RELATIVE BLISTER RUST RESISTANCE OF PINUS STROBUS 

 IN SOME PARTS OF EUROPE 



John Gremmen 

 Section of Forest Pathology and Resistance Research 

 Forest Research Station, Wageningen, The Netherlands 



ABSTRACT 



The last 40 years of European work on resistance to the white 

 pine blister rust disease (pathogen Cronartium ribicola) is 

 reviewed. Dutch experimental work testing resistance of various 

 Pinus strobus provenances and a few seedling progenies from 

 crosses among phenotypically resistant P. strobus selections 

 has been disappointing. Neither resistant provenances nor 

 individual trees have been observed. Work is continuing with 

 more carefully selected test materials. Some German workers 

 have reported "resistant biotypes" and "resistant provenances," 

 while others have shared the Dutch experiences of failing to 

 find resistance in seedlings of crosses among phenotypically 

 resistant P. strobus parents. Infection of susceptible root- 

 stocks has caused problems in interpreting results of some 

 experiments. Some observations on "natural resistance" of 

 P. strobus in Europe are unexplained. They may be the result 

 of environmental conditions inhibiting development of the 

 pathogen. More work on physiological races of C. ribicola 

 is needed. The foundation of disease gardens outside North 

 America, wherein various races of the rust can be brought 

 together with potentially resistant white pine materials and 

 the association studies in detail, is strongly advocated. 



INTRODUCTION 



In our mind we go back to 1927, the year when eastern white pine 

 {Pinus strobus L.) got a first class funeral at a German forestry meeting 

 in Frankfurt /Main. The tree succumbed as a result of blister rust attack 

 (pathogen Cronartium ribicola J.C. Fisch. ex Rabenh,). The funeral sermon 

 was delivered by Professor C. von Tubeuf, the well-known plant pathologist 

 Nevertheless, in 1934 the coffin was reopened by Dr. Wappes at a forestry 

 meeting in Bonn, and what appeared? Although buried at Frankfurt the 

 tree was still alive. One year later rehabilitation followed at a 

 Wtlrzberg meeting and replanting of the tree in the "middle of the German 

 forest" was authorized. 



Since 1939, Dr. H. van Vloten had pleaded for this beautiful and 

 valuable forest tree in The Netherlands, arguing, "Must we abandon the 

 introduction of exotic trees in our forests because of certain diseases? 

 No, as little as we like to do without our potato from South America, or 

 our cereals and fruit trees from elsewhere in the world " (author's 

 translation) . 



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