WHITE-PINE BLISTER KUST. 



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 Ribes, and the removal of the diseased plants or parts of them. 



QUARANTINE. 



In North America (131, p. o4-oo), 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 

 wath 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 uninfectod sections. The 

 quarantine line estabUshcd 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 



