208 JOURNAL OF AGRTCULTURE OF P. R. 



BUCKSKIN OR SHARK SKIN. 



Buckskin is a disease -of the epidenu or outer skin of the fniit 

 only. The outer layer of cells is killed and takes on a character- 

 istic gray, scaly appearance. The entire surface of the fruit is in- 

 volved. An affected fruit ceases to grow and in addition to a very 

 thick rind is generally lacking in juice so as to be of no economic 

 value. ]\Iost affected fruit fail to reach any considerable size. 

 Buckskin is readily distinguished from rust-mite injury, tear stain- 

 ing, melanose, and similar injuries to the surface by the fact that 

 it covers the fruit uniformly, is light in color, and comparatively 

 smooth to the touch. 



It is more common on lower branches or in the center of the 

 tree. The amount present varies greatly from year to year, being 

 very abundant one season and entirely lacking the next. Tn some 

 cases spraying with Bordeaux mixture has apparentl}^ increased the 

 amount, and in others has been reported as preventing it. It is al- 

 together probable that several causes operate to produce the same 

 effect. Those suggested have been the combined action of mites and 

 surface-growing fungi, and the alternation of periods of drouth and 

 heavy rainfall. 



SMOKY FUNGUS (Lepiothyrium sp. ?) 



This fungus is of comparatively common occurrence, particularly 

 on the orange, but is, as a rule, overlooked by the grower. It forms 

 irregular and often very extensive patches on the surface of the 

 fruit. The fungus growth is confined, for the most part, to the re- 

 gioiis between tin oil cells, dimming the color of the fruit, and giv- 

 ing rise to the common name. Because of this scanty hal)it of growtli, 

 it has generally been considered as dust only. The brushes in the 

 packing houses generally eliminate it sufficiently well, so that there 

 is no loss through lowering of grades. Where lime-sulphur is used 

 in the grove, this fungus will be siLfficiently well controlled. 



MINOR DISEASES AND DEFECTS. 



Many minor diseases and blemishes occur on the fruit, leaves, 

 and twigs, but all are either of so slight importance as to wai-rant 

 no control measures, or are checked by operations designed to pre- 

 vent more important troubles. 



