Download presentation
Presentation is loading. Please wait.
1
POSTHARVEST PATHOLOGY
Prepared by: Hamid Salari Assistant professor Department of Horticulture
2
Postharvest pathology
Severe infection by fungus and bacteria Fruits are acidic thereby more susceptible to fungus Vegetables are less acidic thereby susceptible to bacteria 5-10 per cent of total postharvest losses Crops like banana are more susceptible Diseased fruits produce more ethylene
3
Common postharvest diseases
Infection may occur either in preharvest or post harvest Infection may occur through a. direct penetration through skin b. natural openings c. injuries
4
Common postharvest diseases are:
5
Gray mold Soft, light brown areas on the fruit which enlarge rapidly
Fruits are covered with gray, dusty spores, which give the disease its name "gray mold." Cause: Botrytis cinerea
9
Black rot larger brown, dead but firm areas Cause: Physalospora obtusa
12
Bitter rot circular brown spot is the first symptom Cause:
Glomerella cingulata
14
White rot bitter rot
15
Blue mold Soft, watery spots
The decayed portions are sharply separated from the healthy tissues The spots range in color from brown to pale straw Show all possible variations in size Cause: Penicillium expansum
18
Anthracnose whitish, water soaked lesions up to 3 mm in diameter
Infected fruit eventually dry down to form hard, black, shriveled mummies. Cause: Colletotrichum acutatumÂ
22
Stem end rot Water soaked areas Brown to black color Cause:
Phomopsis sp.
26
Sour rot Symptoms include a soft watery rot with leakage of berry juice, and a distinctive vinegar smell Cause: Colletotrichum candidum Under investigation
30
Fusarium rot Symptoms of Fusarium fruit rot vary depending on the Fusarium species: F. graminum, F. acuminatum, F. culmorum, and F. moniliforme produce a distinct reddish or purplish pigmentation in the diseased area F. semitectum, F. equiseti, F. scirpi, and F. solani produce brown internal lesions; a cross section of a mature lesion reveals a dry, brown, spongy rot
33
Wet rot Fruits rot rapidly and white fungal mold appears on the infected area the heads are white to brown but turn purplish-black within a few days water-soaked and soft An entire fruit can rot in a 24 to 48 hour period Symptoms usually begin on the blossom end of the fruit. Cause: Choanephora cucurbitarum
35
Brown rot first appears as small, circular brown spots that increase rapidly in size Infected fruit eventually turn into shriveled, black mummies that may drop or remain attached to the tree through the winter. Brown rot can be serious on injured fruit such as cherries split by rain. Cause: Monilinia fructicola
39
Alternaria rot more or less round, brown to black lesions
weakened tissue Cause: Alternaria spp.
44
Ring rot appearing as only a broken, sporadically appearing dark line, or as a continuous, yellowish discoloration Causes: bacterium Clavibacter Pythium spp.
47
Bacterial soft rot softening and water soaking
yellow initially, turning brown as the disease these organisms generally appear just before or at the time of harvest or in storage. Cause: Erwinia carotovora
50
Factors affecting development of infection
Surrounding environment Temperature Relative humidity Chilling injury Mechanical injury pH of the produce Ripening conditions….etc
51
Control of PHD It depends on: The ability of treatment
Level of infection Sensitivity of host produce To control PHD understanding of: Nature of disease Conditions promotes occurrence are important
52
Control methods Chemical Physical Biological
53
Chemical method Different chemicals are used for different diseases
Benzimidazole fungicide Guazatine fungicide Chlorine, wash water Sulphur dioxide, grape guard Fungicide should be applied within 24 hours of harvest
54
The success of chemical control depends on:
The depth of infection The growth rate of infection Temperature Humidity Depth to which chemical can penetrate Spray load of chemical
55
Physical method Low and high temperature Modified atmosphere
Hot water dip (50-55 °C) Modified atmosphere Irradiation Good sanitation
56
Biological BioSaver (pseudomonus syringea [29.8%])to control postharvest rots of pome fruits, gray mold, blue mold Aspire (yeast) (Candida oleophila) to control postharvest rots of citrus fruits, green mold
57
Thank you
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.