16 
BULLETIN 957, IT. S. DEPARTMENT OF AGRICULTURE. 
Inoculations of Cronartium ribicola 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 fungus 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 blister 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 controlle'd 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 
