10 
It is certain that our common scab is much more common and 
disfiguring throughout the United States than it is in Europe, and 
the injuries caused by the fungus Ehizoctonia to potatoes in the West 
are greater than any reported from Europe. 
COMPARISON OF POWDERY-SCAB INJURIES. 
Common scab produces a roughened spot or pockmark on the 
tuber, which in its worst stage mar cover the whole potato. Under- 
neath the scab spots, however, a cork layer is formed and the potato 
remains sound. It is not more subject to decay than other potatoes, 
and the actual injury from a food standpoint is due to the greater 
loss m peeling before cooking. 
Powdery scab in its milder form causes no greater outward disfigu- 
ration than common scab, but there is less of a cork layer formed 
and a progressive decay frequently follows. The cankerous stage of 
powdery scab is more objectionable than any phase of common scab 
and is as bad as the wart disease. Finally, no means of controlling 
powdery scab through the disinfection of seed potatoes, as practiced 
for common scab, has proved wholly satisfactory. 
All these considerations led the Department of Agriculture to the 
conclusion that measures for preventing the introduction of powdery 
scab into the United States were not only fully justified, but were 
demanded by every rule of prudence and precaution. 
Most foreign countries have long since wisely adopted a simdar 
procedure with reference to American potatoes, mainly on account 
of the Colorado potato beetle. Canada maintains a complete em- 
bargo against all European countries, and most of the English 
colonies restrict the importation of potatoes to a greater or less extent 
on account of the wart disease and other troubles. 
OTHER REASONS FOR POTATO REGULATIONS. 
Experience gained in the enforcement of the potato quarantine 
order of September 20, 1912, and further investigations of potato 
diseases and insect enemies have shown that more efficient and log- 
ical means are required for the adequate protection of this country 
against the potato parasites of the world. 
Where a quarantine is laid against a whole country on account of 
an infection limited to a small portion of that country, the justice 
of the act is questioned by residents of the disease-free districts, yet 
there has been no means of limiting quarantines by other than national 
boundaries except through the active cooperation of the foreign 
government. - 
Where a quarantine is laid against one country and not against 
another concerning a commodity like potatoes, which is a staple ar- 
.; 
