Longan production in Asia - United Nations in Indonesia

Table 19. Planted area and production of longan in Vietnam
Year
Region
Mekong delta Northern region Southeast region
Area Production Area Production Area Production
(ha) (metric (ha) (metric (ha) (metric
ton)
ton)
ton)
1998 28,600 270,000 4,000 40,000 1,314 10,000
1999 30,030 280,000 5,000 50,000 6,570 35,000
Source: Nguyen (2000).
16. PROBLEMS FACED BY LONGAN PRODUCTION
Countries producing longan, including China, Thailand and Taiwan Province of
China, have reported almost common problems in longan production. These common
problems include:
a) Biennial bearing: The main problem faced by commercial orchards is
irregular flowering and biennial bearing. Trees tend to overcrop some years and this is
followed by a light crop the next year. In Thailand, the production figures for 1990-1994
(Table 16) reveal a very clear pattern of biennial bearing. A similar pattern of biennial
bearing is exhibited by the production figures for Taiwan Province of China during 1995-
1998 (Table 18). Prices obtained by the longan growers have been dictated by the
quantum of production. When there is a good harvest the price of longan drops to a low
level and vice versa.
b) Small fruit size: This problem is particularly acute in Taiwan Province of
China where there is a need to have cultivars producing large fruits (Yen and Chang,
1991). In Florida, the demand for large fruit is most critical. So far, the cultivar ‘Kohala’
has been able to produce the desired fruit size through pruning of flower panicles
(Campbell, 2000). In Thailand, ‘Biew Khiew’ produces large fruit size but is limited by
its biennial bearing habit.
c) Witches’ broom disease: This disease is prevalent in producing countries in
Asia. Though there are resistant longan cultivars, the lost of production through infection
by this disease can be quite substantial as revealed by the figures from China.
d) Fruit bats: This pest has been reported to cause serious problems during
fruiting seasons of longan in Thailand and Australia. A high cost has been incurred to put
up protective netting around the perimeter of the orchard or over each tree.
e) Large unmanageable tree-size: Under the conventional planting system the
trees tend to grow very tall and management and harvesting of such trees can be difficult.
Thus a way has to be developed to prune the trees to a manageable height. Also high
density planting together with pruning or root restriction can be practiced to reduce the
tree height.
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