It is good practice to harvest the fruit at the optimum stage of maturity in order to obtain good quality fruits with the optimum storage life. However, if the fruits are to be transported to distant markets, harvesting may have be done at the minimum stage of maturity at which the fruit quality is readily acceptable when ripe to ensure maximum storage life.

Reliable maturity indices need to be applied to determine the best time for harvesting. There are several indices that are normally used to predict the maturity stage of mango for harvesting, which include the age of fruit, external fruit appearance, and flesh colour and fruit density. The suitability of these indices may vary depending on fruit variety .

The suitable age for picking mango can be calculated either from the time of flower bloom or fruit-set. The suitable time for harvesting several mango varieties in Malaysia is shown in Table 1 .

The use of fruit age as an index of maturity is even more important when the fruit is bagged on the tree as the fruit inside the bag cannot be seen. Some growers like to harvest over-mature or partially ripe fruits. They claim that these fruits are sweeter and more palatable. Nevertheless, picking fruits at a partially ripe stage – after 12 weeks from fruit-set – is not recommended for the Chokanan variety because this fruit is prone to have jelly-seed symptoms that affect fruit quality.

The changes in fruit shape and physical appearance of some mango varieties can clearly be observed when the fruit attains the correct maturity stage for harvesting. Most mango varieties are flat in shape when they are immature. Mature fruits develop full cheeks, a broader apex and the rounding of the ventral edge with a stretched, smooth and shiny skin.

The condition of the fruit shoulder may also be used to identify fruit maturity. Fruits with outgrown ventral shoulders or shoulders of the same level with stem end are ready for picking. Some growers determine fruit maturity by looking at flesh colour. Mature fruits exhibit a yellowish white flesh with a fibrous seed coat. Fruits with white flesh are not mature.

Table 1: Age of different varieties of mango recommended as a minimum maturity stage for harvesting

The appearance of white powdery materials called “bloom” on the fruit surface may occur on fruits at a certain stage of fruit development close to maturity. The formation of bloom may also be used as a maturity index for some varieties like Harumanis and Masmuda.

Fruits can be harvested about a week after the white bloom is formed. At this stage the bloom is easily removed from the fruit surface especially when the fruit is rubbed. The fruit skin looks shiny and waxy underneath the bloom.

The changes in fruit density or specific gravity during the growth and development of the fruit may also be related to fruit maturity. Fruit density can be measured using the floatation method by floating the fruit in water. Fruits that sink in water have a density of more than one and are considered mature, while immature fruits have a density of less than one and float in water.

Only mature fruit should be harvested to ensure good quality mango when fully ripe. Harvesting must be properly and carefully done to minimise mechanical injury to the fruits. Harvesting should be done by experienced pickers and they should be provided with adequate picking tools.

Pruning should be incorporated into harvest so that the fruits are harvested by cutting their stalks as close to the last leaves as possible with the use of a pair of secateurs. However, this method of harvesting is only possible with shorter trees and where fruits are within the reach of pickers.

A ladder or other harvesting devices may be necessary with taller trees and where fruits are beyond reach. Harvesting may be aided with a net fitted to a metal ring attached to a long pole. The finger-like metal rods assist in separating the fruit from the stalk. Harvested fruits are caught in the net.

Mangoes should be harvested with a length of stalk attached to the fruit. Latex exudes from fruit that is detached from the stalk, and causes staining of the peel, which reduce the quality of the fruit. To reduce the problem with latex, harvest between mid-morning and mid-afternoon when the fruit has lost some of its turgor and latex flow is minimal.

Another technique to reduce latex staining is to remove the peduncle after harvest and place the fruit stem-end down on gunnysacks or sheets or paper for a few hours to allow the latex to drain out completely.

Latex stains can also be avoided by washing the fruit immediately after harvest and leaving the fruit to dry with their stem-ends down.

Harvesting should preferably be carried out during the coolest part of the day – in the early mornings or late afternoons. Do not to pluck the fruit when it is wet from dew or rain as wet fruit will overheat if not well ventilated, and are more likely to decay.

Fruit pickers normally carry picking baskets with them during harvesting. Once picking baskets are full they are emptied into suitable bulk containers such as bamboo baskets or returnable plastic containers located at strategic points which are later transported to in-field collection centres or the packinghouse. Avoid overfilling the baskets as they may cause considerable damage to the fruit due to fruit falling to the ground or the stacking of baskets during transportation.

Harvested fruits should be protected in the field by putting them under shade when transport is not immediately available to haul them to a collection centre or packinghouse. Fruits left exposed to direct sunlight will get very hot and deteriorates rapidly. The occurrence of fruit injury during handling can be minimised by using containers of suitable loading capacity lined with good cushioning materials such as gunnysack, newspapers or sponges and by proper fruit arrangement.

Small trucks or trailers attached to tractors may be used to transport the fruits to a collection centre or packinghouse. Farm roads should be kept in good condition because great damage can be inflicted on produce carried over rough roads in unsuitable vehicles. Containers must be loaded on vehicles carefully and stacked in such away that they cannot shift or collapse, damaging their contents.