72 U.S. DEPT. OF AGRICULTURE MISC. PUB. 939, 



The resistance of different pine provenances against snow-blight 

 attacks. Experiments, conducted in a special "snow-blight nursery," 

 consisting of fastening snow-blight mycelium to pine seedlings of vari- 

 ous origins, show that plants of a northern provenance are more re- 

 sistant to snow blight than those of a southern provenance — a result 

 agreeing with old observations of spontaneous attacks in pine cultures. 

 According to Langlet (1936), there is an apparent connection in the 

 way that needles on plants of northern origin with a higher dry sub- 

 stance (and sugar content) are not attacked to the same degree as 

 needles on plants of a more southern origin with lower dry substance. 



Literature : 



Bjorkman, E. Studies on the biology of the Phacidium-blight 

 {Phacidium infestans Karst.) and its prevention. Medd. Stat. 

 Skogsforskn. inst. 37. 1948. 



Faull, J. H. A fungus disease of conifers related to the snow 

 cover. Jour. Arnold Arboretum 10. 1929. 



Langlet, O. Studien uber die physiologische Variabilitat der Kief er 

 und deren Zusammenhang mit dem Klima. Beitrage zur Kenntnis 

 der Okotypen von Pinus silvestris L. Medd. Stat. Skogsf ors. anst. 

 29. 1936. 





