February 1, 1915.] 



THE INDIA RUBBER WORLD 



257 



Rubber Essays of Universal Value. 



THIS is a collection of twenty-six papers read at the Interna- 

 tional Rubber Congress, held at 1 '.ataxia, in October, 1914 — ■ 

 a gathering of which the wprld would have heard much 

 . more if it had not been for the mighty conflagration which burst 

 upon Europe just before the lime set for the meeting. The 

 papers all deal with problems connected with the production of 

 crude rubber, and to that extent may be said t<> represent the 

 planter's point of view. They are, however, the work of broad-: 

 minded scientists who are concerned with the problem of pro- 

 ducing the best article at the lowest cost. Not once is struck the 

 false note of regarding the producer's interest as different from 

 that of the consumer. 



One of the most original and interesting of these papers is 

 that of W. J. Gallagher, on "The Significance of Branching in 

 Young Hevea Trees." Everybody knows that a tree or plant de- 

 prived of its proper amount of light will 

 grow spindling, lifting its bead ever 

 higher, while the stalk is thin and 

 weak. In the rubber tree it is evident 

 that a thin stalk means a low bark area 

 and a lessening of the latex producing 

 cells. Mr. Gallagher takes the very 

 practical view that no amount of sun- 

 light is going to do the tree much good 

 unless there are leaves to receive and 

 utilize that light, in turning the crude 

 sap into plant building material. To 

 yet a large leaf area there must be 

 branches, and a young tree growing up- 

 ward without branches is, though grow- 

 ing in the open, much in the same con- 

 dition as if it were growing in a thicket. 

 This is theory. A test was made in a 

 field containing a number of branched 

 and unbranched trees 2 l /z years old. 

 The former showed a uniformly better 

 girth. A later measurement showed a 

 growth of girth in the branched trees 

 of 3.2 centimeters, while the unbranched 

 showed a gain of less than one centimeter. Branching having 

 been induced, later, on the unbranched trees, they showed an 

 actually greater rate of growth than the naturally branched 

 trees. Other experiments .confirmed the theory and showed 

 among other tilings that the difference in branches and leaves 

 had more effect on growth than the use or lack of manure. 



As to methods of inducing branching, topping will at once sug- 

 gest itself, but Mr. Gallagher points out that this plan has serious 

 objection His plan is stripping the young tree of its leaves — 

 not by picking, but by cutting — leaving the petiole attached to 

 the tree. In a few days this drops off and a young branch de- 

 velops in the leaf scar, the result being a fine, well-balanced 

 head He does not believe in excessive pruning, but thinks the 

 branches settle the question themselves in the survival of the 

 ttest. He thinks branches should be allowed from 7 feet up- 

 ward. There is no light gained for the leaves by stilting the 

 crown a few feet. He says if the, time comes that the plantation 

 as a whole needs light the remedy is not to cut out branches 

 but trees. 



Mr. Gallagher says: "Topping should be done, if done at all, 

 before the trees are two years old. The top should be cut off 

 with a sloping cut. which should be immediately tarred. The cat 

 should be made in the uppermost whorls of leaf traces, and 

 not necessarily at ten feet high, but, in the best , place, nearest 

 to ten feet Thus A is made at the right place. R is not. 



The Right and 

 Wrong Way in 

 Topping. 



This brings us to the subject of thinning, which is considered 

 in a paper by Mr. E, 1'.. Skinner. In the matter of close plant- 

 ing the experiei the rubber grower is not analagous to 

 that of the northern fruit grower, a fact which had to be learned 

 by hard experience. With tile latter the produce of the young 

 lOd as the ..Id and the whole field may be swept 

 clear iratively low cost. Hut with rubber, immediate 

 returns are the least and, as the planting is for not less than a 

 lifetime, the future of the big trees is the first consideration. 

 Careful experiment shows con lusively that the yield, pound for 

 pound, is better on widely planted than on closely planted equal 

 , and of this, according to Mr. Skinner, at least 10 per 

 cent, more is No. 1 rubber. Ill addition, he shows, conclusively 

 mei tmg arguments to the contrary, that the cost of harv. 

 per acre is less with wide than with close plantings. In the 

 beginning Mr. Skinner would plant about 100 trees per acre, and 

 these he would reduce not by cutting out rows, but by selection 

 for elimination of the least shapely or thrifty, and after bearing 

 has begun, of the least productive trees. Always he would have 

 the end in view that the remaining trees must have all the light 

 and air they need. When the elimination of a tree is decided 

 upon he would have it out and done with. The system of pol- 

 larding or cutting away the top and tapping the dying stump, 

 he says, does not pay for the labor and nuisance entailed. 



The subject of "Seed Selection" is treated by Dr. P. J. S. 

 Cramer, Chief of the Plant Breeding Station at Bliitenzorg. 

 The points he makes are briefly summarized and are as follows : 

 Choose seeds from old trees whose qualities have been tested 

 by long experience. Choose, of course, the best from every point 

 of view, yield, health, size and sturdiness. Do not tap the trees 

 selected as seed bearers; let them put all their energies into 

 giving strength and vitality to the seeds. If possible have one 

 part of the plantation set aside for seed bearing and cut out all 

 inferior trees so that there will be no deterioration by cross fer- 

 tilization. Use seeds from your own plantation ; what you want 

 is not only seeds from trees which produce well, but which will 

 produce well under the peculiar conditions of your plantation. 

 If it is not possible to furnish your own seeds get them from a 

 similarly located plantation and from trees of known history. 



Several papers treat of diseases of Hevea and the best means 

 of counteracting them, but that of H. Colenbrander is of par- 

 ticular interest in telling how vigorous and courageous treat- 

 ment saved a plantation of 3-year old trees infected with Fomes 

 Semitostus, the white root fungus ,li-ease. In this case the usual 

 work of freeing the soil from infection was carried out, but by 

 the time it was done nearly all the trees were infected. 



In the drastic treatment which was administered to the i 

 badly infected the trees were actually lifted from the ground, 

 the tap roots, most of the main roots and- all the hair roots were 

 removed and the little left thoroughly soaked with disinfectant. 

 The trees were left with so little root support that they had to 

 be propped up to Wee], them from toppling over. The leaves 

 dropped off. and of course growth ceased while the trees, out of 

 their reserve Strength, were developing new leaves, new hair 

 roots and. finally, a new system of main roots. But the check 

 was only temporary, and after 3 months growth was resumed 

 with full vigor.. It would make an American orchardist rub hi- 

 eyes to learn that the cost of all. this work was less than 20 cents 

 per. tree in American money equivalent. 



The tempting subject of catch crops is considered in several 



papers,, and while- all seem to wish it were possible to realize a 



reyenue from the ground on which the young rubber trees 



are maturing, not one is able to suggest any crop or- plan which 



makes any sure promise of profit. 



