Canker Disease Threatens Coast Live Oaks in Calif.

Trees with telltale signs of infection have been found in six California counties, from as far south as Orange to as far north as Monterey

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    NEWSLETTERS

    TK
    Carlsbad Lagoon
    This image, from CarlsbadLagoon.org, shows the Coast Live Oak - a tree considered the “crown jewel” of California’s native flora.

    California's coast live oaks are facing a big, new threat carried by a tiny, burrowing beetle.

    Foamy bark canker disease develops from a fungus hosted by western oak bark beetles -- and it is very bad news for the stately trees.

    The Orange County Register reported Sunday  that scientists in California have not seen the beetles carrying the fungus before.

    After infected beetles bore into the trees, the fungus blocks water and nutrients from circulating. Eventually, reddish sap and cream-colored foam begin to ooze from the trunk and branches. Slowly, the tree dies.

    Once the sap and foam stop flowing, the only immediate evidence of a problem is the small holes that the beetles created to get inside the tree.

    If just the branches are infected, they can be pruned to stop the spread of the disease.

    "When the infestation is on the trunk, there is nothing that can be done and the tree will die," said Akif Eskalen, a plant pathologist at the University of California, Riverside, whose lab issued an alert on the disease several weeks ago.

    While the total number of affected oaks is unknown, trees with telltale signs of infection have been found in six California counties, from as far south as Orange to as far north as Monterey. Graduate students at UC Riverside plan to look more extensively at the full range of the threat.

    The disease is raising concerns about both fire danger -- dead trees offer powerful fuel for wild land blazes -- and habitat loss.

    "Lots of our wildlife -- the deer, lots and lots of birds, even the mountain lion -- seek shade in these oaks," Allan Schoenherr, a former Fullerton College ecology professor, said.

    Other species rely on the trees for either shelter or food, including birds of prey, woodrats, salamanders, owls and California quail.

    Humans, too, look to the trees -- for their beauty.

    "When I think of coast live oaks, I think of beautiful shaded canyons in our wilderness parks and regional parks," said Laura Cohen, a resource specialist with OC Parks. "For those of us who prize a walk in the woods, it is an unimaginable loss."