Nov. 29, 2011 — COLLEGE
STATION, Texas — Texas remains mired in one of the worst droughts in state
history and it’s creating disastrous effects on trees and forests across the
state.
After one of the driest years on record,
many shade trees went into dormancy as early as August, dropping their leaves
and branches in a desperate act of self-preservation. Meanwhile, pine trees
with normally thick, green crowns ended up cloaked in red, dead needles while
foliage on cedar trees turned completely brown.
The sight has created a dramatic effect on the Texas landscape and left
many landowners wondering whether or not their tree is dead — or if it might
recover and produce new leaves next spring.
Assessing trees damaged or killed by drought can be tricky, according to
Dr. Ronald Billings, Texas Forest Service Forest Health Manager. He suggests
grouping the trees into three different categories — definitely dead, likely
to live and questionable — to help with the task.
Definitely Dead
It is easier to
make this call for pines, Ashe junipers (cedars) and other needle-bearing,
conifer trees. The determination can be more difficult for hardwoods, which
are more commonly thought of as shade trees. In most cases, a red pine is a
dead pine, Billings said, explaining that the same can be said for cedars
with red needles. Once all or most of the foliage of a pine or cedar tree
turns red or brown, the tree is incapable of recovering.
Pine
trees in this stage probably are already infested with tree-killing bark
beetles and will eventually harbor wood-boring insects, termites and other
critters. Such trees should be cut down and removed, particularly if they are
likely to fall on homes, buildings or power lines.
Shade trees —
like water oaks, for example — that have lost all their foliage and are
beginning to drop limbs or lose large patches of bark are most likely already
dead and should be removed. Hypoxylon canker, a fungus that appears as gray
or brown patches on the trunk of the tree, is another sign of a dead shade
tree.
Likely to Live
This category includes
shade trees with at least some green or yellow leaves still attached to the
limbs. In fact, even those that have dropped all their leaves may still be
alive. Some native shade trees, such as post oaks and live oaks, are more
drought resistant than others like water oaks or elms.
You can use
a scratch test to determine if the tree is dead or just dormant. If you
scrape the bark off a small branch or limb and find green, moist tissue
underneath, the tree is still hanging on, waiting for the next rain. That
means you may need to wait until spring to see if the tree makes a recovery
— unless the tree starts to drop large branches and patches of bark, which
is a sign of death. If there is no green, moist tissue, the tree is likely
dead.
An exception is the baldcypress, which also is known as a
cypress tree. The tree is a conifer, but unlike pines and cedars, its foliage
generally turns red and drops from the tree in the fall or during periods of
drought stress. Cypress trees usually will re-sprout in the spring. If in
doubt, apply the scratch test or wait until spring to be sure.
Pines with a few yellow or red needles scattered throughout an otherwise
green canopy have a good chance at survival. Pine trees typically shed a
large portion of their older needles every year as winter approaches, and
then put on new needles in the spring.
Though it’s not as feasible
to water your forest, any yard trees that show signs of life (green inner
tissues or green foliage) should be watered deeply to reduce lingering
drought stress.
Questionable
Questionable
trees are those that appear to fit somewhere between the Definitely
Dead and Likely to Live categories.
A pine that is
topped with brown or red needles but still has green foliage in its lower
branches is alive, but likely will eventually die. That’s because bark
beetles likely will invade the lower trunk at some point, killing the tree
in stages.
When inspecting a questionable pine tree, look for
popcorn-sized masses of resin (pitch tubes) or brown dust in the bark
fissures. These are early signs of attacks by pine bark beetles. The foliage
of the infested pine may still be green, but the tree is doomed. This is
particularly true if you find bark beetle galleries or trails beneath the
bark. Pines with these signs of bark beetle attack should be removed as soon
as possible.
In the case of shade trees, those that have many
dead or dying limbs or mostly bare branches may or may not survive. A few
green, yellow or red leaves may remain for awhile as the tree slowly dies,
or it may recover when rains return.
It’s important
to note that not all trees may be stressed from the drought alone. Some
trees may also be suffering from insect infestations, disease or other forest
health problems. If you’re unsure or have any questions, visit the Texas Forest
Service web site or check with a certified arborist, forester or tree care
professional.
Deciding whether to remove a
questionable tree can be a tough decision for both property owners and
professional tree care experts. Removal should be considered if a severely
drought-stressed or fire-damaged tree is close to a house or other structure
on which it might fall. If it is away from such areas, it may be more feasible
to wait and see if the tree makes a comeback.
Resources
James
Houser, Regional Forest Health Specialist in Austin
512-339-4589, jhouser@tfs.tamu.edu
Dr. Ronald Billings, Forest Health Manager in College Station
979-458-6650, rbillings@tfs.tamu.edu
Holly Huffman, Communications Specialist in College Station
979-458-6605, hhuffman@tfs.tamu.edu
- Not sure what
kind of tree you’ve got? Check out Texas Forest Service Tree ID.
- View examples of trees in each of the above three categories in the
Will my tree make it? Assessing tree damage from droughtphoto album.
Need more help?
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Texas Forest Service
Contacts:
Joe Pase, Regional Forest Health
Specialist in Lufkin
936-639-8170,
jpase@tfs.tamu.edu