270 



THE MONTHLY BULLETIN. 



One of the most valued qualities of the tree was its apparent resistance to disease. 

 Forty to fifty years ago a disease of white pine seedlings, which affected the young 

 stem and killed the plants, was discovered abroad, without at the time causing much 

 alarm. It was not until much later, about the nineties of the last century, that 

 European foresters began to realize the importance of the disease. The nurseries 



Fig. 77. — White pine seedling infected with white pine blister rust 

 (Peridermium strobi). On the swollen stem the secia appear in shape of 

 white delicate bladders. The secia have broken open and are shedding 

 the seciospores. (Photo by C. R. Pettis.) 



suffered increasingly serious losses, and at the present day the cultivation of this 

 valuable tree has practically been discontinued in England, Holland and Denmark, 

 while in Germany and France it appears to be simply a question of time when white 

 pine will no longer count in the scheme of forestry. 



The origin of the disease is not definitely known. In all probability it is indige- 

 nous to western Siberia and eastern Russia, where it attacks the stone pine (Pinus 



