DISEASES OF CACAO 173 



Symptoms. 



The first positive symptoms are manifested on pods about 

 8-10 cm. in length, and may take the form of a small protuberance 

 or a certain amount of discoloration. When the pods which 

 show these external signs are cut open it is observed that dark 

 brown veins are present in various parts of the interior. In 

 more developed pods the external signs of the disease may be 

 slight, there may be one or more dark spots on the surface, or 

 they may be more or less completely invested with a whitish 

 growth of the fungus. 



In the first case the pods show abnormality in form or appear 

 somewhat discoloured, presenting areas of a bluish or yellowish 

 colour as if premature maturity were being attained. In the 

 second form the diseased pods display on their surface dark grey 

 spots of different sizes from 0.5 to 3 or 4 cm. in diameter. In the 

 third form the pods from an early stage are partly or completely 

 covered with a dense and shaggy growth of the fungus 1-2 mm. 

 thick, white on the margin and slightly yellow or ashen in the 

 centre and bearing an abundance of conidia. 



When fully diseased pods are cut open it is observed that the 

 interior of the husk, the central tissues, the pulp, and the seeds 

 have become enveloped in watery matter and in some cases a 

 quantitj' of water can be drawn off from the pod. The contents 

 of the pod are found surrounded by a dark brown coating, which 

 carpets also the interior partitions of the husk. The husk itself, 

 when cut, exhibits black or dark brown strands or spots in its 

 tissues and sometimes small watery cavities or areas surrounded 

 by a definite dark-brown boundary. In addition there may be 

 areas which present a striped or mottled appearance. 



Observations on diseased pods have indicated that infection 

 can only occur in their younger stages. 



The causative fungus is a species of Monilia probably undes- 

 cribed. Monilia fructigena is well known as the cause of the 

 wide-spread brown rot of plums and other rosaceous fruits in tem- 

 perate countries. 



Sph^eonema Black Spot and Bark Rot. 



Two affections previously undescribed, caused by a fungus 

 of the genus Sphaeronema, have been found by J. B. Rorer to be 

 generally distributed in Ecuador. Like Phytophthora, the fungus 

 produces a disease of the pods — black spot — and a bark rot which 

 is so closely associated with wounds from the too ready cutlass 

 of the labourer that Rorer has given it the name Enfermedad 

 del Machete. 



Black Spot. 



This affection first declares itself on pods which are almost 

 ripe. One or more dark spots appear on the surface, and gradu- 



