THE 



TROPICAL AGRICULTURIST 



AND 



. MAGAZINE OF THE 



CEYLON AGRICULTURAL SOCIETY, 



Vol. XXXVIII, COLOMBO, MAY 15th, 1912, No. 5. 



RUBBER TAPPING IN CEYLON. 



In the last number of the Tropical Agriculturist we reprinted an article 

 entitled Notes on Tapping from the India Rubber Journal tor February 24th. This 

 article embodied a criticism of our Circular, Notes on the Tapping of Hevea Rubber 

 by the method of Paring. (Circulars and Agricultural Journal of the Royal Botanic 

 Gardens, Vol. VI., No. 2, October, 1911.) 



Two points in the Circular at e criticised. With regard to the first of these 

 we do not think there is any real ground for disagreement between the Editor of 

 the India Rubber Journal and ourselves. In fact, it would seem that we have only 

 expressed the same opinion in slightly different words. The view of the India 

 Rubber Journal is that •' the four years' interval for bark renewal which we have 

 laid down, should only under very exceptional circumstances be reduced." Our own 

 statement is as follows :" Tapping of the renewed bark maybe begun after three 

 years on large and vigorous trees, and these may be roughly defined as trees which 

 have reached a girth of 3 feet at 3 feet from the ground at the period in question." 

 Now, if tapping was begun when these trees were 18 inches in circumference at 3 feet, 

 such trees will.have increased in girth at the rate of six inches a year during the 

 first three years of tapping. There can be no doubt that*such a rate of increase is 

 quite exceptional in Ceylon. Therefore, we go on to say at the end of the same para- 

 graph, ", we should recommend an interval of four years rather than one of three 

 except under very favourable circumstances." 



Our intention was and is to recommend an increased interval rather than a 

 reduced one. In the second edition of Mr. Herbert Wright's " Hevea Braziliensis," 

 published in 1906, the author wrote, " If the area is excised at such a rate that the 

 whole of the bark is removed in three years, the oldest renewed tissue, by the time 

 it can again be tapped, may be considered near maturity, and can be operated on 

 with comparative safety." That advice wa3 taken by a large number of planters 

 in Ceylon, and the view that a longer interval is required if the full vigour of the 

 trees is to be pi eserved, has only recently begun to gain ground. It is our object 

 to accelerate the progress of this view, and we cordially endorse the present opinion 

 of the Editor of the India Rubber Journal chat four years should be regarded as the 

 minimum safe interval. We are quite prepared to find that even this interval will 

 have to be increased as the result of further observations on bark physiology. Our 

 subsequent remarks will be found to have some bearing upon this point, 



