BREEDING POPLARS RESISTANT TO VARIOUS DISEASES 



V. Steenackers 

 Poplar Institute^ Graamnont 3 Belgium 



.ABSTRACT 



Poplar culture in Europe is threatened by several diseases, 

 especially since it is based mostly on a small number of 

 PzpuMus euramericana (the hybrid of P. deltoides x P. nigra) 

 clones. Securing multiple resistance to diseases of the 

 locality is a necessary first step in any long-term poplar 

 breeding prcgrarr. . 



Activities of the author's Institute in testing resistance 

 of thousands of new clones of 4 Populus spp. to diseases 

 caused by Taphrina aurea 9 Marssonina bmmnea, M. populi, 

 Melampsora spp., Septoria populi, Septotinia populipoeda, 

 VotkichLza populea and Aplanobacterium populi , plus a virus, 

 are reviewed. For each poplar: disease combination highly 

 resistant (even immune) clones have been selected. Certain 

 P. deltoides clones have been selected as resistant to the 

 above disease organisms except /.. populi; however, a few of 

 these clones are even resistant to this bacterial canker. 

 P. nigra clones are generally resistant to bacterial canker, 

 but not to Z. populea. Clones of P. trichooarpa resistant 

 to bacteria canker are opening up new possibilities for 

 utilizing this poplar. 



Clones demonstrating multiple resistance are transplanted to 

 plantations, which after 8-10 years become seed orchards and 

 breeding arboreta. Orchard clones are used in a continuing 

 program of greenhouse, full-sib matings . Fi and v 2 families 

 or clones with sufficiently high multiple resistance have 

 been obtained from crossings of P. deltoides x P. triohocarpa 

 crosses. Studies on the heritability of resistance to the 

 various poplar diseases are underway. 



INTRODUCTION 



Although many diseases can affect poplar species and their hybrids, 

 poplar cultivation in Europe has for years been based on a very few 

 Populus euranericana (Dode) Guinier (the hybrid of P. deltoides Bartr. x 

 P. nigra L. clones. Consequently, poplar cultivation is permanently 

 I threatened by diseases. 



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