and Magazine of the Ceylon Agricultural Society. 



83 



THE RUBBER PLANTING POLICY. 



The current opinions regarding the most 

 profitable species to cultivate are based on re- 

 sults of only a few years' standing, and though 

 they are sufficiently distinctive to allow us to 

 say that some species are capable of yielding- 

 excellent crops of rubber, they cannot in any 

 way be accepted as final. The fact that Ilevea. 

 brasiliensis has so far given the best yields does 

 not entitle anyone to even say that it will, in 

 the long run, be the most profitable to cultivate ; 

 still less is one justified in condemning other 

 species because their yielding capacities have 

 not, in the first year of tapping, proved equal 

 to Para rubber trees. A certain amount of 

 definite knowledge can be gained by a micros- 

 copic analysis of the plant structures possess- 

 ing the ch annels wherein latex accumulates ; a 

 study of these particulars enables one to ap- 

 proximately gauge the rubber capacity of each 

 species and the best methods of tapping them • 

 but experiments initiated by men with a 

 knowledge of these vital points are of little, if 

 any, practical importance until thoy have been 

 tested in and out of season through a period of 

 many years. We are not aware of any complete 

 scheme of experiments which have been carried 

 out on trees of Fie us elastica, Cctstilloa elastica, 

 Funtumia eladica, and the various species of 

 Palaquium, Ficus, or Landolphia, and until the 

 necessary results are available, there is nothing 

 to justify the condemnation of any one of these 

 species. 



Rambong Rubber. 



Planters have been able by very simple 

 implements and methods of tapping to ob- 

 tain very profitable yields from Para rubber 

 trees, and taking such as a standard, they 

 have felt justified in recommending the destruc- 

 tion of Ficus elastica trees because the latter 

 have not, in the same or a longer period of time, 

 given similarly good results. But they have 

 evidently not been aware of the fact that the 

 laticiferous system of Ficus elastica is entirely 

 different from that in Ilevea brasiliensis and 

 requires an entirely different system of tapping. 

 Furthermore, the poor results have all, so far, 

 been chronicled from work carried out on trees 

 of this specis which have been allowed to grow 

 in their own way ; the formation of ridges and 

 crevices on the fluted stems of such trees appre- 

 ciably reduces the available tapping area, and 

 the interlaced aerial roots prevent that super- 

 vision which is necessary if the rubber has to 



more than pay for the cost of harvesting. From 

 a plant sanitation standpoint a block system of 

 unlike species is desirable ; Ficus elastica is in- 

 digenous in the Indo-Malayan region, and is of 

 a vigorous and hardy type ; these and 

 many other reasons can be brought for- 

 ward to support our contention that this species 

 should not be entirely lost sight of at the pre- 

 sent time. 



YIELDS FROM PARA RUBBER TREES. 



In recent issues of the " India-Rubber 

 Journal " we have given up-to-date information 

 regarding the yields obtained on all the pro- 

 minent Para rubber estates in the Indo- 

 Malayan region during the last three years. 

 The year 1906 showed a large increase per 

 tree, and the present year has been charac- 

 terised by a further total increase from most 

 of the estates. But it is fairly safe to say 

 that the yields have, more often than not, been 

 obtained from the primary bark by a system 

 of tapping which has necessitated the removal 

 of a large proportion of that tissue. There 

 are very few records available showing the 

 rubber obtained from the renewed bark, and 

 we are, in a great measure, ignorant of the 

 yielding capacity of the newly-formed elements. 

 The increased yields per tree have, in some 

 instances, been secured by almost com- 

 pletely stripping the cortex ; in other cases 

 the total increase has been due to a larger 

 number of trees having attained the minimum 

 tapping size. There is, therefore, very little 

 reliable information on which the planter can 

 confidently and accurately calculate the probable 

 future annual returns from Para rubber trees. 



YIELD PER UNIT OF BARK. ' 



It is possible, in virtue of the nature of the 

 laticiferous system of Ilevea brasiliensis, to 

 form an approximate idea of the minimum 

 yielding capacity of trees of known sizes and 

 ages. This can, to some extent, be done by 

 keeping careful records of the amount of bark 

 removed and the yield of rubber obtained on 

 each section of the estate. On several properties 

 the amount of bark removed at the end of a 

 year has been determined and the yield of 

 rubber per unit of bark excised established. 

 The results, however, have been of very little 

 value, for the simple reason that the bark has 

 often been removed so quickly that latex 

 similar in composition to that in the primary 

 bark has not been allowed to accumulate 

 either in the remaining primary or in the 

 subsequently formed renewed tissues. The 



