New York Agricultural Experiment Station. 233 



severe. On some of the affected black currant plants nearly every 

 leaf was thickly covered with rust. Outside the Station grounds 

 only a single affected leaf was found. This led to the suspicion that 

 the outbreak originated on the Station grounds. As the few five- 

 leaved pines in the immediate vicinity of the Station appeared 

 healthy, attention was directed to Eriksson's theory. It was sus- 

 pected that the fungus had been introduced with some Ribes plants 

 imported by the Station from England two years earlier. Accord- 

 ingly, the entire plantation was dug up and burned in an attempt 

 to eradicate the disease. 



During 1907 and 1908 no trace of Cronartium was seen. In Sep- 

 tember, 1909, after a very thorough search, a single affected leaf 

 of red currant was found in a plantation one-half mile west of the 

 Station. During 1910 none was found. 



In August, 1911, a second outbreak occurred on the Station 

 grounds in a currant plantation set out in 1908 and 1909. These 

 were all native plants. A few black currant plants were attacked 

 severely and several varieties of red currants, also, showed some 

 infection. This time the affected plants were not destroyed and 

 no attempt was made to determine if neighboring plantations were 

 affected. 



In the autumn of 1912 there was an epidemic of the currant rust 

 at Geneva. It occurred on black currants in nine nurseries and ten 

 fruit gardens. In a nursery one-half mile north of the Station almost 

 every leaf on 15,000 black currant plants was affected. One of the 

 affected currant plantations was located about five miles southwest, 

 another five miles northwest and a third about two miles northeast 

 of the Station. These were the outposts of the disease. See 

 Map 1. 



During the six years intervening between the outbreaks of 1906 

 and 1912 the senior author had inspected, repeatedly, many pine 

 trees in the vicinity in an attempt to locate the source of infection. 

 Moreover, since 1909 the nursery inspectors located at Geneva had 

 been constantly on the lookout for diseased pines. Nevertheless, 

 none were discovered and the origin of the outbreaks of felt-rust 

 remained a mystery. The failure to find any affected pines becomes 

 more significant when it is stated that the number of five-leaved 

 pines growing in the vicinity of Geneva is small. A few miles north 

 of Geneva there is a large natural grove of white pine, but the fact 



