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
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
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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