PINUS STROBUS IN EUROPE 123 



on these soils. Pinus griffithii is grown and bred on difficult sites. 

 It's rather common as an ornamental in the lower Po River valley where it 

 reaches 40 feet tall, then begins to break down. The breakdown may be 

 due to inadequate soil drainage; soils involved are rather unsuitable. 



WICKER: I have a question for Dr. Holzer. In one of your slides you 

 showed a small pine growing at high elevation, with a needle cast. Do you 

 know the cause of this needle cast; is it climatic or biotic? 



HOLZER: It's a fungus infection, Lophodermium. 



CALLAHAM: I have only seen Pinus strobus and P. griffithii in 

 northern Italy through very fog-shrouded, rainy climates. Around Lake 

 Maggiore and Lake Como both species grow very well around the old villas 

 where planted as ornamentals. These are the sources of the seed that 

 Emma De Vecchi reported as being spontaneous P. strobus x P. griffithii 

 hybrids. They are being used extensively in planting programs by the 

 Burgo Company in Turin. 



BINGHAM: I have a question for Dr. Holzer. Is there any pattern in 

 the growth of Pinus oembra from the eastern distribution in Rumania vs. 

 growth of the western distribution in France? 



HOLZER: No materials exist in my tests; only elevational materials. 



BORLAUG: I would like to ask Dr. Holzer how frequently it is that 

 you find individual P. oembra seedlings with much greater growth? In your 

 slide there were a couple of seedlings--presumably of the same age--that 

 were 2 or 3 times as tall as the others. Is this a frequent occurrence? 



HOLZER: The slide in question showed a trial of progenies of selected 

 trees from several stands. Here we found that progenies of several mother 

 trees gave different growth. This is as much as we know at present, except 

 that there is altitudinal differentiation within the same stand. Only time 

 will tell. 



DE JAMBLINNE: I would like to know if there is increased blister rust 

 resistance of Pinus strobus, through some silvicultural treatments in 

 Germany. 



HATTENER: I haven't heard anything about that; nor is it covered in 

 Dr. Schmitt's paper. 



DUFFIELD: I don't know whether anybody can answer this, but it struck 

 me that Pinus monticola* s reputation in Europe is not nearly as good as it 

 might be. Is there any knowledge at all of the provenances used? 



HOLZER: I have no knowledge of the provenances involved in the few 

 P. monticola plantings I covered. 



DUFFIELD: Yet we have very different races of P. monticola with 

 which to breed. 



