WHITE-PINE BLISTER RUST. 11 
nartium ribicola attacked Ribes aureum and R. odoratum after they 
reached Europe. Their susceptibility also indicates that they are 
not original hosts of the fungus. 
Summing up the evidence available, it appears (1) that Cronarlium 
ribicola is Asiatic in origin; (2) that it spread in the early 1800's 
into western Russia, whence it eventually spread well over Europe 
(41) ; (3) that it was brought to North America in young trees of 
Pinus strobus; and (4) that comparative studies (50) show that 
Cronartium occidentale is distinct. 
HOSTS OF CRONARTIUM RIBICOLA. 
Pines Infected and Likely to Become Infected. 
Cronartium ribicola has attacked 11 of the white pines in the 
countries, Provinces, and States indicated in the following list : 
Pinus aristata Engelmann in England (20a). 
ayacahuite Ehrenb. in Scotland and England. 3 
cembra L. in Russia (58, 93), Switzerland (39, 40, 123, Germany (72, 77, 174, 177), 
U. S. A. (Mass., Minn.). 4 
excelsaWall. in Denmark (120), Germany (99), U. S. A. (Mass.). 
fiexilis James in Germany (173), Sweden, 5 U. S. A. (Mass., Minn., Iowa). 
koraiensis Sieb. and Zucc. in Sweden. 5 
lambertiana Douglas in Belgium (101), Germany (62, 173). 
monticola Douglas in Belgium (101), England (79), Germany (70). 
parviflora Sieb. and Zucc. in U. S. A. (Mass.). 
pence Gris. in Germany (173). 
strobus L. in Austria-Hungary (178), Belgium (70), Denmark (81, 115, 117, 119, 
120), Finland (54, 83), Switzerland (40), France (70), Germany (70), Great 
Britain (111), Holland (70), Ireland (42), Norway (70), Russia (27, 58, 120), 
Siberia (161), Sweden (131 5 ), Canada— Ontario (23, 56) and Quebec (107, 
121), U. S. A. (Conn., Ind., Iowa, Maine, Mass., Mich., Minn., N. H., N. J., 
N. Y., Ohio, Penn., R. I., S. Dak., Vt., Va., Wis.). The fungus has occur- 
red in a number of these States only on diseased pines shipped from outside 
points. 
In every case the disease attacked these pines naturally in out- 
break areas of Europe and North America and is not known to attack 
any of the pitch pines, although some of them have been present in 
infected areas. Whenever the other white pines are continuously 
exposed to the fungus they will be likely to develop the disease. The 
blister rust was first found on the different species of pines as follows : 
Pinus strobus. Russia in 1854. Pinus ayacahuite. Great Britain in 1908. 
lambertiana. Germany in 1887. fiexilis. Germany in 1914. 
cembra. Russia in 1890. pence. Germany in 1914. 
monticola. England in 1898. parviflora. United States in 1916. 
excelsa. Denmark in 1902. koraiensis. Sweden in 1920. 
aristata. England in 1907. 
3 Communicated in a private letter from Dr. A. B. Borthwick, of Scotland. 
4 The statements concerning occurrences in North America are based on records and specimens in the 
Office of Investigations in Forest Pathology. 
ft Trivate letter from W. Stuart Moir, Office of Blister- Rust Control. 
