not alone in threatening shade trees
Non-native pests menace U.S. landscape
By Tom Henry
May 4, 2004
Many Americans celebrated Arbor Day for the 119th time
this year, unaware that the man who founded the event
was a transplanted Detroit-area resident upset over the
lack of trees in Nebraska.
There's irony to that fact, for many tree-lined streets
that Arbor Day founder J. Sterling Morton enjoyed while
he lived in the Detroit area are now under threat.
Although the Detroit area is not as barren as Nebraska
was when Mr. Morton founded Arbor Day in 1885, 6 million
ash trees in southeastern Michigan are dead, dying, or
being cut down because of a devastating foreign pest,
the emerald ash borer.
Drastic as that sounds, it could be only the beginning
of an altered landscape for Michigan, Ohio, and Indiana.
Officials are so worried about the havoc the bug could
cause that they have begun discussing the possibility
of cutting a huge swath across those states.
Canada clear-cut 84,000 ash trees across Ontario's southwestern
peninsula a few weeks ago.
A semicircle running south from Michigan into northwestern
Ohio and northeastern Indiana would involve tens of thousands,
if not millions of ash trees, creating a firebreak-like
barrier up to 6 miles wide, said Sharon Lucik, spokesman
for the U.S. Animal Plant and Health Inspection Service
in Brighton, Mich.
The cost could be millions of dollars and the project
could take eight years, said Bob Waltz, an Indiana Department
of Natural Resources entomologist.
In 1962, diseased elms on Fulton Street were removed,
part of a city-wide project to remove infected trees from
( THE BLADE )
With billions of trees, this region doesn't appear to
be in any imminent danger of becoming treeless.
Yet forestry experts and nursery owners admit the emerald
ash borer is one of many threats causing anxiety over
the fate of some species of trees that provide the region
with shade and beauty, and even help cleanse the air.
"We are now seeing an array of threats to Ohio's
forests that are unprecedented," said Tom Harrison,
a veteran plant pathologist for the Ohio Department of
Agriculture who's studied such issues for more than two
Besides the emerald ash borer, there are other threats
to our trees, some already in this region and some feared
to be on their way. Among them: Asian longhorn beetles,
gypsy moths, beech scale insects, hemlock woolly adelgid,
and sudden oak death fungus.
The fungus, first noticed in central California oaks
in 1995, may have been spread by a Los Angeles nursery.
A shipment to the Cincinnati area is under review by investigators.
"I think we've had more exotic pest flare-ups in
the past four to five years than we have had in the past
20 years combined," Mr. Harrison said.
Contributing to the declines are developers who clear
land for more housing subdivisions and retail plazas.
Maintenance activities by FirstEnergy Corp. and other
utilities to trim back trees from power lines to prevent
blackouts are factors as well. Many trees also are felled
by oil companies to maintain an aerial view of their pipelines.
Attacks and response
Remember Dutch elm disease?
It began in Cleveland in 1930, when the disease started
its stranglehold on the American elm tree, one of the
nation's most popular shade trees for residential neighborhoods.
By the 1960s, elms were struggling to survive.
Most people today don't remember when the American chestnut
tree was the dominant hardwood species in the eastern
United States, including Ohio, where it once was the state's
most common tree. An exotic fungal disease known as chestnut
blight wiped out the species by the 1950s.
Years later, butternut trees - a relative of the black
walnut highly valued for furniture - were decimated from
much of the continent by another fungus.
The U.S. Department of Agriculture's Forest Service has
described the loss of those species as "three American
tragedies," each caused by fungal diseases from other
Today, few state or federal officials from this part
of North America spare any adjectives when discussing
the potential impact of the tiny Asian beetle.
"The emerald ash borer is the worst of the bunch,
because it's so devastating to its host tree," said
Mr. Harrison, who heads up Ohio's emerald ash borer task
Michigan Department of Agriculture Director Dan Wyant
even went so far as to formally declare the bug a menace
"It's hard to survey or detect," Mr. Harrison
said, "and you must take draconian measures to get
rid of it when you find it."
Those draconian measures include cutting down more than
20,000 ash trees in Ohio this year alone, including about
15,000 in northeast Columbus, one of several pockets of
the Buckeye State where the beetle has been detected.
About 1,500 trees were targeted for destruction in the
vicinity of Hicksville, Ohio, and an additional 450 in
the Perrysburg/Rossford area. Hundreds were destroyed
last year in western Lucas County, near Whitehouse, and
hundreds more will be coming down as soon as this week
near Ohio's latest confirmed site, south of Toledo Express
That's because with no safe, foolproof pesticide developed
to kill this bug, protocol calls for destroying all ash
trees within at least a half-mile radius of known infested
sites. The idea is create a gap big enough to cut the
beetle off from its food source. Pesticides are applied
to trees just beyond that perimeter as a backup.
Ohio's figures, however, pale in comparison to what's
been going on in Michigan, where 6 million ash trees have
died or are being cut down.
On Friday, Governor Jennifer Granholm asked President
Bush to declare Michigan a major disaster area to help
make the state eligible for more federal funding for eradication
efforts. The cost of addressing the problem in Michigan
is estimated to be greater than $163 million. The state
has received $29 million from the federal government so
Michigan has quarantined a 13-county area in the southeastern
part of the state seen by experts as the epicenter of
North America's infestation. The bug was discovered in
that part of Michigan in 2002, but officials now realize
it may have been there for as long as a decade. It has
since spread to other parts of Michigan.
Across the Detroit River, at least 84,000 ash trees in
Ontario's southwestern peninsula from Lake St. Clair to
Lake Erie - a swath of land 6.2 miles wide and 18.6 miles
long - were clear-cut this year. That $12 million project
was an attempt to prevent the beetle from spreading to
other parts of Canada.
Emerald ash borers also have been found in Indiana, Maryland,
In the case of Maryland and Virginia, the infestation
was blamed on a Michigan nursery owner who ignored the
state's quarantine and shipped infested ash trees there.
Stuart Leve pleaded no contest in November to 123 counts
of violating Michigan's emerald ash borer quarantine and
plant health laws. He was sentenced Dec. 10 by District
Court Judge Brian MacKenzie in Novi, Mich., to the maximum
sentence of $12,300 - $100 for each count - and was ordered
to pay $16,000 in restitution to a Maryland nursery that
had unknowingly purchased infested trees from him.
The judge left open the possibility of ordering Mr. Leve
to pay thousands more in restitution to Maryland and Virginia
for their expenses, officials said.
Drew Todd, state urban forestry coordinator for the Ohio
Department of Natural Resources, said the emerald ash
borer has the potential of being every bit as devastating
as Dutch elm disease.
"From a potential damage standpoint, it is very
similar," he said. "It has the potential to
alter the composition [of the landscape] drastically."
Mr. Harrison agreed. "Dutch elm disease didn't kill
all the elms in a year or two. Whether or not the current
containment efforts [for the emerald ash borer] work -
that's still in the cards."
Many of the problems faced by trees in the Great Lakes
region parallel threats that have emerged in the world's
largest collection of fresh surface water: The onslaught
of exotic species.
Invasive species have hitched rides in the wooden shipping
crates and ballast water of ocean-going ships, gotten
off in the vicinity of port cities such as Detroit and
Toledo, then blitzed the North America ecology with a
set of problems many scientists here have never seen before.
Invariably, the destruction has created new learning
curves - but it's often been a game of catch-up, because
officials admittedly haven't known what to predict whether
it's on the land or beneath the water.
Scientists acknowledge the problem will get worse because
of emerging global trade markets.
Increased trade with Asia has the potential of causing
more ecological threats, because Asia's climate has more
in common with North America's than Europe's, experts
"It's inevitable that we're going to have invasives
that get established and disrupt the ecology," said
Dan Herms of the Ohio Agricultural Research and Development
Center in Wooster, Ohio. Mr. Todd agreed. "As the
world economy evolves and the ease of shipping increases,
there are more and more opportunities for these things
to happen," he said.
They and others are looking beyond the traditional ivory
towers of a major university for help: the U.S. Department
of Homeland Security.
Officials believe the attempt to slam the door on exotics
will benefit greatly from the government's enhanced efforts
to keep out terrorists. That's because security includes
better detection of chemical agents, not just people.
Invariably, that should lead to better detection of biological
pests foreign to North America, they said.
"There's a lot more emphasis being paid to the ports,
not just in looking for terrorists but also for pests,"
Mr. Harrison said.
The evolving changes are hard on people like Tom Oberhouse,
who owns North Branch Nursery, Inc., in Pemberville, one
of northwest Ohio's largest tree farms. Although not in
a quarantined area, he said he's all but given up on the
ash making a comeback as a landscaping tree.
White ash is Ohio's third-most common tree, with an estimated
3.8 billion statewide. They have contributed millions
of dollars to the economies of Michigan and Ohio in nursery
sales because of their popularity as a landscaping tree.
They've also contributed millions of dollars because
of their role in manufacturing. Ash is used to make products
ranging from wood flooring to baseball bats; in Ohio,
the manufacture of ash-made tool handles is one of the
state's larger businesses.
"The emerald ash borer is kind of all-consuming
at this point," Mr. Oberhouse said.
Mr. Oberhouse said the bug's threat is the worst he can
recall in his 24 years in the nursery industry. He said
he is hopeful a pesticide will be developed, but doesn't
see that reversing the damage to nurseries.
"Most people don't want a tree they have to put
pesticides on every year," he said.
In the aftermath of Dutch elm disease, ash trees were
seen as a shade-tree replacement for the loss of elms.
Now, hybrid elms that are resistant to Dutch elm disease
are displacing ash as landscaping trees, Mr. Oberhouse
Call it another sign of homogenization among continents:
Scientists are in the early stages of coming up with a
hybrid ash that would be resistant to the emerald ash
borer. They're studying ash trees in Asia that can tolerate
the bug. A collaborative effort among Michigan, Ohio and
federal scientists is underway at the Michigan State University
Tollgate Research and Education Farm near Novi, Mich.,
about an hour north of Toledo. On April 24, officials
planted 800 trees, including two species of Asian ash.
"Two years ago, none of this seemed real significant
to me," confessed Mr. Herms, an Ohio researcher involved
in the effort. He now is confident that ash hybrids will
be developed that are resistant to the emerald ash borer.
Years ago, a knee-jerk reaction to attacking tree problems
such as the emerald ash borer might simply have been mass
fumigation with chemicals.
In the late 1950s, DDT was used to curb Dutch elm disease.
Much of it was surplus chemical left over from World War
II, when it was used to help the military combat malaria
or yellow fever.
After studying bird deaths on the Michigan State University
campus that had been linked to DDT, however, researchers
eventually concluded that robins were poisoned by eating
DDT was later blamed for decimating America's bald eagle
population because it made eagle eggshells thin and vulnerable.
In 1962, Rachel Carson published her landmark book, Silent
Spring. The book has connections to Dutch elm disease,
in the sense that it begins with a description of a strikingly
eerie silence that could have befallen the nation if robins
and other birds continued to die from DDT
Ms. Carson, a former aquatic biologist for the U.S. Fish
and Wildlife Service, was lauded by Time magazine as one
of the most influential people of the 20th Century for
awakening the scientific community to the dangers of chemical
Since then, the chemical industry's products have come
under closer scrutiny and a new generation of scientists
has grown up looking for links between excessive use of
chemicals and cancer, with the latest research evolving
toward birth defects, reproduction problems, and child
"Silent Spring still has an impact on what our scientists
are doing and how they're doing it," Mr. Todd said.
Looking for solutions other than pesticides "reduces
your arsenal to some degree and rightfully so," Mr.
Harrison said, "because there are some tools you
use that are worse than the actual pest."
Cutting down trees is an alternative. Considering the
outcry that chopping down a property owner's trees can
generate, officials say they appreciate the public's sacrifice
to accept the destruction being done in some areas in
an effort to halt the emerald ash borer's spread.
"This is a very drastic thing for us," Mr.
Harrison said. "We don't take pleasure in taking
these trees down. It strikes a little bit of emotion in
you that you didn't know you had. It's hard."