New York Agricultural Experiment Station. 239 



not start into growth until about February 15. Their slowness in 

 starting appears to have been due to their not having had a suffi- 

 ciently long period of rest. However, once started, they made a 

 vigorous, normal growth. They were kept under observation until 

 May 7, but no Cronartium appeared upon them. Neither did any 

 appear on the 12 black currant plants which Dr. Stone sent us from 

 Ipswich, Mass. These latter were two-years-old plants which had 

 been affected with Cronartium in the outbreak at Ipswich in the 

 autumn of 1912. 4 They were planted in the greenhouse January 

 6, began to put out leaves January 28 and were under observation 

 until April 17. 



INOCULATION EXPERIMENTS AT GENEVA. 



When it became evident that the Cronartium would not reappear, 

 a series of inoculation experiments was undertaken with affected 

 currant leaves wintered out-of-doors in wire cages. The previous 

 autumn these leaves had been thickly covered with Cronartium 

 which was mostly in the telial stage. They were brought into the 

 laboratory, March 27, and allowed to dry. They were then ground 

 into fine powder which was made into thin mush by stirring in a 

 quantity of water. 



Experiment No. 1. — On April 1 a quantity of the currant-leaf 

 mush was applied to the leaves of four of the currant plants by means 

 of a paint brush. The plants were small ones with new shoots 6 

 to 10 inches long and 20 to 30 leaves each. Every leaf was coated 

 with the inoculating material on the upper surface and some, also, 

 on the lower surface. After inoculation the plants were covered 

 for 48 hours with bell-jars lined with moistened filter paper. During 

 daylight the plants were shaded by covering the bell-jars with 

 burlap. The leaves were damp all the time and during the last 24 

 hours most of them showeu a row of water drops around the margin. 



Experiment No. 2. — On April 4 four more plants were inoculated 

 as in Experiment No. 1. 



Experiment No. 8. — On April 7 four more plants were inoculated 

 as in the preceding experiments except that the bell-jars were left 

 over the plants for 72 hours. The leaves were still wet when the 

 bell-jars were removed. 



4 Stone, G. E. A new rust. Mass. Sta. Rpt. 25:41. 1913. 



