the lower part ; spore masses inconspicuous, pink ; no setae known ; 

 spores varying" in shape from cylindrical to falcate; in size from 

 3.4-10.2 mu. or to 25.5 mu. in length, or 5.2 to 22.1 ; from 1-eelIed 

 to 3-eelled. (Plate XXVIII, fig. 15.) 



This variation in septation ni^turally throws this fungus out of 

 the genus CoUetofrichum but as its manner of growth and spore forma- 

 tion is typical of ColletotricJium it is here considered in this group. 



COLLETOTRICHUM B. 



]\Iycelial growth in cultures scanty, white, cottony, spore masses 

 conspicous, pink ; spores cylindrical, rounded at both ends, 3.4—5.1 X 

 13.6-14.4 mu., spore formation typical of the genus, setae not seen. 

 (PI. XXVIII. fig. 18-20. 



COLLETOTRICHUM C. 



Found on the cane in the field as well as on cane in damp cham- 

 bers ; profuse cottony white growth in cultures ; minute slightly 

 pinkish spore masses arising from tiny black spots on midrib or blade 

 of leaf; setae absent or commonly present, straight or flexuose, aver- 

 aging 80 mu. long ; spores thick, falcate, averaging 6.8 X 17 mu. 

 (PI. XXVIII, fig. 10-12.) 



The above data combined with the fact that red rot has never 

 been found in connection with red striping at any stnge of growth 

 renders the latter worthiness as a means of diagnosis of the former 

 disease in Porto Eico. 



WITriERTI]\ 



This disease is, as its name indicates, characterized by a withering 

 of the tip of a green leaf or the margin of the leaf. The aifected 

 portion becomes brown and dead, and on it appears one or more 

 fungi. Hormiacfella is common in such cases. In addition, the form 

 of Collet oiriclunn described above as CoUetotrichum C, is common; 

 as well as Periconia sacchari, and Spharrella saccJiari. 



Under ordinary conditions these fungi may be found on almost 

 any withered leaf. In 1913, a case was noted at Naguabo in which 

 D-625 was severely affected by wither tip at about eight months of 

 age, a very unusual circumstance, but other than these fungi nothing 

 could be found to account for the condition. The plants w-ere all 

 well rooted, w^ere not unusually affected by insects, and seemed to 

 be green healthy plants excepting for the tips of the leaves. 



Cobb (15) described a similar disease from Hawaii and figured 

 setae and spores Mdiich correspond to those of HonniacteUa, but with- 

 out suggesting a name. 



207 



