The Sugar Apple, or what is more commonly known in Australia as the Custard Apple is native to Central and South America, but now is common throughout the world's tropical areas. Of the Annonas, it is the most widely-distributed species.
It is a small semi-deciduous tree reaching 4 to 6 metres in height. The bark is light-brown and of an even texture. The tree often produces multiple stems and responds well to pruning.
The leaves, which are from 50 to 100 millimetres long, are light green and smooth in texture. The flowers, which are produced on the woody stems and branches, are singular or in clusters of two to four. They are greenish-yellow in colour, about 20 millimetres long, the three, thick outer petals are oblong, rounded at the ends; the inner petals are minute, ovate. A highly purgative tea can be made from the roots and a mildly laxative and tonic tea from the leaves. The crushed leaves and seeds are considered to have insecticidal properties.
The fruit is highly esteemed in many countries and ranks amongst the finest dessert fruit in the world. It is round to heart-shaped, between 50 - 125 millimetres in diameter and pale green in colour. The fruit is what is technically known as a syncarp, which means that it is a compound fruit consisting of numerous fleshy carpels which are fused together within the skin. Many of these carpels contain brown seeds about the size of an average bean. The pulp is of a smooth custard-like texture and the flavour is excellent. It is delicate, sweet, subacid, and tastes similar to blanc-mange. The Sugar Apple or Custard apple as we know it, is rarely seen on our local markets, and should not be confused with the Atemoya custard apple which is grown commercially in N.S.W. and Queensland and often available here. The Atemoya is a larger fruit, has less seeds and is more aromatic in flavour.
The Sugar Apple is a common sight in many Top End gardens and has been here since early settlement. Because the ripe fruit is relished by some of our native animals, namely birds, flying-foxes and possums, it is now naturalized here, due to the wide spreading of seed. The main crop comes late wet season, however the tree will continue cropping throughout the year if watering is maintained. The fruit should be picked before it has ripened fully, as in the later stages, it ripens very quickly, and thus gives the birds the upper hand.
After flowering, as the fruit forms, the many bumps which cover the carpels and form the skin, become more and more defined. When the fruit reaches full size, the green bumps become separated by a creamy-yellow colour between them. The fruit is ready for harvest when it reaches this stage and when it feels slightly spongy in comparison to previously being rock hard. Once picked, the fruit should be left in a cool place to ripen, then it becomes soft and is ready to eat within a couple days. If desired, this process can be slowed down by refrigeration.
This tree is a very hardy species, it can withstand drought for a considerable period of time, but cannot withstand frost or long cold periods. It is a good choice for our climate and termite attack is rare, although some instances have been recorded. It is tolerant of most soil conditions, although like most trees, it succeeds best in rich, sandy loam, and likes to be well-drained. The tree prefers an 'open forest' situation, not being over-shaded, and an annual light pruning is beneficial. Application of manure and fertiliser assists cropping and is essential in attaining large fruit. Insect pests which affect the sugar apple are few and usually only occur if the tree is in a poor state of health or growing in a position which is adverse to its requirements.
Most common of these pests are Whitefly and Mealybugs. Whitefly is seen under the leaves in the pre-adult stage, the small, black, scale-like creatures are only 3 millimetres long and have scattered soft spines on their upper surface. Mealybugs are white, fluffy, from 3 to 6 millimetres long and covered with a waxy secretion. They are yellow when squashed, and if there are only a few present this is the best method of control. Both Whitefly and Mealybugs can be controlled by spraying with a mixture of Pyrethrum and White Oil, or preferably Summer Oil, and the operation should be done in the late afternoon to prevent leaf-burn. Squirting the undersides of the leaves with the hose is an effective method of deterring these sort of insects.
Sugar apples are mostly propagated by seed, although some grafted cultivars do exist. Seedlings can fruit in 2 to 3 years and such a hardy tree with such delicious fruit should find itself in every Top End home orchard.
DATE: November 1982
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