Fusaria of Potatoes 123 



dichotomous key to the species of fusarium and fusarium-like 



fungi of potatoes 



Page 



a. Conidia 37 not typically dorsiventral, apex rounded, apedicellate Ramularia 264 



b. Conidia typically one-septate 



c. Average diameter of one-septate conidia 4.9 M R. eudidyma 264 



cc. Average diameter of one-septate conidia 3.9 M R. Magnusiana 265 



bb. Conidia typically two-septate R. Solani 267 



aa. Conidia typically dorsiventral, apex more or less attenuate, mostly pedicellate 



FUSARIUM 125 

 b. Conidia typically one-septate, three or more septa never present. .Section Dimerum 125 



c. Ventrally straight F. affine 126 



cc. Ventrally curved F. dimerum 127 



bb. Conidia typically three- or more septate 



c. Dorsiventrality slight Section Ventricosum 128 



d. Chlamydospores terminal only F. cuneiforme 129 



dd. Chlamydospores terminal and intercalary F. ventricosum 128 



cc. Dorsiventrality distinct 



d. Conidia apedicellate, true pionnotes present. . Section Eupionnotes. F.udum 131 

 dd. Conidia pedicellate, true pionnotes absent 



e. Conidia with gradually attenuated, pointed apex 



f. Conidia prominently broader in the middle, apex long and narrow, most 



prominently pedicellate Section Gibbosum 133 



g. Dorsally more or less hyperbolic F. gibbosum 133 



gg. Dorsally more or less elliptic 



h. Aerial mycelium poorly developed, fruiting layers in form of a pseu- 



dopionnotes F falcatum 135 



hh. Aerial mycelium well developed 



i. Conidia typically five-septate F. falcatum var. fuscum 138 



ii. Conidia typically five- to seven-septate F. caudatum var. Solani 140 



ff. Conidia of about equal diameter for a more or less considerable part of 

 their length, apex not very lon^ 

 g. Conidia typically five-septate; typical color of conidial masses red, of 

 substratum pink to orange and brown-red; no terminal chlamy- 

 dospores 

 h. Chlamydospores absent 



i. Microconidia typically absent Section Roseum 142 



j. Blue sclerotia present F. acuminatum 142 



jj. Blue sclerotia absent 



k. Conidia typically in pseudopionnotes; aerial mycelium weakly 



developed or absent F. metacroum 143 



kk. Conidia typically in distinct sporodochia; aerial mycelium 

 well developed 

 1. Sporodochia small, borne on aerial mycelium and without 



plectenchymic base F. subulalum 147 



11. Sporodochia large, with plectenchymic base 



m. Six -septate conidia typically present F. effusum 151 



mm. Six-septate conidia typically absent 



n. Five-septate conidia dominant type F. lucidum 157 



nn. Three- and five-septate conidia about equally present, 



or three-septate dominant F. truncalum 155 



37 The term convlia is used here, in this key and elsewhere, in the sense of macroconidia. 



