RUBBER PLANTING 189 



The same fungus attacks the fruits of Hevea, 

 especially in wet seasons. The pods turn black and 

 sodden, and rot upon the trees. Beyond the loss of the 

 seed crop, little harm appears to be done directly to the 

 trees, but the diseased pods serve as centres of infection, 

 and thus increase the chance of the disease developing 

 upon the bark. The only possible treatment is to collect 

 and burn the diseased fruits. 



The spread of canker is greatly facilitated by the 

 shade consequent upon close planting. In districts 

 where the disease is prevalent it is therefore desirable 

 that the trees should be widely spaced. Where they are 

 already closely planted, the question of thinning out 

 becomes a serious one, but if it is decided to fell a 

 certain proportion of the trees, the stumps and larger 

 roots should also be extracted in order to avoid danger 

 from root disease. It is understood that experiments 

 are being tried in Ceylon to find out whether the 

 tapping area can be sprayed with some substance which 

 will prevent the germination of the fungus spores, whilst 

 not injuring the quality of the rubber prepared from the 

 latex. Such spraying is not likely to be of much use so 

 long as rain water is allowed to flow over the surface of 

 the tree, whilst, if the trunk can be kept dry, the germi- 

 nation of spores will probably be checked as effectively 

 as by a fungicide. The provision of rain guttering 

 above the tapping area seems therefore to be a most 

 desirable measure in all districts where rubber canker is 

 prevalent. 



