Mango Postharvest Manual CARD Project 050/04VIE Version APRIL 2007 By Dr Roberto Marques, Dr Peter Hofman, Robert Nissen QDPI&F Ministry of Agriculture Development & Rural i © The State of Queensland, Department of Primary Industries and Fisheries [2007] Copyright protects this work Except as permitted by the Copyright Act 1968 (Cth), reproduction by any means (photocopying, electronic, mechanical, recording or otherwise), making available online, electronic transmission or other publication of this work is prohibited without the prior written permission of The Department of Primary Industries and Fisheries, Queensland Inquiries should be addressed to copyright@dpi.qld.gov.au (Ph: +61 3404 6999) ii CARD VIETNAM 2006 MANGO POSTHARVEST TRAINING MANUAL Introduction Key production practices affecting postharvest quality Know your mango (postharvest biology) 3.1 Fruit ripening and quality loss 3.1.1 Respiration rate 3.1.2 Ethylene production 3.1.3 Loss of water (transpiration) 3.1.4 Fruit changes during ripening 3.2 Main causes of quality loss after harvest 3.2.1 Inadequate temperature control 3.2.2 Mechanical damage 3.2.3 Sapburn and skin browning 3.2.4 Postharvest diseases and physiological disorders 3.2.5 Treatment injuries Take care of your mango (postharvest technology) 4.1 Harvesting and field handling 4.1.1 When to harvest your mango 4.1.2 How to recognise when mango fruit are mature: maturity indices 4.1.3 How to harvest your mango 10 4.1.4 Desapping 11 4.1.5 Field packing and transport 13 4.2 Packhouse operations and practices 13 4.2.1 How to sort/grade your mango 13 4.2.2 How to pack and label your mango 15 4.2.3 Postharvest treatment to control rots 16 4.2.4 General recommendations for the packing shed 16 4.3 Ripening and storage of your mango 17 4.3.1 Temperature management 17 4.3.2 Pre-cooling and transport 18 4.3.3 Forced-air cooling 18 4.3.4 Guidelines for temperature management 19 4.3.5 Controlled ripening 21 4.4 How to transport your mango to the retailer 21 4.5 Know your market (customer requirements) 21 iii Causes and solutions of the main postharvest defects of your mango 23 5.1 Anthracnose 23 5.1.1 Treating fruit with a hot dip 24 5.1.2 Treating fruit with a flood spray 25 5.1.3 Sanitation 25 5.2 Stem end rot 26 5.3 Bacterial black spot 27 5.4 Sapburn 28 5.5 Skin browning 29 5.6 Sunburn 30 5.7 Abrasion damage 31 5.8 Pressure damage 32 5.9 Impact damage 33 5.10 Rhizopus rot 34 5.11 Black mould 35 5.12 Alternaria-rot 36 5.13 Stemphylium rot 37 5.14 Sooty mould 38 5.15 Grey mold 39 5.16 Blue mold 40 5.17 Mucor rot 41 5.18 Cytosphaera rot 42 5.19 Lenticel spotting 43 5.20 Abnormal ripening 44 5.21 Jelly seed 45 5.22 Stem end cavity 46 5.23 Internal breakdown 47 5.24 Chilling injury 48 5.25 Heat injury 49 5.26 Failure of skin to yellow 50 5.27 Fumigant injury 51 5.28 Fruit fly damage 52 5.29 Mango seed weevil damage 53 iv CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Introduction The successful marketing of fresh fruit requires careful attention to detail during production to produce a quality fruit, and also during postharvest to reduce loss of quality of the harvested fruit After spending a lot of time, effort and money on crop production, it is logical also to spend resources to protect the value of the product after harvest Fresh mango fruit are highly perishable, especially in tropical environments because of high temperatures Care needs to be taken during harvesting, handling, transport, and distribution to ensure that the fruit reaches the consumer in good condition Growers, collectors, traders, and retailers should receive appropriate instruction on how to use the most appropriate postharvest practices, based on the characteristics of the product, needs of the customer, cost of technology, and market conditions This manual presents the basic principles of postharvest biology that affect fruit quality, as well as the key postharvest practices that should be used to ensure quality mango are marketed Commercial practices were organised in a sequence aimed at maximising costumer satisfaction, highlighting the benefits and providing practical recommendations for each step from harvest to customer The causes and solutions of most postharvest defects of mango are presented This document is not intended to be an exhaustive book on mango postharvest, but will summarise the key issues as they relate to improving existing supply chains in Vietnam More detailed information is available in the Vietnamese translation of the Queensland DPI&F Agrilink Mango Information Kit Postharvest Physiology Training Manual Page CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Key production practices affecting postharvest quality Although good postharvest practices are essential to reduce quality loss during handling and distribution, they cannot improve fruit quality beyond that achieved at harvest The application of good crop management practices is essential to ensure good quality at harvest Major postharvest problems relating to disease, insects, and fruit appearance can be reduced by good production practices Some of the main production practices that affect mango fruit quality are: • Use of appropriate cultural practices that allow healthy tree and fruit development, including a balanced fertilisation program (especially nitrogen and calcium), proper irrigation (if necessary), and tree canopy management to ensure that pest and diseases can be managed well, and harvesting is efficient • Orchard hygiene to reduce fungal infections that start on the fruit on the tree, and insect damage These practices include removing fruit left over on the trees or on the orchard floor, removing dead branches that can contain fungal spores, and cleaning bins or containers that have been in contact with soil • Disease management (especially anthracnose) through an effective spray program aimed at reducing infection of flowers and fruit • Integrated pest management (IPM) to monitor and control orchard pests such as fruit flies, seed weevils, scales and other pests that cause skin defects that reduce fruit quality The above is a very brief summary of the importance of good production practices in producing quality fruit More detailed information on these practices can be obtained from the Vietnamese translation of the Queensland DPI&F Agrilink Mango Information Kit Postharvest Physiology Training Manual Page CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Know your mango (postharvest biology) 3.1 Fruit ripening and quality loss There are many reasons for quality loss after harvest Some of these are the result of the normal processes of the fruit as it "moves" from the unripe to the ripe, then to the senescent or decayed state These processes cannot be stopped, but we can use practices to minimise or slow down these processes to extend the life of the product Others factors that reduce quality are the result of external practices which adversely affect the produce, and which need to be minimised or managed appropriately Fruit development Growth maturation mature ripening senescence Figure Maturity and ripening in relation to other stages of the fruit growing process The major factors that affect quality after harvest are: 3.1.1 Respiration rate Fruit are alive and continue to have active biological processes operating after harvest The process of senescence (aging leading to death) commences immediately after harvest This process of deterioration has to be managed to reduce quality loss Common symptoms of senescence are excessive softening, tissue breakdown, diseases, loss of colour, loss of flavour, and off-flavours Controlling respiration rate is the main way of controlling fruit shelf life • The mango fruit continue to use oxygen and produce carbon dioxide after harvest, a process called respiration • During respiration, heat is also produced • Mango has a moderate respiration rate and undergoes a burst of respiration that coincides with the start of fruit ripening (called climacteric respiration, see Figure 2) • After reaching a peak, respiration falls again • The rate of fruit deterioration relates largely to their respiration rate Postharvest Physiology Training Manual Page CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 • The higher the air temperature, the higher the respiration rate • Control of temperature is crucial to minimising loss of quality because it slows down respiration and delays senescence • There are other ways of slowing down respiration, for example by controlling the concentrations of oxygen and carbon dioxide This is referred to as controlled atmosphere or modified atmosphere storage, but strict control of temperature is required for these practices to be effective Climacteric (ripening fruit) Respiration rate Eg Mango CO2 output Heat output O2 Consumption Non-climacteric Eg Orange Time Figure Respiratory patterns of fruit during ripening 3.1.2 Ethylene production Ethylene is a natural plant hormone that is involved in plant growth, development, ripening and senescence • Ethylene is a key component of ripening in climacteric fruit such as mango In these fruit ethylene production rates increase during ripening, and added ethylene can stimulate ripening • Ethylene in the air around produce can have both a positive and negative effect o The positive effect is when ethylene is used to control the ripening of climacteric fruit, so that the ripening of the fruit is more predictable and makes marketing easier o However if unwanted ethylene builds up in the air around sensitive produce, it can speed up ripening, so that the fruit ripen is too quickly and can spoil before being consumed • Fruit ethylene production rates increases with higher air temperatures, fruit physical injuries (called wound ethylene), and rots 3.1.3 Loss of water (transpiration) All plants lose water through a process called transpiration • Transpiration continues after harvest • It results not only in direct weight loss (reduces the saleable weight), but also reduces appearance and textural quality (shrivelling, softening, etc) Postharvest Physiology Training Manual Page CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 • Water loss increases with higher air temperatures, lower relative humidity of the air, more air movement across the fruit surface, and fruit surface injuries 3.1.4 Fruit changes during ripening Ripening is the combination of processes involving changes in fruit quality attributes that leads to good eating quality Both chemical and sensory qualities of the mango fruit change as they ripen (see Figure 3) The main changes are: • Texture: firmness decreases (softening of the flesh due to changes in the cell walls) • Colour: generally (depending on the cultivar) skin colour changes from green to yellow (mostly because of destruction of the green pigment), and the flesh from a pale yellow to a darker yellow • Flavour: sugars increase (due to conversion of starch to sugars) and acidity decreases (due to breakdown of acids) in the flesh Relative change Firmness Eating ripe Skin colour Sugars Acidity Time Figure Main changes in mango fruit during ripening 3.2 3.2.1 Main causes of quality loss after harvest Inadequate temperature control Temperature is the environmental factor that most affect the deterioration rate of fruit after harvest • The higher the temperatures, the higher the respiration rate, ethylene production, transpiration, spore germination, and growth rate of pathogens • The rate of deterioration of fruit typically increases 2-3 times for each increase of 10 oC above the optimum 3.2.2 • Mechanical damage Can cause loss of appearance Postharvest Physiology Training Manual Page CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 • Can also increase water loss, increase respiration and ethylene production, and allow entry of disease organisms • Symptoms of mechanical injuries can appear externally (cuts etc) or internally (bruising and cracking of the flesh) • They may be visible almost as soon as they occur, or they may only become visible at some later time • Injuries can occur at any stage of harvesting, packing, transport and marketing The major types of mechanical injury are: Bruising • May not be obvious quickly, and only appear as an area susceptible to breakdown (discoloured) as the product is marketed • Can be caused by impact or pressure damage • Impact damage can occur from dropping of individual produce or packages, or from hard knocks on equipment and during transport • Pressure damage can occur in product stacked too high or packed in a package unable to support the required weight Abrasion injury (rubbing) • Leads to rupture of cells, loss of water, and cell death, resulting in dry black or brown areas on the surface • May be visible immediately, but frequently takes several days to become visible • Common causes are rubbing of produce against dirty or rough surfaces of containers and equipment, and rubbing of loosely packed produce during transport Cracking and splitting • Caused by heavy impacts to hard products • Can occur when a single fruit is dropped on to a hard surface, a container of fruit is dropped or loose fruit bounce against each other during transport 3.2.3 Sapburn and skin browning Sapburn • Mango fruit spurt a highly caustic sap when the stem is first removed from the fruit (spurt sap), which causes severe injury to the fruit skin (dark spots, blotches or streaks around the stem end of the fruit and down the cheeks) • Sap is then released more slowly over about hour (ooze sap), causing mild injury (light-brown discolouration to the skin) • The amount of sap exuded by fruit varies with cultivar, maturity (less mature fruit has more sap) and time of day (more sap in the morning) Skin browning Postharvest Physiology Training Manual Page CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.15 Grey mold Cause The fungus Botrytis cinerea Symptoms A brown, firm decay develops from the stem end or from wounds, affecting a large portion of the fruit The affected surface becomes covered with grey or brown fungal growth containing a mass of spores Occurrence Grey mould is favoured by cool storage conditions (13-20°C) and occasionally affect fruit during controlled atmosphere storage (5% 02, 2% C02) at 13°C) Infection can occur via wounds, damage tissue, or the remains of flowers Spores may carry over from other hosts (e.g tomatoes, strawberries) previously stored in the coy tamer or coolroom The spores are air-borne Control Maintain good hygiene in the packinghous4 and storage facilities There are no fungicides approved for control of grey mould on mangoes The hot water-fungicide dip applied for anthracnose will control strains of B cinerea that are not resistant to benzimidazole fungicides Grey mould of mango fruit Postharvest Physiology Training Manual Page 39 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.16 Blue mold Cause The fungus Penicillium expansurrz Symptoms A soft, pale-brown decay of the skin and flesh develops at the stem end or in wounds, and may spread through the entire fruit White, powdery spore masses, which become blue when mature, may develop on the stem end, at wound sites or in internal cavities at the stem end Occurrence Blue mould is likely to occur only in the final weeks of long-term storage in controlled atmospheres (5% 02, 2% C02, 13°C) when anthracnose and stem end rot have been well controlled The fungus is widely distributed in soil, in decaying organic matter and facilities used for storing citrus, where spores form under moist conditions Spores are air-borne The fungus is a weak pathogen and infection can occur only through wounds Secondary spread may occur during storage Control Observe hygiene recommendations for control of rhizopus rot Avoid wounding fruit Specific fungicides have not been approved for the control of blue mould of mangoes Hot water and fungicide treatments applied for anthracnose control during controlled atmosphere storage will provide some control of blue mould Blue mould on mango fruit Postharvest Physiology Training Manual Page 40 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.17 Mucor rot Cause The fungus Mucor circinelloides Symptoms A pale, grey-brown, watery rot of the skin and flesh develops at the stem end as the fruit ripens, and may spread through the entire fruit Occurrence Mucor rot is likely to be serious only in the final weeks of long-term storage in controlled atmospheres (5%02, 2% C02, 13°C) The fungus is widely distributed in soil and in decaying organic matter Infection occurs via wounds or damaged tissue Mucor rot is favoured by cool storage (13-20°C) Secondary spread may occur during storage Control Follow hygiene recommendations for the control of rhizopus rot Avoid wounding fruit No fungicides are registered for control of this rot in mangoes Do not place fruit on the ground while bleeding sap from them Mucor rot of mango fruit Postharvest Physiology Training Manual Page 41 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.18 Cytosphaera rot Cause The fungus Cytosphaera mangzferae Symptoms Symptoms of cytosphaera rot appear as the fruit ripens A slow-spreading, sunken, tan lesion extends from the stem end Fruiting bodies (pycnidia) may appear on the surface of established lesions, followed by a collar of white mycelium at the stem end Occurrence Cytosphaera rot is rarely seen Its presence may sometimes be masked by other more aggressive stem end rot fungi Before the appearance of fruiting bodies the symptoms resemble lesions caused by Aspergillus niger Control Measures recommended for stem end rot are effective Cytosphaera rot of mango fruit Postharvest Physiology Training Manual Page 42 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.19 Lenticel spotting Cause Certain growing conditions and post-harvest handling procedures can damage the lenticels on the fruit surface Symptoms The corky tissue in lenticels on the skin swell and becomes pronounced The lenticel then darken making the fruit look spotty This becomes more obvious as the ripening fruit changes colour from green to yellow On ripe fruit, damage appears similar to chilling injury Occurrence Lenticels are the breathing pores on the surface of mango fruit Conditions that damage the lenticels promote lenticel spotting For example, the disorder can occur when fruit have been held too long in washing water or in dips, particularly if detergents have been added Fruit that have been on the tree during heavy rain sometimes show milder symptoms Control Do not exceed a dipping time of minutes in the recommended hot water/fungicide dip Avoid immersing the fruit in water for more than 15 minutes during post-harvest handling Lenticel spotting of mango fruit Postharvest Physiology Training Manual Lenticel spotting of mango fruit Page 43 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.20 Abnormal ripening Cause When mango fruit start to ripen, their respiration rate rises dramatically If fruit respiration is disrupted, abnormal ripening may occur Symptoms Fruit in poorly regulated controlled atmosphere (CA) storage may develop unpleasant odours and unpleasant flavours Fruit coated with waxes or other materials may fail to ripen or may develop unpleasant odours and unpleasant flavours Occurrence CA storage can extend storage life of mangoes by or weeks However, precise control of the atmosphere is essential Oxygen levels below % and carbon dioxide above 12% will cause abnormal ripening Coating the fruit skin with wax or other materials can restrict the movement of gases between the air and the fruit Lack of oxygen, and build-up of carbon dioxide and other by-products of metabolism within the fruit can cause abnormal ripening or failure to ripen Control In controlled atmosphere storage, precise control of the atmosphere is essential atmosphere should contain at least 1% oxygen and not more than 8% carbon dioxide The storage Do not coat the fruit with waxes or other materials that excessively restrict gas exchange External appearance “skin is green and mango fruit Internal appearance “skin is green and mango soft eating ripe” fruit soft eating ripe” Postharvest Physiology Training Manual Page 44 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.21 Jelly seed Cause The cause of jelly seed is unknown Symptoms Watery translucent tissue spreads out from around the seed The disorder can also develop in the pulp away from the seed, and areas of affected flesh expand and coalesce around the seed Affected flesh has a foul taste which has been described as “acidic and overripe” Occurrence The disorder is normally evident at harvest, but worsens as the fruit ripen There are marked differences in cultivar susceptibility: Kensington Pride is not susceptible; Facel is slightly susceptible; Tommy Atkins is highly susceptible Control The incidence of jelly seed may be reduced by harvesting fruit as early as practicable but not so early that they are immature Internal jelly seed symptom of mango fruit Postharvest Physiology Training Manual Page 45 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.22 Stem end cavity Cause The cause of this disorder has not yet been clearly established Symptoms Internal: affected fruit have a distinct cavity in the flesh at the stem end between the seed and the stem attachment The flesh surrounding the cavity may show a grey-brown discolouration and have an abnormal, open texture Irregular tissue strands may be found within the cavity In ripe fruit, soft, soursmelling flesh may extend from the cavity down and around the seed These symptoms may also be associated with internal cracks surrounded by white tissue External: visible external symptoms appear only in severe cases when the cavity reaches to the under-surface of the skin A grey-brown sunken area then develops in the skin of the fruit near the stem attachment If no visible external symptoms are apparent, the disorder may be detected in ripening or ripe fruit by pressing the tissue next to the stem with the thumb If the tissue gives easily as pressure is applied, then the stem end cavity is usually present Fruit with the disorder may fall before harvest Occurrence Stem end cavity affects Kensington mangoes in particular, as well as some other cultivars The disorder is more prevalent in fruit harvested late in the season Fruit maturing late in the season can be more severely affected Mature, hard, green fruit have a low incidence of stem end cavity, although fruit that not release sap when the stem is removed after harvest are suspect T he disorder is rarely seen in small fruit, i.e smaller than 220 g or count 25 Control Harvest fruit at the green mature stage before they have started to ripen on the tree If ripening fruit are harvested, check their stem ends for discolouration and a spongy feel before packing Postharvest Physiology Training Manual Page 46 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.23 Internal breakdown Cause The cause of this disorder has not been clearly established Symptoms The disorder typically occurs at the stem end A watery patch develops in the flesh, often with discoloured strands In severe cases, the flesh collapses, leaving a cavity where only the fibres remain External symptoms are a dark-green patch on the skin and premature softening of the cheek Mild cases of the disorder may show no external symptoms Occurrence The disorder has occurred in recent years in new mango varieties Keitt and Delta R2E2 in districts throughout Queensland The disorder has been observed in the following: • fruit harvested late in the season-in most fruit showing symptoms, the seed had begun to germinate • large fruit from trees bearing a light crop • fruit from young trees that had received heavy applications of nitrogen fertiliser • fruit from orchards with high vigour, and growing on soil low in calcium and boron Control Avoid excessive use of nitrogen, and ensure calcium and boron levels are adequate Harvest the fruit before they become over-mature Internal breakdown of mango fruit Postharvest Physiology Training Manual Page 47 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.24 Chilling injury Cause Storage of mangoes at temperatures below their chilling threshold (10-13°C) leads to tissue damage The lower the temperature, and the longer the storage period, the more severe are the symptoms Symptoms Mature green fruit: the skin shows blotchy areas of dull, dark grey discolouration, particularly on areas of blush or sunburn Surface pitting may occur Fruit ripen unevenly or may fail to ripen The skin colour is poor, as are flavour and aroma development Ripe fruit: ripe fruit injured by chilling show dark spotting of the lenticels and have dull skin Chilled fruit may have an acid or tart taste Infection by disease organisms is enhanced by chilling damage Occurrence Chilling symptoms may not be evident during cool storage, but may become obvious during handling after storage Ripe fruit are less susceptible to chilling injury than green mature fruit Control Store most cultivars from most mango growing areas at 10-13°C In retail outlets where a 10-13°C coldroom is not available, mangoes may be stored for no longer than days at temperatures between 5°C and 10°C Do not store at temperatures less than 5°C To ripen fruit to an acceptable colour and flavour, hold them at 20-22°C Chilling symptoms of ripe mango fruit Postharvest Physiology Training Manual Chilling symptoms of green mango fruit Page 48 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.25 Heat injury Cause Excessively high temperatures can injure fruit during hot water/fungicide treatments for disease control and heat treatments (water and air) for insect disinfestation Symptoms Symptoms are not immediately apparent, and show up only after the fruit have cooled Damage to the skin shows as a grey or brown irregular scald, and the flesh is no longer firm In severe cases, the skin can be completely scalded and the fruit fails to ripen normally Internal damage shows as white spots in the flesh, or a hard, white layer of varying thickness directly under the skin Cavities can also develop in the flesh and the surface can appear sunken Occurrence The extent of injury depends on the length of time fruit are exposed to high temperature, as well as on the temperature Scald develops if either the temperature is too high or the period of exposure is too long Treatment times can be exceeded if fruit move too slowly through dipping tanks Fruit can also be scalded if the dip solution is poorly circulated, allowing hot spots to develop in the tank If fruit are packed hot, the areas where they touch each other can develop scald Similarly, fruit put on racks to dry after dipping may develop scald where they touch Fruit are more prone to damage just after harvest Susceptibility varies between fruit from different districts, and increases greatly during cool, wet weather Ripening fruit appear more prone to damage than green mature fruit Control Make sure that equipment used for heat treatment (water or air) is calibrated and the treatment conditions have been correctly set Allow a minimum of hours (preferably hours) between harvest and treatment Do not cool-store fruit before treatment The maximum temperature and time for disease control in Kensington mangoes is 52°C for minutes Do not exceed either duration of dipping or dip temperature During cool, wet weather, reduce the temperature to 48-50°C Agitation of the dip helps distribute heat and prevents `hot spots' in the tank Using a powerful recirculating pump is preferable to stirring or paddling Allow fruit to cool freely after treatment and before packing External heat injury symptom on mango fruit Postharvest Physiology Training Manual Internal heat injury symptom on mango fruit Page 49 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.26 Failure of skin to yellow Cause The skin fails to yellow when fruit ripen at temperatures above 25°C Symptoms Although the mango flesh ripens normally, the skin remains green with blotches of yellow Occurrence Ripening begins after a mature green mango is harvested, and the fruit gradually becomes edible The skin colour of varieties such as Kensington changes from green to yellow The texture of the flesh changes from firm and crisp to soft The characteristic mango aroma and flavour also develop However, at temperatures above 25°C, the skin colour does not fully develop, even though the flesh ripens normally Control Ripening the fruit at a temperature of 2022°C will result in acceptable flavour and skin colour External appearance “skin is green and mango fruit soft eating ripe” Postharvest Physiology Training Manual Page 50 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.27 Fumigant injury Cause The fumigants ethylene dibromide (EDB) and methyl bromide (MB), used for insect disinfestation, may injure mango fruit when applied incorrectly Symptoms Fumigants can cause dark discolouration of the skin of affected fruit Occurrence EDB and MB are being phased out as disinfestation treatments However, fruit damage will still be a concern until alternatives are found Control Do not exceed the recommended concentration, time or temperature for fumigant application Insect injury Methyl bromide injury of mango fruit Postharvest Physiology Training Manual Page 51 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.28 Fruit fly damage Cause Fruit flies of the genus Bactrocera, especially B tryoni, the Queensland fruit fly, and Ceratitis capitata, Mediterranean fruit fly Symptoms The fruit fly leaves an inconspicuous oviposition site (`sting') on the skin of the fruit when laying eggs Small white larvae emerge from the eggs and consume the fruit flesh Occurrence In areas where fruit flies are endemic, they are an occasional problem in backyard mango trees Fruit fly is mostly well controlled in commercial orchards by pre-harvest spraying Mature green fruit are generally not susceptible Control Pre-harvest control includes population management (e.g release of sterile male fruit flies) and/or insecticide application during the period when fruit are susceptible Populations can be monitored by trapping Harvest mature green fruit Post-harvest disinfestation is by fumigation Insecticides and heat treatment are possible alternatives QLD Fruit Fly Postharvest Physiology Training Manual Qld fruit fly damage of mango fruit Page 52 CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 5.29 Mango seed weevil damage Cause The mango seed weevil Sternochetus mangiferae Symptoms There are no apparent external symptoms The larvae of the seed weevil are found in the seed of the mango fruit Occurrence In regions where this pest is endemic, the incidence of infestation can be high Control Control of the pest in the orchard by using recommended pest management techniques is important Because of the inaccessibility of the weevil in the seed, post-harvest control is difficult Currently, there are no effective post-harvest treatments for the control of mango seed weevil Mango seed weevil Postharvest Physiology Training Manual Page 53 ... Agrilink Mango Information Kit Postharvest Physiology Training Manual Page CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Know your mango (postharvest. .. 3404 6999) ii CARD VIETNAM 2006 MANGO POSTHARVEST TRAINING MANUAL Introduction Key production practices affecting postharvest quality Know your mango (postharvest biology) ... for details) Postharvest Physiology Training Manual Page CARD Project 05004 VIE Improvement of Vietnamese Postharvest Practices and Supply Chains - July 2007 Take care of your mango (postharvest