We used chi-square analysis (Snedecor 1956) to test for independence of selected comparisons 

 of spore type, spore source, and temperature for inoculation success and presence of teliospores. 

 In addition, the pattern of subculture age at teliospore appearance was recorded for all cool 

 chamber aeciospore lines that produced three subcultures. 



RESULTS 



As expected, the single aeciospore isolates placed in tlie cool chamber provided a higher 

 success rate than tliose placed in the warm chamber (table 1). But the warm chamber isolates 

 developed slightly faster. All the infections that appeared by 65 days were evident in 14 

 days in the warm chamber; but cool chamber infections were not evident until the 21 day inspectior 



There was a significant difference due to temperature in teliospore production by 49 days 

 by aeciospore cultures (table 2) . The cool chamber isolates showed a significant increase in 

 percent producing telial columns. 



Table I. --Percent of single aeciospores of Cronartium ribicola that produced infections 

 on leaf disks of Ribes hudsonianum var. petiolare within 21 days when grown 

 in a cool and a warm chamber , both under 16 hr days 



Chamber temperature 



Infections 

 Yes Xo 



Total 



Percent 



55°F+2 (13°C+1) 



86 



443 



529 



16 



70°F+2 (21°C+1) 



35 



494 



529 



7 



Total 



121 



937 



1058 



11 



= 24.28 P of larger = 0.0005 



d.f. = 1 



Table 2. --Percent of single aeciospore cultures of Cronartium ribicola that produced 

 teliospores by 49 days after inoculation when grown on Ribes hudsonianum 

 var. petiolare INT Clone-1 at cool and warm temperatures under 16 hr days 





Tel iospores 







Chamber temperature 



Yes 



No 



Total 



Percent 



55°F+2 (13°C-1) 



43 



39 



82 



52 



70°F+2 (21°C+1) 



o 



13 



15 



13 



Total 



45 



54 



97 



46 



X^ = 7.75 P larger x^ = 0.01 



d.f. = 1 



3 



