CITRUS DISEASES. 45 



Progress of disease investigations. 



It has been true, most unfortunately, that along with the rapid 

 development of the citrus industry certain diseases, several of them 

 very severe, have made their appearance. As early as 1901 the 

 presence of scab was mentioned in the first report of the INIayagiiez 

 Experiment Station, and in several succeeding reports, particularly 

 those for 1903, 1904, 1909 and 1913, reference was made to this and 

 other citrus diseases. 



Investigations commenced in 1915 hy this Experiment Station, 

 revealed that for a consideral)le period the groves had been suffering 

 from the attacks of certain diseases, particularly scab and foot-rot. 

 The first disease to assume importance was foot-rot, which for a time 

 • took on an epidemic character, but had by 1914 practically subsided 

 as a result of the use of resistent stocks and improved cultural 

 methods. 



Tlic situation with regard to fruit rots or shipping rots became 

 so serious that in 1913 help was asked of the United States Depart- 

 ment of Agriculture. Observations were made of the condition of the 

 fruit as it appeared on arrival at New York, and the fungi involved 

 were studied in the laboratories at Washington. Mr. C. W. Mann, 

 of the Bureau of Plant Industry, was sent to the Island and made a 

 tour of the citrus-growing sections to investigate the status of 

 affairs here. The report of his work has been published as Bulletin 

 No. 7 of this Station. 



Since about 1913, the scab situation has been serious, the bulk 

 of the fruit of some growers commonly being so badly disfigured as to 

 be unsalable, excepts as culls. Other diseases, of minor importance 

 in themselves, have in the aggregate produced no inconsiderable 

 losses. 



It is impossible to arrive with any degree of accuracy, at the total 

 loss to be charged to diseases, so many separate items composing the 

 whole, and this being in turn so intimately connected with the damage 

 to be charged to insect pests and mechanical injuries. Then again, 

 ^he loss from many diseases — for example, die back or bark rot, 

 . ivhich lessen the crop production over a series of years, or may even 

 •destroy a tree — cannot be figured on any definite basis. 



A very rough estimate, but at the same time a most conservative 

 one, will place the annual financial loss suffered by the growers and 

 to he charged to the various diseases including shipping rot. at five 

 per cent of the crop, or approximately .^100,000. In the case of 



