48 JOUENAL OF AGRICULTURE C)F P. R. 



warrant its publication, and that it may serve as a bgsis for futnn' 

 work by pointing ont the problems yet unsolved. 



GENERAL CONSIDERATIONS. 



Before taking up the specific diseases, there are certain general 

 considerations which will be treated in some detail, since they are 

 of the utmost importance to the growei'S. These, in brief, arc the 

 relation of cultural practices to health and disease in the grove, and 

 general account of methods of control and prevention. 



It is most difficult to draw a line between health and disease in 

 plants. In a broad sense a tree may be said to be sick or diseased 

 when it departs from the normal, but here again the difficulty is en- 

 countered of determining just what constitutes a normal tree. The 

 normal of certain groves would in others be considered as decidedly 

 abnormal. Without attempting to settle the question, consideration 

 will be given tg such a])normalities or injuries as are capable of caus- 

 ing, either directly or indirectly, financial loss by cutting down yield 

 or rendering fruit unsalable. 



Disease in a broad sense may be due to any one of a great variety 

 of causes, principal of which, as far as the present subject is con- 

 cerned, are those due to fungi, insects, cultural conditions, and 

 physiological or unknown causes, the last so intimately connected 

 with the preceding point as to be hardly separable. Insect injuries, 

 while serious, are excluded from this paper, their study coming in 

 the field of entomology. Bacterial diseases, though serious in other 

 regions, are fortunately as yet unknown, or of negligible importance, 

 in Porto Rico. A detailed exposition of the specific deseascs due 

 to fungi or to unknown causes will constitute the body of this paper. 



This leaves for consideration at this point the important topic 

 of the effect of cultural practices on disease. This will be of par-- 

 ticular value at this time, when so many of the groves are suffering 

 from an apparent decadence, although still comparatively young. It 

 is the writer's belief that the cause for this condition lies in neglect 

 or faulty application of the points about to be considered. 



RELATION OF CULTURAL PRACTICES TO DISEASE. 



Many growers fail to realize the effects, both direct and indirect, 

 that cultural practices (cultivation in a broad sense) can have ju 

 the general health of their groves, and the resulting amount and 

 character of the fruit produced. There are indeed several common 

 diseases, of no little importance, which are directly accounted for by 



