BREEDING OF WHITE PINE AT THE INTERSPECIES LEVEL 549 



BORLAUG: I would agree with you, Dr. Heimburger, that in the first 

 backcross there is plenty of variation and so you can pick the trees you 

 want . 



DE JAMBLINN'E: Have you noticed any differences between hybrids when 

 P. peuoe pollen of different provenances are used? 



HEIMBURGER: Well, not exactly. We have, of course, as I showed on 

 Wednesday, several populations of P. yev.ce from different areas, and the 

 one from Finland seems to be better than the others. Firms veuoe is very 

 uniform, but in resistance, of course, all of the problems here are now in 

 weevil studies. Finns pence is extremely variable with differences 

 between populations and from tree to tree to weevil damage. But there is 

 not too much variation in hybrids. 



VAN ARSDEL: How many seed sources of P. peuoe have you been using? 



HEIMBURGER: Seed sources, as I showed you before, number about a 

 half dozen or so, but we have collected scions from many arboreta in 

 Europe and North America of the flowering phase and have then pollinated 

 them with white pine. 



VAN ARSDEL: Those are from different arboretums ; they are not from 

 different parts of the range in the Balkans. 



HEIMBURGER: No. we don't know where they come from. .And the same 

 thing with P. griffithii. We have obtained material from several places 

 and largely of unknown origin but still many of them are quite good. In 

 fact, one tree I showed you in the slides accompanying my Wednesday paper 

 is quite promising. 



