Mango harvest criteria can vary with local consumption patterns and distance to the market. Time from flowering combined with fullness of mango cheeks is the commonest criteria. Producers must decide whether to harvest as soon as the market price ensures a reasonable return or to leave the crop in the field to obtain maximum yield. However, waiting too long for yield increase may drastically shorten the marketable life of the produce and lower the sale price. This balance is a critical factor in determining the grower's income from the crop. In practice the total harvest period is very short and the grower has very little time in which to make the correct decision. Mango fruits fall into this category and are best harvested using clippers and placed in harvesting bags carried by the harvester. With large trees, fruits are harvested by the use of picking poles, with or without attached clippers, equipped with bags into which the fruit fall (See Figure 27. Harvest tool with mangoes and Figure 28. Mango harvest tool).

Figure 27. Harvest tool with mangoes.

This method is rather slow and requires considerable experience and skill, but is essential if high quality fruit is required. Alternatively the fruit is picked by the harvester either on a ladder or who climbs the trees and throws the fruit to a skilled 'catcher' on the ground or into a large net. Pulling out of stems from fruit when harvesting has to be avoided at all costs because broken skin at the point of attachment of the stem is particularly susceptible to a decay condition known as stem end rot.

Figure 28. Mango harvest tool.

Mangoes normally reach maturity in 4 to 5 months from flowering. Fruits of "smudged" trees ripen several months before those of untreated trees. Experts in the Philippines have demonstrated that "Carabao" mangoes sprayed with ethephon (200 ppm) 54 days after full bloom can be harvested 2 weeks later at recommended minimum maturity. The fruits will be larger and heavier even though harvested 2 weeks before untreated fruits. If sprayed at 68 days after full bloom and harvested 2 weeks after spraying, there will be an improvement in quality in regard to soluble solids and titratable acidity.

When the mango is fully-grown and ready for picking, the stem will snap easily with a slight pull. If a strong pull is necessary, the fruit is still somewhat immature and should not be harvested. In the more or less red types of mangoes, an additional indication of maturity is the development of a purplish-red blush at the base of the fruit. A long-poled picking bag which holds no more than 4 fruits is commonly used by pickers. Falling causes bruising and later spoiling. When low fruits are harvested with clippers, it is desirable to leave a 4 inch (10 cm) stem to avoid the spurt of milky/resinous sap that exudes if the stem is initially cut close. Before packing, the stem is cut off 1/4 in (6 mm) from the base of the fruit.

Yield

The yield varies with the cultivar and the age of the tree. At 10 to 20 years, a good annual crop may be 200 to 300 fruits per tree. At twice that age and over, the crop will be doubled. In Java, old trees have been known to bear 1 000 to 1 500 fruits in a season. Some cultivars in India bear 800 to 3 000 fruits in "on" years and, with good cultural attention, yields of 5 000 fruits have been reported. There is a famous mango, "Pane Ka Aam" of Maharashtra and Khamgaon, India, with "paper-thin" skin and fibreless flesh. One of the oldest of these trees, well over 100 years of age, bears heavily 5 years out of 10 with 2 years of low yield. Average annual yield is 6 500 fruits; the highest record is 29 000.

Average mango yield in Florida is said to be about 30 000 lbs/acre. One leading commercial grower has reported his annual crop as 22 000 to 27 500 lbs/acre. Maturity Mangoes are generally harvested at physiological mature stage and ripened for optimum quality. Fruits are handpicked or plucked with a harvester. After harvest the fruits are usually heaped under a tree on the ground. Bruised and injured fruits develop brown to black spots during storage making the fruits unattractive. Moreover, injuries to the peel or to the stalk end serve as avenues for invasion of microorganisms and lead to rotting of the fruits. Post harvest losses in mangoes have been estimated in the range of 25 to 40 percent from harvesting to consumption stage. If proper methods of harvesting, handling, transportation and storage are adopted, such losses could be minimized. The harvesting in mango should be done in the morning hours and fruits should be collected in plastic trays and kept in shades. The fruits should not be allowed to fall on the ground as the injured fruits cause spoilage to other healthy fruits during packaging and storage. Fruits harvested with 8 to 10 mm long stalks appear better on ripening as undesired spots on skin caused by sap burn are prevented. Such fruits are less prone to stem-end rot and other storage diseases. Fruits harvested by stick are injured and/or bruised due to impact resulting in decay, poor quality and attract low price. To overcome these problems, a simple, low cost and portable mango-harvesting device has been designed and developed at CISH, Lucknow (Central Institute of Sub-tropical Horticulture (CISH), India). Mango fruits are taken into the pouch and held between the divider and knife and as the device is pulled the blade cuts the pedicel. The fruits are then conveyed through a nylon chute to collecting boxes without bringing down the device every time. This saves time and protects fruits from mechanical damage; it also protects operator's hand from the sap (plant fluid), which flows from the point of detachment.

Transportation

Mangoes are hand-packed in single layer fibreboard trays. Plastic and papier-mâché inserts with moulded cups or channels are available in a range of counts. (The most commonly used vary between 10 for large fruit to 20 to 25 for smaller fruit). These inserts help speed up the packing process. Trays also come in different depths to accommodate larger fruit. Trays should packed so that fruits hold each other firmly in place, with no movement when the lid is closed and should weigh at least 6.8 kg. A carton can lose around 400 g in transit resulting in a very loose pack at the market. After transit a standard carton should weigh 6.5 to 7 kg.

This method is costly both in carton cost per kilogram of fruit as well as time and labour. A cost saving method would be by volume filling large cartons. Using this method fruit is still graded to size but the carton is simply filled until a required weight is reached. Trials using 10 kg and 18 kg cartons transported by refrigerated trucks arrived at markets in good condition of both fruit and cartons. Despite the fact that the mangoes were in good condition, prices received were relatively low. This may be the way to send consignments to supermarket chains and other bulk purchasers in the future, but at present the highest prices are still received for trays. (Poffley et al., 1999).

Grading

Fruit may be sized by eye, dimension or weight using mechanical or electrical sizing equipment. Within each package fruit may not vary in diameter by more than 10 mm. If the fruits are graded according to their size, weight, colour and maturity, both the producer and consumer are benefited. It has been observed that bigger size fruits take 2 to 4 days more in ripening than smaller ones. Hence, packaging of smaller fruits with larger ones should be avoided to achieve uniform ripening. Immature, overripe, damaged and diseased fruits should be discarded.

Packing

Fruit can be prepared for packing in three ways:

1. With stems removed. A sap flow will occur if the stems are removed. The initial spurt of sap will burn the fruit, leaving a blemish that will develop during storage and transport. Sap burns must be avoided. Clip the stems short, while holding the fruit with the stem end down. Place the fruit on a de-sapping bench and allow them to drain for 20 to 30 minutes until the sap flow has stopped. A fine water spray over the fruit helps to reduce the chances of sap burn. Recent trials in Queensland have found that dipping fruit in water containing 1 ml/l of wetting agent reduces the risk of sap burn even further.

2. With stems attached. Trim stems as described in the Harvesting section. More care is required when handling this fruit so that stems are not accidentally broken.

3. In a 450 x 290 x 105 mm (internal dimensions) telescopic tray. This package is robust and it presents and protects the fruit well. A plastic cup insert, called a plix liner, is used. This acts as a packing guide and also 'nests' the fruit. For best presentation, pack the fruit with the stem end down and convex curve up. This position also prevents any sap that oozes after the fruit has been packed from spoiling the appearance of the fruit. The package must be packed firmly and have a gross weight of 7 to 7.5 kg. Stickers identifying the brand are important. They should be distinctive in colour and simple in design. Fruit, which is nearly always removed from the package for retail display, cannot be identified without a sticker (Agriculture Western Australia, 1998).

Full-telescopic two-piece fibreboard carton ("banana" type) or one-piece waxed self-locking ("bushel" type) cartons may be used. The bursting strength is 275 psi. Central dividers and shredded paper may be used to assist with carton strength and product protection. Where staples are used for carton construction, care should be taken to ensure complete staple closure to avoid fruit damage. Carton internal dimensions: 20 by 51 by 34 cm (7.9" by 20" by 13.4") and 29.5 by 44 by 29.5cm (11.6" by l7.3" by 11.6").

Wooden boxes are commonly used for packaging and transportation of mango fruits. Under dynamic transport conditions nails come out due to vibration and puncture the fruits, which result in bruising, decay and low price of fruits. Further, too much ventilation affects the quality of fruits due to shrinkage, loss in weight, colour, etc. To overcome these problems, CFB (carton fibreboard) Boxes of 5 kg and 10 kg capacity for packing and shipping of mango fruits successfully as an alternative to traditional nailed wooden boxes. The use of CFB boxes for packaging for the domestic market is also the need of the hour due to scarcity of the wood and environmental concerns. For export purposes, CFB boxes are already in extensive use. Paper scraps, newspapers, etc., are commonly used as cushioning material for the packaging of fruits which prevent them from getting bruised and spoiled during storage and transportation. Low-density polyethylene (LDPE) lining has also been found beneficial as it maintains humidity, which results in lesser shrinkage during storage. Wrapping of fruits individually (Unipack) with newspaper or tissue paper and packing in honeycomb structure helps in getting optimum ripening with reduced spoilage. Normally the lid of the wooden boxes is nailed with an area of 5 to 7 cm high in the middle. This puts pressure on the fruits during transport and results into reduced quality. Therefore, farmers should be very careful while packing the fruits.

Export Grading and Packing

The fruits are checked prior to packing to ensure the absence of blemishes, bruises, insect and mechanical damage. Fruits are graded in each carton according to the variety, size (giving a range of counts for each shipment) and maturity. Mangoes are packed in single layer one- or two-piece full-telescopic, self-locking fibreboard cartons (bursting strength requirement 250 to 275 psi). Ventilation and handle holes provide adequate ventilation and ease of handling (Medlicott, 2000).

Some mango varieties required to meet specifications for export, are presented in Table 4.

Table 4. Specifications for export varieties.