THE AUTHOR 



R. G. KREBILL, Plant Pathologist, stationed at the Forestry Sciences 

 Laboratory, Logan, Utah, joined the Intermountain ' Station staff 

 in 1962. He holds the bachelor of science degree in forestry 

 from the University of California and the doctoral degree in plant 

 pathology from the University of Wisconsin. He has published 

 many articles on rusts of conifers, and recently has undertaken 

 research on diseases of trees and shrubs important to wildlife 

 and recreation. 



ACKNOWLEDGMENT 



Special recognition is extended to George E. Gruell, Teton Na- 

 tional Forest, and Norbert V. DeByle, Intermountain Station, for their 

 encouragement and advice on aspen ecology and the ways of wildlife; to 

 Chester E. Jensen, Intermountain Station, for his help in sampling 

 design; to T. E. Hinds, Rocky Mountain Station, for training in recog- 

 nition of aspen diseases; and to Jack D. Rogers, Washington State Uni- 

 versity, and Flora G. Pollack, USDA Agricultural Research Service, 

 Beltsville, who helped identify specimens of some of the problem fungi. 

 To these and other helpful friends, the author is deeply grateful. 



