DISEASES OF CACAO 175 



of the fruits, which may be of any age. These spots are at first 

 moderately light-brown in colour, but later become darker and 

 are sunken below the general surface level of the pod ; they are 

 usually limited in extent and irregular in outline, while the 

 tissues in the centre of the spots become hard and dry. The 

 tissues of the rind below the spots are brown and diseased, and 

 the causative fungus penetrates as far as the beans. When the 

 spots are commencing to dry, small yellow pustules, not as much 

 as I mm. in diameter, break through the epidermis. These are 

 closely crowded and become pink as they develop, so that the 

 centres of the spots are covered with an almost continuous 

 pink coating consisting of millions of small, colourless, unicellular, 

 hyaline spores belonging to a species of Colletotrichum. In 

 some cases the spots fuse with one another and produce large 

 discoloured areas, while in extreme cases the whole pod may 

 become discoloured and completely destroyed ; this is especially 

 the case with young pods." 



The disease is much less prevalent than Phytophthora rot, 

 but can occur under conditions of dryness in which the former 

 disease is absent. 



Identity of the Fungus. 



A disease which closely resembles the West Indian anthracnose 

 in its characters has been recorded by Busse from cacao in the 

 Canieroons, and is attributed to Colletotrichum incarnatum Zimm. 

 (C. TheohromcB App. et Strunk), originally described from coffee 

 in Java. The same fungus occurs on cacao pods in Ceylon. 



In the West Indies C. Theobromicolum Delacroix, C. kixificum, 

 Van Hall et Drost, and C. Cradwickii Bancroft have been des- 

 cribed from cacao pods. Whether these are really separate from 

 each other and from the Old World species, and how far any or 

 all of them give rise to disease cannot at present be stated. 



" Male " Cacao 

 In each of the cacao-growing islands it is a familiar experience 

 that an occasional tree occurs which persistently produces 

 enormous and quite abnormal numbers of flowers thickly dis- 

 tributed over its stem and branches, without setting more than 

 a very occasional and often imperfectly developed pod. Trees 

 of large size and high vigour have been seen in which this con- 

 dition was reported to have prevailed throughout their history, 

 and this persistence appears, so far as the information collected 

 by the writer goes, to be characteristic. Beyond casual attention 

 no investigation of the condition seems to have been made, its 

 rarity having allowed it to be passed over for matters of more 

 direct importance. Appearances are against the idea of com- 

 municability and hence of parasitic origin, since surrounding 

 trees, in cases observed, have shown no sign of alteration after 

 years of close contact. 



