centimeter long by four to six millimeters wide. Spots due to Hel- 

 minthosporium are generally larger, more irregular, and more numer- 

 ous. The spots rarely coalesce as mentioned by Butler, nor does the 

 leaf appear to die prematurely. Spores are produced on the under 

 surface, and are typical. A second conidial (pyenidia) stage de- 

 scribed by Butler has not been found in Porto Rico. It has been 

 collected on two varieties only, Otaheite and P. R. 217. Other than 

 from Porto Rico this disease has been reported only from British 

 India by Butler (10). 



Cercospora longipes Butler. 



Elongate spots on both sides of the leaf, often confluent, at first 

 red, drying to a straw color with a brown ring; liyphae collected in 

 gregarious heads, and generally on the under surface of the leaf, 

 flexnons. brown, above geniculate or denticulate, 100-20 X 4 mu., coni- 

 dia obclavate, tapering upward, straight or curved, 4-6 septate, 

 40-80 X 5 mu. Description after Butler. 



Porto Rico. — On living cane leaves, Rio Piedras, Feb. 10, 1914, 

 1641, March, 1917, 6315. Not common. (PI. XXXI, fig. 11, 12.) 

 Original determination by J. A. S. 



RED STRIPE of THE LEAF. 



This disease is characterized by a reddening of the midrib, which 

 may vary in length from a mere spot to almost the entire length of 

 the blade. The stripes may be continuous or as is a very marked 

 characteristic at times may occur in sections of varying length with 

 apparentl}^ normal areas between. In advanced stages the center 

 of the stripes on the upper surface becomes a dull brown and fruiting 

 pustules will be found. (PI. XXV, fig. 6.) 



The injury due to this disease is neglible under Porto Ricau con- 

 ditions, but Edgerton (2'5) has demonstrated that in Louisiana the 

 red stripe characteristically gives Colletotnchum falcatum when cul- 

 tured, and may be taken as an early symptom of infection of tlie 

 plant by this fungus. Stevens of Florida corroborated Edgerton 's 

 findings. For this reason some studies have been conducted to ascer- 

 tain the significance of red stripe in Porto Rico. 



These liave been carried out by isolations from red stripe specimens, 

 by inoculations, and re-isolations. A number of different fungi have 

 been encountered in the course of this work, mostly forms of Cnllcio- 

 irichum. 



In a series of isolations commenced October 1, 1912, four of nine 

 tubes yielded a form called Collet otrichum C and one tube Collcio- 

 trichum. A. Those remaining were discarded because of contamina- 



205 



