"Sudden oak death"

The phrase refers to a disease caused by Phytophthora ramoru, a fungus that affects oaks and other plants.  The Guardian had an article today about the devastation occurring in parts of the U.K. -

In woodlands around the UK, just as here in Afan Valley, south Wales, the race is on to fell thousands of trees in a desperate effort to contain a new disease which poses a threat to British forests on a scale not seen since Dutch elm disease wiped out millions of trees, changing the landscape of the country for ever.

Already 3,000 hectares of larch forest – one hectare is about the size of a football pitch – in Wales, Devon, Cornwall, Somerset and Northern Ireland are known to be infected by Phytophthora ramorum – sudden oak death – which comes from the same family as the potato blight organism that caused the Irish famines in the 19th century...

In 2003, it turned up in a handful of oaks, but they seemed to have resistance and the outbreak did not seem to be too worrying. Then last year, taking everyone by surprise, the phytophthora jumped species and rapidly began infecting and killing the commercially important Japanese and European larch trees. It has also been found in several conifer species, including Douglas fir...

"I think we can forget eradicating it; we have to work with nature and we're going to have to live with it. The question is whether or not we're lucky and have a fighting chance at containing it," he added. "Unfortunately we are very fond of exotic plants from other parts of the world, and that leaves the door wide open to risk."..

The disease may have arrived in the U.K. from the U.S., where it has been present for years.  This map shows areas in this country at risk for the disease:

Those interested (or potentially affected) can read more at Wikipedia, and at this resource page for the Northeast Plant Diagnostic Network.