Nov. t, 1915 
Potato Tuber-Rots Caused by Fusarium Spp . 
191 
Burbanks were rotting after incubation for 25 days at 23.5 0 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 
reisolated strains of Fusarium oxysporum 
Strain No. 
Variety of potato. 
Number of 
tubers. 
Incubation 
period. 
Average 
temperature. 
Percentage 
of tubers 
rotting. 
Days . 
°C. 
'Jersey Peachblow, . 
4 
19 
23. I 
100 
Idaho Rural. 
18 
19 
23. I 
100 
2 997 . 
Early Rose. 
5 
19 
23. I 
IOO 
People's. 
5 
19 
23. I 
IOO 
Jersey Peachblow. . 
4 
19 
23. I 
IOO 
Idaho Rural. 
17 
19 
23. I 
IOO 
2 999 . 
Early Rose. 
6 
19 
23. I 
IOO 
People’s. 
6 
19 
23. 1 
IOO 
Netted Gem. 
9 
21 
25.6 
IOO 
304 . 3 '> 2 QQ 7 . 
Idaho Rural. 
21 
21 
„r fx 
IOO 
People's. 
7 
21 
j* ^ 
25. 6 
IOO 
Idaho Rural. 
A 
VI 
20. 4. 
IOO 
3 ° 45> z 997 .•' 
Netted Gem. 
Burbank. 
4 
A 
O i 
37 
20. 4 
20 . 4 
IOO 
IOO 
Pearl. 
4 
0 f 
37 
20. 4 
IOO 
Green Mountain_ 
z 
5 1 
17. 8 
0 
104.8 . 
.... do.. 
1 
18. 4 
TOO 
_do. 
10 
24 
24. 6 
IOO 
_do. 
1 
51 
x 7 .8 
IOO 
2413. 
_do. 
1 
Si 
18. 4 
IOO 
-do. 
10 
14 
25 - 7 
IOO 
(Burbank. 
10 
25 
23- S 
50 
3395 > 24 i 3 . 
Netted Gem...._ 
19 
25 
23 - 5 
95 
Pearl. 
17 
25 
* 3 - 5 
IOO 
> =* reisolation of. 
Fusarium Wollenw.— F. hyperoxysporum 3273; 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 io-day-old potato cylinder. 
After 14 days’ incubation at an average temperature of 25.7 0 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 0 . 
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 37 
