8 Research Bulletin No. g 



it as a new species. He told the writer in 1013 that he felt con- 

 vinced that we had described one and the same thing. Comparative 

 studies made by the writer during the past year verify this point of 

 view, and since the Nebraska publication by Wilcox, Link, and 

 Pool (40) did not appear in print until 19 13, the name F. tricho- 

 thecioides should be adopted. 



Wollen weber (4 1, 42) published a further paper in which he 

 categorized the Fusarium spp. very sharply, dividing the genus 

 into sections on the basis of physiological (that is, pathogenicity) 

 and morphological (that is, conidia and chlamydospores) characters. 

 F. oxysporum was again established and taken as the representative 

 of the section Elegans, which comprises vascular parasites; and 

 F. trichothccioidcs was put into the section Discolor, which com- 

 prises parenchyma destroyers. He distinguished sharply between 

 these and also between the vascular ring-discoloring Fusarium 

 species of section Elegans and the tuber-rotting Fusarium species 

 of sections Discolor, Gibbosum, Martiella, etc. 



Referring to the papers by Smith and Swingle (35), Manns 

 (24), and others, particularly to that by Manns, he writes: "They 

 do not separate fusarioses causing tuber rot from those causing both 

 the wilt diseases of the plant and ring discoloration of the tuber, 

 so that the reader might conclude that both wilt disease and tuber 

 rot are caused by the same organism." Referring to his own experi- 

 ments, he writes: "It also brings out the striking fact that the 

 fungus, a typical xylem inhabitant, does not entirely destroy the 

 tuber without the help of tuber rot Fusarium or bacteria," and 

 " the fact that F. oxysporum causes the wilt of growing potato plants 

 and only uses the xylem of the stem end of tubers for over-wintering, 

 without producing a rot of the parenchyma, leads to interesting 

 comparisons with the following 4 species which are able to destroy 

 the tuber entirely from artificial wounds, namely, F. coeruleum 

 (Lib.), F. trichothccioidcs Wr.," etc., and finally "the fact that the 

 latter (F. oxysporum) cannot produce a tuber rot gives a biological 

 contrast to the wound parasites of the tuber, and the fact that they 

 cause the wilt disease of the growing plant presents a contrast to 

 the saprophytes." 



