WHITE-PINE BLISTEE RUST. 
81 
with other species, (6) by the judicious selection of planting sites for 
pines, and (7) by such minor methods as spraying, close pasturing 
of Kibes, and the removal of the diseased plants or parts of them. 
QUARANTINE. 
In North America (131, p. 54-55), Canada took the first official 
action against the white-pine blister rust, placing it on her list of 
proscribed plant diseases and later prohibiting the entry of all 
5-leaved pines from 
all other countries. 
Since then (2) a quar- 
antine has been de- 
clared against the 
shipment of Ribes 
from points east of a 
line between Saskat- 
chewan and Alberta 
to points west of that 
line. The shipment 
of Ribes to points 
west of this line is 
allowed from points 
in the United States 
south of the above 
protected area. 
These modifications 
are made to help 
protect the western 
white-pine area from 
the shipment of this 
disease in nursery 
stock, and to connect 
with the Mississippi 
Valley quarantine 
line in the United 
States, which has 
been established 
Fig. 13.— Outline map of North America, showing the quarantine 
lines established by the United States Department of Agriculture to 
control the white-pine blister rust by prohibiting the shipment of the 
host plants from infected territory to uninfected sections. The 
quarantine line established by Canada to prevent the shipment of 
diseased nursery stock across the prairie region from the eastern 
Provinces is also shown. 
with this end in view (fig. 13). The United States Government in 
1912 (94) put in force a regulatory act controlling the entry and 
movement of nursery stock. This act prohibits the entry of 5-leaved 
pines and of Ribes from Europe, Asia, and Canada; forbids the 
shipment of such stock from the eastern section of the country to 
points west of the western boundaries of the States of Minnesota, 
Iowa, Missouri, Arkansas, and Louisiana; and also forbids the 
46103°— 21— Bull. 957 6 
