MORE ON THE MANGOSTEEN
SCIENTIFIC NAME: Garcinia mangostana
FAMILY: Guttiferae
MYTH
Literature on the mangosteen, Garcinia mangostana, has been known to claim the trees all originated from the same genetic clone with no variations. The literature further relates that male trees are not known to exist.
REALITY
Anthony Lamb, working for the Agricultural Research Station at Tenom in Sabah, reported coming across male-flowered mangosteens during his horticultural explorations into the Borneo rain forests. Ripe fruit is supposed to be a uniform dark purple, yet I have seen copper-colored ones in Bali. Its size can vary, with some trees producing larger fruit than others. The fruit shape is not consistent; some are almost round while others tend to be oblong. If I remember correctly, the oblong varieties tend to be more acid in taste than the round. The bearing habits can vary from tree to tree with some producing regular heavy harvests, while others have light crops or none at all. Certain trees exhibit a tendency toward having a bitter yellow sap that penetrates the ripe fruit, making it almost worthless.
TAPROOTS
In the past, great emphasis has been placed on having deep pots for growing mangosteens. This was to allow the taproot to have plenty of room before reaching the bottom of the container. I found these deep pots had problems when it came to removing the plant and setting it in the ground. Without enough root density penetrating the potting-up medium, most of this fell away leaving the exposed roots bare with hardly any soil attached. When I grow seedling mangosteens I start them out in small containers. After they have reached two or three inches in height, I upend the pot, removing the plant with the soil intact. If the taproot appears I cut it off. This is to prevent it balling up in the bottom of the container. What I am after is a better distribution of the roots with more horizontal growth and less growth straight down. The first set of new leaves that appear after cutting the taproot tend to be smaller in size. However, those that follow are as large as if the taproot had been left intact.
PROPAGATION
The traditional way of propagating mangosteens is by seed. Unfortunately, the seed has a very short viability. It should never be allowed to dry out. If you need a week or more before being able to pot them up, they should be placed in an airtight plastic bag with sphagnum moss and allowed to germinate. I have never had success in air layering mangosteens, even when the marcot was left on over a year.
However, I found I could root three out of five cuttings. To do this, I used an acid sphagnum moss-type growing medium placed in a gallon pot. I took terminal cuttings about four or five inches long, and cut off the lower leaves so I could push the stems into the soil after first dusting the ends with a rooting chemical such as Rootone. A clear plastic bag was placed over the top of the container and supported by four bamboo stakes to hold the plastic enclosure away from the cuttings. After about seven months in 72% shade, the cuttings should commence putting on a flush of growth. The resulting rooted cuttings have a more horizontal growth pattern than plants grown from seed.
I found mangosteens easy to cleft graft using a plastic bag enclosing the scion. If they take up too much space, cut each leaf in half. This grafting technique can also be used to graft mangosteen onto related Garcinia as a rootstock. I've got graft takes using G. spicata and G. hombroniana as rootstocks. The hombriana was successful, while the spicata, after an initial period of growth, finally died. What we are after is a rootstock the mangosteen will grow on that tolerates alkaline soil.
PESTS
Mangosteens grown in Florida appear to be relatively free of pests and disease. I lost well over half of one mangosteen crop to red banded thrips which mummified the fruit.
COLD TOLERANCE
In spite of being an ultra-tropical tree, mangosteens can tolerate. temperatures of short duration down to 32°F. A few degrees colder and you will lose your tree. Flushes of new growth, however, are killed back to the previous mature foliage by cold of slightly below 40°F. It is therefore better to time your fertilizer applications so as to avoid encouraging new winter growth.
SOIL pH
Mangosteens require an acid to neutral (pH 7) growing medium. If this were not so, we would find homeowners growing this tropical fruit in the Florida Keys on their high pH sand, marl and rocky limestone soils.
SHADE
This Garcinia is indigenous to the rainforests of the Asiatic tropics. Seeds that drop to the forest floor receive very subdued light that filters through the dense overhead jungle canopy. To simulate this, I use a 63% shade cloth enclosure that both reduces the sun's intensity and protects the young tree from strong winds. After the plant reaches a height of six to eight feet, it can be grown in full sun without shade.
LEAF BURN
In my location, a half mile inland from the ocean, I frequently have a winter leaf tip burn. This is from salt in the air carried over from the sea during times of high on-shore winds. Excessive fertilizer applications can cause the same symptoms as well as growing of the tree in locations subject to frequent gusty air blasts without wind protection.
CONSUMPTION
Mangosteens should be eaten as soon as possible after harvesting. This is because when the fruit is first picked, the thick rind is soft and easily split open with a slight pressure of the fingers. As the fruit ages, its outer shell becomes hard, eventually so hard that it is extremely difficult to open. This degree of hardness is a good indication of the freshness of the fruit and the quality of the pulp.
EVALUATION
The mangosteen has been referred to as the 'Queen of Fruits'. Some consider it the world's most delicious fruit. The writer believes the mangosteen would win out over nearly any other tropical fruit being taste-evaluated for the first time. Its rich, wonderful flavor with a delicate blend of slight acidity and sweetness gives it a universal appeal that is hard to fault.
DATE: May 1994
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