniles and eggs of nematodes Management Crop rotation with graminaceous hosts Inclusion of non-preferred hosts like mustard, sesame, maize, wheat, etc., in the cropping system Intercropping of marigold with tomato reduces nematode population Nursery should be raised in nematode free sites or fumigated beds Deep ploughing of infested fields during summer. Three summer ploughings at 10 days interval reduces juvenile population Flooding the field for prolonged periods Use of biocontrol agents like Paecilomyces lilacinus (egg parasite) Nursery bed treatment with metham sodium (Vapam)@25ml/m 2 or Carbofuran@0.39g a.i/m 2 Bare root dip treatment in EC formulation of systemic pesticides like Dimethoate or Phenemiphos for 6-8 hours before transplantation Grow resistant varieties like Hissar Lalit and PNR-7 Integration of three summer ploughings or use of treated nursery with spot application of carbofuran @1 kg a.i/ha at transplanting stage have been found successful to manage nematode population in tomato. 60
LECTURE 11 DISEASES OF CRUCIFERS 1) Club root of crucifers or Finger and toe disease: Plasmodiophora brassicae Fairly severe in hilly regions on cabbage, cauliflower and other crucifers. Fields once infested with the club root pathogen remain so indefinitely and become unfit for cultivation of crucifers. Symptoms Infected plants have pale green to yellowish leaves initially. Later, infected plants show wilting in the middle of hot, sunny days, recovering during the night Stunting of above ground parts and reduction in size of heads Characteristic symptoms become apparent in advanced stage of root infection as spindlelike, spherical, knobby, or club-shaped swellings. The swellings may be few, or they coalesce and cover the entire root system Disease cycle P.I: Soil borne resting spores, which survive for longer periods in soil (10yrs.) Collateral hosts: Broccoli, Brussels sprout, cabbage, cauliflower, Chinese cabbage, mustard, raddish, turnip S.I: Resting spores or zoospores carried through irrigation water or by root contact Favourable conditions It occur at a temp range of 12-27 0 C (25 0 C) High soil moisture Neutral to acidic soils 5-7.0 pH Management Use of seedlings from disease free fields Plant cabbage and other susceptible cruciferous crops in well drained fields that have a pH slightly above neutral (usually about pH 7.2) Crop rotation does not work since pathogen persists long in soil. Add hydrated lime to soil to increase pH to 7.2 ( 6weeks before planting @ 2.5T/ha) Avoid excess irrigation Treat the soil of seed bed areas with chloropicrin, methyl bromide or vapam two weeks before planting. Drenching soil with a solution of Brassicol (Pentachloronitrobenzene) 61
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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
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: Management All collateral hosts in
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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