From the Archives
of the Rare Fruit Council of Australia, inc.
Longan is a crop little known in Australia.
Thailand, however, Mr B. J. Watson, a senior horticulturist in the
Department of Primary Industries, found it to be an industry of
appreciable size and complexity.
During a recent private visit,
Mr Watson learned that Thailand produces around 145,000 tonnes of
longan fruit annually. By comparison, Thai crop figures for litchi are
22,660 tonnes, rambutan 574,850 tonnes, guava 79,700 tonnes and mango,
The industry is widespread, covering areas in
the north and north east, as well as some centres in the central
plains. The most important areas of production, however, are the Chiang
Mai-Lamphun-Prae districts, lying 18 degrees N. The total crop area in
1975 was reputed to be 24,169 ha.
A considerable portion of the
crop is canned at the peak of the season but the fresh fruit market is
the most lucrative for growers. It is surprising that the industry is
less than 100 years old, A Chinese settler reputedly brought the first
cutting, possibly an air layer, to Hang Dong in Chiang Mai district in
1896. Following that event, more cuttings were brought in, ostensibly
Another story suggests that seeds were bought in
Bangkok, grown on there, and later established at Chiang Mai where the
environment best suited the crop. The oldest tree in Chiang Mai is
documented at 75 years old. It is of the Daw variety and now stands 18m
high with a spread of 20m. It currently yields from 460 to 1380 kg. a
First impressions of the range of Thai longan varieties
indicate that there are few differences in fruit characteristics and it
would take some time to become familiar with them. Fruit skin colour is
fairly uniform - a dull golden brown. Conformation is round to
heart-shaped, with some having pronounced shoulders. Fruit weight is 11
to 20g with 50 to 90 fruit per kg. There are many thin-fleshed
seedlings termed Tammada (common) which are also marketed, but
discounted in price. The number of these poor types gives weight to the
theory that the 'varieties' which were asexually propagated, were in
fact introduced as clones. They have a penchant towards hard-fleshed
(crisp) fruit, generally, and dislike soft juicy varieties.
have a high sugar content (18 degrees Brix) which is higher than most
other fruit. The most popular varieties, in order of maturity, are:
Daw - (Early) - maturing late June to late July
Dang - (Red Stem) - maturing mid-July to early August.
Chompoo - (Pink Flesh) - maturing mid-July to early August.
Hae - (Water Chestnut) - maturing mid-August to early September.
Biew Kiew - (Lopsided fruit) - maturing mid-August to early September.
Bai Dum - (Black Leaf) - late August to late September.
comparison, Dang, Chompoo and Haew are harvested in Cairns from late
January to late February - a fairly similar seasonal pattern. Daw is of
excellent quality, besides being the earliest in the season. Dang is a
heavy-bearing variety with fair quality fruit, but it is not
particularly crisp. Choopoo has a faint pink tinge in the flesh and is
of high quality. However it is not canned because of this coloration -
pure white flesh is apparently preferred. Haew is popular in the market
and is a good canning variety, but it has a pronounced alternate
bearing habit. Biew Kiew has crisp, cream-coloured flesh, is a heavy
cropper and not alternate bearing. Bai Dum is a very late season
variety, and bears regularly. However, Bai Dum has poor shell colour,
and it often develops sooty mould on over-ripe fruit.
at Chiang Mai-Lamphun are grown predominantly on heavy alluvial soils,
adjacent to permanent streams or seasonal water courses. It appears
that these areas have a permanently high water table, which obviates
the necessity for irrigation. These areas are also fairly fertile.
Conversely, this seasonally-flooded land appears to be unsuitable for
most other tree crops, with the exception of litchi.
recently, plantings have been made on better-drained soils but
irrigation during the fruit filling period is necessary to achieve
reasonable yields. Litchis do not appear to be as remunerative as
longan in the Chiang Mai area, and whilst there is a considerable
number of trees, the preferred areas are further north at higher
elevations, principally the centres of Chiang Rai and Fang.
Chiang Rai, longans flower in January to March (July to September in
Queensland), whereas for the mid-season varieties, flowering in Cairns
is September-October. The subsequent period. of fruit development
appears shorter in Cairns (five months) as compared with six to seven
months in Chiang Mai. This is surprising in view of the greater heat
units available in Chiang Mai in late spring and summer. However,
minimum night temperatures are lower in Chiang Mai in mid- to late
winter. The pattern of rainfall distribution is similar for both
centres. The majority, if not all trees, are grown from air layers.
Mid-summer is the main propagation period. Tree spacing is generally
14m, with 50 trees per hectare.
Orchard size is variable, with
from a mere six or seven trees to 50 ha for an individual owner. Tree
owners are not necessarily the land owners. All trees are either
permanently propped or 'mounded' progressively. Mounding consists of
piling soil around the butt, often to a height of two metres. This is
done in summer. Although the region is not subject to cyclonic winds,
storm winds do damage trees, with limb breakage or trees falling to one
side. This has been the same experience in Cairns, particularly after
the trees reach an age of five to seven years. Growth rates are very
fast when compared with other tree crops, and this tends to add to the
instability. It is suggested that grafted trees behave better, but
there appear to be few in Thailand.
The trees are pruned
rigorously, removing all water shoots and small branches from the
interior of the tree, and the skirt is not allowed to reach the ground.
A similar system is followed with litchi. Fertilising is minimal, using
some peanut husk mulch and wood ash, but very little in the way of
familar NPK mixtures. Some proprietary liquid fertilisers-hormones are
applied as drenches close to the trunk in April and again in December.
No details on the formulation of these mixtures could be obtained,
although samples were brought back to Australia.
harvest, the panicle remains are pruned off. It is stated that because
of contract picking, often too much of the branch was removed with the
fruit and that, with a short season available for growth (August to
December), there was too slow and too late regeneration, leading to
biennial bearing problems. This problem is not encountered with the
litchi crop since harvesting is completed in May and there is ample
time for new growth prior to the next season's flowering.
pests are flower caterpillars, fruit fly and fruit bats. There is a
government-backed spray program from February to July, and this costs
growers only 15 cents per tree per application. On some orchards, fruit
panicles are bagged against fruit fly and bats but the practice is
The social organisation of the longan harvest is
complicated. There is a heavy reliance by tree growers on forward
payment, whereby, at flowering time, contracts are let for sale of the
crop. The contractor may win or lose on the deal, based on his
prediction as to the yield. The average value placed on a tree for
contract purchase for one season is $45. Thus, in any one orchard,
there may be up to three interested parties - the landowner, the tree
owner and the contract harvester.
Trees are picked from bamboo
ladders. The racemes are broken off and sorted on the ground by women.
Stalks of 100 to 200 mm are retained on the fruit as the predominantly
ethnic Chinese export market demands stalk attached. Apparently this
practice is steeped in history and the quality of the fruit is supposed
to be retained longer. However, the largest grower at Chiang Mai
considered that quality is unimpaired when all raceme stalks are
removed and the fruit is marketed and consumed within 72 hours. Fruits
are invariably packed in baskets of 23 to 24 kg capacity. These are
trucked to Bangkok, and if for export, then flown to Singapore,
Malaysia, Hong Kong and the Philippines.
Fruit prices to the
growers-contractors in the 1979 season were 50¢ to $1.10 per kg
for fair to first-quality fruit. Returns for thin-fleshed seedling
fruit were as low as 10¢ per kg, but these trees yield from 300 to
400kg consistently. Retail prices for Thai fruit in Singapore and
Philippines ranged from $2 to $4 kg. Fruit in Singapore is sold within
a period of 48 to 60 hours after harvest in Chiang Mai. Under the Thai
fruit-grading system, 'A' grade fruit standards are for 55 to 75
fruit/kg and 'B' grade is for 76 to 80 fruit/kg.
There is little
evidence of precooling or refrigerated storage, but ice is used to cool
fruit on sale in Malaysia and Singapore. Statistics provided for 1975
show an average of six tonnes per hectare of 120 kg per tree - trees of
all age groups included. Up to 1380 kg in one season has been recorded
on a 75-year-old tree, but in a low density planting. For 12- to
15-year-old trees, the yield range is from six to 170kg/tree, there
being an average of one poor, one fair and one excellent crop in three
years. Seedling 'Tammada' trees bear consistently in the range of 300
to 400 kg for 12 to 15 years of age.
Prices to growers average $3.50
per kg, but reached $13 in April-May 1979 when there was a very light
crop. There is no doubt, that once given the taste, most Australians
would react favourably to high-quality longan varieties.
It is a
very 'morish' fruit. It is likely that in some areas between far north
and southern Queensland, climatic conditions would be quite suitable
for longan production. However, site selection would be critical. Deep
alluvial soils in areas protected from strong winds w,ould be
preferred. Development of mechanical harvesting would appear
achievable. Most of the best Thai longan varieties and a few from
Hawaii and Florida have now been imported and will become increasingly
available as nurseries commence propagation. The crop warrants trial
throughout the State.
N.B . Production at Walkamin - approximately 4 weeks later than Cairns.