840 
Journal of Agricultural Research 
Vol. XXI, No. II 
from which no specimens have been secured. The data presented here 
must, therefore, be considered incomplete. The status of these diseases is 
better known in western Oregon, the region west of the Cascade Moun¬ 
tains, than it is in the central and eastern portions. 
Verticillium albo-atrum has been found in 16 counties, which embrace 
most of the important potato-growing areas of the State (fig. 5). It is 
widely distributed and of common occurrence at least in western Oregon, 
and every season causes an appreciable loss in many fields. The highest 
percentage of plants wilted from this fungus found in any commercial 
field was 30* The more usual amounts found are from 5 to 7 per cent. 
In the work on certification of potatoes in 1918, Verticillium-wilt was 
Fig. 5.—Map of Oregon, showing the localities where Verticillium albo-atrum has been collected on pota¬ 
toes during the past few years. 
the second factor in the order of importance in causing the failure of 
fields entered to pass the inspections. In this certification work or in 
any seed plot improvement work it is very necessary, therefore, to give 
due consideration to the nature of the disease and to the ways in which 
it is disseminated. 
The yields of plants affected with Verticillium-wilt are usually greatly 
reduced, which may be indicated by a few specific examples. 
Two plots of potatoes consisting of 73 hills each were grown in 1917 to 
test the influence of Verticillium-wilt on the yields produced. The seed 
tubers used were produced by apparently wilt-fr£e plants and gave 
Verticillium albo-atrum in no case in cultures made before planting. 
They were each cut in two lengthwise, one half being planted in one plot 
