SUMMARY. 



1. Hevea-canker has been foiind in Java, Sumatra and Borneo. 



2. The symptoms of canker appear in the following order : . 



lo. The disease is usually discovered by the cessation 

 of the latex-flow. 



2o. In the outer bark claretcoloured patches are to be 

 seen, when the cork-layers of the bark are shaved 

 off. In many cases these patches begin at the cuts 

 and run downwards. 



3o. A discolouration sets in of the inner layers of the 

 cortex which become greyish or slightly brown-colou- 

 red just outside the cambium. This discolouration 

 starts from the claret-coloured patches, but extends 

 over a iarger area and subsists after the disappearence 

 of the patches. 



4o. Woody tissue is formed round the dead brown cells 

 in the inner cortex, by the action of a secondary or 

 wound-cambium. This formation of wood in the cor- 

 tex goes on for several months, perhaps for years af- 

 ter the canker-infection is over. 



3. The measures advisable to get rid of the canker are the 

 following. 



lo. By all possible measures lessen the humidity of the 

 plantation and give free access to air and sunlight; for 

 this purpose removing the intercrops, thinning-out and 

 pruning the trees or draining may be advisable 

 according to circnmstances. 



2o. Cut out thoroughly all diseased tissues of the cortex 

 but leave the cambium undisturbed. Train a special 

 gang of labourers for this work. 



3o. Desinfect the tap - knives by means of formaline and 

 spray the sterns with Bordeaux mixture. 



