I 



FusARiA OF Potatoes 123 



DICHOTOMOUS KEY TO THE SPECIES OF FUSARIUM AND FUSARIUM-LIKE 



FUNGI OF POTATOES 



Page 



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



b. Conidia tj'pically 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 typicallj' 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. a fine 126 



cc. Ventrally curved F. dimerum 127 



bb. Conidia typically three- or more septate 



c. Dorsiventrality slight Section Ventricosutn 128 



d. Chlamydospores terminal only F. cuneiforme 129 



dd. Chlamydospores terminal and intercalary F. ventricosum 128 



cc. Dorsiventrality distinct 



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

 dd. Conidia pedicellate, true pionnotes absent 



e. Conidia with gradually attenuated, pointed apex 



f . Conidia prominently broader in tlie 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 typicallj^ five-septate F. falcatum ^^3,t . fuscuvi 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; t.ypical 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. acuminatu7n 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. subulatum 147 



11. Sporodochia large, with plectenchymic base 



m. Six-septate conidia typically present F. efusum 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 



2' The term conidia is used here, in this key and elsewhere, in the sense of naacroconidia. 



