EXTERNAL APPEARANCE OF THE RIND DISEASE. 



So confused is the literature on this subject that it will make 

 the discussion clearer to state once for all that the rind disease is 

 considered primarily a disease of the rind of the cane. "Whatever 

 effect there is upon other parts of the cane is considered secondary 

 in ascertaining the cause of the trouble, although it may as a matter 

 of fact be primary in the point of time in the life history of the 

 fungus itself. 



The external symptoms of the rind disease are primarily the 

 appearance of numerous black pustules breaking through the rind 

 of the cane. (See Plate I.) From these pustules oozes a coherent 

 mass of spores which on exposure to the dry air hardens somewiiat 

 in the form of a stalk, varying in size and form from patelloid to 

 subclavate or cylindrical, up to 1 or 2 mm. in length. Sometimes 

 they appear merely as numerous tiny black threads breaking through 

 the rind. When these black pustules appear, the tissues of the cane 

 itself are already discolored and diseased. The relations of other 

 symptoms of disease are complicated with the presence of other fungi 

 and will be left to a fuller discussion further on. It will be noted 

 that there are a few eruptions on the rind that are caused by dif- 

 ferent fungi. These will all be discussed in their proper place. The 

 preceding brief diagnosis of rind disease will be used as a basis foi- 

 discussing the history and full nature of the fungus and the disease 

 caused by it. 



THE AUTHOR'S INVESTIGATIONS OF THE RIND DISEASE. 



FIELD NOTES IN I^RTO RICO. 



Conditions under which the rind fungus have been noted in Porto 

 Rico are extremely variable. It has never been observed in fields of 

 young green cane excepting in shoots injured or killed by some other 

 fungus such as Marasmius- sacchari or by such insects as the changa, 

 the whitegrub, the root weevil, or the moth stalk-borer. In such 

 cases it can hardly be considered more than a saprophyte. 



In cane over six or eight months old this fungus can almost 

 invariably be found on the leaf -sheaths of the cane, not universal 

 on all stalks, nor on all varieties, but at least common in the ciine 



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