post harvest diseases of citrus
DESCRIPTION
This presentation is done by 2010/2011 batch of Export Agriculture students of Uva Wellassa University of Sri Lanka as a requirement for the subject which is “Post harvest technology”. Note that the information included here is relevant to Sri Lankan condition.TRANSCRIPT
Introduction• By the year 2050, the world population is expected to reach 9
billion people
• Demand for food will increase by 60 percent ( United Nations Food and Agriculture Organization)
• Increasing food production is not enough
• Roughly one-third of the food produced in the world goes to waste – a staggering 1.3 billion tons every year
• In the fight against global hunger, we must also address postharvest los.
• Postharvest loss - Collective food loss all along the food production chain, from harvest and handling, to storage and processing, to packing and transportation
• The causes of postharvest loss are varied and complex, depending upon weather, region, and crops
• But common culprits in the developing world include lack of proper storage, lack of transportation, and lack of information on where and how food is lost
• To escape from this problem, it is require to do “Proper Post Harvest Handling”
Post Harvest Handling
• In agriculture, postharvest handling is the stage of crop production immediately following harvest, including cooling, cleaning, sorting and packing
• The instant a crop is removed from the ground, or separated from its parent plant, it begins to deteriorate
• Post-harvest treatment largely determines final quality, whether a crop is sold for fresh consumption, or used as an ingredient in a processed food product
• Effective handling decreases postharvest losses
Citrus Non climacteric fruit Major Growing Areas : Dry and Intermediate
zones Economics & Marketing availability
Lemon : April - August Lime : April - July Grapefruit : May -August
Scientific Classification
• Kingdom : plantae• Phylum : magnoliophyta• Class : magnoliopsida• Order : sapindales• Family : rutaceae• Genus : citrus L.
Important Species Citrus aurantiifolia – Key Lime Citrus maxima – Pomelo Citrus medica – Citron Citrus reticulata – Mandarin orange
Important hybrids Citrus × aurantium – Bitter orange Citrus × latifolia – Persian lime Citrus × limon – Lemon Citrus × limonia – Rangpur Citrus × paradisi – Grapefruit Citrus × sinensis – Sweet orange Citrus × tangerina – Tangerine
Most of these varieties are resistant to post harvest losses
Postharvest Deterioration Harvested fruit continue respiration Loose water but not replaced The respiratory rate of the rind is nearly ten
times as high as that of vesicles Rind plays a important physiological role in the
qualitative changes in storage Respiratory rates are stimulated by dropping
and bruising
• Normally 30-40% of Citrus fruit loss due to lack of proper post harvest handling practices
• Visible characteristics change in post harvest losses– Anatomical Characteristics– Physiological Characteristics– Morphological Characteristics
POST HARVEST HANDLING OF CITRUS
01. Physiological Disorders
• Influence quality in the markets
• Causes: Pre- and post-harvest factors • Pre harvest: B, and Cu deficiency,
ammoniation, Zebra skin, fruit-splitting, creasing, sun burn, wind scar and freezing
• Postharvest factors:– Temperature, humidity, gaseous composition,
mechanical stress and aging
• Disorders: Puffiness, pitting, chilling injury, granulation, oleocellosis,
stem end down, stylar-end breakdown, and freezing injury
Blossom-End Clearing
BEC has also been referred as “wet bottoms,” “stylar-end clearing,” “water bottom,” “waterlog,” and “wet wick” Symptoms:– translucent, water soaked appearance of the
fruit peel (commonly at the blossom end)– caused by internal bruising and juice leakage
from juice vesicles
BEC affected fruit develop off flavors Visible within 24 hours after bruising Can affect up to 90% of the fruit in some loads
External symptoms of blossom-end clearing on grapefruit (left) compared to an un-injured fruit (right)
Factors Involved in BEC Development Fruit characteristics;– Seedless grapefruit (e.g. 'Ruby Red' or 'Marsh') are
most affected– Small fruit likely to develop BEC than large fruit– Thicker-skinned fruit develop less BEC than thin-
skinned fruit under the same conditions – The severity of BEC varies widely from year to year
and from grove to grove– BEC develops most often in late-season fruit
• Rough Handling– BEC never occurs while fruit are still attached to
the tree– Never develop on fruit handled very gently– Rough handling is the primary cause of fruit BEC– Most BEC develops as a result of rough handling in
the packing house
• Temperature & RH–BEC increases with higher temperatures–Harvesting earlier in the morning ,when
fruit temperatures are cooler will reduce the incidence of BEC–Holding fruit at low humidities prior to
packing increases fruit susceptibility to BEC compared to holding it at high humidities
Recommendations to Reduce BEC
• Carefully handle fruit during all harvesting and packing operations
• Harvest fruit earlier in the morning when fruit temperatures are lower– Be cautious, however, that fruit are not so turgid
that oil spotting (oleocellosis) results• Allow susceptible fruit harvested under warm
conditions to cool overnight (e.g. to 70oF or below) before packing
• Always hold fruit under high relative humidities
Other Physiological DisordersI. Granulation• Fruit which is dry or ricey• Causes:–over maturity, sun burn, freezing, lack of
water, excessive tree vigor, mite damage, cool, dry and windy conditions
• Keeping trees well irrigated will avoid fruit from drying out
2. Oleocellosis (Oil spotting)• Navel oranges, lemons, and limes mostly
affected.• Oil released from broken peel oil cells in the
flavedo.• Oils are toxic to the surface of the peel and
cause necrosis of the surface cells• Can reduced by avoiding harvest until the fruit
get turgid
Chilling Injury (CI)
• Collapse is not targeted oil glands• A collapse of discrete areas of the peel from
sunken darkened lesions which will slowly expand.
• Low RH enhance CI • Waxing-Reduce but not eliminate CI
Stem-End Rind Breakdown• Thin skinned fruit are more affected than thick
skinned fruit.• Collapse of rind tissues resulting in sunken
brown area which is irregular in shape.• Narrow ring of unaffected tissue immediately
around the stem area which has no stomata.• Control
-Hold fruits at high RH
Post Harvest Diseases of Citrus Fruits
Anthracnose- Colletotrichium gloeosporioides Septoria spot- Septoria depressa Blue & Green Mould-
Penicillium digitatum (green mould) P. italicum (blue mould)
Sour Rot- Galactomyctes citri-aurantii
Anthracnose Symptoms
⁻ Superficial leathery appearance⁻ Silver/grey to dark lesions⁻ Tear-staining pattern ⁻ Pink spores under humid conditions
Occurrence⁻ Infection occurs by rain-splash during autumn⁻ Ethylene degreening increases sensitivity to
anthracnose
• ManagementDead wood should be pruned as the fungus
harbours in dead branchesCopper-based fungicides application before
monsoonal rainsPostharvest treatment with Benzimidazole
fungicides may reduce fruit losses
Septoria spot• Symptoms
Dark brown collapsed lesions, with a purple tinges Black specks develop in decayed area
• Occurrence
Mainly inland citrus regions Fruit more susceptible after frosts
• Management Field application of copper-based fungicides
Blue & Green MouldSymptoms
Softening of damaged tissue White fungal growth, which progressively
turns blue or green as spores develop Occurrence
Infections develop from damaged areas The growth of mould increases with
storage temperatures Late season fruit more susceptible
Management
Good hygiene and sorting
Sanitation destroys spores in recirculating water and packing line equipment
Apply postharvest fungicides within 24 hours
Lower storage
Sour Rot• Symptoms
Very soft, watery decay Distinct margin between decayed & healthy tissue
• Occurrence Infection occurs in damaged fruit Sour rot spores in soil can accumulate in
recirculating water in dips and drenches
• Management Careful handling reduces rind damage Apply Guazatine fungicide within 24hrs of harvest
Postharvest Storage
• Citrus fruits have relatively long post harvest life
• Loose skinned fruits easily deteriorate at high humidity
• Pre storage curing of the fruits also reduces decay and chilling injury during storage
• Each variety has different optimum conditions for storage
Controlled-atmosphere storage
Research has been done Commercially not used because:– Economic reasons–Physiological characteristics of fruit– Elevated CO2 has no beneficial effect
– Low O2 stimulates ethanol and acetaldehyde
Group Members
UWU/EAG/11/0026 S.Rishibamathana UWU/EAG/11/0027
T.A.D.D.L.Thanaweera UWU/EAG/11/0028 D.N.Nanayakkara UWU/EAG/11/0029 Y.S.M.M.P.Yallarawa UWU/EAG/11/0030 M.Aphinaya UWU/EAG/11/0031 R.A.S.N.Ranasinghe