4.2.3 Situation found concerning abundance of neem trees and of raw material supply

Sadao, the local name for Thai neem (Azadirachta siamensis), can be found in the north, central, north-east and south of Thailand. It is popularly used as a farm border and a roadside tree and grows well at altitudes below 200 metres (Willan et al. 1990). Similarly to "Sadao Thai", the other two varieties, A indica and A. excelsa, are naturally found in western and southern parts of Thailand respectively. Due to the fact that Thai neem is naturally widespread, this species is considered as the main source of raw material for commercial production in Thailand.

It is estimated that today there are approx. 1 million neem trees in Thailand, of which 70% are A. siamensis. In the 1990s the Forestry Department and private entrepreneurs started to use neem in their reafforestration activities, mainly with Thai neem. Some entrepreneurs established large plantations of 300 000 trees.

A siamensis is not as suitable for pesticide production as A indica. The reason is its generally lower azadirachtin content. Additionally, the higher chlorophyll content of the kernels leads to faster degradation of azadirachtin compared to the kernels of A. indica and greater difficulties in drying the kernels for storage.

The botanical characteristics and chemical composition of A. siamensis are different from A. indica and A. excelsa as shown in Tables 23 and Table 24 respectively.

Table 23: Botanical characteristics of three neem species

Source: Tran, 1988

Table 24: Major chemical constituents of three neem species

Compound identified as 1 -trigloyl-3-acetylazadirachtol (Kalinowski et al. 1997)
Source: Ermel et al. 1997