Sudden Oak Death

October 23, 2008

Sudden Oak death (SOD), which, at the moment, is confined to the West Coast, has been compared to the chestnut blight in its potential to devastate Oak and Tan Oak Trees. The invasive mold that cause SOD, Phytophthora ramorun, (a close relative of potato late blight), is a spreading quickly throughout California and is now in 14 coastal counties from Monterey to Humboldt and in a small portion of southwest Oregon: it has also been found in nursery stocks in Washington state and British Columbia. It is believed the mold was introduced to California in the 1990ís through nursery stock form Asia.

Once an oak tree gets infected with SOD, death is quick — between six months and two years. The leaves first turn pale, and then brown, followed by oozing bark cankers. The tree will either die from drought because the mold spores block water flow, or by starvation if the spores infest the leave and inhibit photosynthesis.

So far, only chemical treatments (systemic fungicides and surfactants) have been available to help combat the disease. However, these chemicals are only effective as a preventative measure for high-value trees in yards and landscapes; they do not cure SOD, and are useless for trees devastated by the disease.

The researchers found that when the SOD spores were exposed to extracts from the heartwood of incense cedar, western red cedar, Alaskan yellow cedar, western juniper or Port Orford cedar, the spores were destroyed and fungal cell growth was stopped.

It is not an exact science yet, but it is the closest study to date that looks very promising.

Santa Ynez Valley Tree Care • 688-5580 • Lic. #750949

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Santa Ynez Valley Tree Care
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