Post harvest diseasesPost 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

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

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

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- Anthracnose- ColletotrichumColletotrichum capsicicapsici

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 cinereaBotrytis 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 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

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 Late blight -Phytophthora-Phytophthora capsicicapsici 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

FungusProduces microscopic, asexual spores called sporangiaSporangia - spherical to pyriform, hyaline, papillate and have a long pedicel attached to the base of the sporePathogen grows well between 25 and 30oC

Mode of spreadSurvives in the soil in host debris Roots, stems, and mummified fruits left in the field after harvest, harbor the pathogen for monthsPhytophthora 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