Oak Woodlands Seedlings Life
in Mature Trees Key
to Oak Species |
Sudden Oak Death As the
name suggests, Sudden Oak Death means oak die within a month or so
of looking poorly.
This new disease organism either became obvious
or newly arrived in California in the late 1990's and threatens not only
oaks, but many
other plant
species.
The
causal agent is an odd life-form called Phytophthora (pronounced
Phy-TOFF-thor-uh). It is like a fungus, and like an algae. It can make
spores that can persist
in the soil and
mud, and it makes motile, swimming forms that can work their way up a
tree stem, but only when everything is wet and it can swim. Starting
from the "zoospore", or "resting spore", Phytophthora grows long, hollow tubes in a microbial mat that spreads into the vessels
in plants that
conduct water. Oaks produce a characteristic reddish black oozing, sticky,
viscous liquid and very suddenly, all the leaves turn brown and die. |
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