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work of thinning out dragging on for a long time, but there is less 

 crop lost this way, as each round the trees which are not paying 

 their way are removed, giving the advantage to the adjacent trees, 

 the yield per acre is not greatly j'educed and the cost of tapping is 

 automatically reduced. 



With present day planting thinning out should not pr-esent any 

 great difficulty as provision can be made for thinning out in 

 the early stages. The time for thinning out is just as soon as gi-owth 

 is being hampered by branches interlocking, probably when the trees 

 are about four years old. If a clearing is planted 20 ft. x 20 ft. with a 

 view to thinning out later to leave say 70 or 80 trees per acre, the 

 trees to be removed could be marked after careful examination 

 and comparison with adjacent trees, and any branches interfei'iug 

 with the development of the favoured trees could be removed 

 periodically as the necessity occurred. The marked trees could in 

 this way be tapped for a considerable time in the regular round, 

 enabling a fair return of latex to be obtained before they are finally 

 removed and leaving them with very few heavy branches to cause 

 damage while they were being felled. Of course, the ideal system 

 would be to allow each tree eventually the same space, but this, 1 

 fear, would be impossible in practise, as weak unhealthy trees are 

 frequently found side by side and have to be i-emoved, while good 

 trees have to be left near each other to make up the number per acre. 



There are various methods of removing the tree. Some recom- 

 mend pollarding the first stage, tapping the stump so long as it gives 

 latex, then removing it. This system I have found not at all 

 profitable. It is much moi'e difficult to remove the pollard than it is 

 the whole tree, as in the latter case the head gives leverage when the 

 side roots are cut away, while the pollard has to be lifted bodily 

 from the ground. The pollards yield very little latex after the first 

 few tappings, and tappers are inclined to be careless with the tapping 

 of them, and this carelessness, like other diseases, soon spreads to the 

 good trees. The roots of the pollards too are still feeding and the 

 adjacent trees are not benefiting to the same extent as if the ti^ees to 

 be cut out had been removed wholesale. 



Another system is to cut off the tree about a foot above the 

 ground, but since the discovery of Ustulina zonata I fancy this 

 system is not much in favour. 



The most satisfactory way is to cut out the tree about two feet 

 below the level of the ground, removing as many of the side roots as 

 possible without interfering with the roots of the adjacent trees 

 which are to remain. The cut out ti-ees and branches should be 

 burned, or otherwise r-emoved as quickly as possible, to prevent an 

 invasion of borers and the spread of disease. 



I have to thank the General Rubber Co., Sumatra, for the 

 privilege of seeing their report on thinning out and for permission to 

 use their recommendations. 



