PARA-RUBBER CULTIVATION 401 



for a greater development of leaf-canopy to hasten the increase 

 in girth. In rubber cultivation, however, thickness rather than 

 height of trunk is desired from the beginning, so the trees must 

 be planted much wider apart than appertains in ordinary 

 forestry, in order to afford room for an early and ample pro- 

 duction of foliage. 



The first areas laid down with Para rubber were 

 planted with trees ten feet apart, roughly 400 to the acre. It 

 became evident in a few years that the growth in thickness 

 would be greatly retarded if the trees were allowed to continue 

 so crowded, consequently thinning has had to be practised. 

 Wider planting is now more generally undertaken, and a 

 distance apart of twenty feet (100 trees per acre) is commonly 

 followed. Even at this interval the shoots of adjoining trees 

 will often begin to interlace in five or six years' time, about the 

 period when tapping can be commenced. Judicious thinning 

 might be started now by removing the least desirable trees after 

 thoroughly tapping them. 



The correct planting distance to be pursued is still an open 

 question. Time will doubtless show whether room for the 

 ultimate possible extension should be provided at the outset, or 

 whether a closer distance should be adopted while the trees are 

 young, to be followed by thinning later. In the latter case 

 probably more rubber may be obtained per acre during the first 

 couple of years of tapping, but this may be at the expense of 

 future yields. The present view appears to be rather that 

 within reasonable limits a closely planted acre of rubber is 

 worth no more than, if as much as, a widely planted one. 



Straight v. Forked Trunks. — Since tapping is usually confined 

 to the basal six feet of trunk, and since trees which fork early 

 have generally a greater basal girth than those of the same age 

 which remain straight, attention has been turned to the desira- 

 bility of artificially inducing trees to fork early, in order to 

 hasten their increase in girth. This can be accomplished with 

 the least injury and trouble by what is known as " thumb-nail '' 

 pruning. The terminal bud is pinched out when the young- 

 tree has reached a height of about ten feet ; forking then takes 

 place, and further pruning can be practised if necessary to reduce 

 the number of main branches. Wickham 1 strongly recommends 

 this practice, and considers the ideal tree-form for Hevea to be 



1 Wickham, loc. cit. p. 22. 



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