16 BULLETIN 951, U. S. DEPARTMENT OF AGRICULTURE. 



Inoculations of Cronartium ribicoJa on Ribes. 



In 1888, Klebahn (63, 64) made the first known successful inocu- 

 lations of this fungus on Ribes. Since that time a number of inocu- 

 lations have been made in Europe by Klebahn (65, 66, 67, 68, 69, 

 70), Wettstein (70), Rostrup (118, 119, 120), Sch(/>yen (124), Eriksson 

 (31, 33), Tubeuf (167), Hennings (53), Sorauer (129), Tranzschel 

 (92), Neger (100), Ewert (36, 37), Naumann (36), and Jaczewski 

 (58, 59). The published accounts of most of these experiments are 

 very fragmentary and lack many essential details. In fact the 

 attitude of the European investigators seems to have been that of 

 mild interest in a new fmigus rather than that of intensive study of 

 a new parasite and of the destructive disease caused by it. 



Fig. 12. — Outline map of the northeastern part of the United States, showing (by black dots and cross 

 hatching) the known distribution of white-pine bhster rust in North America to and including 1918. For 

 distribution to the end of 1919, see figure 2. 



Since the summer of 1909 the writer and his collaborators have 

 made repeated tests under controlled and natural conditions of all 

 species and of all varieties of the cultivated species of Ribes that 

 could be obtained. In the earlier work complete records were not 

 kept, but in the last few years the records were made to cover all points 

 likely to be of value. Hundreds of inoculations have been made on 

 the more susceptible species to keep the fungus growing in vigorous 

 condition, without records being made. It was felt that green- 

 house tests alone were not dependable for susceptibility data. 

 Therefore, in 1916, a test plat was located upon Block Island, R. I. 

 This island lies 12 miles from the nearest projecting point of the 

 mainland and 15 miles or more from the main shore line. No white 

 pines are on the island and but few cultivated Ribes. It was chosen 



