In some cases it is impossible to grow any cane whatever on what 

 apears to be fairly good soil. Furthermore, in many fields of healthy 

 looking cane it is not uncommon to find an enormous number of 

 stalks completely rotted. 



In the course of the field work carried on by this department, 

 numerous cases of loss (totalling many acres) from root disease, 

 rind disease and other causes have been investigated. To the losses 

 from the all-sufficient array of common diseases heretofore known, 

 is now added the epidemic in the northwestern quarter of the Island, 

 where the monetary loss has already reached a total of some hundreds 

 of thousands of dollars. It should by no means be considered that 

 diseased cane is more abundant than healthy, but rather that it is 

 often found very abundant over large areas, and far more prevalent 

 than should be the case. 



Although sugar cane diseases have been studied for many years, 

 yet even today there is considerable contradiction to be found in 

 the literature on the subject as to the cause of certain diseases and 

 as to their relative importance. This lack of unanimity of opinion 

 is partly due to inaccurate, or to incomplete work on the part of 

 some of the investigators, but is also due in part to the fact that certain 

 fungi causing disease vary in their behavior in different localities, 

 in different countries, and in different varieties of cane. 



For these reasons the work of sugar cane pathologists in other 

 countries may be taken as only suggestive as to the probable con- 

 ditions in Porto Rico, and the local problems must be worked out 

 here on the Island itself. In addition to working over parasitic 

 fungi that have been studied by others, there are also constantly 

 arising new problems more or less peculiar to this country. 



The following report is intended to be a complete discussion of 

 the cane fungi of Porto Rico, so far as they have been determined 

 and so far as definite knowledge has been obtained regarding them. 

 The report includes not only popular descriptions of the fungi, 

 and the diseases which they cause, but tecvhnical descriptions of 

 the important forms as well, since it is desired that the planters 

 may be informed of the various destructive fungi present in their 

 cane fields, and at the same time it is important that other workers 

 in the subject may be in a position to know what fungi occur, together 

 Avith the symptoms of the resulting diseases. 



It is perhaps needless to say that there is still much to be learned 

 about the cane fungi of Porto Rico, especially as regards problems 

 of control, but nevertheless it seems eminently desirable at the present 

 time to issue in one report such data as is available, inasmuch as 



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