192 



Journal of Agricultural Research 



Vol. V, No. s 



days at average temperatures of 19.7° and 20.4°, respectively. Seven 

 reisolations were identified. 



F. hyperoxysporum 3399; isolated from Ipomoea batatas from Lincoln, 

 Ark., by Mr. L. L. Harter. Determined by Miss Ethel C. Field and the 

 author. Culture used for inoculation, 20-day-old cotton stem. As 

 given in Table II, after 51 days' incubation at an average temperature 

 of 21.5°, the results were as follows: Of the four inoculated tubers of 

 each of the varieties Idaho Rural, Netted Gem, Burbank, and Pearl 

 o, I, I, and 4 tubers were rotting, respectively. The organism was 

 recovered by four isolations. 



F. hyperoxysporum 3489; reisolation of strain 3399. Culture used for 

 inoculation, 8-day-old potato cylinder and rice culture. This strain was 

 considerably more active than the parent strain 3399. All tubers were 

 rotted after an incubation of 25 days at 23.5°. Six reisolations were 

 made. 



Table II gives the results of the inoculations with F. hyperoxysporum. 



Table II. — Results of the inoculation of different varieties of potatoes with original and 

 reisolated strains of Fusarium hyperoxysporum 



Variety of potato. 



Incubation 

 period. 



Average 

 temperature. 



Percentage 

 of tubers 

 rotting. 



3273 • 



3343>3273- 



3399- 



3489>3399 . 



Days. 



Green Mountain 



Idaho Rural 

 Netted Gem 

 Burbank. . . , 



Pearl 



Idaho Rural 

 Netted Gem 



Burbank 



Pearl 



Burbank. . . 

 Netted Gem 

 Pearl 



16, 

 17' 

 17 

 18. 



25-7 

 19.7 

 19.7 

 4 

 4 

 5 

 5 

 5 

 5 

 5 

 5 

 23-5 



100 

 100 

 100 



100 

 100 

 100 

 100 

 o 

 25 

 25 

 100 

 100 

 100 



> = reisolation of. 



Fusarium vasinfectum Atk. — Inoculations were made with F. vasin- 

 fecium isolated from cotton and a similar organism from okra to determine 

 whether this species, which is closely related to F. hyperoxysporum, 

 w^ould cause a decay of potatoes. Although considerable decomposition 

 occurred in the inoculated tubers, a scrutiny of the data summarized 

 below reveals the nonconclusive nature of the results obtained. 



F. vasinfectum 1855; reisolated by Dr. Wollenweber, in December, 

 1912, from the vascular system of a cotton plant wilting as a result of 



