Table 12. --Number of single aeciospore cultures of Cronartium ribicola growing on 

 INT Clone-1 of Ribes hudsonianum var . petiolare that produced telial 

 columns at various times after inoculation contrasting 1976 isolates 

 grown at 70°F+2 (21°C+1) with 1979 isolates grown at 55°F+2 (13°C+1) 





Days 



after 



inoculation 





Isolate population 



21 



28 



35 



65 



Total 



1976 warm aeciospores 







3 



20 



202 



225 



Lv/y cool dcClOsporcb 



n 

 u 



9 



11 



45 



C Q 

 DO 



Total 







5 



31 



247 



283 



= 11.48 P of larger 

 d.f. = 3 



= 0.01 











Table 13. --Patterns of variation within 



18 single aeciospore lines 



and among 



subcultures within 



lines in days to 



appearance of teliospores . Cultures were growing on detached leaves of Ribes hudsonianum var. petiolare 

 at 55°F+_2 (13°C+1) (16 hr days) for 49 days 



Single Aeciospore Lines (C = cool; W = vsfarrn) 



Urediospore 

 Subculture 



C-1 



C-26 



W-2 W-3 C-42 



C-44 



C-35 



C-18 



W-4 



C-50 



W-34 



C-31 



C-63 



C-22 



C-71 



W-7 



-70'J 



1 



21 



21 



21 21 21 



21 



21 



21 



21 



21 



28 



28 



28 



28 



28 



28 







2 



21 



21 



21 21 21 



21 



21 



21 



28 



49 



20 



20 



20 



20 



20 



20 







3 



21 



21 



21 28 28 



28 



28 



49 



28 







28 



28 



49 



49 















—.This parent aeciospore culture produced T in 56 days. 

 —This parent aeciospore culture produced T in 48 days. 



DISCUSSION AND CONCLUSION 



Cultures of C. ribicola obtained from aeciospores or urediospores differ in patterns of 

 teliospores production. However, one cannot say if most aeciospore-derived infections are 

 unable to produce the teliospore stage or if it just takes longer. The answer could come from 

 experiments designed to allow the aeciospore derived cultures to grow but to prevent all 

 possibility of urediospores reinfecting the leaves on which they were produced. 



Anotlier conclusion is that temperatures near 55°F (13°C) stimulate both infection success 

 and teliospores production for both aeciospore- and urediospore-derived detached leaf cultures 

 of C. ribicola. 



8 



