Protecting oaks from fatal wilt disease
We are getting a large dead oak in the front yard
taken down. The tree died in the summer of 2002 and for various
reasons it was not removed sooner. Anyway, since we have a
fireplace we would like to keep the wood to burn. Is if there is a
way to tell if the tree died from oak wilt or just the stress from
building our home? Unfortunately the contractors weren't real
careful around the trees and I know some of this tree's roots were
lost when the septic field went in.
I've read information on line from the USDA as far as
symptoms of oak wilt and such, however when the tree died I wasn't
really aware of the disease. The USDA indicates that once a red oak
gets the disease it defoliates rapidly. I know this tree did not
drop its leaves until the following winter when all the other oaks
did. I'm not sure if this is a red or white oak. We do have both on
Because we have other oaks around us I don't want to
jeopardize their health. What I've read indicates that wood from an
oak wilt dead tree should be covered with plastic with the edges
buried for 6 months to kill the disease.
Is there any way to tell if this tree died from oak wilt
and am I going to have to do more than just stack the wood and wait
to burn it in my fireplace?
Construction is a tree killer but you're right to be concerned
about oak wilt (Ceratocystis fagacearum), a fungus disease
that's on the increase. It quickly kills oaks in the red oak group
(black-, red-, and scarlet oaks, which have leaves with sharply
pointed lobes) and causes loss of limb and sometimes death in the
white oak group (including white-, swamp white- and burr oaks,
which have leaves with rounded lobes).
The fungus kills by invading, proliferating within and plugging
water-conducting tissues in a tree. Leaves brown, wilt, then die,
usually between late May and August, and many leaves drop early.
Branches die. An infected white oak may simply lose limbs, might
decline and die over years, or might survive as a symptomless
carrier of the disease. A red oak, even a very large one, is likely
to wilt and die in just a few weeks.
The disease moves through natural root grafts between an
infected tree and nearby trees of the same species, or by spores
moved by beetles from under the bark of a dying or dead oak to
wounds and weak places on other oaks.
The fungus may be active in dead wood for a year, and in roots
for up to 4 years. That's why it's strongly recommended that dead
oaks be removed at once, the wood chipped very small, burned or
covered to prevent insects getting into it, all before the next
growing season when insect movement and root growth can spread the
There is no cure for a tree infected with oak wilt so when an
oak dies suddenly or has other symptoms of this disease it's wise
to protect nearby oaks. That involves prompt removal of a dead
tree, trenching three to four feet deep halfway between that tree
and adjacent trees of the same species to break root connections,
and, in some cases, treating nearby trees with fungicide
Your two-year dead wood can probably be stacked as firewood but
for the sake of your other oaks, call in a certified arborist.
Request an assessment of the situation and specific recommendations
for the remaining oaks.
Oak pruning time begins after killing
The smell of fresh cut oak attracts various beetles that may
bring with them the spores of the deadly oak wilt disease. The only
safe time to prune oak trees is between late November and late
March. Pruning cuts made then have time to dry and seal over before
disease-bearing beetles begin to fly again.
Still have potted perennials, but no time to plant
The root of a hardy plant is its least hardy part. In a pot with
its sides exposed to the weather, lacking the insulation of soil,
even the hardiest perennial can die over winter. Move pots into an
unheated garage, group them on the north side of a building and
bury them in a leaf pile, or dig a trench into which to sink the
pots, then fill around them with leaves.
Green thumbs up
to washing your windows, for healthier houseplants and lighter
spirits during short winter days.
Green thumbs down
to the funereal look of burlapped evergreens. If it has to be
wrapped to survive, why have an evergreen there?
Originally published 11/13/04