From the Archives of the Rare Fruit Council of Australia, inc.
by G. Barbeau


Seasons in Australia are opposite to those in the US.  Summer is Dec. Jan. Feb. Autumn is Mar. Apr. May. Winter is June July Aug. Spring is Sept. Oct. Nov.

The Red Pitaya, A New Exotic Fruit


The Red Pitaya, also called Strawberry Pear (Hylocereus undatus Britt. and Rose) is a spiny tropical cactus originating in Central America. It is cultivated in Nicaragua over a 150-hectare area on the west and south slopes of the Mount Santiago volcano, about 20km from Managua.

The fruit of the cactus is very attractive, with a distinctive appearance and a vivid red colour. In recent times, several consignments of this fruit have been exported to European countries.

The Fruit
The pitaya bears a large fruit which is pink, red, or mauve in colour, weighing around 250-350gm. The oval or rounded fruits have skins on which strongly or weakly expressed scaly markings appear; these scales correspond to the bracts of the flower. The flesh is dark red, approaching mauve in colour, and contains numerous tiny shining black seeds. Between the flesh and the skin there is a thin mucilaginous layer.

The fruit is pulped for juice, used in ice cream, or added to fruit salads. It does not have a strong taste, so lime juice is often added to bring out the flavour.

According to Incer [1959], the fruit is useful in combatting anaemia. In Colombia, Becerra [1986] has noted that the pitaya (in this instance the yellow-fruited variety, Cereus triangularis Haw.) contains the heart tonic captine; whether this is also true of the Red Pitaya of Nicaragua is yet to be determined.

The skin and the mucilaginous layer together make up 30-50% of the fruit weight, with this proportion varying with variety and fruit size. A Nicaraguan study [Campos-Hugueney, 1986] has shown that the pulp contains 84.4% water, 0.4% fats, 1.4% protein, 11.8% carbohydrates, 1.4% cellulose, and 0.6% ash. It also detected the presence of vitamin C (8mg/100g) and traces of vitamin A. The pulp colour is due to anthocyanins.

Ecology
The pitaya is a species of dry tropical climates. Its heat requirements are high - the average temperature should be 21-29°C, while the maximum can go to 38-40°C without the plant suffering any apparent harm. Water requirements are modest (600-1300mm), with alternating wet and dry seasons. Excessive rain leads to flower drop and rotting of immature fruit. For good production, the plants need a lot of sunshine.

The pitaya is a species which has been shown to have resistance to the sulphurous gases emitted by the Mount Santiago volcano. This explains the location of its present area of production, as growers in that area have hardly any other feasible alternative apart from pineapples.

Plant Development
The plant grows in the form of jointed stem segments. Each segment can reach a length of 2m and be 3-7 cm across. Each segment has three, or occasionally four, longitudinal ridges, along which lie small swellings equipped with spines.

The segments easily form aerial roots, which they use to attach themselves to supports. These can be living or dead, such as trees, wooden or cement posts, stone walls, or volcanic rocks. These roots can extend down to the soil to extract nutrients from it.

The pitaya is found wild over most of Nicaragua. Seeds are spread by birds, and may be found germinating high up in tall trees, such as Pithecolobium saman, Enterolobium cyclocarpum, and Crescentia cujete.

In cultivation, pitaya is propagated by stem cuttings, put directly in place at the end of the dry season. Usually three segments are placed around a living tree support; in current plantings, these supports are on a 3 x 5 m grid.

The best living posts are leguminous trees which root easily from large cuttings, such as Erythrina species and Gliricidia sepium. Other species used include Bursera simaruba, Spondias purpurea, Crescentia cujete, and Cordia species. The living posts must be pruned regularly so that they do not shade the pitayas too much.

Flowering
Flowering is initiated at the end of the dry season, in April, and continues through the wet season, to October. It seems to have a dependence on day-length (photoperiodism); irrigating plants during the dry season does not initiate flowering unless it is already close to the normal flowering time.

Flowers appear individually on the lateral stem ridges. They are large, perfumed, ivory white in colour, with a great many stamens. They open at nightfall and close at daybreak, with each flower lasting only one night.

Flowering in cultivated plants goes according to well-defined cycles, with all the flowers of the same plant, and all the plants of the same clone, developing according to three phases. Phase 1 is the appearance and development of flower buds, lasting 15-16 days; Phase 2 is flowering, lasting 3-5 days; and Phase 3 is the development and ripening of the fruit, which takes 30-35 days from flowering.

Flowering may have barely ceased when the flower buds of the following cycle appear. So it is possible to find flower buds, young fruits, and almost ripe fruits on the same plant at any given time.

Theoretically it would be possible to have 7-9 separate fruiting cycles during one wet season. In practice, 5 or 6 cycles occur, probably due to climatic or nutritional limitations. Fruit drop in immature fruit is an important occurrence, but its cause is not known.

Varieties
There are no varieties in the proper sense, only clones which differ markedly in such things as type of stem segment, colour and shape of fruits, skin thickness, and scale expression. One clone is spineless. Other plants differ in flowering season, some being late, others early. It will be of interest to find out if these variations have a genetic basis or are more due to environmental factors. In either case, these variations offer the possible of extending the production season.

Growers have assigned descriptive names to some clones, such as 'rosa' (pink), 'mariposa' (butterfly), and 'orejona' (big-ears).

Cultural Requirements
During the three years of first establishing a Pitaya plantation, it is possible, and even desirable, to intercrop, as long as the low intercrop does not compete with the pitaya cultivation. Kidney beans are the commonest intercrop. In recent years, some growers have interplanted with pineapples. These plants have the advantage of better resistance to sulphurous gases from the volcano, and allow earlier recovery of the initial investment. Whatever, it is desirable that the pineapples be eliminated after two harvests.

No formal fertilizer trials have been carried out. Growers will apply urea or a complete fertilizer if this is economically worthwhile to them. Some have applied fertilizer as a foliar spray - this can bring about flowering several weeks earlier and reduce immature fruit drop.

Each year, rotted support posts must be replaced and weak ones reinforced. Maintaining the supports is one of the biggest costs to the grower.

Pruning living posts is an ongoing cost in pitaya culture; a balance needs to be maintained between growth of the living posts and that of the pitaya, which must not be excessively shaded. The pitayas themselves must also be trimmed to keep their volume down and permit movement along the interrows.

Pitayas have only superficial roots, and so are very vulnerable to damage if the soil is worked. In mature plantations the recommendation is to avoid working the soil, and control weeds with a herbicide instead.

Pests and Diseases
As a cultivated plant locally selected from the wild, the pitaya is subject to attack by numerous locally-evolved pests and diseases. According to Urbina [1989], the most important problems are due to:

• The larva of a beetle, Cotinus mutabilis, which chews the stem segments and favours infestation by pathogenic fungi;

• A winged insect, Leptoglossus zonatus, which sucks the sap of the stems and fruits, leading to marks and deformations. This is also suspected of transmitting fungal and bacterial diseases;

• Ants, particularly leaf-cutting ants of the genus Atta, which can cause great damage to fruits. The ants attack the scales and so the fruit skin, weakening the fruit and rendering it liable to disease attack and skin splitting when ripe;

• Often some stem segments show symptoms of a watery rot, which may be limited to a single segment without affecting those above and below. The segment later dries out, leaving only the main veins. The problem is due to a bacterium, Xanthomonas campestris;

• A fungus problem, called 'fish-eye', where a fungus of the genus Dothiorella causes brown circular spots, 1-3mm across, to appear on the stems. When the infection is severe, the spots can join up, and the surface available for photosynthesis is greatly reduced.

Finally, mention should be made of damage caused to ripening fruits by birds, lizards, and rodents.

Yields and postharvest factors
The first harvest can be expected 18 months after planting. Using local measures, a yield of 300 dozen fruits can be expected per hectare in the second year, equivalent to 0.8-1.0 t/ha. Yields increase progressively up to 3000 dozen fruits (10-12 t/ha) by the fifth year, which corresponds to the mature stage of establishment.

Each clump of adult plants produces about a dozen fruits per cycle between June and November, that is 5-6 dozen fruits per year. Production records show a number of peaks, corresponding to the different flowering cycles.

Fruits can be harvested once the colour of the skin starts to change from green to red. They are then held in a shaded spot which is sheltered from birds and rodents. The fruit should be cut off with secateurs, since it has no real fruit stalk and if it is just twisted off, this tears the fruit skin at the point of attachment and makes it unsalable.

Preliminary studies on fruit keeping have shown that:

• Fruits harvested green, two days before the expected colour change, ripen normally at ambient temperatures (25-30°C) and have a keeping life of 9-11 days;

• Fruits harvested at the colour change keep for 7-8 days;

• Fruits harvested fully ripe, that is when the skin has become fully red, remain good for eating for 5-6 days at ambient temperatures;

• Ripe fruits left on the plant keep for 8 days after the colour change, provided they are not eaten by birds.

Fruits kept in cool storage (10-12°C) for a week continue to ripen, but more slowly, and colouration is less intense. After removal from cool conditions, ripening is accelerated.

After four days, fruits harvested just ripe begin to rot. Those harvested at colour change or green remain presentable for 5-7 days.

So cool storage slows ripening of green or turning fruit, and can prolong its life. While a little skin colouration may be sacrificed, the pulp colour does not seem to be affected.

The influence on lifetime of higher and lower temperatures, and of different clones, remains to be evaluated.

References
Becerra, O.A. (1986): El cultivo de la pitaya. Federación Nacional de Cafeteros de Colombia.
Campos-Hugueney, L. et al. (1986): Advances en la tecnología de la pitahaya (Hylocereus undatus). Bol. Tecn. LABAL, Nicaragua.
Incer, B.J. (1959): Carácteres geobotánicos y flora medicinal de la región de Chontales. Thesis, UNAN, León, Nicaragua.
Villegas, Marcelo (1990): Tropical Bamboo. Rizzoli, New York.
Sarmiento Gomez, Eduardo (1989): Frutas en Colombia. 2 ed. Ediciones Cultural, Bogotá
Urbina, B.P. (1989): Caracterización a nivel de campo y laboratorio de las plagas y enfermedades más importantes del cultivo de la pitahaya en la IV region (masyay) Nicaragua. Unpublished thesis, ICSA, Nicaragua.

[Based on an article La pitahaya rouge, un nouveau fruit exotique, published in the magazine Fruits, Vol. 45, No.2, 1990. Translation from French: David Noël] WANATCA Yearbook 1993




Back to
Pitaya Page



Bibliography

Barbeau, G. "The Red Pitaya, A New Exotic Fruit." rfcarchives.org.au. Archives of the Rare Fruit Council of Australia. Embassy of France, Apartado 1227, Managua, Nicaragua. July 1993. Web. 21 June 2017.

Published 21 June 2017 LR
© 2013 - growables.org
about credits disclaimer sitemap updates