Sept, i, 1921 
Transmission of Some Wilt Diseases in Seed Potatoes 83 7 
Table IV. —Transmission of organisms from seed potatoes to yields in six varieties , 
season of igiy a 
Organisms iso¬ 
lated from seed 
potatoes. 
Num¬ 
ber 
of 
hills. 
Tubers in yield from which were isolated— 
Totals. 
Verti¬ 
cillium 
albo- 
atrum. 
Fusa¬ 
rium 
radicx- 
cola. 
Fusa¬ 
rium 
oxyspo¬ 
rum. 
Other 
Fusa¬ 
rium 
species. 
Miscel¬ 
laneous 
fungi. 
No 
organ¬ 
ism. 
Verticillium albo- 
airum. 
325 
29.7 
48 
4.4 
17 
1. 6 
28 
2. 6 
360 
32.9 
316 
28. 9 
1,094 
100 
Fusarium radici- 
cola. 
21 
3 
2. 1 
13 
9.0 
5 
3 - 5 
2 
1.4 
67 
46.5 
54 
37 - 5 
144 
100 
Fusarium oxy¬ 
sporum. 
146 
IOI 
9 - 7 
89 
8.6 
39 
3-8 
19 
1.8 
346 
33-2 
447 
42.9 
1,041 
100 
Other Fusarium 
species. 
16 
8 
7.0 
3 
2. 6 
5 
4-3 
20 
17.4 
79 
68. 7 
115 
100 
Miscellaneous 
fungi. 
M 3 
X 3 X 
13-3 
39 
3-9 
4 
•4 
27 
2.7 
293 
29. 7 
493 
50.0 
987 
100 
None. 
• 
204 
18. 9 
42 
3-9 
17 
1. 6 
3 i 
2.9 
3 i 7 
29.4 
466 
43-3 
x , °77 
100 
Totals. 
628 
772 
17-3 
234 
5-3 
82 
1.8 
112 
2.5 
1,403 
3 i -5 
1.855 
41. 6 
4.458 
100 
oln ea eh box the upper set of figures shows the number of tubers which in culture gave the results indi¬ 
cated in the headings of the intersecting columns; and the lower right set of figures gives the percentage 
this number is of the total tubers represented in the horizontal column. 
Similarly Fusarium oxysporum occurred somewhat more abundantly 
in yields grown from known F. oxysporum infected tubers than it did in 
those grown from tubers not known to be infected with this fungus, 
though in some cases the differences were very slight. For instance, 
3.8 per cent F. oxysporum infected tubers came from seed known to be 
infected with F. oxysporum , whereas 3.5 per cent, almost as much, came 
from seed tubers which cultures had indicated to be infected only with 
F . radiciola when planted. It is true with F. oxysporum also that in 
practically every lot of potatoes cultured it was secured from at least a 
few tubers, even though it was apparently not present in the seed potatoes, 
indicating that it came from the soil and may be rather commonly dis¬ 
tributed. This is in agreement with the findings of other workers (j, 6 ). 
The small amount of wilt (Pi. 140, B) caused by this fungus in western 
Oregon and the low transmission from the seed potatoes to the yields, 
which was rather unexpected, is thought to indicate that this disease is 
