THE JOURNAL 



OF 



THE DEPARTMENT OF AGRICULTURE 



OF 



PORTO RICO 



Vol. II April, 1918 No. 2 



CITRUS DISEASES OF PORTO RICO.' 



By John A. Stevenson, Pathologist, Insular Experiment Station. 



INTEODUCTION. 



The citrus industry in Porto Rico, in so far as the production of 

 fruit for export is concerned, dates from about 1902, and for a 

 number of years was confined to orange growing ahnost exclusively, 

 grapefruit production not having reached a figure of any importance 

 until 1907. The early exportations were from seedling trees growing 

 in groups, or as scattered specimens through the upland coifee dis- 

 tricts of the Island, where they were used to a considerable extent for 

 shading the coffee, fruit production being a secondary consideration. 

 Limes and lemons existed as individual trees for a home supply only, 

 and the grapefruit was practically unknown. 



Once initiated, the planting of citrus groves, for the most part 

 limited to several varieties of oranges, w^as taken up rapidly, and 

 before many years extensive groves were in existence along the north 

 coast between Carolina and Arecibo. For a number of years atten- 

 tion was concentrated on the orange, but the grapefruit rapidly 

 came into favor, so that for the past few years practically nothing 

 but the latter fruit has been set in new groves, or extensions of 

 old ones. 



^Moreover, the practice of budding over orange to grapefruit has 

 been common, so that at the present time the production of grape- 



' Tliis paper is based on the work carried on by the writer as jjart of his official dn- 

 ties over a period of nearly four years. Acknowledgment is made of assistance received 

 >jQ to Mr. R. C. Rose, assistant pathologist now on leave for war service; to Mr. W. V. 

 Tower, formerly director, for encouragement at all times; to the citrus growers of the 

 Island wlio have shown all possible courtesies in the course of the field work; and to the 

 Porto Rico Fruit Exchange, which has given most substantial assistance to the project. 



7.1 order that the greatest possible amount of information on the various diseases 

 •aig'.it be presented to the growers, the publications of the experiment stations of Florida 

 and California, and of the United States Department of Agriculture, as well as other sources, 

 have been drawn upon, where the matter contained was applicable to local conditions. 



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