258 



C. D. Sherbakoff 



absent; plectenchymic sporodochia often present; aerial mycelium well 

 developed; color of conidia from white to olive, of substratum from pale 

 yellowish to olive (on agar rich in glucose and on potato tuber plug). 



Hab. On rotted tubers of Solanum tuberosum, in Oregon, Idaho, and 

 California. 



F. radicicola differs from F. Martii and F. Martii var. viride by shorter 

 macroconidia; from F. Martii var. minus by absence of prominent plecten- 

 chymic sporodochia; and from F. striatum by well-developed aerial my- 

 celium and by typical absence of pseudopionnotes. 



Fig. 47. — Fusarium radicicola. a, Conidiophore, b, sporodochial conidia, from 67-days-old 

 culture on potato stem plug; c, aerial and pseudopionnotal conidia from 12-days-old culture 

 on hard lima-hean agar; d, conidiophore {magnification 250 times) from J^S-days-old culture 

 on rye straw; e, chlamydospores, f, aerial conidia, g, conidiophore {magnified 250 times), from 

 73-days-old culture on red raspberry cane plug; h, conidia from the surface of original stem- 

 end rotted potato tuber; i, conidia from J^S-days-old culture on rye straw; j, conidia from pseudo- 

 pionnotes in 7 -days-old colony in petri dish on hard 'potato agar; k, conidiophore from the sur- 

 face of original stem-end rotted potato tuber; l, aerial conidia close to substratum from 64-days-old 

 culture on hard lima-bean agar; m, chlamydospores produced in mycelium and conidia from 

 173-days-old culture on corn agar; N, conidia, o, spore ball, both magnified 250 times, from 

 3-days-old hanging drop culture in potato decoction in van Tieghem cell; p, chlamydospores 

 from 82-days-old culture on potato tuber plug; Q, conidia and conidiophores from 26-days-old 

 culture on oats 



Production of macroconidia in sporodochia was observed to be abun- 

 dant only under certain conditions (not well determined as yet), but 

 usually microconidia alone are the dominant type. The Oregon speci- 

 mens, from which cultures of the fungus were first obtained, showed a 



