SCIENTIFIC NAME: Casimiroa edulis
FAMILY: Rutaceae

What looks like a Granny Smith apple, has the texture of a perfect Avocado, and tastes of pear, peach, banana, and custard apple? The answer is a native tree of the Central American Highlands (500 to 1800 m) called the White Sapote. Botanically it is Casimiroa edulis; the species is in the family Rutaceae, which also includes Citrus. Their mutual affinity can be seen in the seeds, as those of Casimiroa are a replica of an orange pip magnified by ten.

This handsome tree reaches a height of 15 m, and is drought resistant. It does not do well in areas subject to heavy rainfall, and in particular hates lowland humid tropical conditions.

The White Sapote has been distributed around the world, and is fruiting successfully in areas such as California, Florida, the Mediterranean, the drier parts of Hawaii (Kona and Pohomoho), Northern India, Florida and Sydney.

The tree can be evergreen or sporadically deciduous, whereby even in the warmer months it will suddenly decide to shed its leaves for a fresh batch.

The White Sapote is well known for its spectacular yields, with several hundredweight being commonplace. The outstanding example is the cultivar "Chestnut", which in 1971 bore three tons of fruit.

This delicious fruit tree caught the imagination of Californian nurserymen and horticulturists more than fifty years ago, when a number of selections were made, including the everbearing variety "Suebelle". Some of these cultivars were imported into Australia as long ago as 1937 when at least one nursery offered them for sale. During the past six years a large number of the extant varieties available in California, Florida and New Zealand have been imported into Australia: "Blumenthal", "Vermont", "Vista", "Wilson", "Dade", "Pike", "Lomita", "Te Puna", "Henrickson", "Denzler", "Ortego", "McDill", "Golden Globe", etc.

The White Sapote is adaptable to a wide range of soils, preferring a slightly acid sandy loam. However, it grows well on any well-drained soil type including Florida soils with a pH of 8.5. It is totally intolerant of any degree of waterlogging.

Insect pests are few. Black Scale is a common infestation which can be controlled simply with a spray of white oil diluted 1:80. If the infestation is heavy, a follow-up spray three to four weeks later is required. Unfortunately, this year has revealed that fruit fly will sting the fruit while it is still hard.

Tree training is essential. Most varieties, if allowed to grow on their own accord, will grow their single leader with no branching for four metres or more, eventually recurving under its own top-heavy weight. It is necessary to cut back the leader by one-third when approximately one metre high. Subsequent branches will have to be treated in a similar fashion. After three to five such prunings the Casimiroa smartens up and branching occurs at the appropriate intervals, maintaining the desired symmetrical crown.

A related species, Casimiroa tetrameria, the "Woolly-leaved Sapote", produces similar fruit, with a stronger, more resinous flavour. It seems likely that some selections are the result of interspecific hybridization between these two Casimiroa species. The variety "Max Golden" is known to be a selection of C. tetrameria.

In spite of its deliciousnes and tremendous yields, only very minor commercialization has taken place. This has been partly due to a lack of an organized, concerted effort, but is primarily due to the short shelf life of the fruit. Even though the fruit can be picked rock hard from the tree and still develop full flavour, once it starts to soften (three to four days after harvest), the fruit must be consumed within seventy-two hours. Furthermore as the fruit softens, unsightly bruises show up. In spite of this, several small orchards are being planted. Perhaps the advances in post-harvest handling will help to overcome the shelf-life problem.

From Perth to Adelaide, and on into the drier tropical zones of Australia, Casimiroa edulis is a must for any backyard enthusiast. One tree will feed an entire block.

Note: Paul Recher with his wife run Fruit Spirit Research Nursery and Garden, at Dorroughby, N.S.W. 2480. There they have 43 acres of warm subtropical land devoted to the assessment of a wide range of plants from all around the world, their speciality being subtropical and tropical fruits and nuts. In the past five years they have planted more than 800 species, of which over 200 have edible parts. Some of these have come from such diverse places as Ecuador, Malawi, the Ivory Coast and China. The nursery is one means by which this considerable trials programme can be financed.

Paul Recher

DATE: July 1983

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