June, 1909.] 311 



SYSTEMS OF TAPPING CEAItA 

 RUBBER TREES.* 



By Jarbd G. Smith, 



Special Agent in charge of the Hawaii 

 Agricultural Experiment Station, 



AND 



*Q. Q. Bradford, 

 Assistant in Rubber Investigations. 



(Prom the Philippine Agricultural 

 Review, Vol, IL, No. 2, February, 1909.) 



A striking; characteristic of the Ceara 

 rubber tree is that it sheds its bark at 

 frequent intervals. The outer bark is 

 tough and papery. As a new growth of 

 bark forms immediately outside of the 

 cambium layer, the outer bark dries and 

 sloughs off. This process is continuous. 



Before beginning tapping the entire 

 outer bark should be removed from the 

 trunk without injuring the living inner 

 bark. This is easily done with a curved- 

 blade knife shaped like a pruning hook, 

 making one vertical cut and peeling off 

 the bark in rings. 



There are four systems generally 

 employed in tapping the Ceara and 

 other rubber trees in rubber-producing 

 countries. These are the half herring- 

 bone, the full herring-bone, the spiral, 

 and the vertical cut systems. The half 

 herring-bone consists of a single vertical 

 cut with laterals about a foot apart at 

 an oblique angle extending half around 

 the tree. The full herring-bone consists 

 of a vertical cut with oblique laterals on 

 both sides extending entirely around 

 the trunk of the tree. The spiral is a 

 single or double oblique cut extending 

 from the bottom to the top of the 

 tapping area without vertical channels. 

 In the vertical system there are from 

 one to half a dozen vertical cuts with- 

 out oblique laterals. _ 



The Ceara rubber tree differs from 

 both the Castilloa and Hevea in the 

 rapidity of the coagulation of the latex. 

 For this reason it has been found that 

 the system of vertical cuts is the best. 

 The station has carried on a large 

 number of experiments in the methods 

 of tapping. It has been found that the 

 average Ceara rubber tree stops its flow 

 of latex by complete coagulation within 

 from two to five minutes when the 

 latex is permitted to flow in the wound 

 without the use of water. By trickling 

 water over the wound the period of 

 flow may be extended to several minutes, 



* Extract from " The Ceara Rubber Tree in 

 Hawaii," Bulletin No. 16 of the Hawaii Agri- 

 cultural Experiment Station. 



Saps and Exudations. 



but if the water is rendered alkaline with 

 ammonia the period is extended some- 

 times from thirty to forty minutes. 



It has also been quite definitely deter- 

 mined that a system of single or double 

 vertical cuts, from 3 to 6 inches apart, 

 without any oblique laterals except 

 at the base, for the purpose of con- 

 centration of all the latex at one point, 

 gives the heaviest yield of rubber and 

 the least waste. A vertical cut is much 

 more easily made than either the spiral, 

 half herringbone or full herringbone 

 oblique cuts. Another point in favour 

 of the vertical cut is that the wound 

 thus formed heals with the greatest 

 rapidity 



The first cut should be extremely shal- 

 low. The cut should be flat, with sharp 

 sides one-eighth of an inch wide, and, 

 if practicable, not more than one thirty- 

 second of an inch in depth— the thinnest 

 possible shaving. It is especially im- 

 portant in young trees not to cut too 

 deeply, because the bark is very thin, 

 and there is great danger of perma- 

 nently injuring the tree by cutting 

 through to the cambium, The second 

 tapping should be in the same cut with- 

 out widening it. The next cut and the 

 cuts of each succeeding day, as long as 

 the tapping period lasts, should be to 

 simply freshen the wound at one side 

 only of the vertical incision. In this 

 way the tapped area will be extended 

 gradually in one direction around the 

 trunk and will be followed by rapid 

 healing of the wound from the opposite 

 margin of the cut. The number of ver- 

 tical cuts will depend on the diameter 

 of the trunk. They should be no less 

 than 4 or 5 inches apait, because the 

 daily tappings drain the latex from the 

 bark for from 1 to 2 inches in every direc- 

 tion from the wound, Enough uninjured 

 bark must be left between the wounds 

 to admit of rapid recovery and not to 

 interfere seriously with the vital pro- 

 cesses of growth. 



Time to Tap. 

 The best time to tap Ceara rubber 

 trees is at night or during the early 

 morning. If tapping is done during the 

 day it should be on the shady side of the 

 tree. The reason for this is because of 

 the tension of sap and latex in the body 

 of the tree. Evaporation of water from 

 the leaves is most rapid during the day- 

 time. The greatest activity in pump- 

 ing up water from the soil is also in the 

 day. Under tha action of direct sunlight 

 the leaves accumulate great quantities 

 of starch and sugars. At night there is 

 a transfer of carbohydrates in soluble 

 form from the leaves to those parts of 

 the tree where growth and the forma- 



