DISEASES AND ENEMIES 257 



cacao, the Brazilian planters should be careful that the 

 same thing does not happen to them. 



The disease has been successfully eradicated on the 

 plantation " Susannasdaal " by a method applied under 

 the direction of the Government Experiment Station. 

 It consists of pollarding, i.e. removing the entire leaf- 

 bearing crown of the trees (Fig. 86), so that, when 

 all the leaf-bearing branches have been cut off, nothing 

 remains but the trunks and the leafless main branches. 1 

 Immediately after cutting, all wounds are treated with 

 black tar. After this operation the only sources of 

 infection left are any spores which may have settled on 

 the trunk and on the uncut branches. To destroy these 

 the trees are sprayed with a 3 per cent solution of blue- 

 stone, or sulphate of copper, without addition of lime. 

 All lopped-off branches and leaves are collected in heaps 

 and burned. In each field a few open spots can generally 

 be found where this can be done without harming the 

 cocoa and the shade trees. In Surinam the trees give 

 no fruits in the first year after pollarding ; in the second 

 year an average of 60 kilograms per acre, in the third 

 year 160 kilograms, and in the fourth year the normal 

 crop of more than 200 kilograms is again obtained. 



The fields, once treated, must be kept under control. 

 It was at first thought that the regular removal of 

 the few reappearing witch-brooms and hardened fruits 

 would be sufficient, but it is now believed that at least 

 one spray per year with Bordeaux mixture must be 

 added to this treatment. 



Experiments are at present being made to see if the 

 infection could also be eradicated without the removal 

 of the whole crown of the tree, but by giving only a 

 very thorough pruning and spraying, removing at the 

 same time all dead and diseased parts. It is hoped that 

 in this way the normal yield may be re-obtained at an 

 earlier date. 



1 Further details of the method may be found in the article on this disease 

 by Van Hall and Drost ; it appeared as Bulletin No. 16 of the Surinam Dept. of 

 Agr., and has been translated into English by Dr. Fredholm (Proc. of the Agr 

 Soc., Trinidad, Dec. 1909). 



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