ribis. One variety of R. aureum (Jelly) showed traces of rust. 

 Four varieties of R. rubrum (Prince Albert, Gondouin White, 

 Stultz and an unknown variety) and two varieties of R. aureum 

 (Crandall and Utah Golden) were entirely free from rust. 



The infested currant plantation was adjoined on the west by a 

 plantation of goseberries containing many different varieties. 

 Only one variety (Pearl) was affected and this hut slightly. 



In another part of the Station grounds, near the Director's 

 residence and about forty rods east of the infested plantation, 

 there are planted sixteen different species of Ribes, including R. 

 aureum, but neither R. nigrum nor R. rubrum. Of these only 

 one species, R. irriguum, was affected. There were two plants of 

 R. irriguum and both were severely attacked. 



DESCRIPTION OF THE FUNGUS. 



The fungus Cronartium ribicola was first described and named 

 by Dietrich fifty years ago. It appears during the summer and 

 autumn as a conspicuous orange-colored powder on the under sur- 

 face of the leaves of various species of Ribes (currants and goose- 

 berries). Two forms of spores, uredo- and teleutospores, are pro- 

 duced on Ribes leaves. The uredospores are ellipsodial to ovoid, 

 19-35 x 14-22 M with orange-colored contents and borne in sori 

 forming pustules. The teleutospores are elongated, unicellular 

 and massed together into peculiar orange-colored columnar pro- 

 cesses which attain a maximum length of about two millimeters. 

 These processes are usually curved. To the unaided eye they ap- 

 pear like coarse, yellow plant hairs, hence the German name 

 "Filzrost" (felt-rust). 



Another form (the aecidmm form) of the currant rust fungus 

 occurs on the trunks and branches of Pinus spp., especially the 

 white pine, Pinus strobus, producing a disease called blister rust 

 (Blasenrost of the Germans). The pine-inhabiting form was first 

 described by Klebahn in 1887 as a distinct species and by him 

 named Peridermium strobi. Subsequently, through inoculation 

 experiments made by Klebahn and others, it was conclusively 

 proven that Cronartium ribicola on the currant and Peridermium 

 strobi on the pine are not separate species but only different stages 

 of one and the same fungus. 



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