Post-Harvest Diseases and Their Prevention in Horticultural Crops

Post-Harvest Diseases and Their Prevention in Horticultural Crops

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  Post harvest diseasesand their Preventive measures Prepared by Umesh Timilsina Assistant Professor CNRM, Bardibas Agriculture and Forestry University
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  Post harvest Disease •Post-harvest diseases are one of the major causes of quantitative and qualitative losses in horticultural crops after harvesting. • These diseases develop during harvesting, handling, transportation, storage, and marketing, reducing shelf life and market value. • It is estimated that 20–40% of fruits and vegetables are lost globally due to post-harvest diseases, with losses being even higher in developing countries due to inadequate storage and handling facilities. • A post-harvest disease is any disease that develops after harvest during handling, storage, transportation, or marketing and causes deterioration in the quality and quantity of horticultural produce.
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  Disease Development Pathogen (Aggressive/Virulent) Environment (Favorable) Commodity (Susceptible) Disease Fig: Interactionof Commodity, Pathogen and Environment for disease development
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  Causes of Post-harvestDiseases • Mechanical injuries during harvesting and handling • Infection by fungi, bacteria, or yeasts • High temperature • High relative humidity • Poor sanitation • Improper storage • Insect damage • Delayed cooling • Contaminated packaging materials • Poor ventilation
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  Classification of Post-harvestDiseases A. Based on Nature of Infection 1. Latent (Quiescent) Infection • A latent infection occurs when the pathogen infects the crop before harvest but remains dormant until the fruit ripens or storage conditions become favorable. Characteristics • Infection occurs in the field. • Symptoms appear after harvest. • Common in climacteric fruits. Examples • Anthracnose of mango • Stem-end rot of mango • Anthracnose of papaya Anthracnose of mango and papaya Stem-end rot of mango
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  Fig: The processof latent infection
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  Anthracnose of Bananaand Mango
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  2. Wound Infection •Infection occurs through mechanical injuries (cuts, bruises, cracks, punctures, or abrasions) produced during harvesting and handling or by insect injury. • Wounds need not be large for infection to take place and in many cases may be microscopic in size. Characteristics • Requires wounds for pathogen entry. • Common during transportation and storage. • Progresses rapidly under high humidity. Examples • Common postharvest diseases resulting from wound infections include Blue and Green mould (caused by Penicillium spp.) and transit rot (caused by Rhizopus stolonifer). • Bacteria such as –Erwinia carotovora (soft rot) are also common wound invaders. • In potato, Erwinia (soft rot) infection occurs at harvest but rotting occurs later in storage.
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  3. Natural OpeningInfection • The pathogen enters through natural openings such as stomata, lenticels, stem ends, or blossom ends. Examples • Stem-end rot • Bacterial soft rot 4. Out rightly visible disease before harvest • Usually the pathogenic microorganisms are abundant in plant debris, soil and the environment. • During rain or the wind, these propagating structures are transported to the fruits and various plant organs. • When they got favorable environment, they produce lesions, canker, scab, necrotic spots etc. • Often fruit trees have chronic infected lesions which is the source of infection for many post harvest diseases. • Eg. Canker, Scab etc.
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  Classification Based onCausal Organism A. Fungal Diseases • Fungi are the most important cause of post-harvest losses. Common Fungi • Colletotrichum spp. • Botrytis cinerea • Penicillium spp. • Rhizopus stolonifer • Alternaria spp. • Aspergillus spp. • Fusarium spp. • Lasiodiplodia theobromae
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  B. Bacterial Diseases CommonBacteria • Pectobacterium carotovorum (formerly Erwinia carotovora) • Dickeya spp. • Pseudomonas spp. • Xanthomonas spp. C. Yeast Diseases • Common in fruits with damaged skin. • Examples: • Candida spp. • Saccharomyces spp.
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  Major Post-harvest Diseasesof Fruits Disease Crop Causal Organism Symptoms Preventive Measures Anthracnose Mango, Papaya, Banana Colletotrichum gloeosporioides Black sunken lesions Hot water treatment, fungicides, careful handling Stem-end rot Mango, Citrus Lasiodiplodia theobromae Rot starts at stem end Proper harvesting, stem clipping, fungicides Blue mold Apple, Pear Penicillium expansum Blue-green fungal growth Avoid injuries, cold storage Green mold Citrus Penicillium digitatum Green powdery growth Sanitation, fungicide treatment Rhizopus soft rot Peach, Strawberry Rhizopus stolonifer Soft watery decay Rapid cooling, avoid injuries Gray mold Grapes, Strawberry Botrytis cinerea Gray fuzzy mold Low temperature, proper ventilation Black mold Onion, Garlic Aspergillus niger Black spores between scales Proper curing and dry storage
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  Major Post-harvest Diseasesof Vegetables Disease Crop Causal Organism Symptoms Preventive Measures Soft rot Cabbage, Carrot, Potato Pectobacterium carotovorum Soft watery tissues with foul smell Sanitation, avoid injuries, refrigeration Rhizopus rot Sweet potato Rhizopus stolonifer Soft watery decay Curing and careful handling Black rot Sweet potato Ceratocystis fimbriata Dark black lesions Cure roots before storage Dry rot Potato Fusarium spp. Dry shriveled tubers Proper curing and storage Gray mold Tomato Botrytis cinerea Gray fungal growth Cold storage and ventilation Alternaria rot Tomato Alternaria alternata Black sunken lesions Sanitation and fungicides
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  Major Post-harvest Diseasesof Ornamentals Disease Flower Causal Organism Symptoms Preventive Measures Gray mold Rose, Carnation Botrytis cinerea Gray mold on petals Cold storage, sanitation Stem rot Chrysanthemum Sclerotinia sclerotiorum Stem softening Remove infected flowers Bacterial soft rot Gladiolus Pectobacterium carotovorum Soft watery corms Dry storage and sanitation Fusarium rot Gladiolus Fusarium oxysporum Dry corm rot Fungicide treatment and healthy planting material Black spot after harvest Rose Diplocarpon rosae Black leaf spots Field disease management and sanitation
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  Symptoms of CommonPost-harvest Diseases • Soft watery rot • Dry rot • Black lesions • Brown discoloration • Foul odor • Fungal mycelium • Mold growth • Fruit collapse • Water-soaked tissues • Tissue shrinkage
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  Factors Favoring Post-harvestDiseases Factor Effect High humidity Promotes fungal growth High temperature Accelerates pathogen development Mechanical injuries Entry point for pathogens Delayed cooling Increases infection Poor sanitation Higher contamination Poor ventilation Increases disease spread Improper packaging Moisture accumulation
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  Preventive Measures ofPost harvest Diseases A. Pre-harvest Measures • Use disease-free planting materials. • Grow resistant or tolerant varieties where available. • Follow balanced fertilization. • Maintain proper irrigation and drainage. • Control insects and field diseases. • Apply recommended fungicides when necessary. • Harvest at propr maturity.
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  B. Harvesting Measures •Harvest during cool hours. • Avoid bruising and cuts. • Use clean harvesting tools. • Remove diseased produce. • Use clean harvesting containers. C. Packing House Measures • Wash produce with clean, sanitized water. • Disinfect equipment and containers. • Grade and sort carefully. • Remove infected produce immediately. • Use clean packaging materials.
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  B. Post-harvest Treatments 1.Hot Water Treatment Thermal death point of pathogen: 50-55°C for 5-10 min Effective for Anthracnose and stem end rot of mango.  Fungicidal treatment+ hot water- effective. • Commonly used for mango, papaya, and citrus. 2. Fungicide Treatment Most of the fungicide ineffective- pathogens are deep seated. Deep seated- Systemic fungicide- strong penetrating power- Benomyl, Benlate, Thiobendazole, Topsin M-45, Imazalil, Prochloraz, Fludioxonil
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  Hot Water Treatment
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  3. Biological Control Beneficialmicroorganisms: Bacillus subtilis Pseudomonas fluorescens Trichoderma harzianum Candida oleophila 4. Edible Coatings Chitosan Aloe vera gel Carnauba wax Beeswax • These coatings reduce moisture loss and slow disease development.
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  5. Controlled Atmosphere(CA) Storage • Low oxygen (O ) ₂ • Increased/Elevated carbon dioxide (CO ) ₂ Benefits: • Slows pathogen growth. • Reduces respiration. • Extends shelf life. 6. Refrigeration or low temperature treatment • Delays ripening, suppress rapid growth, development, reproduction and multiplication of pathogens.
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  7. Modified AtmospherePackaging (MAP) • Maintains favorable gas composition around the produce. • Delays disease development and ripening. 8. Use of vegetable oils/Plant extract Garlic extract which contains Allicin (antibiotic) can be used for the control of pathogenic fungi and bacteria. Garlic, Sesamum oil and ginger extract significantly reduce the post harvest diseases in banana (Timilsina, et al., 2017). 9. Wrapping and bagging Prevents sporulation of individual fruits or bunches. Wrapping bunches of banana and grapes with paper of plastic prevents disease as well as uniform fruit development. Apple, pear etc. fruits can be wrapped individually by paper bags.
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  Integrated Management ofPost-harvest Diseases • Harvest healthy produce. • Prevent mechanical injuries. • Maintain strict sanitation. • Pre-cool immediately after harvest. • Store at recommended temperature and humidity. • Use fungicides or biological agents where appropriate. • Maintain the cold chain during storage and transportation. • Monitor produce regularly and remove infected items promptly.