i8o 



to kill a Para rubber tree within a couple of years, but from 

 observations made on trees which have been rapidly tapped on the 

 paring and spiral system, very little doubt exists in my mind as to 

 the results obtainable. On such trees the spiral system can be 

 adopted, and at the end of twelve months the tree should be 

 removed and the stumps extracted. The unwillingness of the 

 planters to actually fell the trees so tapped is said to be encouraged 

 by results obtained on some estates, where it is reputed that the 

 total yield, per acre, appears to be approximately the same, no 

 matter whether the trees are distanced ten or twenty feet apart ; 

 I have never seen any figures or authoritative reports which prove 

 this. 



The interference in growth, in trees originally planted ten feet 

 apart, will vary with the soil, climatic, and other conditions ; but 

 in the case of unpruned Para rubber trees at Peradeniya, and 

 others in relatively poor soils in the low-country of Ceylon, I have 

 previously explained that there is no very serious interference in 

 either root or foliar development up to the period specified. 

 Occasional branches and roots will overlap, but not to any great 

 extent except under very good conditions ; the exhaustion of the 

 surface soil may be partly balanced by the application of manures. 

 If, however, the estate is not thinned out, considerable interruption 

 in the radial growth of stem and root structures will undoubtedly 

 occur, and it remains to be proved whether the trees on such a 

 property make up in number what they lack in size. 



The liability of weak and close-planted trees to the attacks of 

 fungi and insects has been raised as an objection against this 

 system; the liability of the bark, exhausted of late, to insect pests 

 applies to that on any tapped tree, but in neither case would it be 

 possible to completely extract the latex from such tissues except 

 by killing them, a procedure not yet recommended. The liability 

 to root rot would be largely overcome by extracting the stumps, 

 as is recommended on the clearing itself ; on the Yatipawa plan- 

 tation where the roots of felled rubber trees were allowed to 

 remain in the soil and decay, the remaining trees have recently 

 been described as healthy ; perhaps this apparent immunity can 

 be associated with the age of the felled and remaining trees, or with 

 the difficulty with which the root-rot fungus actually commences 

 on Para rubber stumps. On most estates the root fungus is trans- 

 mitted from the roots of trees other than rubber, which ramify in 

 the soil and reach the rubber roots no matter how widely the latter 

 may be planted. It has been questioned, in view of the fact that 

 the roots of jak and cotton trees, etc., traverse a greater distance 

 than that between any two rubber plants as at present planted, 

 whether the difference in distance between Para rubber trees 

 planted ten and fifteen or twenty feet apart appreciably affects the 

 spread or distribution of the root fungus. It cannot be doubted 

 that the closer the roots the greater is their liability to catch 

 whatever fungus is in the soil, but as against such a disadvantage 

 has to be set the advantage of the produce obtained even allowing 

 that the roots are not removed but left to decay. 



