New York Agricultural Experiment Station. 007 



As the currant drops its leaves in the fall, it has generally been 

 believed that the plant retains no fungus fruiting bodies in the spring 

 which can infect either currant or pine; but that new outbreaks of 

 the currant rust must again originate in the pine blister-rust fungus. 

 But outbreaks of currant rust on the Station 

 Mysterious grounds, first in 1906 and again in 1911 and 1912, 

 outbreaks. cast some doubt on the assumption that the fungus 



cannot pass the winter on the currant and renew 

 the disease there without the intervention of the pine blister-rust 

 form. Quite careful search had failed to reveal the disease on pine 

 trees anywhere near the Station or near other currant plantations 

 about Geneva, in which the felt-rust had appeared. 



This was a rather serious matter; for if the fungus can remain 

 alive on the currant over winter it would be unsafe to ship currant 

 plants from any rust-infected section. The risk to the, pine would 

 be too great. 



To test the possibility of this overwintering and 

 Fungus reinfection of currant in the spring from the felt- 



does not rust form of the fungus, about 500 yearling plants of 



survive black currant were dug in November, after the 



winter on leaves had fallen, from a nursery near Geneva in 



currant. which practically every leaf had shown the disease. 



These were distributed to various students of 

 plant disease, widely separated over the northeastern United States, 

 and were, after a season of rest, brought into greenhouses and forced 

 into growth. In no case did the disease reappear. 



This was true, also, in those cases where an attempt was made to 

 spread the infection by means of the fallen leaves. Many of these 

 leaves were saved and kept outdoors in wire baskets until spring, 

 when they were brought into the greenhouses and used to inoculate 

 the currant plants growing therein. No disease resulted, although 

 every condition was made favorable for germination of the fungus 

 spores if any living ones had been present. The same plants, or 

 others under the same conditions, took the disease very readily 

 when inoculated from the fruiting bodies of the fungus found on 

 pine trees. 



For, after very careful search by nursery inspectors 

 Diseased of the State Department of Agriculture, two such 



pines found. diseased trees were finally found, at quite a distance 

 from the Station, it is true, but in such a position 

 that it was possible to trace to them, through intervening currant 

 plantations, the origin of the very puzzling outbreaks previously 

 observed on the Station grounds and elsewhere. After the greenhouse 

 experiments failed it became morally certain that there must be 

 some such trees; and the nursery inspectors determined to examine 

 every five-leaved pine anywhere in the vicinity of Geneva. The 

 two found were in a bunch of eight culls left in the nursery block 



