Cultivation

Planting

         Pits of 60cm × 60cm × 60cm size are dug and left open to sun for a week. They are filled with top soil mixed with 25–30kg of well-decomposed farmyard manure. Custard-apple should be transplanted 5m × 5m apart (400 plants/ha). However, setting plants closer may be preferred. Plants spaced at 4m × 4m (625 plants/ha) not only accommodates over 50% additional plants/unit area but promotes better fruit set by improving pollination, a problem in annonas. Due to larger canopy, atemoya and bullock’s heart require a plant-to-plant spacing of 6m × 6m and cherimoya and sour-sop 8m × 8m spacing.

        Planting should be carried out preferably in spring so that plants establish roots in summer, start growing as the weather warms up and put up vigorous growth during rains. However, if adequate irrigation facilities are lacking, monsoon is the optimum time for planting. To keep the graft-joint well above the ground is a must. As soon as a young tree is planted, it should be irrigated till it establishes.

Pruning

Annonas require little pruning. It is essential to develop a good crown and better yields over a long period of time. Without pruning, the plants become bushy and their bearing efficiency comes down. Hence, timely removal of misplaced limbs is necessary to build a strong framework. Selective and mild pruning of deadwood and very old branches should be carried out to avoid congestion and encourage well-spaced branching. Severe pruning is detrimental for the plant growth. Yellowing of leaves starts as the harvesting season of fruits ends. The leaves begin to drop with the onset of winter and fresh growth occurs in spring. Flowering occurs singly or rarely in small clusters mostly on current season’s growth and occasionally on old wood. Training to a single stem is the only option when rootstock is employed.

Manuring and fertilization

Applying manures and fertilizers to custard-apple is not common but its plants respond very well to fertilization, increasing vigour, yield and fruit quality. Fertilizer application checks decline and extends longevity of trees. To specify the precise dose common to all soils is difficult, but general recommendations are given in Table 2. The area below the crown of trees should be cleaned of weeds. Then apply fertilizers in the basin under the tree but not within 30cm of the trunk. Subsequently it is desirable to irrigate the trees and incorporate the fertilizers. Fertilizer application should coincide with rapid vegetative growth and fruit development. As fruits are borne on new as well as old wood, application of slightly higher dose of N is not harmful.

Aftercare

        After planting, the young plants must be watered and supported by stakes to keep them erect. To start with a 60cm × 60cm basin around the plant is adequate. Regular watering during dry periods, occasional hand digging of the basins to check weeds, to keep the soil loose, attending plant-protection measures, manuring, removing of sprouts on stock and building up of a good framework are necessary cultural operations. The basins around the plant should be enlarged as the plants grow bigger. They should be made little larger than the spread of the plant.

In young orchards, a lot of land remains vacant between the rows for 4–5 years. Hence, short-duration vegetables—tomato, onion, chilli, okra, brinjal, radish or cowpea, greengram, horsegram, or any green manure crop—can be intercropped. These crops should not be raised too near the tree, lest they compete with them for nutrients.

Irrigation

           Most of the annonas produce a moderate crop even in the absence of irrigation. Irrigating plants at least during flowering and fruit development is essential. Fruit quality is superior in irrigated plants with more edible pulp/ segment. Plants receiving regular water grow luxuriantly with each bearing. Pruning, fertilization and irrigation are quite essential to get maximum yield.

In regions having limiting water, pitcher, trickle or drip irrigation systems help in judicious use of water. Fruits are raised as rainfed in low rainfall areas land shaping to divert rain water near the plantation may be taken up. Contour terraces, contour bunds and micro-catchments also help in efficient water use. Even ploughing of the plantation during rainy season helps better conservation of moisture. Custard-apple plants especially in neglected areas are benefited from these operations.

Harvesting and Postharvest management

        Custard-apple starts bearing fruits at the age of 4–5 years. It declines by about 15th year depending upon the maintenance. Custard-apple produces single crop in a year during August–October in south India and September–November in north India. On maturing, fruits turn light green. The inter-areolar space widens, the fruits turn creamy-white. Custard-apples are harvested manually when they are fully mature but still firm. If they are left for a longer time on trees, they split open and are spoiled. About 4–5 pickings are required. Occurrence of deformed fruits is due to carpels with unfertilized areoles failing to grow. Fruit yield varies widely from tree-to-tree. Normally a 7-year-old tree produces 100–150 fruits, the total yield being 7 tonnes/ha.

        Bullock’s heart and cherimoya are ready for harvesting during January–February and December–January, yielding 50–75 fruits/plant. Since both have thick stalks, it is necessary to harvest them with the stalks using secateurs. Atemoyas are somewhat early (September–October) and are shy-bearer. Higher yield (50–60 fruits) may be obtained with hand-pollination. Sour-sop, the largest annona, produces about 25 fruits/tree during June–August in south India.

             Annonas are climacteric fruits. Custard-apple takes about 3 days to ripen, while others 4–7 days. Prior to ripening the pulp of matured custard-apple is not separated into segments or flakes. It is only during conversion of starch to sugar this differentiation occurs. In ripe fruits of bullock’s heart and cherimoya the pulp is more or less homogeneous mass of closely cohering carpels which cannot be separated easily.

           Ripe fruits of custard-apple and sour-sop are very fragile and with the slightest pressure, the fruits easily get disintegrated into segments. Hence extra care is necessary while handling. Ripe custard-apples can be stored for about 2 days, but other annonas can be stored for 3–4 days. This may be partly due to the characteristic feature of the rind. In bullock’s heart and cherimoya, the carpels are not associated with external areolar divisions on the rind and the surface appears to be contiguous or almost fused unlike that in custard-apple. Thus the fruits do not split easily along the deep furrows between the interareolar spaces, the weakest portions of the rind.

             Custard-apple, atemoya, bullock’s heart and cherimoya are normally used as fresh fruits. Ripe fruits are popular among the poor. The unripe fruits of custard-apple are eaten in Andhra Pradesh after baking or roasting. The raw fruits of sour-sop are commonly used to prepare soup or vegetable.

            The pulp of custard-apple mixed with milk is made into a delightful drink or ice-cream. Development of a repulsive off-flavour on heating beyond 65°C and presence of gritty cells are major constraints in processing custard-apple. But its juice is a potential ingredient to prepare squash, syrup, nectar and a fermented alcoholic beverage. Jam, jelly, conserves and tarts can also be prepared from the pulp of custard-apple. It is also possible to can the pulp. The sweetish sour flesh of sour-sop is fibrous, juicy with pleasant aroma and is amenable for preparation of ice-cream, sherbat and syrup.