Fusaria of Potatoes 



229 



44. Fusarium trichothecioides Wr. (Figs 1, Ui and Vi, and 38; PI. iv, 

 fig. 8) 



Jamieson, C. O., and Wollenweber, H. W., Journ. Washington Acad. 



Sci. 2:146-152, fig. 1. 1912. 



Syn. Fusarium tuberivorum Wilcox and Link, Nebraska Agr. Exp. Sta., Research bul. 

 1 : 48. 1913. 



Conidia of comma and discolor 

 types the former predominating 

 and under ordinary cultural con- 

 ditions occurring almost exclu- 

 sively, mostly 1-septate, 16 x 4.6 

 (14-17 x 4.2-5.4) n, often 0- to 

 3-septate, seldom 4- or 5-septate, 

 6-septate rare; sporodochial co- 

 nidia sickle-shaped, 3- to 5-sep- 

 tate, 24-42 x 4.5-5.5m- 52 Typical 

 conidiopho es of comma stage 

 shown in figure 38. Sporodochial 

 conidiophores similar to those of F. 

 discolor. F. trichothecioides can be 

 recognized at once by color and 

 appearance of its powdery masses 

 of spores produced on aerial myce- 

 lium (PI. iv, fig. 8). Chlamydo- 

 spores few and not prominent. 



Hah. On rotted tubers of So- 

 larium tuberosum, United States. 



This species is noticeably dif- 

 ferent from all other species of the 

 section Discolor. It is listed 



Fig. 38. — Fusarium trichothecioides. a, Conidia 

 from ^1-days-old culture \on rye straw; b, 

 conidia from 70-days-old culture on potato 

 stem plug; c, conidia from 73-days-old culture 

 on red raspberry cane plug; d, conidia from 

 15-days-old culture on slightly acidified hard 

 potato agar; e, chlamydospore in conidium 

 from 73-days-old culture on red raspberry 

 cane plug; f, conidiophores (magnified 250 

 times) from 70-days-old culture on potato stem 

 plug; e, conidiophores from 15-days-old culture 

 on slightly acidified hard potato agar; h, 

 conidia from 5-day s-old culture on hard lima- 

 bean agar; i, comma, J, discolor, type of co- 

 nidia from 5-days-old culture on potato tiber 

 plug 



Perhaps it should be made 



under this section chiefly because 



of its resemblance in the sporodochial form. 



the type of a new section. 



The organism, under the name F. tuberivorum Wilcox and Link, was 



" The size of 3- to 5-septate conidia is as given by Wollenweber. The writer isolated this Fusarium 

 from specimens of rotted potato tubers received from North Dakota in July, 1912, and from Texas in 

 December, 1913. No special study of this organism was made at first, because it is easily recognizable 

 even after a superficial examination, and also because its description as given by Wollenweber (see Jamieson 

 and Wollenweber, 1912) is entirely sufficient for its identification. 



