Fusarium in Tuber Rot and Wilt of Potato 11 



The first inoculations were made in December 1914. The cut 

 ends of 20 Early Ohio tubers were wetted with spore suspensions 

 of F. trichothecioid.es and 5 tubers were kept as controls. Four 

 inoculated and one control potato were kept in each compartment 

 at a temperature of 25 1 ' C. in an almost saturated atmosphere. 

 After 4 weeks all of the inoculated tubers were in advanced stages 

 of rot. 



On January 31, 3 potatoes were inoculated according to the 

 second method with / ; . oxysporum, and 3 with /■'. trichothecioides, 

 and kept at 20 C. until February 17. .Two of the former set were 

 slightly rotted and one totally, while the entire latter set was rotted 

 severely. The controls showed no rot i fig. 1 ). 



On January 15 another series was started which was kept at a 

 temperature ranging from 15-20° C. until February 15. Six sets 

 of 3 tubers each were started and each set was kept in a separate 

 sterile chamber. 2 tubers of each set being inoculated by smearing 

 cut surfaces with agar grown inoculum. Sets I, II. and III were 

 inoculated with /•". oxysporum, and sets IV, V, and VI with F. tri- 

 chothecioides. In set I, one inoculated tuber was rotted, while the 

 other and the control were sound; in set II. one was deeply rotted 

 and the others sound; in set III, one was deeply rotted and the 

 others sound; in set IV, two were rotted and the control sound; 

 in set V, two tubers were rotted slightly and the control sound; and 

 in set VI. two tubers were rotted and the control sound. 



F. oxysporum and F. trichothecioides were re-isolated from these 

 rolled tubers by placing tissue cut from such tubers on plated glu- 

 cose agar. Nothing other than the organism with which the tuber 

 had been inoculated developed. Inoculum from these plates was 

 used, in infecting tubers again with the same results. 



Since these results were at variance with the statements of 

 WoLLENWEBER the experiments were repeated with hundreds of 

 tubers, and the results were verified. 



Discussion. — Tubers inoculated with F. oxysporum did not 

 develop the ring discoloration that is considered characteristic of 

 the activity of /•'. oxysporum, but a general rot of the whole tuber. 

 Generally, however, this was not a dry rot, but a rot that resembles 

 more the soft rots of bacterial origin, although it is not accompanied 



