Sept, i, 1921 
Transmission of Some Wilt Diseases in Seed Potatoes 839 
Nevertheless, the results so far as they go are in agreement with the 
findings of Pethybridge (9) in Ireland, who has demonstrated that this wilt 
fungus is not localized at or near the stem end of affected tubers. There 
is, therefore, no particular value in the attempt to avoid Verticillium- 
wilt in seed potatoes by discarding the stem ends and planting only 
the eye ends of tubers suspected of containing this wilt fungus. Reliance 
for the control of this disease should rather be placed on other methods 
which have been demonstrated to be effective. 
Table \ .—Transmission of organisms from, different portions of the same seed tubers 
and from whole seed tubers to the tubers yielded by six varieties, season of IQIJ 
Origanism isolated from 
seed potato. 
Number 
of seed 
pieces 
planted. 
Percentage of same organisms in yields as was present in the 
seed potato according to kind of seed piece used. 
Stem 
pieces. 
Eye 
pieces. 
One 
longitudinal 
half. 
Other 
longitudinal 
half. 
Whole 
tubers. 
Verticillium albo-atrum . . 
Fusarium radicicola . 
Fusarium oxysporum .... 
151 
21 
I46 
22. 7 
12. 9 
2.9 
24. 6 
4-3 
2.3 
17.4 
4 . 5 
7 - 7 
20. 5 
5 * 9 
5-8 
35 
14. 7 
3-8 
Fusarium radicicola occurred noticeably more in the yields from the 
stem pieces than from the eyepieces, 12.9 per cent and 4.3 per cent, 
respectively. The number of seed pieces planted containing this fungus 
were so few that definite conclusions can not be drawn, and the differences 
noted might not hold true in an examination of a larger number of cases. 
Fusarium oxysporum was transmitted to such a small extent in any 
of the potatoes experimented with that it is difficult to judge whether 
the stem-end pieces tend generally to give more disease than the eye-end 
pieces. A few tubers, though, apparently gave striking evidence of this 
tendency (PI. 139, C). For instance, one infected tuber gave 75 per 
cent infection in the yield from the stem-piece plant and no infection 
in that from the eye-piece plant;- another gave 33 and 14 per cent, and 
another gave 10 and o per cent, respectively. The average results, 
however, do not point strongly in this direction, and it is apparently 
true with this organism also that the practice of discarding the stem 
ends of seed potatoes is not a reliable method for the control of the 
disease and ought to be abandoned in favor of other more effective 
methods. 
DISTRIBUTION AND IMPORTANCE OF VERTICILLIUM ALBO-ATRUM 
FUSARIUM OXYSPORUM, AND FUSARIUM RADICICOLA IN OREGON 
Although there has been no opportunity to make a systematic survey 
of these potato diseases in the entire State of Oregon, a number of 
scattered collections have been made in different regions and many 
specimens have been sent in by growers and by county agricultural 
agents. There remain sections, however, where potatoes are grown and 
