This project was funded by the USDA Specialty Crop Block Grant program (grant numbers ODA-2577-GR and ODA-3557-GR).


Luisa Santamaria, assistant professor, Extension plant pathologist in nursery crops; and Chal Landgren, professor, Extension Christmas tree specialist; both of Oregon State University.


The authors thank the following peers for the review of these diagnostic cards and for their helpful comments and suggestions. In alphabetical order:

  • Michael Bondi–Oregon State University
  • Gary Chastagner–Washington State University
  • Rick Fletcher–Oregon State University
  • Alina Freire-Fierro–Drexel University
  • Carla Garzon–Oklahoma State University
  • Dionisia Morales–Oregon State University
  • Kathy Riley–Washington State University
  • Helmuth Rogg–Oregon Department of Agriculture
  • David Shaw–Oregon State University
  • Cathy E. Thomas–Pennsylvania Department of Agriculture
  • Luis Valenzuela–Oregon State University