This includes about Identification of Post harvest Diseases of Fruits, Vegetables and their causal agents.

1. POST- HARVEST BIOLOGY
Identification of Post harvest
Diseases of Fruits, Vegetables
and their causal agents.
H.G. Amal Sudaraka Samarasinghe

2. Date:- 5th of July 2019
Title:- Identification of Postharvest Diseases of Fruits and Vegetables
Objectives:-
• To identify the symptoms of postharvest diseases in fruits and vegetables.
• To identify about the causative agents of postharvest diseases.
• To get familiarized with the possible integrated management practices in order to prevent
postharvest diseases.
Introduction:-
Postharvest is referred to as the time period after harvesting. Postharvest period ends when
the food comes in to possession of the final consumer. During this period food losses may occur due
to several reasons. Due to postharvest losses both quantitative and qualitative reductions take place
in food, yet still reduce product value. Postharvest diseases are one of such major methods of food
losses. The diseases which develop on harvested parts of the plants like seeds, fruits and also on
vegetables are the post-harvested diseases. The harvested products may get infected on the way to
storage or to market or even before their final consumption. The plant parts may get infected in the
field, but expression of symptoms may take place later, at any stage before final consumption.
Losses due to postharvest disease may occur at any time during postharvest handling, from
harvest to consumption. When estimating postharvest disease losses, it is important to consider
reductions in fruit quantity and quality, as some diseases may not render produce unsaleable yet still
reduce product value. For example, blemished fruit may not be sold as fresh fruit but may still be
suitable for processing, in which case, it brings a lower price. It is also important to take into account
costs such as harvesting, packaging and transport when determining the value of produce lost as a
result of postharvest wastage.
Losses due to postharvest diseases are affected by a great number of factors including:
commodity type of cultivar susceptibility to postharvest disease, the postharvest environment
(temperature, relative humidity, atmosphere composition, etc.). produce maturity and ripeness stage
of treatments used for disease control . produce handling methods of postharvest hygiene.
The plant products may get infected by microorganisms and cause rotting or decaying — partially
or totally. The quantity of plant products becomes reduced due to the above infection. The seeds or
grains may get damaged by accumulation of toxic substance, the mycotoxin produced by the infected
microorganism.

3. Fruits can be subjected to a variety of roots and decay caused by fungi or bacteria. These
organisms may cause soft spots or light brown lesions on fruits and vegetables.
Postharvest diseases may start before or after harvesting. Plants or fruits infected in the field
may not develop symptoms until stored. Once in storage, infections continue to develop on fruits and
vegetables. Wounds, cuts or bruises caused during harvesting are common entry points for bacteria
and fungi.
Spread of the infection usually requires the presence of warm temperatures and high
moisture, although some storage rots can continue to develop at low temperatures.
Proper postharvest management should be done to prevent / control postharvest diseases of
fruits and vegetables.

4. Post-harvest diseases of Fruits
and their causal agents.

5. Papaya Anthracnose
Casual Organisms:- Colletotrichum gloeosporioides
Figure 1: Papaya Anthracnose disease Figure 2: pink colour fungus spores
Symptoms:-
• Small pink color dry spots are appeared as the initial symptoms of anthracnose of papaya.
• After turn into small tan to gray spots on papaya fruit or foliage.
• These spots grow, they become large water soaked, Sunken, Round Lesions appear on the skin.
• These spots trees.
• Centers or top of the blacken spots appeared with fungal mycellium and spores which are salmon pink
in color.
• Fruit beneath gets extremely soft.
Control measures:-
• Prevention of injury
• Apply fungicides
E.g.:- Moncozeb
• Proper sanitation practices and always sanitize tools to prevent the spread of diseases.
• Use cultural control measures like harvesting mature fruit promptly, instead of leaving it on the tree.
• Remove all dead leaves and fruit from the garden.
• Cleaning up weeds or other garden debris can prevent the spread of papaya anthracnose from rain
splash back and plant-to-plant contact.
• Using hot water treatment (48 °C for 20 minutes)
• Spraying Copper oxychloride 0.3% or carbendazim 0.1% at 15 days interval.
Impacts:-
• Cause for post-harvest losses
• Decrease fruits quality

6. Pineapple stem end rot /Water blister of Pineapple.
Casual Organisms:- Thiclaviopsis paradoxa
Figure 3: Pineapple stem end-rot/Black rot disease
Symptoms:-
• Infection starts from stem ends.
• Watery appearance
• Latter stages, infected tissues turn into dark colour (spores)
• Brown colored water soaked appearance can be observed.
• The skin flesh and core disintegrate
Control measures:-
• Harvest with long stalk.
• Avoid mechanical damages during harvesting and plucking fruits with fine sharp tool and also avoid
mechanical damages during storing and transportation.
• Using chemicals to stem end ,grading,washing, discarding infected items, dry cleaning, storing under
controlled conditions.
• Irradiation.
• Using proper containers to contain.

7. Avocado stem end rot
Casual Organisms:- Dothiorella dominicana
..Phomosisapp.
..Botryodiplodiatheobromae
..Lasiodiplodia theobromae
Figure 4: Avocado stem end rot disease
Symptoms:-
• Starts from stem end and proceed.
• Dark brown/ black colour area near the stem and outside.
• Small, purplish brown spots may appear on any part of the fruit, most often at the stem end.
• As fruit ages, the surface lesions gradually enlarge and become sunken and black.
• Contain and appear fibers inside the fruit.
• Finally decay spreads throughout the fruit.
Control measures:-
• Spraying of fungicides in the pre harvesting stage.
• Established host plant resistant.
• Harvest fruits with long stalks.
• Using waxing treatment.
• Treating the whole fruit with fungicide dipping in it.
• Avoid harvesting of immature fruits.
• Established host plant resistant.
• Using proper standards baskets and sacks.
.

8. Mango Anthracnose
Casual Organisms:- Collestrotrichum gloeosprioudes
Figure 5: Mango Anthracnose disease
Symptoms:-
• Initially black color superficial lesions are appeared.
• Then they are become sunken lesions.
• Mature lesions show minute black bodies of fungi projecting through the skin (mycelium).
• Fresh issues under lesions become deterioration.
• Dark depressed circular lesions develop on the ripening fruit and increase rapidly in size.
• These lesions are usually restricted to the peel, but in severe cases the fungus can penetrate even the
fruit pulp.
• In advanced stages of infection, the fungus produces abundant orange to salmon pink masses of
conidia appear on the lesions.
Control measures:-
• Use of clean containers to handle of fruits.
• Inter planting mango with other type of trees which are not hosts of Mango Anthracnose.
• Pruning trees year by year and removing fallen parts debris from the ground.
• Using pre harvest fungicides.
• Immediate application of fungicide paste to the cut end.
• Use resistant plant varieties.
• Maintaining proper hygiene in the packing station.
• Immersing the fruits in hot water bath containing fungicides.
• Maintaining proper field sanitation.

9. Banana Anthracnose
Casual Organisms:- Colletotrichum musae
Figure 6: Banana Anthracnose disease
Symptoms:-
• First appear in the flowers.
• Infection starts from the ankle side.
• Infections begins as small black circular spots on the feel of fruits.
• If it comes from the plant side, appears from the crown.
• Affected fruits ripen prematurely and disease may spread to crown and affect other fingers also.
• The first symptoms may also appear long after harvest, during transportation or storage.
Impacts
• Quality and appearance reduces.
Control measures:-
• Apply fungicides.
E.g.:- Indofil 45 – to the bunch, Bavistin
• Avoid damage to the banana tissue during harvesting, transportation, packaging and storage.
• Preventing stress during harvesting and storage.
• Washing before packaging (spores and mycelium can be removed) Washing of peels of harvested
fruits.
• Clean processing stations and storage facilities to prevent post-harvest contamination.
• Remove decaying leaves and remaining floral parts.

10. Mango stem end rot
Casual Organisms:-Dothiorella dominicana
...Phomosis app.
...Botryodiplodia theobromae
...Lasiodiplodia theobromae
Figure 7: Mango stem end rot disease
Symptoms:-
• A dark rot develop from the stem end as fruit ripen after harvest.
• A dark brown to black rot begins at the stem end as a dark brown ring and the rot proceeds towards
the other end from the stem end.
• Fungal mycelium is often visible on the fruit.
• The rot produces dark streaking of the water conducting tissues.
Control measures:-
• Pre-harvest sprays of fungicides.
• Prune-trees to improve ventilation and spray penetration.
• Avoid harvesting immature fruit.
• Storing of fruits after harvesting at -10 ◦C
• Removal of infected pedicel during fruit ripening also helps in keeping the disease under control.
• Use appropriate registered chemicals for post-harvest treatments.
.

11. Banana crown rot
Casual Organisms:- Colletotrichum musae
…Fusarium spp.
Figure 8: Banana crown rot disease
Symptoms:-
• Start with crown surface and spread to the internal region of crown.
• Infection starts with the development of mycelium and this mycelium can spread into pedicel.
• Salmon pink color spores can be seen.
• Radial growth pattern can be observed in the culture plates.
• Molds can penetrate deeply into the crown and the necks of fingers resulting dry black rots.
• Finally they become soften and blacken.
Control measures:-
• Applying fungicides on the crown of Banana as soon as possible.
• Proper field sanitation.
• Prompt cooling to 14◦C.
• Use sharp knives for separating bananas to avoid mechanical damages.
• Maintain proper hygiene in the packaging state.
• Change washing water during washing.
• Hot treatments(such as 5 min in 50◦C)

12. Blue mould rot of citrus / Green mould rot of citrus
Casual Organisms:- Penicillium digitatum
.Penicillium italicum
Figure 9: Blue mould rot of citrus / Green mould rot of citrus disease
Symptoms:-
• Can be appeared on lime, lemon, orange, sour orange, sweet orange.
• Clear water soaked, soft area can be appeared on any place.
• Initial stage, water soak small circular areas can be seen on the fruit peel.
• On that white color mould growth can be seen.
• Mycelium is white (Vegetative).
• Green colour conidia- asexual spores.
• With time, white colour mycelium can be spread.
• In blue mold rot, narrow white color area can be seen, while in green mold rot, wide white color are
presented.
Control measures:-
• Avoid harvesting during raining seasons.
• Applying proper fungicides.
• Cultivating host plants
• Maintain hygiene practices.
• Avoid mechanical injuries.
• Low temperature / refrigerated storage conditions should be maintained.
• Protective coatings should be applied.
• Irradiation.
• Controlled atmospheric storages.
• Proper agricultural practices and handling practices.
Impacts
• The disease is spreading to others by wind and through touching.

13. Post-harvest diseases of
Vegetables and their causal
agents.

14. Fusarium rot in Brinjal
Causal organism : Fusarium spp.
This is a fungi.
Symptoms:
• Initially, wet looking spots which are slightly sunken water soaked areas can be observed
either on blossom end.
• White color mycelium can be seen clearly.
• With time, infected area becomes pale brown color.
• With the time, infected area turned into dark brown color area both in flesh and peel.
• Disease symptoms often appear later in the growing season and are first noticed in the lower
(older) leaves.
Control measures:-
• Maintain proper management and hygiene practices before and after harvesting.
• Manage proper practices and controlled conditions during storage and transportation.
• High Nitrogen fertilizers may increase susceptibility to the disease. So soil types should be
tested and organic fertilizer should be used.
• Apply biological fungicides in correct dosages. [e.g.: Mycostop (1-2 gm/ 100sq ft )]
• Using fungicides (Bovistin, thiram,captan)
• Using proper storage conditions.
• Introduce new pathogen resistant varieties.
• Remove stricken growth and sterilize pruning clippers with bleach.
Impacts:
• Wastage of Brinjals.
• Reduce quality of vegetables.
• Can spread towards other vegetables.

15. Aspergillus rot of garlic/onion
Causal organisms
• Aspergillus niger (This is a fungal pathogen)
Symptoms
• Dark black color streaking appears on the outer surface of the bulb because of the fungal
growth.
• In initial stage, watery appearance can be seen and with time it becomes a dry and black
color mass.
• In bruised area, discolored appearance can be observed.
• At final stage, black color masses of the spores can be seen.
• When higher disease appear, whole bulb become black color because of the fungal growth.
• When infection is very high, whole bulb become dark and weight is lost.
• Also brush area becomes dark color because of the spores
• Dark color spots can be seen in outer skin.
Control measures
• Selection of healthy bulbs for planting and crop rotation should be followed by 3 to 4 years
with other than garlic and leeks.
• Store bulbs dry and practice through curing. (Storage temperatures – 0-2°C, Relative humidity
– 65%-70%)
• Handling of bulbs to avoid bruising also reduce the injury and invasions sites for the fungus.
• Stop irrigations 10 – 14 days before harvesting as the wet soils at harvesting time promote
infections.
• Deep plugging of soil in hot summer season helps to kill pathogens present in the soil with
direct exposure to high temperature.
• Minimizing physical damages during storage by ventilation.
• Preventing the damage of tissues during harvesting and transporting,
• Nitrogen should not be applied 4-5 weeks before harvest as Nitrogen stimulates growth of
soil fungi and makes the onion tissues susceptible for infections.
• Chemical control: post-harvest application of carbendaim at 1% concentration or pre harvest
spray of carbendazim 0.1% (bavistin) before 20 days of harvesting.
• Using control atmospheric conditions.
• Proper field sanitation.
Impacts
• Decrease the quality of bulbs.
• Cause for post-harvest losses.
• Large doses cause for contaminations.

16. Cabbage soft rot
Causal organisms
• Erwinia caratovara, Pseudomonas spp.
•These are bacterial pathogen.
Symptoms
• Dark black color streaking appears on the outer surface of the bulb because of the fungal
growth.
• In bruised area, discolored appearance can be observed.
• At the initial age of the disease, water soaked areas can be seen and with the time, they
become dry.
• At final stage, black color masses of the spores can be seen.
• When higher disease appear, whole bulb become black color because of the fungal growth.
• Initial infections occurs on the outer leaf stoke which is contact with the soil.
• Then it progress to the head.
• They rapidly get enlarge and tissues become soft.
• Within a few days, affected plant parts may turn into dark in color.
• As signs slimy nature of bacteria can be seen.
• An offensive odor usually is present.
Control measures
• Using clean pathogen free seeds.
• Plant resistant cultivars.
• Frequency and source of irrigation water should be controlled.
• It is better to use well water which is generally free of bacteria and stagnant water should be
avoided.
• Harvesting only in dryconditions.
• Removing infected plants immediately and not using them for compost.
• Practicing rotations with disease non-host crops.
• Plants should be cultivated carefully to minimize injury.
• Cleaning walls and floors of storing room with copper-based solutions /bactericides
• Preparing plants in rows to allow.
• Storage house humidity should be kept between 90%- 95% and temperature between 32◦F
-39◦F.
Impacts
• Spread of harsh odor.
• Waste of harvest.
• Spread among other crops.
Bacterial Soft Rot in Tomato

17. Bacterial Soft Rot in Tomato
Causal organisms (Bacterial pathogens)
Erwinia caratovora ssp. Caratovora
Erwinia caratovora ssp. Atroseptica
Bacillus polymyxa
Xanthomonas campestris
Symptoms :
• Initially, slightly depressed lesions appear on the fruit surface.
• Rapid rot is occurred while resulting splitting of the skin.
• With time water soaked areas developed at the margin of the lesion.
• Finally leakage of infective juices and foul odor can be observed.
Control measures :
• Keeping sanitary growing practices.
• Storage warehouses should be removed of all plant debris, and the walls and floors disinfected
with either formaldehyde or copper sulfate between harvests.
• Injury to plant tissues should be avoided as much as possible.
• Humidity and temperature of the storage facility should be kept low using an adequate
ventilation system.
• Control of specific insect vectors.
• Planting vegetables in well –drained soil.
• Controlling watering times and amounts.
• Avoiding damaging while harvesting.
• Removing and discarding infected plants or plant parts.
Impacts
• Losses of tomatoes.
• Decrease the quality of tomatoes.
• Reducing the desirable texture of tomatoes.

18. Altanaria Rot in Tomato
Causal organisms:
• Altanaria alternate (This are fungal pathogens)
Symptoms :
• In initial stage, dark brown color irregular shaped lesions are in blossom and stem end.
• Symptoms can range from small, dark blotches to large sunken areas.
• Brown color lesions appear in the surface and infected tissues become dry and dead. (sunken
lesions)
• Lesions may develop soft, black fungal growth in warm, humid weather.
• With the time, dark brown mycelium can grow.
• Black fungal growth may also develop on existing wounds or lesions.
Control measures
• Maintain proper practices before and after harvesting.
• Maintain proper storage conditions after harvesting.
• Using resistance varieties.
• Selecting better seedsin the field.
• Pick fruits regularly and quickly remove infected fruits.
• Using fungicides(copper sprays for tomato)
• Use proper irrigation systems. (Drip irrigation system.)
• Avoid overhead watering during humid, cloudy weather.
• Lay a mulch of shredded leaves, dried grass clippings or newspapers covered with straw under
plants.
• Good sanitation practices.

19. Impacts
• Decrease the quality of Tomatoes.
•Wilting and loss of harvest.

20. Carrot Soft Rot
Causal organism :
• Erwinia caratovora (bacteria)
Symptoms :
• Infected tissues become watery, soft.
• Characteristic sulfur odor / foul odor associated with the soft rot.
• The decay rapidly consumes the core of the carrot, often leaving the epidermis intact.
• Above ground symptoms include a general yellowing, wilting and collapse of the foliage.
• Cream to tan color infected tissues with watery slimy spots can be observed.
Control measures:
• Maintain a good drainage system in the field.
• The practices that could wound roots should be avoided.
• Avoid prolonged irrigation of mature carrots during warm months of the year.
• After the harvesting, handle the carrots carefully to avoid bruising and store them under cool
conditions.
• In the packinghouse, Carrots should be handled carefully to avoid bruising.
• Add chlorine (Decco 240 and Seachlor 100) to the wash water. It helps to eliminate the soft
rot bacteria from the carrot surface.
• Use copper based fungicides to prevent the activity of the bacterial pathogen. (e.g.:
GREENCOP 500WP, TRINITY GOLD 452WP, COLONIZER 440WP).
Impacts
• Decaying of Carrots rapidly. (Inner core of Carrot mainly)
• Cause for decreasing shelf life.
• Cause for post-harvest losses.

21. Potato soft rot
Causal organisms
• Erwinia caratovara
• This is a bacterial pathogen
Symptoms
• Water – soaked areas and slimy appearance can be identified.
• Rotted tissues that are cream to tan in color and soft.
• Rot begins on the tuber surface and progress inward.
• Infected tissues are sharply delineated from healthy tissues by dark brown or black margins.
• Shallow necrotic spots on the tubers result from infections through lenticels.
• Soft rot can also infect wounded stems and roots.
• Rotting tissue is usually odorless in the early stages of decay.
• There may be foul smelling can be sniffed as the Potato are broken down by bacteria and due
to secondary infections.
Control measures
• Using resistance cultivars.
• Before planting infected tissues should be graded out.
• Adequate crop rotation should be maintained.
• Potatoes should be planted in wet paddock.
• Avoiding wet conditions and store them in less humidity conditions.
• Store them in low temperature conditions.
• Postharvest curing and maintenance of storage temperatures.
• Proper spacing in plants.
• Keeping the garden and tools clean.
• Preventing mechanical damages during harvesting and grading.
• During harvesting only matured tissues should be harvested.
• Use clean water to wash potatoes and avoid water films on tuber surfaces during storage.

22. • Avoiding exposing to direct sunlight.
• Use pathogen free tubers for seed and, warm seed tubers to about 55°F before planting.
• Fungicides do not directly affect these bacterial pathogens, but seed piece treatments with
fungicides can reduce inversion by other fungi and therefore reduce opportunistic infection by
Erwinia spp.
Impacts
• Decaying of Potatoes unnecessarily.
• Lost large portion of harvest.
• Decrease the quality of harvest.

23. Onion Soft Rot
Causal organisms
• Erwinia caratovara
• This is a bacterial pathogen
Symptoms :
• On Onion an infected bulb is pale-brown spots on the skin, soft and watery.
• Rot the entire bulb.
• A foul smelling viscous fluid oozes from the neck when infected bulbs are squeezed.
• Infected Onions appears healthy on the outside and when cut opens some of the inner scales
are brown, wet and have a cooked appearance.
• The neck becomes soft when pressed.
• In the field, the youngest leaves or the entire foliage of affected plants appear bleached and
wilted.
Control Measures :
• Proper land preparation should be done in order to have a well-drained soil.
• Avoid reuse of irrigation tail water and overhead irrigation.
• Prevent bruising and wounding of plants and bulbs during field operations, harvest, and
handling.
• Nematodes and other insects’ pests that serve a vectors of the bacteria to invade the plant
tissues should be controlled.
• Cure bulbs with ambient abundant ambient air until necks are completely dry before storing
bulbs at 32°F - 36°F and 70% less relative humidity.
• Copper bactericides provide some bacterial control when applied before disease is observed.
Using modified storerooms.
• Infected plants should be removed immediately.
• Preventing damage to the whole plant when bulb is developing.
• Avoid mechanical damages during harvesting and after.
• Harvesting after fully mature.
Impacts
• Losses occur during storing.
• Spreads the disease among healthy bulbs too.
• Decrease quality.
•
•

24. Bacterial Soft Rot in Tomato
Causal organisms Erwinia caratovora ssp. Caratovora
Erwinia caratovora ssp. Atroseptica
Bacillus polymyxa
Xanthomonas campestris

25. References:-
Post harvest diseases (2019) Postharvest Diseases of Fruits and Vegetables [Online] Available on:
https://www.elsevier.com (Access on: 6th of July 2019)
Papaya Anthracnose (2015) Anthracnose Of Papaya Trees: Learn About Papaya Anthracnose Control
[Online] Available on:https://www.gardeningknowhow.com(Access on:6th of July 2019)
Pineapple stem end rot (2017) Pineapple: Diseases and Symptoms [Online] Available
on:https://ctahr.hawaii.edu (Access on: 6th July 2019)
Avocado stem end rot (2019) INFECTION OF UNRIPE AVOCADO FRUIT BY STEM END ROT FUNGI
[Online] Available on: https://www.researchgate.net(Access on:6th of July 2019)
Mango Anthracnose (2018)Mango Anthracnose Disease: Present Status and Future Research
Priorities[Online] Available on: https://scialert.net (Access on:6th of July 2019)
Banana Anthracnose(2019) Control of the anthracnose pathogen of banana [Online] Available on:
https://onlinelibrary.wiley.com (Access on:6th of July 2019)
Mango stem end rot (2016) Mango stem end rot pathogens [Online] Available on:
https://onlinelibrary.wiley.com (Access on:6th of July 2019)
Banana crown rot (2018) Crown Rot Disease of Bananas [Online] Available on:
https://www.sciencedirect.com (Access on:6th of July 2019)
Blue mould rot of citrus / Green mould rot of citrus (2019) Control of Citrus Post-harvest Green
Molds, Blue Molds, and Sour Rot [Online] Available on: https://www.ncbi.nlm.nih.gov (Access on:6th
of July 2019)