Contrary to what the name suggests, sudden oak death afflicts many types of trees and shrubs, including azaleas, camellias and rhododendrons. 

The disease is caused by a poorly understood microbe, called Phytophthora ramorum.  This fungus-like parasite has threatened California's oak woodlands since the mid-1990s and has now been detected in plant nurseries in 20 states. 

In the picture above, plant pathologists from the Agriculture Research Service (ARS), Pedro Uribe and Frank Martin, survey a pile of dead hardwoods that were struck down by sudden oak death. 

Uribe and Martin, with their collaborators, have developed a quick genetic test, based on PCR (polymerase chain reaction), which quickly determines whether P. ramorum is present in, say, a piece of leaf or branch.

Besides speeding up the diagnosis of the disease, ARS researchers are coming up with ways to kill the microbes using different fungicides, as well as high temperatures - in case the disease spreads through reused nursery pots.

-- LiveScience Staff

Credit: ARS