April i, 1906. J 



THK INDIA RUBBER \VORLD 



217 



NOTES ON THE "CASTILLOA" RUBBER TREE. 



THE roots of young plants of Castilloa elastica (the 

 Central American rubber tree) are well developed 

 and branch a good deal. They are very thickly 

 clothed with root hairs at the tips. These hairs are 

 very fine and fragile and in transplanting young seedlings 

 great care should be taken not to injure them. I believe 

 that the condition of the roots of a tree makes more diflfer- 

 ence with the amount of rubber it will give than the leaves. 

 A tree with small yield is generally healthy in the leaves, but 

 has some defect in the roots. Transplants are likely to have 

 defective tap roots and on this account blow over. 



There are two distinct types of branches on the Castilloa 

 tree — temporary and permanent. All the branches for the 

 lirst three or four years are temporary. They grow alter- 

 nately on diflerent sides and almost at right angles to the 

 trunk. After some time the temporary branch drops, when 

 beside the scar which is left will be found a small bud. This 

 bud is either to the right or left of the scar, but never above 

 or below it. Whenever one such bud on a tree grows to the 

 right all the other buds do the same, and vice versa. I have 

 never found a tree with buds on both sides. Such buds are 

 the beginning of permanent branches. Onlj' a small number 

 grow into branches, but any of them can be forced b)' cutting 

 through the bark to the wood, above the l)ud, and thus sev- 

 ering the sieve tubes connecting the leaves and roots. These 

 permanent branches project upward at an angle of 45° or less. 

 I'orced branches do not grow as fast as natural ones. The 

 permanent branch bears temporary brandies of its own, and 

 later may bear other permanent branches. 



This question of branching may prove important. Some 

 planters claim that trees that put out permanent branches 

 early grow faster and vield better than later branching trees. 

 Others claim that branching is not good for the trees. I 

 believe that branched trees grow somewhat faster because 

 they get a larger leaf surface, but I do not think that this 

 leaf surface affects the amount of latex. Trees planted far 

 apart branch more freely and earlier than those which are 

 close together. There also seem to be more branches on 

 trees grown in the sun than in the shade. It has been sug- 

 gested that it would be well to grow branches on the trees — 

 by the forced method above described — in such manner that 

 the trees could be ascended hy tappers without a ladder. 

 The fact that some temporary limbs turn permanent might 

 be investigated, and perhaps a way could be found to make 

 them turn permanent at will, if desirable. 



The Castilloa is a fast growing tree. It appears to grow 

 f;ister between the ages of two and four. The leaf surface of 

 the tree, and consequently the amount of light it gets, has a 

 great deal to do with its growth. Shade grown trees are not 

 nearly so large at the same age as those grown in the sun. 

 Some planters believe that trees grown in at least partial 

 shade yield more latex, but if this is so, I do not believe that 

 they yield enough more to pay for the loss in growth, for 

 under any ordinary conditions the trees yield in proportion 

 to their size. Monthly measurement of a large number of 

 Castilloa trees shows that they grow on an average of about 

 % inch per month in circumference. This varies, however, 

 the trees sometimes growing not at all for a month, and grow- 

 ing Yi inch or more the next month. An experiment in the 



affect of tapping on growth did not show that it made any 

 diflerence. 



The proper distance in planting de|)ends a good deal on 

 how soon the plantation is to be tapped. Trees planted 

 10 10 feet begin to crowd each other at about six years. 

 If the plantation is to be tapped at this age, or earlier, this 

 is a good distance for planting. When the trees get older, 

 the poorer and weaker ones can be bled out. The experi- 

 ment of planting four trees in a hole shows that it is possi- 

 ble for two, three, or even all four to grow well and appar- 

 ently not to hinder each other. If these trees continue as 

 they have begun, it seems to me that the way to grow the 

 most good trees on a given piece of land would be to stake 

 the land at a distance of 15 or 20 feet, and to plant a circle 

 of S or 10 trees about each stake. Any trees grown in this 

 way which did not keep up to the others should be cut 

 down, and by the time they are ready to tap there should 

 be three or four good trees in each group. This method 

 would avoid one trouble which has shown itself where one 

 tree was planted to a hole, and that is that when the time 

 for tapping came many of the trees were poor and stunted 

 and not worth anything. This irregularity of growth loses 

 much time and can be avoided where only the best trees are 

 allowed to grow. 



Whatever the method of tapping employed for Castilloa, 

 the healing of the cut requires to be considered. The gene- 

 ral idea has been that the cut must not be made too deep, 

 and this is true to a certain extent. But it may also be made 

 too shallow. Between the bark and the wood is the growing 

 part of the tree, a tissue called cambium. This part alone 

 has the powers of forming new bark and new wood. If a 

 cut is made which does not go into thf cambium, the cut 

 will not heal over with new material. Of course, it will dry 

 up and turn black, and in this way protect the tissue under 

 it, but the piece of bark taken out is gone for good. On the 

 other hand, a cut made just to the cambium will heal 

 quickly. 



The Para rubber tree {Hcvea) shows some important difler- 

 ences in latex from the Castilloa. Of course all that I have 

 noted on this tree is done here in Nicaragua and it 

 may behave differently in Brazil or Ceylon. The first 

 noticeable thing in cutting the Para tree is the small yield. 

 When a Castilloa is tapped the cut is immediately filled with 

 latex, which runs in a small stream from the lower end. The 

 Hevca when first cut shows no latex. In a few seconds it 

 begins to appear in drops on the cut surface and after 3 to 5 

 minutes begins to drop from the end of the cut. The small 

 yield at the first tapping .seems to be balanced by the fact 

 that more can be got by multiple tapping. In Cejdon, ac- 

 cording to report, the yield increases each day, but here I 

 have noticed no increased yield. I tapped one tree nine days 

 in succession, and though it yielded every day (a thing which 

 Castilloa would not do) the yield decreased instead of increas- 

 ing. The Hcvea tree will not do here because there is too 

 much labor involved in multiple tapping. I think the trees 

 here, if tapped rightU', would yield as much as those in Cey- 

 lon, but as labor costs so much more, it would not paj'. I 

 am confident from comparing yields printed in The India 

 Rubber World that Castilloa will yield as much with four 



