Oak killer on the loose

  • California black oak



A new plague threatens thousands of native oak trees in southern Oregon. Sudden oak death, which causes trees to bleed a reddish-black fluid and their leaves to droop and turn brown, has already killed thousands of trees in Northern California. Last month, forestry experts in Oregon learned that the disease had made its way into seven acres of tan oak, some 250 miles from the nearest confirmed California case.

"This is potentially serious, not only to tan oaks and black oaks, but for nursery products as well," says Bruce Pokarney of the Oregon Department of Agriculture.

The disease, present in California since 1995, has been hard to isolate because other plants such as rhododendrons harbor the pathogen. The fungus-like organism, which is related to the one that caused the Irish potato famine, spreads easily through the tires and shoes of backcountry recreationists. The state of California put a ban on the movement of plant products from eight affected counties this spring and Oregon agriculture officials recently quarantined the area north of Brookings, where sudden oak death appeared.

In July, California approved over $3 million for further study and education on the disease, which is caused by a previously unknown species of Phytophora, first isolated by California researchers in 2000. But Oregon officials won't rely on the quarantine or future research: they've ordered the infected stands cut and burned.

Says Pokarney."We've caught it early enough in Oregon that maybe we can do something about it."

Copyright © 2001 HCN and Oakley Brooks

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