842 
Journal of Agricultural Research 
Vol.XXI.No.ii 
albo-atrum. In most cases it has been encountered attacking only 
scattering plants in the field and does not cause nearly so much damage as 
the other wilt organism. Only two fields—one in Lane County and the 
other in Multnomah County, both of western Oregon—have so far been 
reported to or seen by the writer where this fungus was recognized as 
causing a high percentage of disease. In the former field about 10 per 
cent and in the latter about 30 per cent of the plants were affected. The 
reason for these high percentages of infection in these two fields was not 
apparent. 
One test was made at Corvallis in 1917, to determine the influence of 
this disease on the yield. One lot of seed potatoes was inoculated at 
planting time in the 
same manner as in the 
test with Verticillium 
albo-atrum noted above 
and the otlier was left 
uninoculated as a con¬ 
trol. The disease did 
not develop sufficiently 
in the inoculated plot 
to reduce the yield in 
the least, which was in 
considerable contrast 
to the action of V. albo- 
atrum. For where this 
fungus was used 99 per 
cent of the plants 
wilted during the sea¬ 
son and 49 per cent of 
the tubers were infected 
by the same fungus 
when cultured after 
harvest, but where Fu- 
sarium oxysporum was 
used less than 5 per cent of the plants showed wilt and only 6 per cent 
of the tubers wer* infected by this same fungus when harvested. Ac¬ 
cording to all available information this disease must be considered of 
relatively minor importance in western Oregon. The data at hand do 
not justify any definite conclusions as to its importance in the eastern 
part of the State, where it may prove to be more serious. 
There are areas in the Pacific coast and mountain States where the 
Fusarium-wilt is without doubt a factor of considerable importance in 
potato growing. The Plant Disease Survey (12) has published estimates 
showing losses in these States in 1917, ranging from 1 to 30 per cent and 
Fig. 7. —Map of eight western States, showing graphs of the production of 
potatoes in the different States in 1917 and the losses caused from wilt 
due to Fusarium oxysporum. The black area of the graph shows the 
loss from Fusarium-wilt; the white area, the production of potatoes; 
and the entire area, the production of potatoes if there had been no 
loss from Fusarium-wilt. 
