DISEASES AND ENEMIES 261 



the case with the "black rot" fungus. Accordingly, 

 countries with a heavy rainfall e.g. Kamerun suffer 

 particularly from this pest, while many plantations in 

 Java with a comparatively small rainfall are remarkably 

 free. A dense shade and close planting are other 

 conditions which favour the development of the disease. 

 Keduction of shade, a wide planting distance, thorough 

 pruning and good drainage, will help the planter in his 

 fight against the Phytophtlwra, but in spite of these 

 precautionary measures a strong epidemic of black rot 

 will often be experienced in very rainy years. 



A direct method of treatment is accordingly neces- 

 sary in places where the disease is habitually harmful. 

 Spraying with Bordeaux mixture, as already described, 

 has proved to be effective in Trinidad, Ceylon, and 

 Kamerun. Yon Faber l mentions that in one of the 

 experiments in Kamerun the percentage of diseased 

 pods was reduced from 56 per cent to 22 per cent. 

 In this case Bordeaux mixture was mixed with 

 resin and starch in order to make it more adhesive. 

 This, however, does not seem necessary. Wright 2 notes 

 an instance where 19 per cent of diseased pods was 

 found in the unsprayed field, and 8 to 15 per cent in 

 the sprayed plot. The removal and destruction of the 

 attacked fruits is always advisable, but it must not be 

 forgotten that the fungus grows very quickly, and 

 forms its spores a few days after penetrating into the 

 fruit. The diseased pods must therefore be removed 

 as soon as the first spot is seen. The same fungus is 

 the cause of the " canker" disease of the stem and the 

 branches, and of the " chupon wilt" disease. 



INSECT PESTS 



I. Root Insects. The West Indian mole -cricket 

 (Scapteriscus didactylus) is only too well known for 

 its ravages on young cocoa and many other plants 



1 Von Faber, "Die Krankheiten und Parasiten des Kakaobaumes " (Arb. 

 Kais. Biol. Anstalt, 1909, p. 205). 2 Wright, Cocoa, p. 222 



