Hunting ash borers: State officials busy checking for infestation
By Chris Hubbuch / [email protected]

WEST SALEM n Jennifer Krebs peered up at the crown of a tree shading
the back yard on North Lincoln Street. Right away, she noticed the
bare branch.

Carrying a clipboard and wearing a neon green vest, the surveyor with
the state’s Department of Agriculture was tracking down a report of a
possible emerald ash borer infestation.

“I can see why they called,” Krebs said.

The beetles usually infest from the top, so the tree begins dying at
the crown.

The trunk had sprouted new shoots of leaves, another sign of stress.
But Krebs noticed the tree had been pruned.

Then she saw woodpecker holes covering one side of the trunk.

She began looking for the telltale D-shaped exit hole the adult beetle
makes when it emerges. Tiny holes peppered the bark.

Right size, wrong shape.

Bad news for the tree, likely infected by a native beetle, but good
news for the county, which so far has avoided the wood quarantine the
state imposes for a confirmed emerald ash borer infestations.

“This is part of the difficulty in tracking this thing down,” said
Mick Skwarok, spokesman for the agriculture department. “We’ve been
getting a fair number of calls from people with ash trees where the
leaves are dropping off for no apparent reason.”

In 2008, the invasive beetle was found in Newburg, along the northern
Ozaukee and Washington county line, and in April in the Vernon County
town of Victory. Since then, tree specialists have documented
widespread devastation of that area’s ash.

Metallic green and about a half-inch long, the emerald ash borer came
from Asia in the 1990s. Adults lay eggs in the crevices of ash bark,
and the larvae feed on the wood, killing its host.

On its own, the insect migrates slowly — about one-half to 2 miles a
year. But with human help, it can travel great distances in live
trees, firewood or other wood products.

The state Agriculture Department this year will spend nearly $2
million trying to halt its spread.

The greatest threat is in municipalities, where as many as one in four
trees are ash. Although there are treatments that potentially save
infested trees, widespread application is impractical, Skwarok said.

La Crosse Forester Pat Bonadurer figures if the beetle wiped out the
city’s 4,600 ash trees, it would take his department 88 weeks of doing
nothing but removing dead ash.

On any given day, the agriculture department has 45 to 50 workers like
Krebs in the field, setting and monitoring about 8,000 traps and
running down homeowner reports of suspect trees.

Krebs, 23, spends much of her time canvassing the state in a tan GMC
pickup, looking for the beetle that threatens to fell some 765 million
ash trees in Wisconsin and another 900 million in Minnesota. She
inspected six sites Tuesday, in Milwaukee and Lake Winnebago.

Wednesday’s inspection was prompted by a call from the homeowner who
had noticed one of her 30-year-old backyard trees slowly losing
leaves. Then a younger ash in another part of the yard suddenly died.

Screeners at the state call center asked questions to verify the tree
was ash.

“We get a lot of calls about trees that turn out to be elms,” Krebs
said.

Though surveyors rarely see an actual beetle, Krebs has seen plenty of
larvae.

Had she found D-shaped holes, she would have peeled off a piece of
bark to look for the beetle’s S-shaped galleries.

Even then, the state needs larvae to confirm an infestation.

Certain that some other pest was killing the tree on North Lincoln,
Krebs used a hand-held GPS device to measure its exact latitude and
longitude.

She referred the homeowner to an online list of arborists before
heading to Sparta to check another suspected tree.

“We don’t know where these beetles are,” Krebs said. “We rely on
homeowner calls — even if it’s not emerald ash borer.”

HOW TO IDENTIFY AN ASH:
Opposite branching — branches coming off a main stem are directly
opposite each other

Compound leaves: Look for clusters of five to 11 leaflets

Small dots on leaf scars form a semi-circular or crescent pattern

White and green ash have thick, diamond-patterned bark; black ash has
thin, gray, scaly bark.

SIGNS OF INFESTATION:
Crown die-off — look for trees dying from the top

Sucker sprouts — shoots of leaves coming from the trunk signal stress

Woodpecker holes. The birds know when there are bugs under the bark

Look for the D: the emerald ash borer leaves a distinctive D-shaped
exit hole

To learn more about identifying ash trees and signs of the emerald ash
borer, go to emeraldashborer.wi.gov

If you suspect infestation, call the state hot line, 1-800-462-2803.

Source: Wisconsin Department of Agriculture, Trade and Consumer
Protection