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B. The Facts about Sudden Oak Death

Narrator: This is Science Today. For several years a fungus has been infecting and killing many thousands of coastal oak trees in the West. It's called sudden oak death and according to David Rizzo, a plant pathologist at the University of California, Davis, it was first discovered in California in 1995.

Rizzo: We think the main cause of sudden oak death is a fungus or fungus-like organism known as Phytophthora and that is what initially gets in there, it can kill trees on its own, but often it will stress trees that other organisms can also come in.

Narrator: In large trees, Rizzo says the first symptoms are a bleeding or oozing coming directly out of the bark.

Rizzo: Those are the earliest symptoms that we notice. As the tree goes on it shows less vigor and often times though, the tree will apparently appear to die over a period of a few weeks, but the tree has probably already been infected for quite a while before that.

Narrator: Travelers in infected areas can prevent the spread in other regions by making sure they clean traces of soil off shoes or tires. For Science Today, I'm Larissa Branin.