forest products from diminishing forest lands. Certainly it is most 

 timely to seek biologically sound and ecologically safe ivays to prevent 

 forest tree losses that both mar the landscape and lower productivity of 

 the world's forests. Genetic resistance is one means of pest control 

 with all of the required specifications. 



It was in this hopeful atmosphere that the timeliness of an inter- 

 national symposium on the biology of rust resistance in forest trees was 

 perceived. Originally the idea was restricted to white pine blister rust 

 resistance. Thus the present proceedings contains 15 papers assaying the 

 world's white pines--their intrinsic qualities, relative blister rust 

 resistance and international exchange. However, after establishment of 

 the International Union of Forestry Research Organizations (IUFRO), Subject 

 Group on Genetic Resistance to Forest Diseases and Insects--in 1967-- 

 organizers were encouraged to broaden symposium coverage to forest tree 

 rust resistance in general. 



Forest biologists of the U.S. Forest Service, and of many other 

 federal and state forestry services, forestry colleges, and private 

 forestry agencies from around the world attended the Advanced Study 

 Institute and contributed to these proceedings. Their interest, concern, 

 and deep involvement in the problem of increasing the world's supply of 

 wood through development of biologically-safe controls for forest pests 

 is reflected in that attendance, and in the quality of the papers 

 assembled in these proceedings. They are recommended to all biologists 

 who share this concern. 



IV 



