14 BULLETIN 727, U. S. DEPARTMENT OF AGRICULTURE. 



The presence or absence of setae in the acervuli has played a major 

 role in the generic nomenclature of this fungus, since the presence 

 of setae forms the basis for the distinction between Colletotrichum 

 and Gloeosporium. Kriiger, in the publication above quoted 

 (28, p. 299), faces this question as a general theme for the two genera 

 of fungi. Miss Stoneman (50) had previously noted the sudden 

 appearance of setae in cultures of Gloeosporium fructigenum, and 

 Kriiger had also observed this phenomenon in his cultures of the 

 above and other Gloeosporia. 



Frank (19) had noted occasional lack of setae in Colletotrichum 

 lindemuthianum and Miss Stoneman had noted the same in cultures 

 of three species, including Colletotrichum lagenarium. Potebnia 

 (38) later noted the occasional lack of setae in some acervuli of the 

 latter fungus. Kriiger (28, p. 299), working with the fungus of bean 

 anthracnose, confirmed Frank's observation and claimed to have 

 developed at will setose and nonsetose strains. He found that the 

 age of the culture and the nature and moisture content of the sub- 

 stratum acted as controlling factors and concluded that the presence 

 or absence of setae can not be depended upon as a decisive generic 

 distinction in this group of fungi. Kriiger urges the necessity of 

 some other basis of differentiation, such as cultural characters. 



Shear and Wood (45) in 1913 divided the anthracnoses of 45 hosts 

 into five species, of which three are Glomerellae and two are Gloeo- 

 sporia. Of the latter, one is 67. lagenarium (Pass.) Sacc. and Roum. 

 on watermelon, cucumber, and squash. In the whole group of 

 fungi studied they noticed (45, p. 64) that there was great variation 

 as to the presence, absence, and abundance of setae in cultures from 

 the same host and even from the same spore. They also noticed that 

 there was variation in size, length, and septation of setae. In the 

 form from cucumber they noted setae sometimes present in culture, 

 and in the form from watermelon setae were abundant in lesions and 

 in culture. Setae were sometimes present in squash lesions. 



Carsner 1 in 1914, using a strain isolated from a muskmelon fruit, 

 found no setae present and was inclined to retain the name Gloeo- 

 sporium. 



Eriksson (16, p. 125) studied the fungus causing the disease on 

 greenhouse cucumbers in Sweden, found setae present, and as a result 

 of a rather careful review of the literature retained Halsted's name, 

 Colletotrichum. 



To sum up the situation relative to the nomenclature of this fun- 

 gus, we have difficulties arising from several sources: (1) Synonyms, 

 of which Colletotrichum oligochaetum Cav. is an example. (2) Fungi of 

 uncertain identity, such as Gloeosporium orbicula^e Berk, and Volu- 

 tcUa citrulli Stoneman. (3) Halsted's theory that the bean and cucur- 



I Carsner, E. Op. cit. 



