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.
f) Limited market: The demand for longan comes mainly from an ethnic community, Asians in general and Chinese in particular. Sales of longan outside this ethnic market are limited.