The Trail Companion
Sudden Oak Death
Protecting Our Trees
What treatments are available to protect our trees? As a
practicing arborist, I can tell you the best recommendation
for healthy trees is proper. It is not always feasible to
protect trees in a forest setting, though it is done in
some cases. Trees of importance should receive proper care,
- Proper pruning, removing dead, dying and damaged
- Discouraging other insect defoliators, which are on
- Irrigating drought stressed oaks and seedlings during
summer to maintain vigor (during normal rainfall years,
established oaks do not generally need extra water) Slow
water away from the trunks inside the dripline once every
3-6 weeks for about an hour. Do not overwater and keep
water off the trunk of the tree.
- Avoid soil compaction or grade change around the base
of the tree.
- Regularly checking tanoaks and other oaks from March
to October for bleeding from the bark and boring dust
(frass) from beetles.
If trees show symptoms,
measures should be taken to protect still healthy trees,
including proper handling of infected wood:
- Promptly cut down trees showing advanced symptoms.
They are breeding grounds for future beetle attacks on
additional trees. Chip the brush and immediately cover
firewood for six months to prevent further beetle
emergence. Stump grinding is recommended, as beetles are
attracted to stumps as well.
- Do not remove infected wood and brush from the site!
The pathogen can be transported to a previously
unaffected area through firewood, chipped wood, or even
soil on equipment, tires or boots.
|Coast live oak (Quercus
Proper care is the only
option now available to maintain susceptible trees.
Spraying the trunks of individual trees to eight feet above
the ground with the insecticide Astro™ (permethrin)
may slow decline of infected oaks by preventing beetle
attacks, but will not prevent death. The syndrome is not
fully understood and there is no remedy once a tree has
advanced symptoms. Often trees are beyond saving even at
the earliest stages. Hopefully the mystery of Sudden Oak
Death will be solved, or like most plant disease/insect
epidemics, this one will run its course and recede in
For additional information,
see the CAMFER (UC Berkeley's Center for the
Assessment and Monitoring of Environmental Resources)
website and the UC Cooperative Extension Sudden Oak
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- Sudden Oak Death
Oak Mortality Syndrome
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