QUICK GUIDES				UCF 2010-1

Caring for StormDamaged Trees

Information provided by the National Arbor Day Foundationand the International Society of Arboriculture

In the Storm’s Wake
After a major storm, a community is instantly changed.
Buildings may be damaged or destroyed, power lines
down, and trees broken and torn. In the wake of this loss,
neighborhoods and entire cities may experience a sense ofdevastation they have never known before.

Figure 1: Fallen tree due to wind.
Photo: CSFS

“Trees are amazingly
resilient andmany recover withproper care andtime,” said John
Rosenow, presidentof The Arbor DayFoundation.
This Quick Guide wasproduced by the Colorado
State Forest Service to promoteknowledge transfer.
May 2010
www.csfs.colostate.edu“The experiences of many cities whose trees have suffered
severe storm damage show us that the situation may not
be as bad as it first appears,” says John Rosenow, presidentof The Arbor Day Foundation, an organization that helps
people plant and care for trees. “Trees are amazingly resilientand many recover with proper care and time. Despite theurge to do something immediately, people should try to bepatient. As long as there isn’t an immediate physical risk from a damagedtree, my advice is simple: if you’re unsure about its condition, keep the tree
for now.” Any damaged tree that is kept needs to be monitored for signsof weakness. You also should not assume that fertilizer will improve thetree’s situation. Again, the best advice is to be patient and see how the tree
responds.
“Of course, safety is the first major concern,” Rosenow says. “Everyone
should stay away from downed power lines and beware of broken treelimbs that may be ready to fall. Never use pruning equipment near utilitylines.” Downed utility lines should be reported to utility companies or 911
operators.
He adds that citizens’ patience also allows city officials time to organize
and respond properly to the situation. After a major storm, city officials,
utility workers and private tree care firms must first focus on dealing withhazards to life and property. After that, a major task is removal of debris
from the storm, including damaged branches and sometimes entire trees.
Remember, responsibility for streetside trees varies from city to city. The
most complete information about street trees in your community, such as
publicly owned trees and the city’s responsibilities, can be obtained fromyour city forester or other appropriate city agencies.

Use a Certified/Qualified Arborist or Tree Care
Company
Assessing a StormDamaged Tree:• Is the tree healthyand vigorous?
• Are major limbs
broken?
• Has the main treestem been lost?
• Is at least 50
percent of the tree
crown intact?
• How big are thetree wounds?
• Are there
remainingbranches that canform a new branch
structure?

“If a tree is large and the work is
off the ground, or if a chainsaw
is needed, it’s best to contact aqualified arborist,” Rosenow adds.
“They have the equipment andknow how to safely remove broken
or downed limbs and to help
save and repair trees.” If you need
Figure 2: Hawthorn tree (Crataegus spp).
Photo: CSFS
professional help, locate aqualified tree care specialist and check their references.
Three main tree industry groups accredit tree businesses and individuals,
and can be consulted to find or confirm certification of a tree careprovider in your area:•••

American Society of Consulting Arborists (ASCA), www.ascaconsultants.org
International Society of Arboriculture (ISA), www.isa-arbor.org
Tree Care Industry Association (TCIA), www.treecareindustry.org

Do not be pressured by people with chainsaws knocking on your door andoffering to remove or “repair” your trees. Unfortunately, storms seem toproduce such door-to-door callers, most of whom have no training andlittle interest in your trees beyond making a quick buck.
Following are some important tips to consider when hiring a treecontractor:• Make sure they are part of an established business in the community
with a listing in the phone book, usually under “Tree Service.”• Ask to see current certificates of insurance showing that they are
fully insured for property damage, personal liability and workers
compensation.
• If possible, get more than one estimate to ensure that the price iscompetitive with that offered by others for the same services.
• In the case of tree removals, have a clear understanding about whoremoves the limbs and debris from the property, and whether theprice includes stump removal and clean up.

Can these Trees be Saved?

2A storm can leave trees looking like there’s no tomorrow. Major limbs
may be broken or damaged, foliage can be shredded or stripped, or thebark may be torn or gouged. But what at first glance may look like mortal
wounds are not necessarily fatal to a tree. Trees have an amazing ability torecover from storm damage.

Assess the Damage
Before writing off a damaged tree, homeowners should evaluate their trees
by asking the following questions:•

Other than the storm damage, is the tree basically healthyand vigorous? If the tree is basically healthy, is not creatinga hazard, and did not suffer major structural damage,it generally will recover if first aid measures are applied
immediately after the storm.
◦◦•

Monitor the tree before using fertilizer. In somesituations, such as severe wind and hail storms, trees
may lose all or a significant portion of their leaf area, but
still be structurally sound. Do not assume that damaged
trees will benefit from fertilizer or other nutrient applications, as
in many cases they will not. Allow the tree to recover on its own
or make a determination with the consultation of a professionalarborist.

Are major limbs broken? If larger limbs are broken, it will
be harder for the tree to recover from the damage. Whenlarge limbs are broken or hanging, or when high climbing or
overhead chainsaw work is needed, it’s best to hire or consult
with a professional arborist. Arborists have the necessary
equipment and knowledge, and generally are listed in thetelephone directory under “Tree Service.”◦◦ Take safety precautions. Look up and look down. Be on
the alert for downed power lines and dangerous hanging
branches that look like they’re ready to fall. Stay awayfrom any downed utility lines, low-voltage telephone or cable lines
and fence wires. Don’t stand under broken limbs that are hanging
or caught in other branches overhead•

Figure 3: Damage after a tornado.
Photo: CSFS

Figure 4: A company pruning stormdamaged trees. Photo: CSFS

Has the leader (the main upward-trending branch on mosttrees) been lost? In species where a leader is important for
upward growth or desirable appearance, deciding whetherto keep it may be a judgment call. The tree may live without
its leader, but might be a stunted or deformed version of theoriginal.
◦◦ Don’t top your trees! When trees are topped, all of
their branches are cut back to stubs on the mistaken
assumption that reducing the length of branches will
help avoid breakage in future storms. While storm
damage may not always allow for ideal pruning cuts, professionalarborists say that topping is one of the worst things you can do toyour trees.

Figure 5: Avoid topping your trees. Photo:Joseph O’Brien, USDA Forest Service,www.forestryimages.org

3◦◦ Topped trees tend to promote growth of weakly attached branches
that are even more likely to break when a storm occurs. Thetree will need all its
resources to recoverfrom the stress ofstorm damage.
Topping reduces theamount of foliage thetree depends on for the
food and nourishment
needed for regrowth.
(see Figure 9).

If a tree has been
weakened bydisease, there may
be little that canbe done to prevent
major breakage
or loss when thestresses of a storm•occur. However,there are preventive
measures you
can take to help◦◦ Resist the urge to overprune. Don’t worry if the tree’s appearance
isn’t perfect. Missing branches may cause your trees to lookunbalanced or naked. You’ll be surprised at how fast the wounds
will close, grow new foliage and return to their natural beauty.

strengthen your trees
so they are moreresistant to stormdamage.

Is at least 50 percent ofFigure 6: Decay inside this tree made it hazardous
the tree’s crown (branches before the storm occured. Photo: Joseph O’Brien, USDA
Forest Service, www.forestryimages.org
and leaves) still intact?
This is a good rule ofthumb when assessing tree survivability. A tree with less than half of
its branches remaining may not be able to produce enough foliage tonourish the tree through another growing season.

•How big are the wounds where branches have been broken or barkhas been damaged? The larger the wound is in relation to the sizeof the limb, the less likely it is to heal, leaving the tree vulnerable todisease and pests. A 2- to 3-inch wound on a 12-inch diameter limb
will close over with new bark within a couple of years.
◦◦ Remove any broken branches still attached to the tree. 		
Removing the jagged remains of smaller-sized broken limbs isone common repair that property owners can make after a storm(see Figure 10). If done properly, it will minimize the risk of decay
agents entering the wound. Smaller branches should be pruned
at the point where they join larger ones. Large, broken branches
should be cut back to the trunk or a main limb by an arborist. Forsmaller branches, follow the pruning guidelines shown in Figure
11 so that you make clean cuts in the right places, which will help
the tree to recover faster.

Figure 7: A careful assessment of trees
is important before and after a storm.
Photo: Andrew Koeser, International
Society of Arboriculture, www.
forestryimages.org

4•Will remaining branches be able to form a new branch structure?
The remaining limbs will grow more vigorously as the tree tries
to replace missing foliage. Look to see if remaining branches caneventually fill out the tree to resemble its original appearance.

•Is the tree species desirable for its location? If the tree is in thewrong location (such as a potentially tall tree beneath a power line),

or an undesirable species for the property (messy fruit, etc.), it may be
best to remove it if it has serious damage.
Make the Decision
The above questions and suggestions will help you makeinformed decisions about your trees. In general, the answer
regarding what to do about a particular tree will fall into one ofthree categories:
1. It’s a Keeper
If damage is relatively minor, prune any broken branches, repair
torn bark or rough edges around wounds, and let the tree begin
the process of wound repair.
•An Easy Call: A mature shade tree usually can survive theloss of one major limb. The broken branch should be pruned
back to the trunk. In the following months, large wounds
should be closely monitored for signs of decay.

•Minor Damage: Although the tree has been damaged,
enough strong limbs may remain on a basically healthy tree
to make saving it possible.

•Too Young to Die: Young trees can sustain significant damage andstill recover quickly. If the leader is intact and the structure for futurebranching remains, remove the broken branches and let the tree close
over the wounds and recover by itself.

Figure 8: A tree that has lost theleading stem (the main upwardtrending branch). Photo: Justin Meier,International Society of Arboriculture,
www.forestryimages.org

2. Wait and See
If a valuable tree appears to be a borderline case, resist the temptation tosimply cut down the tree and be done with it. In such cases, it may be best
to carefully prune broken branches and give the tree some time to recover.
A final decision can be made later.
•Easy Does It: Resist the temptation to prune too heavily. Remember,the tree will need all the foliage it can produce in order to survive
through the next growing season. Remove only the damaged limbs,
then wait and see what happens.

•Hold Off: A healthy mature tree can recover even when several
major limbs are damaged. With large trees, it is best to consult with aprofessional arborist to assess damage and safely prune and remove
branches.

3. Say Goodbye
Some trees simply can’t be saved or are not worth saving. If the tree has5already been weakened by disease, the trunk is split or more than 50
percent of the crown is gone, the tree has lost its survival edge.

Figure 9: Do not top your trees.
Photo: National Arbor DayFoundation•

Tree Tragedy: This otherwise healthy young tree has lost too muchof its crown, the leafy head that is vital for survival. It probably will
not be able to grow enough new branches and leaves to provide thenecessary nourishment and will never be able to regain its former
beautiful shape.

•Hopeless Case: About all that’s left of this tree is its trunk. The few
remaining branches can’t provide enough foliage for the tree to makeit through another growing season.

•Fond Farewell to a Friend: A rotten inner core in the trunk or
structural weakness in branching patterns can cause a split trunk, thetree equivalent of a heart attack. The wounds are too large to mend
and the tree has lost its sap lifeline between roots and leaves. This tree
is all but dead.

Important Tips when Cleaning Up a Tree

Figure 10: Clean up torm bark.
This will heal the tree faster. Photo:National Arbor Day Foundation•Never top a tree: Never cut the main branches of a tree back to stubs.
Ugly, weakly attached limbs often will grow higher than the original
branches and are more likely to break off in a future storm.

•Clean up torn bark: Smoothing the ragged edge of torn bark helps thewound close faster and eliminates hiding places for insects.

•Three-step process: The weight of a branch can tear loose during
pruning, stripping the bark off the trunk and creating jagged edges
that invite insects and disease. That won’t happen if you follow thesesteps:
1. Make a partial cut from beneath, at a point several inches awayfrom the trunk.
2. Make a second cut from above, several inches out from the firstcut, to allow the limb to fall safely.
3. Complete the job with a final cut just outside the branch collar, theraised area that surrounds the branch where it joins the trunk.

Figure 11: When you prune, use
the three step process to avoid jagged
edges— an invitation for insects anddiseases. Photo: National Arbor DayFoundation6

Reducing Tree Damage in Future Storms
When a major storm strikes, some trees seem to sustain only minor
damage, while others suffer the loss of large limbs or sizable parts of theirbranching structure. In the worst cases, trees may be completely split in
two or may have nothing left but a trunk.

If a tree has been weakened by disease, often little can be done to prevent
major breakage or loss when the stresses of a storm occur. However, homeand property owners can take preventative measures to help strengthen
their trees and resist storm damage.
Visit the following websites for instructions and tips on how to proactively
prune your trees:••••

The Arbor Day Foundation, www.arborday.org
Trees Are Good, www.treesaregood.com
Colorado State University Extension, Master Gardeners, http://cmg.
colostate.edu/
University of Florida, Landscape Plants, http://hort.ifas.ufl.edu/
woody/For more information
on urban andcommunity forestry,please visit theColorado State Forest
Service website atwww.csfs.colostate.edu
or contact your localforester.

Figure 12: A CSFS forester demonstrates proper pruning techniques at aworkshop. Photo: CSFS

www.csfs.colostate.edu
This quick guide was produced by the Colorado State Forest Service (CSFS). CSFS programs areavailable to all without discrimination. No endorsement of products or services is intended, nor is
criticism implied of products not mentioned.

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