SUDDEN OAK DEATH
Adapted from an article
found on http://cemarin.ucdavis.edu/
Treatment and Management
can I confirm that my oak tree has Sudden Oak Death?
Because other organisms and injuries can produce symptoms
very similar to Sudden Oak Death on oaks, homeowners will
not be able to diagnose their trees with absolute certainty.
However, there are some steps that can help you determine
if Sudden Oak Death is a likely possibility. Specific information
that you will need can be found on the website www.suddenoakdeath.org
or be obtained from offices of the University of California
Cooperative Extension, County Agricultural Commissioner, or
California Department of Forestry and Fire Protection (CDF).
First, determine if your oak tree is a susceptible species.
To date, trunk cankers have only been found on the following
tree species: tanoak, coast live oak, Shreve oak, canyon live
oak and black oak. Of these, tanoak is the species most likely
to be killed. Second, determine if you are in an infested
area. Check maps available on the website or contact staff
in local Extension, Agricultural Commissioner, or CDF offices.
If you are outside of an infested area, your tree could still
have Sudden Oak Death, but it would be less likely. Third,
compare the symptoms of Sudden Oak Death with those on your
oak tree. Symptoms are described in brochures and on the website.
Fourth, check other susceptible tree and shrub species nearby.
Do they have symptoms of Sudden Oak Death? The probability
that your tree has Sudden Oak Death will be greater if your
tree is a susceptible species, exhibits typical symptoms of
Sudden Oak Death, and is located in an infested area where
other trees and plants are showing symptoms of Sudden Oak
Death. Confirmation of Sudden Oak Death, however, can only
be done through laboratory diagnosis. Diagnosis of Sudden
Oak Death based on visual symptoms is a judgment rather than
positive confirmation. If you ask a tree care professional
to make such a judgment, determine what training or qualifications
enable them to do this. A Special Note: if you live in a county
that is not known to have Sudden Oak Death but you suspect
that one of your trees has the disease, notify a local office
of UC Cooperative Extension, the County Agricultural Commissioner,
my oak tree has Sudden Oak Death, what are the chances it
There is no way to determine if an individual tree will live
or die. Each tree responds differently to infection, and experience
tells us that it is rare for a pathogen to kill all plants
it infects. Depending on a number of factors, some trees may
never become infected, some may become infected and survive
for various lengths of time, and others may become infected
and die quickly. Because Sudden Oak Death is a new disease
in California, it will take time to determine just how likely
these different outcomes are for different species of trees.
Initial observations tell us that tanoak has a high probability
of being killed by Sudden Oak Death, but some are still expected
to survive. Live oaks appear to have a lower probability of
being killed by Sudden Oak Death, but many live oaks are still
killed by the disease. Sudden Oak Death appears to kill trees
by girdling the main stem or trunk. Therefore, the number
and severity of cankers on the trunk is an indication of how
susceptible the tree is and whether it will die. A green tree
may already be dead if cankers completely encircle the stem.
Bark and ambrosia beetles will attack trees that are stressed,
dying or recently dead, regardless of whether the trees have
Sudden Oak Death. The presence of fine dust in bark crevices,
ranging in color from off-white to reddish brown, is a sign
of beetle attack. Fruiting bodies of the fungus Hypoxylon
occur on portions of the stem that are already dead. If the
fruiting bodies or dust completely encircle the lower stem
of the tree, chances are good the tree is dead even if its
foliage appears relatively healthy. It takes time for the
foliage of a dead tree to dry out and turn brown. Hence, a
dead tree could have green leaves and still look alive for
a period of time.
there any treatments that will cure an infected oak tree or
prevent infection in a healthy oak tree? Are there any activities
that should be avoided to prevent Sudden Oak Death?
There are currently no known cures or preventatives for Sudden
an oak tree with Sudden Oak Death be removed?
A tree with Sudden Oak Death needs to be viewed and treated
differently than a tree without the disease, but the disease
alone is not justification for removing a tree. An important
consideration with respect to any tree is whether or not it
presents a hazard to life or property. All trees present some
hazard, depending on the tree's structural integrity and its
potential to do harm should it fail. Preliminary observations
suggest that Sudden Oak Death increases the risk of tree failure
by providing an opportunity for sapwood decay fungi to enter
the tree. Since heartwood decay is common in many older trees,
sound sapwood is essential to the tree's structural integrity.
If both the sapwood and heartwood are decayed, tree failure
may be imminent. The decision to remove a hazardous tree ultimately
lies with the property owner. In order to get an object assessment
of hazard, contact a certified arborist or other qualified
professional. Any dead tree has an increased risk of failure.
removing a diseased oak tree prevent the disease from spreading
to nearby healthy trees?
The threat of spread is generally not a valid reason for removing
an oak tree with Sudden Oak Death. If an oak tree has Sudden
Oak Death, it will likely be surrounded by many other trees
and plants that harbor the pathogen. Hence, removing one or
even a handful of infected trees will have little or no impact
on local disease levels and spread. The only exception would
be if local regulatory officials (County Agricultural Commissioner
or Department of Forestry and Fire Protection) determined
that an eradication effort was warranted. Eradication would
only be considered under very limited conditions--if the disease
were newly established in an area, the infestation was small,
and the area was well removed from any other infestations
of Sudden Oak Death.
I have my infected oak tree cut down, what should be done
with the wood?
Regulations currently prohibit the movement of infected wood,
plants, and plant parts to areas that are disease-free. This
includes all host species, not just oaks. Local spread of
the pathogen occurs naturally, but long-distance spread occurs
when people move infected host material. If you have infected
trees cut down, make sure the wood and other tree parts are
not transported to disease-free areas. Avoid leaving wood
next to roads where it could be picked-up and transported
off-site by unauthorized parties. The simplest and best way
to deal with infected wood is to leave it on site, for example
by chipping the wood and using it as ground mulch. Larger
pieces of wood may be split for firewood for local use. Do
not stack oak firewood next to living oak trees since this
can lead to insect attack on the living trees. If this is
not possible, consider seasoning the wood beneath a tightly
sealed, clear plastic tarp to prevent the buildup of destructive
Department of Forestry and Fire Protection TREE NOTE #3, Controlling
Bark Beetles in Wood Residue and Firewood, provides specific
guidelines for firewood tarping. If infected wood is removed
from your property, make sure it is utilized or disposed of
in a way that does not spread the disease. Contact your local
Department of Public Works or County Agricultural Commissioner's
office for specific recommendations on handling and disposing
of the wood. If the wood is being sold as part of a commercial
timber harvest, contact the California Department of Forestry
and Fire Protection. Tools and machinery that are used to
prune, cut, or chip diseased trees should be cleaned and disinfected
before use on uninfected trees or in uninfected areas. Some
commonly used disinfectants include Lysol®, Physan20®,
or a 10% solution of industrial bleach (1 part bleach in 9