POST HARVEST DISEASES - PowerPoint PPT Presentation

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POST HARVEST DISEASES

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Post harvest diseases Bacterial soft rot - Erwinia carotovora subsp. carotovora Anthracnose - Colletotrichum capsici Fruit rot - Alternaria solani Gray Mould ... – PowerPoint PPT presentation

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Title: POST HARVEST DISEASES


1
POST HARVEST DISEASES OF CHILLIES
2
Post harvest diseases
  • Bacterial soft rot - Erwinia carotovora subsp.
    carotovora
  • Anthracnose - Colletotrichum capsici
  • Fruit rot - Alternaria solani
  • Gray Mould - Botrytis cinerea
  • Late blight -Phytophthora capsici

3
Bacterial Soft Rot- Erwinia carotovora subsp.
carotovora
  • Symptoms
  • Dark veinal tissue followed by leaf chlorosis and
    necrosis
  • Internal dark brown discoloration
  • Stem cankers develop - breakage of branches
  • Wilting and drying
  • Symptoms on fruits
  • Fruit peduncle - highly susceptible is
    frequently the initial point of infection
  • Both ripe and green fruit may be affected

Post-harvest softening of stem end of fruit
4
  • Initially, the lesions on the fruit are light to
    dark-colored, water-soaked, and somewhat sunken
  • In later stages, bacterial ooze may develop from
    affected areas, and secondary organisms follow,
    often invading the rotted tissue
  • Affected fruit hang from the plant like a
    water-filled bag

Collapsed fruit
Rotting fruit
5
  • Conditions for Disease Development
  • Transmitted by irrigation water, but a wound is
    necessary for infection to occur
  • High rate of nitrogen fertilization is associated
    with increased susceptibility to soft rot
  • Post-harvest soft rot of pepper fruit arises
    when,
  • infected fruit is harvested with healthy fruit
  • harvest containers are contaminated with the
    bacteria
  • fruit is subjected to contaminated wash water,
    contaminated surfaces or soil debris

6
  • Bacterium
  • Gram ve, rod shaped bacterium
  • 1 to 6 peritrichous flagella
  • Epidemiology
  • Warm, moist weather - highly favorable for
    infection
  • Temperature - 25 to 30C, RH - 95

7
  • Disease management
  • Disease incidence could be reduced by
  • Early detection of symptoms
  • Disinfection of pruning tools
  • Avoidance of wounding plants
  • Remove plant debris - fallen, diseased leaves
  • Seed treatment 1 sodium hypochlorite for 30
    sec, then rinse with clean water
  • Avoid planting pepper crops following crops of
    potato or cabbage
  • Rotate instead with crops of bean, corn and
    soybean

8
  • Post-harvest disease management
  • Use chlorinated water to reduce populations of
    soft rot bacteria and to reduce the risk of
    infection during washing
  • Allow fruit to dry thoroughly
  • During packing and storage, the fruit should be
    kept clean and maintained in a cool, dry place

9
Anthracnose- Colletotrichum capsici
  • Ripe fruits turning red are affected
  • Small, black, circular spot appears on the fruit
    skin
  • Badly diseased fruits turn straw colour or pale
    white colour, lose their pungency

10
  • Diseased cut open fruits - lower surface of the
    skin is covered with minute, elevated sclerotia
  • Advanced stage - seeds covered by a mat of fungal
    hyphae, turn rusty in colour
  • Causal Organism - Colletotrichum capsici
  • Mycelium - septate and inter and intra cellular
  • Acervuli and stroma on the stem are hemispherical
  • Conidia - in mass appear pinkish

11
  • Epidemiology
  • Temp - 28oC, RH - 95
  • High humid conditions when rain occurs after the
    fruits have started to ripen
  • Mode of spread survival
  • Seed borne
  • Secondary spread is by air borne conidia rain
  • Flies and other insects responsible for
    dissemination of the spores from one fruit to
    another

12
  • Control measures
  • Use disease free seeds
  • seed treatment - thiram 2 kg/ha or zineb 2.5
    kg/ha
  • Three sprayings with captan 0.2
  • 1st spraying - just before flowering
  • 2nd at the time of fruit formation
  • 3rd - fortnight interval after second spraying
  • Biocontrol
  • P. fluorescens, Bacillus subtilis -effective
    (Rajavel, 2000)
  • P. fluorescens and T. viride (Muthuraj, 1998)
  • Saccharomyces cerevisiae P. fluorescens
    (Jayalakshmi et al., 1998)
  • Essential oil - Nigella sativa - antimicrobial
    activity

13
Gray Mould - Botrytis cinerea
Brownish spots develop near the soil line or
cotyledons
Water-soaked lesions on leaves stems darken
and collapse
14
  • Water-soaked spots that rapidly expand into large
    yellowish-green or grayish-brown, irregular
    lesions that are soft and spongy in texture
  • Velvet-like fungus mycelium and spores are
    produced on the lesion surface under cool, humid
    conditions

Water-soaked spots collapse
15
  • Fungus
  • Botrytis cinerea - abundant hyaline conidia
    (asexual spores) borne on grey, branching
    tree-like conidiophores
  • It overwinters as sclerotia or intact mycelia,
    both of which germinate in spring to produce
    conidiophores
  • The conidia are dispersed by wind and rain-water
    and cause new infections

Conidia and hyphae
16
  • Favourable conditions and spread
  • Fungus sporulation and infection, is favored by
    cool and wet weather
  • Temperatures of 1723C, RH - 90
  • Excessive application of nitrogen makes plants
    such as young transplants more susceptible to
    gray mold
  • High canopy density creates conditions for
    extended leaf wetness at night and subsequent
    increased gray mold severity

17
  • Control
  • Field sanitation - remove and burn decaying
    infected plant parts
  • Space seedlings and transplants to allow for free
    flow of air through the crop
  • Treatment with hot air at 38oC for 48-72 h or hot
    water at 50oC to 53oC for 2 to 3 min

18
Alternaria rot- Alternaria solani
  • Brown lesions surrounded by a yellow halo develop
    on the fruit
  • Lesions enlarge and result in the formation of
    irregular sunken patches with a dark brown margin
    and light grey centre

19
  • Fungus
  • Hyphae - septate, branched, light brown becoming
    darker with age
  • Conidia - single, muriform, beaked and dark in
    color
  • Source of infection - infected seeds and plant
    debris

Alternaria solani conidia. Note the transverse
and vertical septa and the long "beak" (arrow)
Spores of A. solani
20
  • Control
  • Fortnightly spraying of
  • Bordeaux mixture 1.0
  • Copperoxychloride 0.3
  • Difolatan 0.3
  • Mancozeb 0.2
  • Reduction in the pathogenicity and development of
    these pathogens in inoculate peppers,
  • Treatment with hot air at 38oC for 48-72 h
  • Hot water at 50oC to 53oC for 2 to 3 min

21
Late blight -Phytophthora capsici
  • Infected leaf tissue - wilted, light green or
    gray-green, later becoming tan to white and
    scalded in appearance
  • With moisture, leaf spots have a water soaked
    border
  • Fruit rots - irregular in shape and olive green
    or light green with water soaked borders
  • Rots expand rapidly and fruits can be completely
    diseased and desiccated, causing the formation of
    "mummified" fruits
  • Infected seeds are brown and shriveled

22
  • Fungus
  • Produces microscopic, asexual spores called
    sporangia
  • Sporangia - spherical to pyriform, hyaline,
    papillate and have a long pedicel attached to the
    base of the spore
  • Pathogen grows well between 25 and 30oC
  • Mode of spread
  • Survives in the soil in host debris
  • Roots, stems, and mummified fruits left in the
    field after harvest, harbor the pathogen for
    months
  • Phytophthora capsici is also seed borne

23
  • Control
  • Rotation with non-susceptible crops will reduce
    the amount of Phytophthora capsici surviving in
    soil
  • Fresh, clean seeds should be planted in new
    potting mix to establish healthy transplants
  • Monitor seedlings as well as the field and remove
    diseased plants as soon as they occur
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