532 Journal of Agricultural Research voi. xii, no. 9 



to retain their form, leaving but one immature conidium on the sterigma 

 tip, as in Verticillium. 



Furthermore, in the genus VerticilHum, characterized by singly borne 

 or readily separating conidia, we have the anomalous condition of a 

 section of the genus set aside for those species in which the conidia are 

 held together by slime — that is, section Gliocephalum ^ Saccardo (1886). 

 This section of the genus accommodates forms in which the conidia are 

 united in slimy heads — that is, Acrostalagmus. 



The fact that the work of Reinke and Berthold {22) was so generally 

 overlooked is responsible for the confusion of the genera Verticillium and 

 Acrostalagmus. These investigators studied A. cinnaharinus, on which 

 Corda established his genus Acrostalagmus, and concluded that this 

 form genus must be united with the older genus Verticillium Nees. 

 They changed the name of Corda's fungus to Verticillium cinnaharinum. 

 In view of the above, there seems to be no doubt that the genus Acro- 

 stalagmus Corda should be united with the genus Verticillium Nees. 

 Klebahn {14) supports this view. 



The species of Acrostalagmus, described as causing a vascular disease 

 of ginseng, China aster, and black raspberry, may prove upon further 

 work to be identical with each other and with V. alho-atrum, as proved 

 in this paper, for the strains of the latter fungus isolated from okra, 

 cotton, eggplant (Solanum melongena), and potato. Culturally, at least, 

 the strains of the species of Acrostalagmus from ginseng and raspberry, 

 in so far as they have been studied by the writer, are not to be dis- 

 tinguished from Verticillium alho-atrum. The organisms A. vilmorinii 

 Gueguen and V. dahliae Klebahn, as described by their authors, hardly 

 differ sufficiently from V. alho-atrum to be given specific rank. Possibly 

 this is the better treatment of such related forms until their identity 

 is established by careful cross-inoculation work with pure cultures. 

 The minor cultural differences found by the writer in cultures of V. 

 alho-atrum from different hosts are present in parallel cultures of the 

 same strain. Strains of V. alho-atrum which are morphogically indis- 

 tinguishable, isolated from different hosts, and capable of producing 

 the same s)Tiiptoms of disease by cross-inoculation, seemingly should 

 be considered identical. 



The available data on the several strains of Verticillium and Acro- 

 stalagmus thus far described as plant parasites are brought together in 

 tabular form (Table I), in order that comparison may be readily made. 

 The hypothetical identity of all of these strains, suggested by the simi- 

 larity of this data, is strengthened if one consults and compares the 

 descriptions by the several authors. The existing differences seem to 

 be those of variety rather than of species. 



1 Saccardo's section Gliocephalum of the genus Verticillium (Saccardo, P. A. svxlogb funoorum. 

 V. 4, p. 139. Patavii, 1886) is given as Gliocladium by Engler and Prantl (1900) apparently through error. 

 (Engler, A.,andPRANTi„K. naturlichen PFLANzeNFAMHiEN. Teil I, Abt. I**, p. 418,432. Leipzig, 

 1900.) 



