REPORT OF THE COMMITTEE ON WHITE PIXE BLISTER RUST 655 



The first of these inquiries, to be circulated immediately to 

 cooperators in all three continents, would be restricted to the testing 

 of unimproved materials of any and all white pine species as supplied by 

 Kriebel's subcommittee. Generally these would be tested, in large or 

 small tests, at the cooperator's discretion and expense. These "species 

 trials" would be aimed at giving cooperators a greater opportunity to 

 appraise or reappraise white pines perhaps already useful for immediate 

 introduction, and at building a more meaningful and internationally useful 

 white pine species resistance rating. This work should have general 

 interest in all hazard-zone countries, since only fragmentary work has 

 been undertaken to appraise resistant species (P. griffithii, P. peuce } 

 P. armandiij P. koraiensis 3 P. sibirica, etc.) for immediate introduc- 

 tion, or to appraise use of these promising species in hybridization work 

 for improvement of resistance in native species. 



The second of these inquiries would be aimed only at potential 

 cooperators in high-hazard countries of northern Europe and Asia, and would 

 be concerned with the much more detailed and expensive testing of improved 

 P. strobuSj P. montieola, P. tambertiana, and possibly P. peuoe varieties 

 of demonstrated resistance where tested in the U.S.A. and Canada. This 

 second inquiry will be some time in preparation. The Subcommittee agreed 

 that an "Ad Hoc Panel of Experts" (Hoff, Patton, and Zufa, also seeking 

 advice and information on resistant materials from Washington-Oregon, 

 California, and Lake States resistance programs) would assemble necessary 

 information to supplement the inquiry. Included would be (1) information 

 on location and availability of specified materials embodying demonstrated 

 resistance, and (2) where possible, specific information on the host: 

 parasite reactions and resistance genes involved in the resistance reac- 

 tions of the improved material; also recommendations on (3) suitable 

 experimental designs, (4) spacing and numbers of seedlings and families 

 to be tested, (5) methods of exposure to the rust, (6) examination 

 items and timing, and (7) other treatments of seed or seedlings necessary 

 to insure establishment of a suitable test for evaluation of resistance 

 under exposure to possibly new and different races of the rust fungus. 



Hopefully the Ad Hoc Panel will provide this information to Sub- 

 committee Chairman Gremmen within 12 months, allowing him to circulate 

 the second inquiry and receive responsive answers within 12 to 18 months. 



These recommendations and action plans were also discussed and given 

 general approval by the IUFRO representatives and Advanced Study Institute 

 participants at the open meetings August 20 and 23, 1969. 



In closing this report, the Chairman of the White Pine Blister Rust 

 Committee would like to thank the present Leaders of IUFRO Sections 22 

 and 24 (R. Z. Callaham and E. BjCrkman), the Chairman (H. D. Gerhold) 

 of the Intersect ional Working Group, Subcommittee Chairmen H. B. Kriebel 

 and J. Gremmen, and the other 16 members of the White Pine Blister Rust 

 Committee for their staunch and untiring support, for their valuable 

 contributions to Committee work, and for their equally valuable contribu- 

 tions to the Advanced Study Institute. The chairman would also like to 

 acknowledge, with warm thanks, the contributions of other participants 

 of the Advanced Study Institute given at open committee sessions 

 August 20 and 23. 



