INSECTS, DISEASES, AND INJURIES 



155 



Cronartium rihicola, Fischer, which is a most formidable 

 enemy of the white pines (i. e., those in which the needles are 

 in fascicles of five). Without doubt all 

 five-needled pines are liable to be at- 

 tacked if exposed to the pathogen. The 

 fungus was first found in North Amer- 

 ica at Geneva, New York, in 1906, but 

 it is probable that it was present for 

 some years prior to that date. Until the 

 summer of 1921 it was confined to New 

 England, New York, and the Lake States 

 where it has caused very serious losses 

 on the eastern white pine (Pinus Strobus) . 

 In spite of all efforts to prevent its 

 spread to the valuable stands of western 

 white pine (P. monticola) and sugar pine 

 (P. Lamhertiana) in the Western States, 

 the disease was discovered in western 

 British Columbia and in northwestern 

 Washington in 1921. 



In addition to the five-needled pines, 

 the fungus also attacks wild and culti- 

 vated species of currant and gooseberry. 

 Although all species of Ribes are more 

 or less susceptible to attack, the culti- 

 vated black currant (Ribes nigrum) 

 takes the disease most severely. The 

 currant and gooseberry are known as "alternate hosts," in- 

 asmuch as the fungus must pass a portion of its life upon 

 one of these before fresh pines can become infected. 



Pines of all ages are susceptible to the disease. The fungus 

 gains entrance at the bases of leaf-fascicles or directly through 



White pine with bHster- 

 rust. 



