Watch continues for emerald ash borer

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Wednesday, August 6, 2008
— Now that a tree-slaying insect finally has shown up within Wisconsin's borders, what do we do?

What kind of Indiana Jones-style heroism is called for?

Sorry, but the battle against the emerald ash borer is best fought with knowledge, not whips or chainsaws, said Mike Maddox, horticulture educator with the UW Extension in Janesville.

For those who missed it, state officials on Monday announced an infestation of emerald ash borer, or EAB, near Newburg in Ozaukee County.

State workers plan to begin surveys of southeastern Wisconsin trees late this week to determine how far the emerald ash borer might have spread. The goal is to determine the source of the infestation and how widespread it might be.

The state Department of Agriculture, Trade and Consumer Protection also plans to impose a ban on moving wood that might harbor the insect outside of Ozaukee County.

EAB has killed millions of ash trees in other states, most notably in Michigan.

Maddox has been educating the public about the ash-tree-killing bug for years, but he still gets questions from people who need help with the basics. For example, they mistake their maples or lindens for ashes.

Or, they worry about their mountain ashes, which aren’t true ashes and aren’t targets for EAB, Maddox said.

He’s even gotten the question:

“Mike, what exactly is an emerald ash tree?”

There is no such thing, of course. The emerald ash borer is the pest. Ash trees—ONLY ash trees—are potential victims.

Once you know how to spot an ash tree, Maddox recommends looking for signs of dieback, including woodpecker activity. And look for lots of leafy sprouting around the base of the tree.

Those are signs of stress, but not necessarily EAB. Unfortunately, ashes are susceptible to other pests, as well, Maddox said.

Commercially available chemicals might keep EAB away from ash trees, but they aren’t foolproof, and state officials don’t recommend them until the pest is within 12 miles of the tree in question.

Experts once recommended felling all ashes within a quarter mile of an infestation, but that didn’t work, so Wisconsin officials now have a gentler, more pesticide-oriented policy.

Cliff Englert, the city of Janesville tree expert, said the city might consider chemical treatments for a particularly valuable stands of ash or individual ashes that are exceptional in some way, but not until the threat is near.

For now, it’s wait-and-see how the state responds to the Ozaukee County infestation, Englert said.

“Actually, if you think about it, we’ve been living with it 40 miles from our border for about two years now,” Maddox said.

Maddox was referring to the infestation at Lily Lake in Kane County, Ill., which popped up in 2006.

And now it’s even closer. Illinois authorities announced last month that a new infestation was found in McHenry County.

Wisconsin’s only known infestation is a bit farther away from Rock County than those sites in Illinois, Maddox points out, “So for us, it’s going to be business as usual. We’re still going to be scouting for it.”

And Maddox would like more homeowners to learn how to identify an ash tree and to spot signs that their ashes might be under attack.


The UW Extensions’ Mike Maddox recommends this Web site as a primer in identifying emerald ash borer or simply identifying ash trees: www.entomology.wisc.edu/emeraldashborer.

Homeowners who want to be certain that they do or don’t have ash trees may bring a tree branch to Maddox’s office at Rotary Botanical Gardens from 1 p.m. to 4:30 p.m. Tuesdays.

Last updated: 10:03 pm Thursday, December 13, 2012

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