A destructive disease of white pines known as the white-pine blister rust has 

 been introduced from Europe and seriously threatens our white pines. It also 

 attacks the leaves of wild and cultivated currants and gooseberries and spreads 

 for long distances on them. Look for it on pines in May and early June; on cur- 

 rants and gooseberries from June until the leaves are shed. It appears as shown 

 in the colored figures of Plate I. 



Explanation of Plate I. A, A diseased white-pine tree with the blisters 

 broken open, spreading the disease to any currants or gooseberries that 

 may be in the vicinity; B, early summer stage on the lower surface of a 

 currant leaf, repeating on currant leaves during the rest of the season, 

 a new crop of spores appearing every two weeks; C, early summer 

 stage much magnified ; D, late summer and fall stage on the lower sur- 

 face of a currant leaf, spreading the disease back to neighboring white 

 pines. 



Figure 4 (on p. 4) indicates the course of the disease from pine to currant (a to 

 6), from currant to currant (6 to c and d), and from currant back to pine (d to a). 

 The complete circuit from pine back to pine takes one year, but the disease may 

 not develop visibly on the newly attacked pine for a period of several years. 



Copies of this publication may be secured free, on application to the United States 

 Department of Agriculture for Farmers' Bulletin 742. 



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