628 NORMAN E. BORLAUG 



The excellent programs in genetic improvement of loblolly and slash 

 pine being done in North Carolina, Georgia, and Florida have demonstrated 

 clearly how the imbalances between an indigenous pine host and an indige- 

 nous rust pathogen that have been provoked by man using bad timber manage- 

 ment practices, can be brought back to the original level of the undisturbed 

 forest or even further improved while concurrently improving growth rate 

 and tree form. 



IMPROVEMENT IN PINUS MONTICOLA 



Intraspecific Rust Resistance 



The accomplishments of R. T. Bingham and colleagues toward the 

 development of blister rust-resistant western white pine through intra- 

 specific breeding during the past 20 years have been spectacular, if not 

 phenomenal. They have identified more than 3,100 widely dispersed trees 

 of P. montieola that are phenotypically resistant to C. ribicola. Some 

 of the phenotypically resistant trees have been inoculated as grafts and 

 have also been found to be genotypically resistant. They have in effect 

 dug up "fossil" additive polygenes for resistance to C. ribicola where 

 there should have been none based on previous ideas and experiences. 

 They have made controlled pollination test crosses and tested the Fj 

 progeny of more than 400 of these trees, and identified approximately 

 100 individual trees which are good general combiners for rust resistance. 

 Pilot-scale seed orchards have been established employing grafts of the 

 best of these trees, the first of which are now beginning to produce Fj 

 seeds. It is estimated that 30% of the Fj seedlings will be resistant 

 to blister rust. And in their main, first-stage seed orchard program, 

 Fj seedlings that have survived inoculation are being planted in produc- 

 tion seed orchards, to mass-produce presumably 50±% resistant F2 seedlings 

 beginning about 1985. This is a tremendous accomplishment . We all salute 

 you for your achievements. Their second phase plans call for expanding 

 the base of the resistance already in use and diversifying the sources 

 of rust resistance. 



I would like to make a few comments concerning this phase of the 

 breeding program. I think it is urgent to evaluate the remaining 2,700 

 phenotypically resistant trees as soon as possible so that other newly 

 identified resistant trees can be incorporated into the seed orchards 

 and thereby expand the genetic base of the current breeding program. 

 This will probably provide additional genes for protection s but even more 

 important will reduce the chances of encountering other unforeseen prob- 

 lems with insects or other diseases that are of no consequence in the 

 present P. montieola. 



Interspecific Crosses to Transfer Blister Rust Resistance to 

 American Soft Pines 



Although excellent progress has been made toward developing blister 

 rust-resistant P. montieola through intraspecific breeding, there is an 

 urgent need for widening and deepening the spectrum of resistance through 

 interspecific crosses with the resistant Asiatic and European white pine 

 species. Crosses with the Asiatic and European species will not only 

 further diversify the gene pool for resistance to C. ribicola but may 

 simultaneously incorporate other valuable genes into P. montieola (or 

 P. strobus and P. lambertiana ) . 



