When a major storm strikes...
Gail Ruhl, Senior Plant Disease Diagnostician,
Director, Purdue University
When a storm strikes, some trees seem to be able to come through
with only minor damage, while others suffer the loss of large
limbs or sizable parts of their branching structure.
This willow tree (what’s left of it) lost several large
branches during the windy, snowy weather last week. Located beneath
utility lines, this tree has been repeatedly topped over the
years. According to Dr. Alex Shigo, topping is the most serious
injury one can inflict upon a tree. Topping opens the tree
up to an invasion of rotting organisms. Severe topping and repeat
topping can set up internal columns of rotten wood. Rotted individual
limbs, or the entire tree, may fail, often years later in conjunction
with environmental stress factors such as excessive winds, ice
storms and heavy snow. Usually a conk (see image below)
or mushroom "fruiting" body is the first sign of infection.
Prevention: All deciduous
trees can get heart rot. Heart rot fungi, however, do not invade
living wood of healthy trees. Thus, as long as a tree is growing
vigorously, rot will be confined to a small central core. This
is called compartmentalization. If the tree is weakened and
fresh wood exposed by severe pruning or storm damage, decay
fungi can advance to more and more wood.
Control: Minimize pruning
wounds that expose large areas of wood. Carefully remove broken
branch stubs following storm damage. Have suspect heart rot
trees checked by a certified
arborist to determine if sufficient live wood is present
for structural safety. Check trees every few years to be certain
new growth is maintaining sound structure. Large trunks and main
branches with extensive decay may have little sound wood to support
the tree and may cause damage to surrounding buildings or, as
in the case of this willow, power lines and nearby fence.
For more information on topping please see Don't
Destroy Your Large Trees by Topping
Also check out Why Hire an Arborist? (pdf
file) - Down the Garden Path Newsletter, March 1998