DISEASES 167 



Hevea Cacao, and Coffee. The fungus forms a 

 thin film, not much thicker than a coat of paint, 

 on the bark. When actively growing it is of a pink 

 colour, but this changes to a dingy ochre later on ; 

 and the latter colour again gradually gives place 

 to white as the very advanced stages of existence 

 are being reached. The bark then becomes more 

 or less cracked. It often originates in the fork of a 

 tree, and gradually extends until it completely or 

 almost completely encircles the trunk. The bark 

 is killed, cracks and falls off, exposing the wood. 

 When branches are ringed, the portion above the 

 injury dies. The fungus is favoured in its 

 development by moisture. If the patches are 

 small, the bark should be removed, and the wound 

 protected by a coat of tar. The disease is spread 

 by spores carried by wind, and also probably by 

 insects. Spraying the stems with Bordeaux 

 mixture would prevent infection through these 

 agencies. 



