48 HISTORY AND CAUSE OF THE COCONUT BUD-EOT. 



The scale insects, as well as cockroaches, earwigs, ants, and other 

 insects, may cause small mechanical injuries that give the fungus 

 foothold. In order to determine whether the fungus was infectious 

 small pieces of seriously diseased tissue were loosely bound with wet 

 cotton over the sHghtly scratched surface of some leaves, quite low 

 down, where the tissues were just turning green. After six days the 

 trees were examined and the two leaves which had been so thor- 

 oughly wrapped as to remain moist were infected, while those which 

 had dried out were not. On one of them a typical fungous infection 

 extended 3 centimeters beyond the inoculation and on another for 

 the distance of 8 centimeters beyond the wounds. The four other 

 inoculations showed no growth, the inoculation material itself having 

 dried out, which rendered infection impossible. While this was but 

 an incomplete experiment, carried on in a small way, the flourisliing 

 condition of the fungus on the tissues of the two infected leaves 

 would indicate that, given proper conditions of moisture on slightly 

 diseased or wounded tissues, the fungus would make good growth. 

 The fact, however, that these two successful cases did not advance 

 further and did not develop into the sUmy condition and progress 

 downward into a soft rot tends to prove, if any proof is necessary, 

 that the soft-rotted condition in bud-rot is not caused by the fungus. 



SPREAD OF INFECTION. 



For the spread of disease caused by a parasitic organism some 

 carriers of the infection are essential. The bud-rot has been shown 

 on foregoing pages to be due to a bacterial organism and in some of the 

 pages that follow it is demonstrated to be due to a particular organism. 

 The means of spreading the infection from tree to tree has, however, 

 not been ascertained. It has been claimed by some that wind is the 

 chief means and by others that insects play an important part. 



The arguments in favor of wind are based largely upon the obser- 

 vations that the distribution of the infection is sometimes in the direc- 

 tion of the prevailing wind. This condition appears to be true in some 

 cases, but unfortunately for the argument the cases are quite as 

 common in which the spread is against the Avind. Not only this, but 

 the new infections are more sporadic than would be expected. The 

 disease occurred in Baracoa Harbor, serious first on the south side, and 

 from there spread to the east side, skipping over a group of several 

 hundred trees. This spread was off to one side of the usual course 

 of the wind. On the west side of Baracoa Harbor there is a large 

 estate which covers both sides of a small hill, on the one hand facing 

 the sea and the breezes and on the other hand away from the sea and in 

 the direction of the vdnd. The disease has been on the windward side 



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