Potato Tuber-Rots Caused by Fusarium Spp. 



91 



Burbanks were rotting after incubation for 25 days at 23.5° C. Four 

 reisolations were made. 



In Table I are given the results of inoculations with F. oxysporum. 



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

 rcisolated strains of Fusarium oxysporum 



Variety of potato. 



Number of Incubation 

 tubers. period. 



Average 

 temperature. 



Percentage 

 of tubers 

 rotting. 



2997. 



2999. 



3045>2997 • 

 304S>2997 , 



1948 



2413 



3395>24i3 



I Jersey Peachblow . 

 Idaho Rural 

 Early Rose 

 People's 



I Jersey Peadhblow . 

 Idaho Rural 

 Early Rose 

 People's 



I Netted Gem 

 Idaho Rural 

 People 's 



I Idaho Rural 

 Netted Gem 

 Burbank 

 Pearl 



I Green Moimtain. . 

 ....do 

 ....do 



f....do 



]....do 



I. ...do 



I Burbank 

 Netted Gem 

 Pearl 



Days. 



"C. 



23- 

 23- 



23. 1 

 23. 1 

 23. 1 

 23. 1 

 23. 1 



25. 6 

 25. 6 

 25. 6 

 20. 4 

 20. 4 

 20. 4 

 20. 4 

 17.8 

 18.4 

 24. 6 

 17.8 

 18.4 

 25-7 

 23- S 

 23- 5 

 23-5 



100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 



100 

 100 

 100 

 100 

 100 

 50 

 95 

 100 



> = reisolation of. 



Fusarium Wollenw. — F. hyperoxysporum 2>^7y, isolated in October, 

 1914, from a soft-rotting Irish potato from Ocean Springs, Miss. 

 (PI. XV, figs. 1,2.) Cultures used for inoculation, pionnotes on 56-day- 

 old culture on stem of Melilotus alba and a lo-day-old potato cylinder. 

 After 14 days' incubation at an average temperature of 25.7° C. all tubers 

 inoculated with this species were more or less wet-rotted about the inocu- 

 lation pricks and the lenticels, two tubers being completely softened. The 

 organism was recovered by four reisolations. Fifty-one days' incubation 

 at temperatures ranging from 16.3° to 18.4° gave a slight rot in all. A 

 gradual increase was observed with the increase in temperature. At 

 18.4° all were rotted, one being completely destroyed. Four reisolations 

 were made. 



F. hyperoxysporum 3343; reisolation of strain 3273, from rotting 

 Green Mountain potato tubers 15 days after inoculation at 25.7°. 

 Culture used, a 26-day-old stem of Melilotus alba with pionnotes. All 

 of the inoculated tubers of the four varieties Idaho Rural, Netted Gem, 

 Burbank, and Pearl were rotted after an incubation period of 28 and 2,7 



