reason why it should be less destructive in America should it he- 

 come established here. Indeed, it may become even more de- 

 structive. It has not infrequently happened that a parasitic fun- 

 gus introduced into a new country has become more virulent in 

 its attack and caused greater damage than in its native country. 

 There is also the possibility that it may extend its list of host 

 plants. In Europe it is known to attack only four species of 

 Pinus; viz., P. strobus, P. cembra, P. lambertiana and P. monil- 

 cola, all of which bear their leaves in clusters of five. 



TREATMENT. 



Since it is probable that pine trees and Kibes plants are both 

 necessary to the perpetuation of the Cronartium, the destruction 

 of all specimens of either of these two kinds of host must result in 

 the extermination of the rust. Accordingly, the principal 

 method of control recommended by European writers is the de- 

 struction of which ever of the two hosts is the least valuable. 

 Wherever there is danger of the disease, currants or gooseberries 

 should not be planted near white pines. 



It is possible that on currants and gooseberries the rust might 

 be controlled by spraying with bordeaux mixture, but no experi- 

 ments have been made. On the Station grounds one application 

 of bordeaux mixture made as soon as the fruit had set apparently 

 had no effect on the rust. 



BIBLIOGRAPHY OE CRONARTIUM RIBIOOLA AND 

 PERIDERMIUM STROBI. 



With the appearance of Cronartium ribicola in this country 

 there is likely to come renewed interest in it. In order to facil- 

 itate the labors of American mycologists who wish to examine 

 the literature of the subject, the following *biblography has been 

 compiled. It is not quite complete and several of the articles 

 have not been seen by the writer. By far the most important of 

 the references given in Klebahn's book, Die wirtwechselnden 

 Rostpilze, which contains an authoritative resume of the whole 

 subject with numerous citations of literature. 



* For Bibliography see Technical Bulletin No. 2 referred to. 



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