284 THE RUBBER TREE BOOK 



chief objection to the presence of either Robusta coffee or 

 Liberian coffee as an inter-crop, even when the rubber is widely 

 planted, is the fact that both Fomes and pink disease are some- 

 what more prevalent among the rubber where it is interplanted 

 in this way than on areas which are not interplanted with 

 coffee bushes. This has been the general experience of planters 

 in Sumatra. 



Cacao. Cacao is, perhaps, the most objectionable of all the 

 inter-crops mentioned here. It is rare indeed to see a plantation 

 where the cacao bushes are not seriously affected with canker. 

 Add to this the fact that cacao is subject to attacks of Fomes. 

 and it will be realized that its presence in the midst of a rubber 

 plantation is most undesirable. Apart from these objections 

 cacao is dependent on rain, and abundance of it, at exactly the 

 right season, so that it is generally an extremely unprofitable 

 crop to cultivate. Cacao requires very heavy shade if the 

 bushes are to fruit well. The shade given by rubber trees is 

 not sufficient for this purpose, and large shade trees, such as 

 dadaps and Albizzias, have to be grown. The roots of these 

 trees take up a great deal of room and hinder the expansion of 

 the root-systems of the Heveas. Further, the heavy shade 

 afforded by these trees is found, in practice, greatly to retard 

 the growth of Heveas. The usual result in practice is that, 

 by trying to make conditions suit both cultivations, both the 

 cacao and the rubber are poor in appearance, and, sooner or 

 later one has to decide on cutting out one or other of these 

 cultures. 



Coconuts and rubber should never be interplanted. If 

 they are, both suffer, and one or other has eventually to be cut 

 out. The writer has seen many cases of such interplanting, and 

 in every case the inevitable result was that, sooner or later, 

 and better sooner than later, one or other had to be cut out, 

 and the digging-out of the roots was not accompanied without 

 cost. 



