60 CENTRAL AMERICAN RUBBER TREE. 



from cuttings will be easy. The larger the cutting the more promptly 

 the tree may be expected to reach maturity. Probably also the 

 mature wood will root better than the succulent young shoots, as with 

 many other tropical trees. 



CASTILLA AS A SHADE TREE. 



The substitution of Castilla or other rubber-producing species for 

 the unproductive shade trees commonly grown with coffee, cacao, and 

 other tropical crops has been persistently advocated ever since the 

 subject of rubber culture began to receive popular attention. The 

 advantage of such a plan appears so obvious and certain that many 

 experienced tropical agriculturists have been betrayed into direct and 

 even emphatic statements for which the facts have unfortunately 

 failed to provide a warrant. Indeed, it might be said that this phase 

 of rubber culture affords the best illustration of the lack of definite 

 knowledge which hinders practical progress. 



In the first place, the shading of coffee and cacao is a subject upon 

 which there is much popular misconception and difference of opinion, 

 the planters of some regions shading heavily and those of others not 

 at all, and explaining their methods by the most contradictory rea- 

 sons/' It seems, however, that there is not the slightest reason to 

 believe that either coffee or cacao is injured by standing in the sun- 

 light or is in any way advantaged by having its leaves shaded, though 

 in countries subject to a long dry season the shading of the ground 

 and the retention of atmospheric humidity may be beneficial cultural 

 measures. That Castilla is in no way adapted for serving these pur- 

 poses is apparent as soon as it is known that wherever there is a dis- 

 tinct dry season the leaves fall off at exactl} T the time when they are 

 most needed. It is true that they would still be of some service in 

 covering the earth, but, on the other hand, the loss of the accustomed 

 shade renders the atmosphere much drier and may be a distinct injury 

 to the coffee. 



Not only does Castilla thus lack the first qualification of a shade 

 tree, but its cultural requirements and those of coffee are entirely at 

 variance. Castilla seems likely to produce rubber in paying quanti- 

 ties only at low elevations, while the profitable cultivation of coffee is 

 seldom considered possible at an altitude of less than 1,000 feet. In 

 elevated continuously humid coffee districts the rubber trees will hold 

 their leaves but will produce little or no rubber, while to choose an 

 intermediate situation would be more likely to insure two failures than 

 to double the chances of success. 



It is reported that an extensive experiment is being made in Salva- 

 dor with Castilla as a shade tree for Arabian coffee. 6 The altitude is 



"These have been discussed in some detail in Bulletin No. 25, Division of Botany, 

 U. S. Department of Agriculture, entitled " Shade in Coffee Culture. 

 &DerTropenpflanzer, 0:542, October, 1902. 



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