OREGON STATE UNIVERSITY

Program may rescue threatened cedar species

11/18/1996

CORVALLIS - A research program at Oregon State University that dates back more than 40 years is on the verge of success in restoring Port Orford cedar - the most valuable conifer in North America - as a viable tree species.

This tree has some unique ecological characteristics and in the 1970s also formed the basis of a $40 million annual export industry to Japanese markets that prized - and paid a premium - for its attractive, fine-grained wood.

But the invasion of a deadly tree fungus called Phytophthora lateralis posed a major threat to the very survival of Port Orford cedar in recent decades and virtually destroyed its timber export potential.

Now, after years of experimentation, OSU and U.S. Forest Service researchers believe they have successfully identified a group of individual Port Orford cedar trees that are resistant to the fungus.

"Time will tell if this is a genuine solution," said Everett Hansen, an OSU professor of botany and plant pathology. "At this point we're very encouraged. These resistant trees are our only real chance to re-establish Port Orford cedar in places where the fungus has killed older stands."

Some pilot studies are nearing completion, Hansen said, additional steps to further enhance fungal resistance are being taken and seedlings for widespread plantings may be available within a few years.

Port Orford cedar is a native conifer to the southwest corner of Oregon and northern California, and it thrives in some soils that are sufficiently toxic with heavy metals that they kill most other tree species. It's also shade tolerant and fire resistant, and can fill a critical ecological niche in some old growth and riparian ecosystems.

Besides this, Hansen said, the wood is beautiful. It's white, decay resistant, mills well, has a tight grain and closely resembles some cedars native to Japan that are prized there for various ornamental, building and religious temple uses.

As the supply of this wood dwindled in recent years it commanded prices up to $6,000 per 1,000 board feet - often 10 times or more the price of Douglas-fir. The beautiful foliage is also sold widely for decorative use.

But an imported fungus first noticed in ornamental nursery cedars in Washington state in the 1920s cast doubt on the future of this tree species in the Pacific Northwest.

OSU scientists in the 1950s were the first to identify the spread of this fungus to commercial forests, and the problem began to slowly grow. The soil-borne fungus killed the trees by infecting the inner bark of their trunk, literally "girdling" the tree and preventing nutrient flow.

In most Port Orford cedars the fungus caused 100 percent mortality, within a few weeks in seedlings and a few years in larger trees.

In research that picked up speed during the 1970s and 1980s, scientists aggressively began looking for individual trees that seemed to resist the effects of fungal infection. They found about 50, tested and propagated them, and now have tests with seedlings to demonstrate resistance.

Some of the best individual trees continue to thrive 20 years after infection.

Further refinements are expected as the breeding program continues, Hansen said, even though it's still not clear exactly what is giving the trees resistance to the fungus.

"We're not suggesting our resistant trees are immune to this fungus," Hansen said. "But the fungus does appear to grow far more slowly in them, and our goal is to create trees that can live long enough to be ecologically viable and commercially useful."

A 40-50 year old tree would be large enough for some commercial harvest, Hansen said.

In continued studies, OSU scientists are trying to identify additional Port Orford cedar trees from low-elevation sites that may be showing evidence of fungus resistance, so they can improve the resistance mechanisms for future seedlings.

Any private landowners who believe they may have such trees on their property are encouraged to call Hansen, at telephone (541) 737-5243, or contact their OSU county Extension office.

"We may never be able to declare a total victory over this fungus," Hansen said. "Plant breeding is always a continued race against pathogens as they develop and evolve. But we think this approach has great potential to help re-establish this tree commercially and in its natural ecological role."