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acre in the eighth, thirteenth to fifteenth year, after 
which accidents (lightning, wind, etc.) and disease 
may be expected to do all the thinning required. 
On clean cleared properties there is practical im- 
munity from root diseases, but even on such areas 
tree to tree examinations are advisable with stands 
of 65 or less. 
* 
.Much discussion is taking place at the moment on 
drastic and early thinning out by selection, the argu- 
ment being that a small percentage (say 30) of trees 
yield a large percentage (70) of the total crop. 
No records have been taken over a sufficient period 
to give certainty of the constancy of yield on the 
part of these high yielders; on the contrary, it is 
fairly general experience in Malaya that excep- 
tionally high yielders are to be regarded with 
suspicion, either as being already attacked by fungi 
or white ants or as being susceptible to Brown Bast. 
In any case, the response in yield to such drastic 
thinning would not be sufficiently rapid to com- 
pensate for a loss of 30 per cent, of the crop for a 
considerable period — while only a small decrease in 
harvesting cost (itself a very insignificant proportion 
of the whole) could be expected. 
Tapping There has been decided improvement 
Systems. in tapping systems in that more con- 
servative tapping methods are coming 
into general use. Single cuts on one third and one 
quarter of the circumference tapped daily, and the 
single V on one half the circumference tapped on 
alternate days are now the favourite systems, super- 
imposed and half spiral cuts being relatively rare. 
