652 THE FUNGI WHICH CAUSE PLANT DISEASE 



conidia on short conidiophores; microconidia continuous, elliptic; 

 macroconidia falcate-fusoid, 3 to 4-septate, 40-60 x 7-8 n. 



Smith and Swingle ^^ mention 11 described species of Fusarium 

 recorded by Saccardo for the Irish potato, viz.; 



Fusarium oxysporum Schl., F. (Fusisporium) solani (Mart.) 

 Sacc, F. (Fusisporium) solani-tuberosa Mart., F. didymum 

 Harting, F. solani Schl., F. (Fusisporium) roseolum (B. &. B.) 

 Sacc, F. violaceum Fcl., F. casruleum (Lib.) Sacc, F. diplosporum 

 C. & E., F. commutatum Sacc, F. pestis Sorauer, F. seruginosum 

 Delacroix, F. acuminatum E. & E., F. affine Fautr. & Lamb, all 

 of which they tentatively regard as synonyms, attributing such 

 differences as have been noted in descriptions to variations in the 

 environment under which the fungus was growing when described. 

 The potato disease caused is common over a considerable portion 

 of the United States and is variously known as "bundle blacken- 

 ing," "stem rot," "dry end rot," and "dry rot." 



The fungus grows readily on manj'^ culture media, showing large 

 variation with the envirorunent. It is aerobic and tolerates large 

 amounts of malic, citric and tartaric acids. 



F. acuminatum E. & E. Sporodochia gregarious, minute, whitish 

 or flesh-colored; conidia falcate, attenate, 3 to 5 or 6-septate, 

 not constricted. 



Described by Stewart ^ as causing a girdling of potato stems in 

 New York. 



F. roseum-lupini-alba Sacc. 



Sporodochia pulvinate, minute, confluent, cinnabarine; co- 

 nidiophores variable, long, slender, branched, branches nodulose, 

 fusoid; conidia fusoid falcate, 45-55 x 4 ju, 4 to 6-septate. It 

 causes spots on leaves and pods of lupines and attacks the seeds, 

 inducing rot. 



F. cucurbitarise Sacc. is on cucumbers in Queensland. 



F. solani (Mart.) Sacc. 



Sporodochia globose, irregular, white; conidiophores branched;' 

 conidia fusoid-falcate, 3 to 5-septate, 40-60 x 7-8 ii, subhyaline. 



Clinton,^'* also Wehmer '«* and others, have shown this to be 

 the cause of "dry end rot " of stored potatoes. It may be iden- 

 tical with F. oxysporum. 



F. pestis Sor. is given by Sorauer as the cause of "black-leg" 



