244 COCOA 



CHAP. 



viz. a sudden wilting and subsequent drying of the 

 leaves, without falling off. Very characteristic is the 

 longitudinal splitting of the root by radial clefts, the 

 walls of which are covered with a thick felt-like growth 

 of the fungus. 



The fight against these different root-fungi follows 

 the same lines in all countries. First of all they need 

 a very wet medium for their development, and they 

 appear to a destructive extent only in fields where the 

 soil is very damp. Accordingly, proper drainage has 

 often been sufficient to cause the disease to disappear. 

 Secondly, the spread of the parasites through the soil 

 is much favoured by the presence of dead wood, on 

 which the fungus feeds, and is thus assisted to pass from 

 the root of one tree to the root of another. This fact 

 is considered of great importance by the rubber planters 

 of Java and the Straits ; and on low-lying lands, where 

 the white-root fungus was very troublesome, it has 

 often been considered necessary, even in fields with 

 four-year-old Para* rubber trees, to dig out all the dead 

 trunks and roots, or at any rate the trunks from which 

 the fungus has spread. 



The direct destruction of root fungus is not to be 

 neglected wherever it appears. The diseased root-system 

 should be carefully dug out, and it is generally advisable 

 also to dig out the roots of the neighbouring trees, 

 even if they do not appear to have been attacked. 

 When, however, there is no reason to fear a quick 

 spreading of the fungus and the trees are considered 

 valuable, this measure will not be applied before it 

 has been proved to be absolutely necessary, but the 

 infected area should be isolated by a trench 3 feet deep. 

 Finally, it is always advisable to disinfect the soil by 

 means of carbolineum, using one gallon for every 10 

 square metres (12 square yards). For some time after 

 this treatment (perhaps about six months) the soil will 

 remain unfit for plant growth ; the reappearance of 

 weeds generally indicates when it can be planted again, 

 and at this period soil treated in this way is remarkably 



