Annona muricata

Common name: Soursop

Other common names: Brazilian paw paw, Graviola, Prickly custard apple, Soursapi

Names in non-English languages: Philippines French India Spanish Malaysia Thailand German China

Description

Soursop is a custard apple relative bearing large fruit, probably the largest of the custard apples. Originating in humid areas of tropical America and the Caribbean, it is now introduced and cultivated in other regions including parts of Africa, India, Southeast Asia, Australia, Hawaii and the wider Pacific.

It is a small, densely leafy tree 3 to 8 m (10 to 26 ft) tall with a slender trunk and low-branching habit, forming a pyramidal or narrowly rounded crown. The bark is grey or grey-brown and smooth.

The leaves are oblong, 10 to 20 cm (4 to 8 in) long, dark glossy green on top, pale dull green underneath and remain on the tree throughout the year, though there may be some leaf-fall in areas with a long or pronounced dry season.

The flowers are bisexual, with both female and male parts. They are a three-sided pyramidal shape 3 to 5 cm (1.2 to 2 in) long, made up of three outer and three inner yellow petals slightly opening. They are borne singly on the trunk and branches during the humid months of the year and hang down on short stalks giving off a sweet, musky odour that attracts pollinating insects.

The fruit that follow are oval to heart-shaped and large, typically 15 to 40 cm (6 to 16 in) long, up to 20 cm (8 in) wide, weigh from 1 to 7 kg (2.2 to 15 lbs) and have thin green skin dotted with soft spikes. Immature fruit are dark green and firm, becoming pale green and with a musky odour when mature, which signals a readiness for harvest.

After harvesting, the fruit are stored for around four to five days, becoming soft to the touch when fully ripe. The thin skin is easily peeled away revealing soft, very juicy, fibrous white pulp embedded with many large glossy dark brown, oblong seed.

Use

The pulp can be eaten fresh out of hand, though it is more commonly pressed trough a sieve to extract the juice or it is liquefied in a blender. Care is taken to remove the large seeds before processing. In its natural state, the juice or liquefied pulp is milky-white, smooth and has a sweet-sourish, somewhat musky flavour.

Soursop pulp is used in chilled drinks and desserts, including smoothies, ice cream and sorbets. In the West Indies, the juice is extended and smoothed with milk and then spiced with grated nutmeg to make a refreshing drink. The de-seeded pulp is also torn or cut into pieces and added to fruit salads or it can be chilled or frozen for later use.

Climate

Grows naturally and produces a fair to good crop of fruit in sub-humid to humid subtropical and tropical climates, generally in frost-free areas with annual lows of 17 to 25 °C, annual highs of 26 to 34 °C, annual rainfall of 900 to 2500 mm and a dry season of 6 months or less.

Growing

New plants are usually started from seed, but can also be produced using air-layering (circumposing) methods. The young plants are planted out when around 30 cm (12 in) tall, at the start of the rainy season. They develop quickly and may start to flower and fruit in their third or fourth year, depending on the growing conditions.

Growth and fruiting performance is best on rich, free-draining loam and sand soils of a moderately acid to slightly alkaline nature, generally in 5.5 to 7.5 pH range, and on sites with full to partial sun exposure. 

Although moderately drought tolerant, it has a shallow root system and benefits from mulching, especially in areas near the lower end of its rainfall range. It performs poorly on clayey, slow-draining and waterlogged soils, with poor fruit-set and low yields the usual result.

Some of the more popular varieties include ‘Bennett’ (large fruit with flavoursome pulp), ‘Whitman fibreless’ (delicious melting pulp, but a shy bearer), 'Giant' (produces exceptionally large fruit), ‘Morada’ (commercial variety from Colombia), and 'Ratu’ and ‘Sirsak' (from Southeast Asia). There is also 'Mountain', a cold tolerant, highland variety with pale yellow pulp, but the flavour is poor and it is instead mostly used as rootstock for other varieties.

Yields of up to fifty fruit per tree per year have been reported for ten-year-old trees grown under intensive cultivation, however, yields vary greatly among the different varieties and under different growing conditions, with yields from homegrown trees about half to a quarter that of trees in commercial orchards.

Problem features

It has been recorded as a having escaped cultivation and as a weed of the natural environment and agriculture. However, there does not appear to be any records of it anywhere as a serious weed or invasive species, and it is assessed as a low weed risk species for Hawaii, by the Hawaii Pacific Weed Risk Assessment project (HPWRA).

The seed are reported to be toxic and have been used traditionally as an insecticide and fish poison.

Where it grows

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