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
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
Post-harvest softening
of stem end of fruit
Symptoms on fruits
 Fruit peduncle - highly susceptible & is frequently the initial point of
infection

Both ripe and green fruit may be affected

Initially, the lesions on the fruit are light to dark-colored, watersoaked, 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
Rotting fruit
Collapsed fruit
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
Bacterium

Gram –ve, rod shaped bacterium

1 to 6 peritrichous flagella
Epidemiology

Warm, moist weather - highly favorable for infection

Temperature - 25° to 30°C, RH - 95%
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
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
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

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
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
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
Gray Mould - Botrytis cinerea
Brownish spots develop near the soil line or
cotyledons
Water-soaked lesions on leaves & stems darken
and collapse

Water-soaked spots that rapidly expand into large yellowishgreen 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
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
Favourable conditions and spread

Fungus sporulation and infection, is favored by cool and wet
weather

Temperatures of 17–23°C, 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
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
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
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
Spores of A. solani
Alternaria solani conidia. Note the transverse
and vertical septa and the long "beak" (arrow)
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
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
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
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