238 BENT F. S0EGAARD 



PINUS PARVIFLORA SIEB. AND ZUCC, 



This species is native to Japan and the Korean island Utsuryo. It 

 is known in Europe as an ornamental tree and is common in many botanical 

 gardens outside its natural range. Its resistance to attack by C. 

 ribicola has not been investigated in Europe. Schenck (1939) mentions 

 the same level of resistance as shown by P. peuce . The species has been 

 grown since 1889 in Denmark without showing attack by C. ribicola. 



INTRODUCED WHITE PINES FROM NORTH AMERICA 



PINUS ALBICAULIS ENGELM. 



This species is native to western Canada, British Columbia, western 

 U.S.A., Washington, Oregon, California, Idaho, Nevada, Montana, and 

 Wyoming, at high elevations. It is highly susceptible to C. ribicola and 

 is seen very seldom in Europe, even in botanical gardens. 



PINUS FLEXILIS 



This species is native to western Canada and U.S.A., Rocky Mountains 

 from southern Alberta and British Columbia to northern New Mexico. In 

 Europe it is not found outside the botanical gardens. It is highly sus- 

 ceptible to attack by C. ribicola. Eighteen trees in the Arboretum were 

 heavily attacked and some were killed. In Norway (JOrstad, 1949), P. 

 flexilis is heavily attacked; however, in 1923, its susceptibility was 

 reported to be about equal to P. cembra. And a record from Lithuania in 

 1937 reports an attack on P. flexilis in the Kaunas Botanical Garden, 

 where a series of experiments was carried out from 1935 to 1938. 



PINUS LAMBERTIANA 



This species is native to western U.S.A. in the Coast Range and the 

 Sierra Nevada. It is, according to Schenck (1939), as susceptible as P. 

 strobus. A stand in Weinheim in Berckheimschen seemed to be more damaged 

 than P. strobus, which means that it was nearly as susceptible as P. 



monticola. 



PINUS MONTICOLA 



This species is native to western Canada and U.S.A., from southern 

 British Columbia to northern Idaho, northwestern Montana, and eastern 

 Oregon and south through the Cascade Mountains of western Washington and 

 Oregon to the southern end of Sierra Nevada in California. P. monticola 

 is as susceptible to C. ribicola as P. flexilis and P. albicaulis. Pinus 

 monticola has been tried in different European countries, mostly in parks 

 and botanical gardens. Hahn (1929) reports heavy attacks on P. strobus 

 and P. monticola in Scotland. In Denmark, in the Forest Botanical Garden 

 and in the Arboretum since 1937, P. monticola is still alive although 

 infected. 



