DISEASES OF COCONUT igi 



Symptoms. 



The most obvious character of the disease as seen in these 

 islands is that after its onset the leaves come out smaller and 

 smaller in size until in the end, if no recovery takes place, they 

 are reduced to a ridiculous little crown of aborted stumps not 

 more than one to two feet long, which may be borne at the end of 

 a stem perhaps 20 or 30 feet in height. 



Examination of the central shoot reveals the young leaves 

 with brown necrosed spots and patches on the folded leaflets and 

 on the surface of the leafstalk. As the leaves expand the leaf- 

 stalks develop a russeted or corky surface, which later becomes 

 hard and woody, more or less raised and misshapen, and exhibits 

 well-marked cracks. The unyielding nature of the leaves so 

 affected causes those which follow to be more and more severely 

 deformed, and in the later stages the leaflets either do not expand 

 or are almost entirely aborted, and the rachis itself is reduced to a 

 pointed stump. 



Incidence. 



Trees may be affected at 3 or 4 years old and at any later 

 stage. Natural recovery can take place and the affection be 

 thrown off, to recur again or not as the case may be. Most 

 frequently, it would seem, there is little or no natural interruption 

 to the course of the disease and the tree dies. 



Causation. 



Ashby reports that in Jamaica a small yeast occurs in the 

 early spots and on the advancing margin of the hardened areas, 

 and is always obtained, usually alone, in cultures. A similar 

 organism has been found by the writer in Grenada and Trinidad, 

 but inoculation experiments with pure cultures have so far had 

 negative results. 



Control. 



The disease has been found by several planters to be easily 

 treated, and if taken in reasonable time few cases fail to recover. 

 The first essential appears to be to relieve the constricted con- 

 dition of the heart by cutting through the strainers and opening 

 out the leaves, and then it is the practice to pour into the heart 

 milk of lime, Bordeaux mixture, copper sulphate solution, weak 

 Jeyes fluid, or tobacco extract. The last-mentioned substance, 

 obtained from the local tobacco factory and diluted is used with 

 complete success on an estate in Tobago. 



Bitten-Leaf Disease. 



S. F. Ashby has described a disease prevalent on the north-east 

 coast of Jamaica which affects the leaves while still folded in 



