Late Summer!
A long backward look can reveal answers when a big tree
dies
Dear Janet,
I live in an older neighborhood with mature trees on my
lot, including four mature beech trees.
Three years ago I lost one beech near the road and now
one of the four remaining trees (again, near the road) is showing
signs of decline.
Samples sent in reveal no parasites or other specific
problems. I have been told that beeches are sensitive to traffic
vibrations from a road and this may be the cause of the loss. The
beeches in good health are farther from the road.
Because of the privacy afforded by the beeches' low
branches and to maintain some continuity on the lot, it would be
nice to replace the lost beeches with new mature ones. But in view
of the proximity to the road, should replacement with beech trees
be ruled out?
If you advise against beech trees are there any other
trees that you would recommend that have low branches like a beech
and would do well near a road?
J.M.
Dear J.M.,
You're right to hesitate before replanting a species that failed
on your site. However, I'm surprised you'll consider buying a
large, expensive tree without calling in an arborist to assess the
situation.
Until you determine what killed one beech and ails the others,
any choice is a gamble. The problem might be beech-specific but
could be broader, with a negative impact on low-branched alternates
such as basswood, pin oak, bad cypress or dawn redwood.
Beeches do have sensitive roots, more likely to rot than recover
from being crushed or cut. Yet it's unlikely that road vibrations
would affect a beech without similarly affecting other trees along
that road.
What happens to soil near strong vibrations --imagine jack
hammers and pile drivers -- is that it becomes compacted. It's
comparable to what happens during shipping to goods in boxes marked
"some settling of contents may occur." Oxygen is what's lost in the
settling, yet a free flow of oxygen is vital to roots. Some tree
species fail in compacted soil, others tolerate it, but all show
some effect
When a big tree fails in ways noticeable to an untrained eye
it's usually years into a problem. The tree's reserves may have
carried it for a decade or more, masking the decline.
I don't question the results you received from your samples.
Trees in decline from environmental stress frequently have no
significant pests or diseases. Pests that are present may be
secondary to the wasting, opportunists exploiting a weakened
host.
An arborist will probably look at your beeches' growth rate for
the past five to ten years, seeking signs of when the trouble
started. In that discovery may be keys to a solution. As an
example, if a tree began struggling in the year a new driveway was
installed, providing extra water and fertilizer to the undamaged
portion of the roots may speed its recovery.
Short report
Many big trees are stressed this year...
...from oaks and red maples so pale as to be golden, to silver
maples thin enough to see through. Here's how to assess a tree's
growth rate and determine when the trouble began.
Examine an upper branch or a horizontal limb that extends to the
drip line.
Measure how far it grew this year:
- Find the terminal bud at the branch tip, enclosing 2005's
shoot.
- Find the terminal bud scar that marks the start of growth this
spring. On a beech and many other trees that form terminal buds,
this bud scar is distinct and enduring. Look for closely spaced
ridges that encircle the twig like a turtleneck.
- Measure back from the terminal bud to this spring's terminal
bud scar.
Next, determine and record past years' growth. Measure between
each terminal bud scar and the one that preceded it.
Record several branches' growth history. Calculate annual
averages.
Look for coincidences between tree growth and changes in the
environment.
Compare your tree's growth to its species average, as listed in
a book such as Michael Dirr's "Manual of Woody Landscape Plants."
Uppermost branches should meet the species average. Lower and inner
limbs will grow more slowly.
A beech like those in today's question might have this
history:
2004: 7.5 inches, respectable for a beech's lower limbs,
although upper branches should grow 12 to 18 inches per year.
2003: 4.375 inches
2202: 3.25 inches
2001: 3.75 inches
2000: 2.375 inches
1999: 0.125 inches
1998: 0.0625 inches
1997: 0.1825 inches
1996: 3.125 inches
1995: 2.5 inches
1994: 0.1825 inches
1993: 4.625 inches
Considering its history, this tree is not in decline but
recovering from something that occurred in the mid-1990's.
Green thumbs up
to planting spring bulbs deeper than you ever
imagined they could be. Tulips and daffodils planted ten to twelve
inches deep are safe from digging animals. They also emerge a bit
late in spring, less likely to be harmed by spring frost.
Green thumbs down
to abandoning your annuals now. Those like salvia, petunia,
snapdragon and geranium that can handle cool weather will shine
into October if you keep deadheading, watering and fertilizing.
Original publication 9/11/04