tends into the tissues a short distance only, rarely more than an eighth 

 of an inch. Rind disease very often completes the destruction of 

 the attacked stalk. 



Because of the fact that this fungus, a saprophyte only in other 

 parts of the world, was acting as a virulent parasite in l*orto Rico 

 towards several varieties, fears Avere entertained that it might become 

 epidemic. However, there has been in the past year no further spread 

 and it would appear that the disease had reached its limit. The sus- 

 ceptible varieties growing at Rio Piedras have been eliminated and 

 there are at present no signs of the fungus. A similar procedure 

 was recommended for the other localities know^l to be infected. 



Cytospora sacchari Butler. 



Stromata verruciform, arranged in rows, erumpent, pluiilocular^ 

 black, ostiole elongate, single, rarely double ; sporules minute, cylin- 

 drical, slighty curved, obtuse at both ends, 3.5X1-1.5 mu. ; basidia 

 branching, septate, 12-18 mu. Description after Butt<r. 



[^ORTO Rico.^On cane, Rio Piedras, Feb. 1912, 428(\ :\l;iy 24. 1912, 

 4352, Aug. 1912, 4335, July 10, 1912, 4656, Jan. 15. 1914, 1646. Oct. 

 1915, 3217: Carolina, Feb. 18. 1914, 1408; Fajardo. July 6. 1913, 

 4983. Aug. 4, 1913. 1012, Dec. 30, 1914, 2526. June 14, 1915, 2829, 

 Dee. 27, 1916, 5907. On leaf-sheaths, and stalks of living cane. PL 

 XXir, figs. 1. 2: pi. XXVTTT, figs. 1-4.) 



TOP-ROT. 



This is i\ t'Tiii that lias been employed to some extent in tiie litera- 

 ture and i.s used by a great many planters to indicate a diseased 

 condition oF tlie to]). Considerable attention has been given to this 

 disease in Porto Rico hut up to date it has not been possible to arrive 

 with any certainty as to the cause. When a stalk is badly injured 

 by the moth stalk-liorer. tlie top ultimately dies and in tlie rotten 

 mass at tlie center will be found small borers, fly larvae, etc. This 

 is the most common type of top-rot found in Porto Rico, and is ch^irly 

 due to the borer. It is, however, quite possible to find (le:i(i t<»ps or 

 ''dead hearts" as they are called locally, which do not show any 

 signs of in.sect work. In fact a former entomologi.st of this Station 

 in the course of his studies of Diatraca reported that a considerable 

 proportion of ''dead hearts" examined by him were not due to the 

 borer. Cultures of such cases have yielded bacteria and several types 

 of fungi, none of which have produced any results upon inoculation. 



The senior writer observed a plantation in Texas in whicii the 



198 



