FusARiA OF Potatoes 125 



hh. Conidial masses of pale orange to dark chocolate-red in color, my- 

 celium from nearly slightly pinkish to dense carmine red 



i. Conidia much broadened toward apex F. clavatum 234 



ii. Conidia not or only slightly broadened toward apex 



j. Average diameter '1 five-septate conidia from 4 to 4.4 M 



F. discolor 236 



jj. Average diameter of five-septate conidia from 5.8 to 6.8 M 



F. culmorum 240 

 ff. Substratum typically (on a neutral or not strongly acid glucose agar) 

 brownish gray, vinaceous red, vinaceou'? purple, or blue, but never 



carmine red Section Martiel a 244 



g. Macroconidia of even diameter or slightly broader toward apex 



h. Macroconidia comparatively' long and narrow (from 7.4 to 9.3 times 

 longer than broad) 



i. Average three-septate conidia from 37 to 49 M long F. Martii 244 



ii. Average three-septate conidia from 34 to 35 M long 



j. Pseudopionnotes on an agar typically present, aerial mycelium 



poorly developed F. striatum 255 



jj. Pseudopionnotes on an agar typically absent, aerial mycelium 



well developed F. radicicola 257 



hh. Macroconidia comparatively short and broad (only about 5.5 times 



longer than broad) F. Solani 251 



gg. Macroconidia typically somewhat broader tov,rard basal end 



F. coeruleum 260 



DESCRIPTIONS OF SECTIONS, GENERA, SPECIES, AND VARIETIES 



FUSARIUM Link 



Link, Mag. Ges. nat. Freunde 3:10. 1824. Saccardo, Syll. Fung. 

 4:694. 1886. (Cf. AppeL 0., and Wollenweber, H. W., Arb. K. biol. Anst. 

 Land- u. Forstw. 8:60-61. 1910. Wollenweber, H. W., Phytopath. 

 3:24-50, 197-240, fig. 1, Pis. i and iii. 1913; Ber. deut. Bot. Gesell. 31 :17- 

 34. 1913. Journ. Agr. Research 2:251-285. 1914.) 



Hyphomycetes, with from hyaline to bright, but never plain gray nor 

 black, conidia and mycelium; conidia sickle-shaped, septate (usually 

 3- or more septate), apically pointed, mostly pedicellate, not append) c- 

 ulate, noncatenulate; conidia scattered over substratum, in pseudo- 

 pionnotes or in sporodochia, the latter without or with from flat to wart- 

 like plectenchymic substratum, and always without any differentiated 

 enclosing or surrounding structures; conidiophores from simple to irregu- 

 larly verticillate. 



I. Section DiMERUM n, sec. 



Conidia dorsiventral, 1-septate; chlamydospores may be present. 



This section is proposed in order that Fusaria with 1-septate conidia 

 may be included. The two species of this section are comparatively 



