FusARiA OF Potatoes 



179 



4-septate, 3 per cent 



5-septate, 21 per cent, 48 x 4.3ju (sickle-shaped) 

 6-septate, 1 per cent, 55.5 x 4.55^1 (sickle-shaped) 

 7-septate, 0.5 per cent, 69 x 5)U (sickle-shaped) 



In the case of this organism, the average percentage of septation of 

 conidia is of no value because of the great diversity of the forms occurring. 

 Therefore it is a safer basis to consider each stage (sporodochial and from 

 aerial mycelium) by itself separately. 



Fig. 21. — Fusarium arthrosporioides var. asporotrichius. a, Aerial conidia from 7 -days-old 

 culture on hard, lima-bean agar loith 2 per cent glucose; b, sporodochial conidia from 82-days- 

 old culture on potato tuber plug; c, d, conidiophores, from 11 -days-old culture on slightly acidified 

 hard potato agar; e, aerial conidia from 25-days-old cidture on potato tuber plug; f and g, conidio- 

 phores, H, pseudopionnotal conidia, from 11 -days-old culture on slightly acidified hard potato 

 agar; i, conidia from 68-days-old culture on red raspberry cane plug; j, arthrosporium-like, 

 K, normal, conidia from aerial mycelium from H-days-old culture on hard lima-bean agar; 

 L, aerial conidia from 36 -days-old culture on rye grain; M, sporodochial conidia from 14-days- 

 old culture on hard lima-bean agar 



24. Fusarium arthrosporioides var. asporotrichius n. var. (Figs. 1,r and 

 s, and 21 ; PI. vii, fig. 9) 



This fungus is very much the same as F. arthrosporioides, but differs 

 from the latter by typical absence of sporotrichial sporodochia and by 

 more pronounced and common production of from medium to large 

 (up to 3 millimeters in diameter) sporodochia with sickle-shaped, 5-sep- 

 tate conidia, 51.2 x 4.3 (46-59 x 4. 15-4.7) /x, as dominant type. 



