Redwoods and Douglas fir trees in California have been found infected with sudden oak death, the disease which has already killed tens of thousands of oaks in the US.
So far the disease has only been detected in saplings and sprouts of the two commercially valuable varieties, which are now subject to state and federal quarantine rules. The quarantine is not expected to affect commercial lumber production significantly.
Researchers at the University of California say there are no indications the disease is killing any mature trees.
The number of species now affected by sudden oak death stands at 16.
