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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 il- 

 lustration of the lack of definite knowledge which hinders practi- 

 cal 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 reasons.* It seems, hovvever, that there is not the 

 slightest reason to believe that either coffee or cacao is injured 

 by standing in the sunlight, 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 Castilloa is in 

 no way adapted for serving these purposes is apparent as soon as 

 it is known that wherever there is a distinct dry season the leaves 

 fall off at exactly 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 Castilloa thus lack the first qualification of a 

 shade tree, but its cultural requirements and those of coffee are 

 entirely at variance. Castilloa seems likely to produce rubber in 

 paying quantities only at low elevations, while the profitable cul- 

 tivation of coffee is seldom considered possible at an altitude of 

 less than 1,000 feet. In elevated continuously humid coffee dis- 

 tricts 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. 



The suggestion of Castilloa for cacao shade is somewhat more 

 rational, since both trees are natives of the same regions of low 

 elevation. As noted elsewhere, rubber was first planted at Tapa- 

 chula as shade for cacao, but the experiment did not appear pro- 

 mising from the standpoint of the cacao, and was abandoned. 

 Some of the cacao trees still remain, but they have never been 

 vigorous and produce very little. Other causes of failure may, of 

 course, exist, but it seems certain that the close planting which is 

 now favoured would make a rubber plantation a very poor place 

 for cacao, and there is every reason to believe that, while cacao 

 may not be benefited by shade, it may be seriously injured by 

 sudden exposure to the sun, as happens when the leaves of Cas- 

 tilloa fall in the dry season. 



A further difficulty in the use of Castilloa as shade is that in 



* These have been discussed iu some lefeail in Bulletin No. 25, Division of 

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

 Also see Bulletin of the Department of Agriculture, Jamaica, June and July, 1903. 



