RUBBER PLANTING 183 



under which they might become more prominent, with a 

 view to ensuring, if possible, that the necessary con- 

 ditions do not arise. Some of the fungi in question 

 attack the roots, others the stems and others again the 

 leaves, especially in the case of young plants. 



Diseases of the Roots. 



Root diseases are particularly dangerous, because 

 their early stages generally pass unnoticed, and very 

 often the first indication of their presence is given by 

 the death of the tree. Sometimes the main tap-root 

 may be entirely destroyed without any sign of injury 

 appearing above ground, since sufficient supplies of 

 water and salts are provided by the lateral roots to 

 maintain the crown of foliage in a condition of apparent 

 health. One day a storm of wind brings down the 

 whole tree, and the full extent of the injury is disclosed. 

 Occasionally a single lateral root may be discovered 

 showing symptoms of disease. In such a case it may 

 be possible to cut away the diseased portion and to 

 save the remainder of the tree. In the majority of 

 cases, however, the planter must make up his mind to 

 destroy the affected tree in the hope of saving its 

 neighbours. 



Altogether, three different root diseases are at 

 present recognised, which may be readily distinguished 

 from one another on examining the affected roots. In 

 the case of the fungus known as Pomes semitostus, which 



