464 COCOA 



CHAP. 



found to fight the witch-broom disease. It has been 

 shown that it can be combated by " cutting back" the 

 branches, followed by spraying with copper -sulphate. 

 This means that the future of cocoa-growing in Surinam 

 may be regarded with more confidence. 



The witch-broom disease is often accompanied with 

 the " die-back " disease, caused by Diplodia cacaoicola, 

 and in the last ten years the effects of this disease 

 have been in a sense still worse. For, while the witch- 

 broom disease caused a great loss of fruits and a great 

 decrease of the yield, the result of the die-back was 

 a loss of trees. And this amounted to such a high 

 percentage in many fields that several had to be 

 abandoned. 



The table on p. 459 shows how the acreage on the 

 plantations gradually decreased from 15,828 acres in 

 1903 to 13,481 acres in 1908. This is all the direct 

 effect of the die-back disease and an indirect con- 

 sequence of the witch-broom disease, for the loss caused 

 by thrips is only very small in comparison with the loss 

 caused by the die-back. 



Of less importance is the " canker " disease. It 

 appears only here and there in the fields, and seems to 

 get disastrous only in times of heavy rainfall on 

 plantations where the drainage or the embankments 

 are not in order. In the rainy year, 1907, it was 

 evident that the canker appeared as a serious disease 

 only on some plantations along the Saramacca River, 

 where the trees had been standing in the water for 

 several days. 



" Blackening of pods " occurs often when rain falls 

 continuously with very little sun, as sometimes happens 

 in April, May, or June. Against this disease, as well 

 as against the die-back disease, the burying of fruit- 

 shells after breaking would be a very useful thing, for 

 both the Pliytoplithora and the Diplodia live on the 

 shells. But this method is very seldom followed, and 

 generally the heaps of shells remain unburied in the 

 fields. 



