1. Resistance Breeding in Port-Orford-Cedar Against the
Invasive Pathogen,
Phytophthora lateralis
All photos, figures, and graphs: Dorena Genetic Resource Center

2. “There is no known control nor are there any known conditions of soil or climate in areas suitable for POC that may limit disease…
… [furthermore] no evidence of genetic resistance has been found in several thousand trees tested.”
Roth, LE, Trione, EJ, Ruhmann, WH Phytophthora root rot of Port-Orford-cedar. Forest Pest Leaflet Portland, OR: USDA Forest Service, Pacific NW Forest and Range Experiment Station 7p.

3. Resistance Screening and Breeding

4. Results
Of over 10,000 trees tested, 1-2% perform well in screening tests.
Resistance is durable in planted trees after the first 10 years
Resistance-bred seedlings survive better than field-selected seedlings in screening tests.

5. POC Seed Zones 5 breeding blocks: divided along latitude and longitude
Total of 13 seed zones: divided along elevational bands within each block
Seed available for 8 zones since 2005

6. POC Prognosis
Resistance exists and can be selected for
If survival is ensured the first few years, resistance is probably durable
Resistance must be supplemented with the prevention of pathogen spread
More information: Dorena Genetic Resource Center POC breeding program website at