APPENDIX 



AN OUTBREAK OF THE EUROPEAN CURRANT RUST 



(Cronartium Ribicola Dietr.) 



Reprinted from Technical Bulletin No. 2 of the New York 

 Agricultural Experiment Station at Geneva; W. H. Jordan, 

 Director. 



By F. C. Stewart. 



CIRCUMSTANCES ATTENDING THE DISCOVERY. 



While passing the currant plantation on the Station grounds 

 September 26, 1906, the writer observed an unusual appearance 

 of the foliage on some plants. Upon plucking one of the leaves 

 for examination we were astonished to find the under surface 

 yellow with a rust. Even to the unaided eye it was evident that 

 the rust belonged to the genus Cronartium and upon miscroscopic 

 examination in the laboratory it proved to be Cronartium ribicola 

 Dietr., a currant fungus of common occurrence throughout Europe 

 but hitherto unknown in America. 



The plantation in which the rust was found is one devoted to 

 the testing of varieties. It contains about 175 plants and includes 

 51 different varieties representing three species; viz., Ribes 

 nigrum, R. rubrum, R. aureum. Most of the plants were set in 

 the spring of 190.'], being transplanted from another plantation 

 about forty rods away. The remainder of the plants were .set 

 in the spring of 1901. They varied in height from two to five feet. 



Of the 54 varieties, 48 were more or less rusted while the other 

 six were free from rust. The several varieties of black currants, 

 Ribes nigrum,, were most affected — Monarch, Clipper and Star 

 being among the worst and having almost every leaf thickly cov- 

 ered with rust. In spite of this severe attack of rust the black 

 currants were in full foliage. Some of the red and white varieties, 

 R. rubrum, also were severely attacked, but most of them were 

 only slightly affected. The plants of this species had already 

 lost a considerable portion of their foliage from leaf spot, Srptoria 



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