October Silent Alarm: Emerald ash borer ravages the Midwest

BY MIKE MCFADZEN

The Midwest landscape, which is enjoyed by silent-sports enthusiasts, is

covered with dying ash trees, with Wisconsin being particularly hard hit.

The Emerald ash borer (EAB) is doing the damage now found in 51 of the

state’s 72 counties and is wreaking havoc on all four ash tree species. It’s

only a matter of time before most of the Midwest’s ash trees will have the dreaded

beetle. Once infected, the trees are susceptible to blow-down damage. Many land

managers and homeowners are preemptively removing trees to prevent property and

personal injury.

The EAB is an invasive insect whose larvae eat tissues under the bark

of ash trees. Once the damage is visible, it’s too late to save the tree. The

EAB is native to northeastern Asia and was first detected near Detroit in 2002.

It’s thought to have arrived from China in wood shipping crates. This beetle

has spread to 35 states and five Canadian provinces. The insect is a metallic green

color, measuring about 1 centimeter. The best time to see the beetle is on a

warm and sunny afternoon.

The University of Wisconsin-Madison (UW) Russel Laboratory Department

of Entomology is closely monitoring the EAB and its impacts. According to UW,

there are approximately 800 million ash trees in the state, which represent

almost 8 percent of Wisconsin’s tree population. The black ash is the most

common, followed by white, green and blue. Mountain ash is not a true ash

species, thus isn’t affected by the EAB.

“So far, we haven’t seen much of the beetle in northern Wisconsin,”

said UW entomologist PJ Leisch. “But it’s only a matter of time – almost all ash

trees will be affected and die. The beetles like ash trees 1 inch or bigger. Some

small pockets that have been surveyed show a defensive mechanism to EAB. Further

study will be necessary to determine if these pockets can survive the beetle. If

there is a genetic strain showing resistance, they could potentially be bred to

other ash stocks.”

EAB moves to new areas when humans carry it there, usually on firewood.

There is a statewide quarantine on moving firewood due to the beetle.

The ash tree die-off is similar in scale to Dutch elm disease (DEE)

which ravaged elm trees across the country in the 1960s.

DEE is a fungal infection which prevents water movement, causing the

tree to wilt and die.

“Both had drastic die-offs, particularly in urban areas,” Leisch said.

“Unfortunately, in many areas, ash trees were planted to make up for the dying

elm trees.”

Some progress has been made in managing EAB populations.  

“There is a tiny Asian parasitoid wasp that affects the juveniles, eggs

and larvae of the beetle,” said Leisch. “The early research is reassuring, and

the wasp doesn’t disturb any other insects or animals. But it’s very

labor-intensive to produce the wasp, which might be effective against the beetle

in the long run.”

UW has done field trials at sites in the Milwaukee area and other locations

in the state.

Insecticide products are effective against the beetle and can be used

by homeowners and arborists to preserve individual trees.  

“Homeowners can treat small to mid-size trees,” Leisch added. “But once

the damage is obvious, it’s too late.”

Some experts speculate we may discover native insects which attack EAB

and help reduce their populations. Insecticides are not a cost-effective option

for large tree stands such as state and national forests.

For more information on the EAB, location spread and how to protect

your ash trees, visit the UW Russel Labs News and Resources page at labs.russell.wisc.edu/eab/.

State park events coming to

a park near you

The color season is upon us with lots to do throughout Wisconsin. Many

state park friends groups will be hosting events, including hikes, runs or even

a skywatch.      

Visit GET OUTDOORS! for more information on friends groups events at dnr.wi.gov/Calendar/Events/Parks/.

Currently, there are 63 friends groups that support state properties.

Last year 1,337 citizens gave nearly 38,000 hours of service.  Friends groups are non-profit organizations

whose members have an interest in Wisconsin’s natural resources and volunteer

to support Wisconsin’s state parks, forests, trails and recreation areas. 2019 marks

the 30th anniversary of the friends groups formation.

The Friends of the Horicon Marsh host many events at their state-of-art

visitor’s center.

I recently had the opportunity to attend a voyager canoe outing led by DNR

wildlife educator Liz Herzmann and Horicon Marsh Bird Club president Jeff Bahls.

Participants saw a myriad of bird species, including pelicans, herons,

cranes, cormorants and many more, making it a memorable event. Visit the Horicon website for more information on upcoming events at horiconmarsh.org/.

Save the date: The Friends of Wisconsin

State Parks (FWSP) will be hosting their annual meeting and awards at the

Mosinee Brewery on Saturday, Nov. 9.

Try some great beer and food while celebrating with friends. It’s a

great opportunity to support state parks and network with like-minded

individuals. Visit dnr.wi.gov/topic/parks/friends.html for more information.