The disease which develops on harvested parts of the plants like seeds, fruits and also in vegetables are called post-harvest disease. It leads to measurable qualitative and quantitative food loss along the supply chain, starting at the time of harvest till its
consumption or other end uses. In Nepal, different studies have shown the postharvest losses of fruits and vegetables are 20-50% (Gautam and Bhattarai, 2012) and 6-12% losses in worldwide.
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1. The presentation on post harvest disease of fruits,
vegetables, cereals, legumes and their management
Sarad Pokhrel
MSc.Ag Plant Pathology
Agriculture and Forestry University
2. Postharvest Disease
The disease which develops on harvested parts of the plants like seeds,
fruits and also in vegetables are called post-harvest disease.
It leads to measurable qualitative and quantitative food loss along the
supply chain, starting at the time of harvest till its consumption or other
end uses.
.In Nepal, different studies have shown the postharvest losses of fruits and
vegetables are 20-50% (Gautam and Bhattarai, 2012) and 6-12% losses in
worldwide.
3. How grains, ripen fruits and vegetables become subject
to attacks of various microorganisms upon harvesting??
Disease resistance weakens as a result of separation from the parent plant.
Harvested fruits and vegetables are rich in moisture and nutrients, which suit the
development of pathogens.
Upon ripening the fruits and vegetables often become more susceptible to injury.
series of physiological processes occurs during prolonged storage which leads to
the senescence of tissues and, in parallel increased susceptibility to weak
pathogens.
4. Factors affecting disease development
A. Pre-harvest factors, harvesting and handling
Cultivar
Planting materials
Environmental conditions
Cultural practice
Harvesting
5. Factors affecting disease development
B. Inoculum level
C. Storage conditions
Temperature
Relative humidity and moisture
Storage atmosphere
6. Some major post-harvest disease of Cereals
A. Ear and kernel molds of corn
1. Aspergillus species (A. flavus, A.
parasiticus, etc.; Capable of producing an
aflatoxin which is toxic to livestock and
human.
7. Some major post-harvest disease of Cereals
A. Ear and kernel molds of corn
2. Fusarium spp.: white to pink mold;
Fumonisin toxin, which is toxic to
livestock (particularly horses), can be
produced
8. Some major post-harvest disease of Cereals
A. Ear and kernel molds of corn
3. Gibberella zeae (bright pink and red to
white), Potential mycotoxins include
vomitoxin or deoxynivalenol (DON) and
zearalenone(ZE), which are deadly to
livestock.
9. Some major post-harvest disease of Cereals
A. Ear and kernel molds of corn
4. Penicillium spp : Powdery blue-green
mold
.
10. Some major post-harvest disease of Cereals
A. Ear and kernel molds of corn
5. Cladosporium herbarum
6. Stenocarpella maydis(Diplodia): White to gray mold
7. Nigrospora sphaerica, synonym N. oryzae (ear or cob rot)
.
11. Some major post-harvest disease of Cereals
B. kernel molds of wheat
1. Penicillium
verrucosum primarily
produced Ochratoxin,
2. Fusarium
graminearum produced
DON and ZE
3. Aspergillus spp
12. Some major post-harvest disease of Cereals
C. Aspergillus, Penicillium, and Fusarium genera are responsible for production of
most important mycotoxins often occur in rice, which includes:
Aflatoxins
Citrinin
DON
Sterigmatocystin
Patulin, etc.
13. Some major post-harvest disease of Fruits
and Vegetables
1. Fruit rot, dark spot, sooty mold
Primary host: Stone and pome fruits,
grapes, papaya, tomato, pepper,
eggplant cucumber, melon,
watermelon, squash, cabbage,
cauliflower, broccoli, corn, pea, bean.
carrot, potato, sweet potato, onion
Pathogen: Alternaria alternata (Fr.)
Keissler
14. Some major post-harvest disease of Fruits
and Vegetables
2. Gray mold disease
Primary host: strawberry, raspberry, cherry, grape, pome and stone
fruits, persimmon, citrus fruits, tomato, pepper, eggplant, cucumber,
squash, melon, pumpkin, artichoke, cabbage, cauliflower, lettuce, broccoli,
pea, bean, carrot, onion, potato, sweet potato
Pathogen : Botrytis cinerea Pers. ex Fr. Perfect state: Botryotinia
fuckeliana (de Bary) Whetzel
15.
16. Some major post-harvest disease of Fruits
and Vegetables
3. Anthracnose
Primary host: Avocado, mango, papaya,
guava, citrus fruits, Pome and stone
fruits(Bitter rot), Banana(crown rot)
Pathogen: Colletotrichum gloeosporioides
(Penz.) Sacc. Perfect state: Glomerella
cingulata (Stonem.) Spauld & V. Schrenk,
Colletotrichum gloeosporioides ,
Colletotrichum musae
17. Some major post-harvest disease of Fruits
and Vegetables
3. Dry or soft rot
Primary host: tomato, pepper,
eggplant, melon, squash,
pumpkin, watermelon,
cabbage, celery, artichoke,
asparagus, corn, carrot, potato,
sweet potato, onion, garlic
Pathogen: Fusarium spp.
18. Some major post-harvest disease of Fruits
and Vegetables
4. Green mold/Blue mold
Primary host: citrus fruits ( green
mold exclusively), Tomato,
cucumber, melon , pome fruits
mainly, but also stone fruits(Blue
mold)
Pathogen: Penicillium digitatum
Sacc, Penicillium expansum (Link)
Thom
19. Some major post-harvest disease of Fruits
and Vegetables
5.Watery soft rot:
Primary host: Stone and pome fruits.
grape, avocado, papaya, strawberry,
raspberry, cherry, tomato, pepper,
eggplant, carrot, melon, pumpkin,
squash, pea, bean, sweet potato
Pathogen: Rhizopus stolonifer (Ehr. ex
Fr.) Lind
21. Some major post-harvest disease of Fruits
and Vegetables
7. Watery white rot, cottony rot
Primary host: Citrus fruits, cabbage,
cauliflower, lettuce. celery, broccoli,
artichoke, pea, bean, carrot, eggplant,
melon, cucumber, pumpkin, squash,
onion, garlic
Pathogen: Sclerotinia sclerotiorum (Lib.)
de Bary
22. Some major post-harvest disease of Fruits
and Vegetables
8. Brown rot citrus caused by Phytophthora citrophthora (Smith & Smith)
Leon.
9. stem-end and fruit rot, green-yellow mold of citrus caused by
Trichoderma viride Pers. ex S.F. Gray
10. Brown rot of stone fruits mainly, but also pome fruits caused by
Monilinia fructicola (Wint.) Honey
11. stem-end rot, dry black rot of papaya caused by Phoma caricae-papayae
(Tarr) Punith. And so on.
23.
24. 1.Management of post harvest disease of
fruits and vegetables
A. Maintaining the host resistance
Treatments and conditions that lead to delayed ripening and senescence
Indirectly suppress postharvest disease development.
Includes include low-temperature storage, low-O2 and high-C02
atmospheres, ethylene removal from the atmosphere, growth regulators,
calcium application
25. 1.Management of post harvest disease of
fruits and vegetables
A. Maintaining the host resistance
1. Cold storage:
Storage at low temperature is the main method for reducing deterioration of
harvested fruits and vegetables
inhibition of ripening and senescence of the host and extension of the period
during which it maintains its resistance to disease.
inhibition of pathogen development by subjecting it to a temperature unfavorable
for its growth.
26. 1.Management of post harvest disease of
fruits and vegetables
A. Maintaining the host resistance
2. Modified and controlled atmosphere
'CA storage' generally implies precise control of O2 and CO2
concentrations in the atmosphere,
MA storage' is broader and may indicate any synthetic atmosphere, arising
intentionally or unintentionally, in which the composition of its constituent
gases cannot be closely controlled.
27. 1.Management of post harvest disease of
fruits and vegetables
A. Maintaining the host resistance
2. Modified and controlled atmosphere
controlled atmosphere i.e. low O2 levels or high CO2 levels suppress various
stages of the pathogen growth, and its enzymatic activity.
Maintains the resistance of the host to infection by keeping it in a superior
physiological condition
In order to obtain appreciable reduction of spore germination, mycelial growth
and sporulation in many fungal species, O2 concentrations of less than 1% are
required
28. 1.Management of post harvest disease of
fruits and vegetables
A. Maintaining the host resistance
3. Growth regulators
Suppress decay development indirectly, by retarding ripening and senescence
processes in fruits and vegetables
It may be of special importance mainly for fruits and vegetables that cannot be
stored at low temperatures because of their cold sensitivity
Applying the synthetic auxin 2,4-dichlorophenoxy acetic acid (2,4-D) to citrus
fruits prior to storage , resulting in considerable reduction of stem-end rot.
29. 1.Management of post harvest disease of
fruits and vegetables
A. Maintaining the host resistance
4. Calcium Application
Calcium contributes to preserve the structural integrity and functionality of
membranes and the cell wall during fruit ripening and senescence
Calcium treatment may reduce storage disorders, such as bitter pit and internal
breakdown in apples
It was thus found that pre-harvest calcium sprays reduced the rate of storage
losses caused by Gloeosporium spp. in apples, or Botrytis and Geotrichum rots in
stored grapes (Miceli et al., 1999)
30. 1.Management of post harvest disease of
fruits and vegetables
B. Physical Methods
1. Heat Treatments
It may be applied by means of hot water dips and sprays, hot vapor or dry air, or infrared
or microwave radiation
It can be Short-term heating 40°C (generally 44-55°C) for a short time
Long-term heat treatments usually (38-46°C), for a longer duration (12 h to 14 h)
For example, postharvest decay of strawberries caused by Botrytis cinerea and Rhizopus
stolonifer was controlled by exposure of the fruit to humid air at 44°C for 40-60 min.
31. 1.Management of post harvest disease of
fruits and vegetables
B. Physical Methods
2. Ionizing radiation:
may directly harm the genetic material of the living cell, leading to mutagenesis
and eventually to cell death
Due to deep penetration ability, it irradiates microorganisms in wounds, and also
quiescent or active infections.
Presence of oxygen and water content of the cell are major factors for its
effectiveness.
Low doses of UV-C light (wavelength of 190-280 nm) to induce disease
resistance in a wide range of fruits and vegetables
32. 1.Management of post harvest disease of
fruits and vegetables
C. Biological methods
refers to the use of naturally found microorganisms which antagonize the postharvest
pathogens we wish to suppress
Strains of Pseudomonas putida and Chryseobacterium indologenes were found to reduce
the incidence of gray mold rot on fruits under field conditions
Candida oleophila(Aspire) to control P. expansum, Botrytis cinerea, and R, stolonifer
under various cold-storage conditions
Pseudomonas syringae is a biological products for commercial postharvest applications
to citrus fruits:
Field sprays of strawberry flowers with antagonistic non-pathogenic Trichoderma viridae
isolates resulted in a decreased incidence of gray rot (B. cinerea) during storage
33. 1.Management of post harvest disease of
fruits and vegetables
D. Chemical methods
1. Pre-harvest chemical treatments
application of broad-spectrum protective fungicides to the developing fruit on the
plant, in order
to prevent spore germination or
infection establishment in the lenticels or in floral remnants of the fruit.
Oranges are sprayed with benomyl before harvest, to prevent the development of
stem-end rot, which arises from infections of Diplodia natalensis and Phomopsis
citri .
34. 1.Management of post harvest disease of
fruits and vegetables
D. Chemical methods
2. Sanitation
may be achieved through the immediate disposal of every rotted fruit or
vegetable, or by immersing it in a disinfectant solution
Use of chlorinated water at 38-43°C to wash tomatoes in the
packinghouse prevents the buildup of inoculum in the water
Formaldehyde, isopropyl alcohol, quadronic ammonium compounds,
captan or other chemicals must be used for disinfecting packinghouse or
store rooms.
35. 1.Management of post harvest disease of
fruits and vegetables
D. Chemical methods
3. Post harvest Chemical treatments
selection of the appropriate chemical compound depends on
the sensitivity of the pathogen to the chemical substance
the ability of the substance to penetrate through surface barriers into the
infection site
the tolerance of the host, as expressed both by injury and other phytotoxic
effects, and by any adverse effect upon the quality of the product
36. 1.Management of post harvest disease of
fruits and vegetables
D. Chemical methods
3. Post harvest Chemical treatments
Captan (N-trichloromethylmercapto-4-cyclohexene-l,2-dicarboximide), which is
a bicarboximide fungicide, has been proven effective as a postharvest dip against
decay development in various fruits and vegetables, such as strawberries,
peaches, cherries, pears, figs and potatoes
Dicloran (2,6-dichloro-4-nitroaniline, DCNA, botran) is effective against several
postharvest fungi
Sulfur dioxide (SO2) is applied as a postharvest fumigation to grapes in order to
eradicate spores of Botrytis cinerea
37. 1.Management of post harvest disease of
fruits and vegetables
D. Chemical methods
3. Post harvest Chemical treatments
The benzimidazole compounds - thiabendazole (TBZ), benomyl.are active
against a broad spectrum of pathogenic fungi. Like Penicillium digitatum ,
Monilinia fructicola ,Colletotrichum gloeosporioides and so on
Metalaxyl (ridomil), which is an acylalanine fungicide, acts as a strong inhibitor
of the various developmental stages of Phytophthora spp.
Essential oils and plant extracts are sources of antifungal activity against a wide
range of fungi for eg. palmarosa (Cymbopogon martini) and red thyme (Thymus
zygis) showed the greatest inhibitory effect on B. cinerea spore germination at
the lowest concentration.
38. 1.Management of post harvest disease of
fruits and vegetables
D. Chemical methods
3. Post harvest Chemical treatments
Gel derived from Aloe vera plants has been found to have antifungal
activity against four common postharvest pathogens:
Penicillium digitatum, P. expansum, B. cinerea and A. alternata.
The natural gel suppressed both germination and mycelial growth, with P.
digitatum and A. alternata being the most sensitive species
39. 2. Management of postharvest disease of
cereals and pulses
Avoid Infestation of through the use of fumigants. This helps to reduce rapid
growth of storage fungi.
The stored grain should not be unripe or too old; it should be clean, and be free
of mechanical damage
The moisture content should kept at levels below the minimum required for the
growth of the common storage fungi i.e. below 12%
The temperature of stored grain should kept as low as possible, . As it slows
down the respiration of grain and prevents an increase of moisture in grain.
40. 2. Management of postharvest disease of
cereals and pulses
• Ideally, grain should be cooled after drying and maintained at 1°C to 4 °C
for the duration of storage, while during the summer months the grain
temperature can be maintained between 10 and 15°C.
• Both reductions in oxygen tension and increase in carbon dioxide
concentrations can have profound effects on the growth of fungi
• Decreasing O2 to<0.14% and increasing CO2 >50% is required for
inhibition of mycelial growth and will prevent mycotoxin production.
1. For example melons with a thick skin and raspberries with a firm texture are better able, than others, to withstand the rigors of harvesting and handling and should, therefore, have longer storage lives.
2. . For example, high temperature was found to increase Botrytis cinerea infection of tomatoes via the flowers because it increased the rate of flower development and senescence.
3. . For example, high temperature was found to increase Botrytis cinerea infection of tomatoes via the flowers because it increased the rate of flower development and senescence.
4. Wider within-row plant spacing reduced Botrytis rot in strawberries compared with narrower spacing.
