538 P. SCHUTT 



there is little doubt where the investigations have to go. As soon as 

 suitable test material is available, we need an adequate test system for 

 rust races and rust species. 



ENVIRONMENT AND ATTACK 



The mere interactions between meteorological factors and infection 

 biology perhaps can give some practical hints on how to control a disease 

 with simple methods. With the exception of white pine blister rust on 

 Pinus strobus we know very little if anything at all about this side of 

 the host-pathogen-environment complex in forest tree rusts. This should 

 be reason enough why interactions between infection intensity and climatic 

 conditions and especially connections between degree of resistance and 

 nutrition of the host should be investigated more intensely now. 



Finally I would like to point out that experts who have observed the 

 development of our field during recent years agree that interest in the 

 fundamental biological investigations and experiments has markedly 

 increased. The future appears bright, the more since these findings 

 could also help those people who work on other control aspects of the 

 same problem, for we should not forget that resistance breeding is only 

 one method for protecting forest trees against rust fungi. 



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