290 H. D. GERHOLD 



PURPOSES OF INTERNATIONAL TESTING 



Several white pine species already are being tested for resistance 

 against diseases and insects in different regions of the world. It may 

 be assumed, therefore, that there is adequate justification for resis- 

 ance testing in each of the local regions. What purposes can be served 

 by increased international cooperation and coordination among such tests, 

 beyond the summation of their individual purposes? I can think of four, 

 and there may be still others: 



1. To aid in the search for additional sources of resistance genes, 

 by comparing the values of various genotypes exposed to pathogens in 

 different environments. 



2. To obtain for various white pine genotypes fundamental informa- 

 tion about their breadth of environmental adaptability and their resistance 

 to a spectrum of pathogenic races. 



3. To determine the adaptation and resistance of provenances or 

 improved varieties in regions other than those for which they were 

 selected originally. 



4. To utilize test plantings as an early warning system for detect- 

 ing more virulent strains or serious new pathogens. 



It should also be noted that resistance test plantings may be utilized for 

 other pursuits closely related to resistance breeding, such as provenance 

 testing and the preservation of gene resources. 



These purposes illustrate that persons who might wish to participate 

 in an international testing program would do so for different reasons. 

 The reasons of one might not even be fully understood by another. An 

 industrial silviculturist in northern Italy may want to compare the 

 relative merits of various white pine varieties or provenances available 

 from Europe, North America, and Asia. A university pathologist in Sweden 

 may want to compare biochemicals extracted from Cronartium races inter- 

 acting with various host genotypes. A government tree breeder in eastern 

 Canada may wish to estimate genetic variances of weevil resistance that 

 apply to a broad region including northeastern United States. The diver- 

 sity of professions, employers, host species, and pathogens indicated by 

 these examples must be taken into account when plans are developed for 

 facilities and particular experiments. This does not mean that each 

 facility and each experiment can serve all objectives. Facilities and 

 experiments should be efficient in producing as much useful information 

 as possible, but care must be taken that one objective will not be 

 jeopardized by adding another. 



DESCRIPTION OF TESTING FACILITIES 



It would be gratifying if it were possible to build, staff, and 

 operate entirely new resistance testing facilities designed to ideal 

 standards. But I do not know of any single source from which sufficient 

 finances could be obtained. To be more realistic, we should limit our 

 considerations to the capabilities of existing institutions. What 

 attributes should they have in order to participate effectively in inter- 

 national resistance testing? Some of the more important ones include: 



