THEORETICAL bas 



IS ur riuji 



TAXONOMY, CROSSABILITY, AND RELATIVE BLISTER RUST 

 RESISTANCE OF 5 -NEEDLED WHITE PINES 



R. T. Bingham 

 Intermowitain Forest and Range Experiment Station, 

 Forest Service s U.S. Department of Agriculture } 

 Moscow 3 Idaho, U.S.A. 



ABSTRACT 



White pine speciation is summarized, and information on inter- 

 species crossability is assembled. The literature on the extent 

 of white pine blister rust (Cronartium ribicola) infection in 

 species trials of 5-needled Subsections Cembrae, Balfourianae s 

 and Strobi white pines is reexamined, and combined with observa- 

 tional data on infection of these pines in Europe. This 

 existing evidence, plus new evidence compiled at the author's 

 station in northern Idaho, is arrayed and analyzed to provide 

 a tentative ranking of blister rust resistance among 14 of 

 the more than 20 5-needled white pines. The ranking, along 

 with the consolidated and updated information on botanical 

 ranges and crossability of white pines should be useful in 

 the planning of future white pine blister rust resistance 

 breeding. 



INTRODUCTION 



Establishment of a Committee on White Pine Blister rust has revived 

 international interest in blister rust resistance of the world's white 

 pines. This is one of six Committees established by Henry D. Gerhold, 

 Chairman of the IUFRO Intersectional Working Group on Genetic Resistance 

 to Forest Diseases and Insects. 



There are more than 20 of these 5-needled white pine species--several 

 of them are quite inaccessible and not very well known. These species 

 constitute a broad range of breeding materials for use by the resistance 

 breeder against white pine blister rust {Cronartium ribicola J.C. Fisch. 

 ex Rabenh.). At present the resistance breeder cannot even secure, much 

 less work with, all of these species. However, he can direct his program 

 toward those species exhibiting the widest adaptation and the strongest , 

 species-wide resistance. He may be particularly interested in white 

 pines that have evolved near the presumed Eurasian gene center(s) of the 

 rust organism; these pines coexist with the rust in more or less balanced 

 host-parasite systems, indicating possible existence of long-lasting 

 "horizontal" or "uniform" resistance in these species (see van der Plank, 

 1969; Hoff and McDonald, these proceedings). 



A critical examination of the relative blister rust resistance of 

 these white pines is needed as a research tool for the introduction and 

 testing of new white pine species. Also, where the breeder is seeking 

 to improve resistance of susceptible but otherwise locally adapted and 

 important native white pines, an updating of information on interspecies 



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