Nov. 15, 1925 
Longevity of Teliospores of Groruirtium ribicola 
907 
found best for scraping the columns from the leaves to the surface of 
water in small glasses containing 10 to 35 c. c. each, according to their 
size. The telial columns for each glass of water were taken from all 
of the leaves of a given sample. The leaves should be slightly damp 
so as to be pliable without breaking, but not wet enough so that the 
knife edge will scrape water from the leaf tissue, as this will wet the 
columns and they will sink in the water when dropped on the surface 
of it. When they sink they germinate little or not at all, as is true of 
rust spores in general ( 1, 2, 3, 7, 10, 11, lJf). But if dry, they will 
float readily and for a long time. 
/SOULS' 
Fig. 1.—Diagram showing time necessary in* preliminary tests for the germination of telial columns of 
Cronartium ribicola. The curves are based on 3-hour moving averages, and represent the per cent of 
the total number of telial columns germinating. The solid line represents the results from telial columns 
produced on Ribes nigrum stored indoors 5 days. The dash line represents those from R. americanum 
stored indoors 15 days. The dotted line represents those from R. nigrum stored indoors 25 days 
f 
LENGTH OF THE GERMINATION PERIOD 
The teliospores were germinated outdoors, shielded from sun and 
rain, for a period of 16 to 18 hours. Under the conditions of this 
work, this length of time was necessary for the maximum amount of 
germination to take place. This period was unexpectedly long in 
comparison with 6 hours required in previous years to germinate 
freshly matured teliospores {22, 17). 
Some tests were made to determine the hourly germination of 
telial columns which had been stored for various lengths of time. 
Table III and Figure 1 give the results of these tests. The writers’ 
experience shows plainly that the time necessary for germination 
increases directly with length of time of storage in a dry condition. 
