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pure cultures of Phytophthora omnivora, De Bary, and with them to 

 reproduce the pod disease by inoculation ; and finally, he refers to the 

 work of Mrs. Van Hall in Surinam (1909) on the canker disease which 

 was said to be caused by Spicaria colorans, n. sp. Having thus des- 

 cribed the work of previous investigators on pod disease and canker 

 of cacao, the author is careful to point out that whereas pod disease 

 has been shown by inoculation experiments with pure cultures to be 

 caused by Phytophthora omnivora, the canker has never been repro- 

 duced by infection with spores derived from pure cultures. 



A description of the life-history of Phytophthora omnivora, is 

 given, being based on the results of infection experiments. The fun- 

 gus is shown to be capable of penetrating the unbroken surface of a 

 pod either through the epidermis or through a stoma. When the 

 tissues of the pod have become invaded by the fungus the mycelium is 

 said to pass backwards to the cushion and to produce a cankered 

 appearance of the cushions and of the surrounding area of the bark. 

 Other infection experiments showed that the fungus could spread 

 from the stem to the pods. 



A careful description is given of the inoculation experiments 

 carried out with the following species : — Phytophthora omnivora, 

 Diplodia cacaoicola, Nectria Theohromae, Nectria Bainii, Calonectria 

 JJavida, Spicaria colorans, and two species of Sphaerostilbe. Positive 

 results were obtained only with Phytophthora omnivora and Diplodia 

 cacaoicola, and only in the case of the former was the cankered ap- 

 pearance oi the stem produced. The author, therefore, concludes that 

 the canker is caused by Phytophthora omnivora, and that the other 

 species of fungi mentioned above, with the exception of Diplodia 

 cacaoicola, are incapable of affecting the healthy tissues of the plant. 

 The infection experiments were numerous and in each case a pure 

 culture of the fungus was employed. 



The remedial measures which are recommended for treatment of 

 the canker and pod disease are : — 



(1) . Spraying the pods with a fungicide, in which experiments 



are said to be in progress for the purpose of determining 

 the best fungicide and the most suitable time of appli- 

 cation. 



(2) . Cutting out the cankered area on the stem. 



(3) . Avoiding needless wounding of trees and unnecessary 



shading. 



(4) . Better drainage. 



Phytophthora omnivora occurs as parasite wherever the cacao 

 plant is cultivated ; but it has hitherto been supposed to be confined 

 to the pods, causing a disease known in the West Indies as " black 

 pod-rot." The author's conclusion that the canker and pod-rot are 

 caused by the same fungus is, therefore, contradictory to the results 

 obtained by previous investigators. His work is, however, accurately 



