November, 1909.] 



389 



Saps and Exudations, 



reduce the value of the whole break, and 

 at the samel time do harm to the good 

 name of the estate for sound rubber. 



Block rubber has great advantages 

 over the other forms, in that it is less 

 bulky and costly for storage and trans- 

 port, less liable to any damage by damp 

 or heat in transit. Many leading manu- 

 facturers and technical experts in 

 Europe considei that the block rubber 

 possesses more of the desirable qualities 

 of the Brazilian Para than crepe or 

 sheet ; and the only objection which 

 any of them make to block is the fact 

 that it cannot always be examined for 

 internal impurities without cutting each 

 block. This drawback is obviated if the 

 blocks are made only 1 to H inches 

 thick Avhen they are transparent, and 

 any opaque object included in them can 

 be detected by holding them up to the 

 light. 



Distances between Trees. 



The average number of trees per acre 

 on rubber estates in Malaya in 1908 was 

 168, or 16 feet by 16 feet apart ; the statis- 

 tics for 1907 showed that on the 31st of 

 that year the average was 153, or 17 feet 

 by 17 feet apart. 



This, for many reasons, is an improve- 

 ment. It is to be regretted that the 

 cultivation of rubber is too young an 

 industry to have sufficient experience of 

 old trees planted at different distances 

 apart to judge of this important question. 



The reasons against close planting in 

 rubber— i.e., 12 feet by 12 feet, or 302 per 

 acre, or closer — are : — 



That it prevents the tree from growing 

 with full vigour and to the greatest 

 possible size, forcing it to run up to the 

 light and giving it no room for lateral 

 branches. 



That it increases the cost of collection 

 of rubber, since a larger number of trees 

 have to be tapped for the same amount 

 of rubber. That if it is found necessary 

 to give the trees more room, the cutting 

 out of a portion of them is fraught with 

 much danger to the remainder, inasmuch 

 as each dead rubber tree, root or portion 

 of root, is a potential centre of root 

 disease, and may harbour white ants. 



That the spread of fungal and insect 

 disease is helped by the crowding to- 

 gether of the trees. 



The advantages claimed for close plant- 

 ing are :— 



That it gives for the first years of 

 tapping as much larger yield of rubber. 

 There is not a great amount of evidence 

 on this point, but such evidence as there 

 is seems to point to it being true that a 

 larger yield of latex and of dry rubber 



can be obtained at any rate in the first 

 three or four years of tapping. It is also 

 claimed that the closeness of the trees 

 more quickly produces shade over the 

 ground and so prevents the growth of 

 weeds. The whole question of weeding 

 is being considered at the present time, 

 and if it is believed that to cover up the 

 ground with a green manure is the best 

 method of cultivation, then the fact that 

 close planting reduces the cost of weed- 

 ing is of no value. 



That in order to compensate for the 

 casual losses of trees, which in the course 

 of time must necessarily occur, more 

 trees should be planted than are wanted. 

 The answer to this is that where trees 

 are planted at large distances, 30 or 

 more feet apart, supplies come on with- 

 out difficulty, and it is only in crowded 

 estates that difficulty is found in re- 

 placing casualties. 



To plant more rubber trees than it is 

 intended to permanently keep on the 

 estate, and afterwards by cutting out to 

 reduce the number, is a dangerous 

 policy. No one acquainted with diseases 

 in plants would deny that to leave the 

 dead roots of trees of the same species 

 in close proximity to the roots of living 

 trees is most likely to encourage root 

 fungus and insect pests, while the cost of 

 removing the roots, even if the trees are 

 cut out when quite young, is prohibitive. 

 If a planter finds it necessary to give 

 more growing room — i.e., space for the 

 branches and leaves of some of his 

 trees — it is preferable to pollard some of 

 the trees, and allow them to grow slowly 

 underneath the branches of the un- 

 pruned trees, rather than to leave the 

 decaying roots of dead rubber trees, 

 which he has cut down, dotted all over 

 his fields. 



Cover Plants instead of Clean 

 Weeding, 

 The question as to the relative advan- 

 tages of clean weeding and the use 

 of cover plants (the use of which 

 has been advocated in my annual 

 reports for the last three years) is gradu- 

 ally being seriously considered by the 

 practical planter, and many thousands of 

 acres of rubber, certainly not less than 

 15,000, are now cultivated with various 

 cover plants. 



It needs but little observation of rub- 

 ber clearings to decide that an immense 

 amount of top soil, containing a large 

 proportion of humus, has been washed 

 away from sloping land to the detri- 

 ment, both present and future, of the 

 rubber. An examination of the water 

 in the drains of flat land, which is dark- 

 coloured when the clearing is first opened 



