Cities debate how to care for trees infected with EAB

By Grace King, Mt. Pleasant News


WINFIELD ? It was last year when Winfield Public Works Director Chad Venghaus began noticing a change in the ash trees around town.

With leaves sprouting smaller and yellow in color, entire branch systems dying, sprouts popping out in places on the tree where they shouldn?t be and ?D-shaped? exit holes on the bark, it was time to address the problem ? the emerald ash borer (EAB) had struck Winfield.

EAB is native to Asia, where it doesn?t harm ash trees at as high a rate as it does in the U.S. because of the native enemies there. EAB attacks live, healthy trees by burrowing in the bark and disrupting the trees vein system, which carries water and nutrients throughout it. Eventually, this causes the tree to slowly die.

The EAB can only fly a mile or two on its own. The real damage happens when the insect is at its larva stage.

When people cut down trees to transport for firewood or other purposes, the larvae stay in the wood until they are grown and infect other trees from there. As adults, EAB are green, shiny beetles that can only fly one or two miles.

?If they were left to their own devices, they would spread slowly,? said Lisa Louck, DNR District Forester. ?However, they can move from firewood very easily... if it?s greater than a two-inch piece of chip, larva can still be living there and hatch out successfully.?

So far, Venghaus has counted a total of 80 ash trees in his jurisdiction that are infected with the invasive insect, but he said it is just a matter of time before every ash tree within 15 miles of an infected tree also will be infected with EAB.

While the city doesn?t yet know how they will tackle such a large infestation, Venghaus said that they have a lot of research to do on the subject in a short amount of time. If Winfield City Council approves treating the trees, the best time to do so is in the spring, Venghaus said.

But the question of treating ash borer trees versus cutting them down is more complicated than that. While by Venghaus? estimate it will cost less than $100 a year to treat one tree, that tree could live for another 15 to 20 years, which would cost $1,500 over the tree?s lifetime. On the other hand, cutting down a tree would cost almost $1,000 up front.

Louck said that a general rule of thumb is if the three is no more than 20 percent infected, using a chemical treatment for EAB could be somewhat successful; however, ?Insecticide will have its own issues,? Louck said. ?Chemical treatment should only be done on one or two trees in your yard that already have maturity, not five to 10 trees that are only 30 feet tall at the time.?

Tim Egli, of Egli Landscapes, Inc., is also not on board with chemically treating trees, saying he doesn?t think it will be financially beneficial to the customer long-term. He also thinks cities are being misinformed on the process of chemically treating for EAB and they should speak with cities in Michigan and Wisconsin who have been dealing with it for the past 20 years.

The questions that still need to be asked are do you believe the treatment was a good option for the town? Was the treatment worth the money? Are there counties that are still treating trees?

?I don?t think you?re going to get a good answer from a treating company in the state of Iowa because at the end of the day, they?re making money,? Egli said.

Instead of chemically treating ash trees, Louck typically recommends cutting down a tree and replacing it with a different species, saying we don?t know what the next EAB could be.Louck equates the EAB?s impact on ash trees to the impact of Dutch elm disease on elm trees in the 1970s. ?We have already recreated history by having all the elm trees die with Dutch elm disease and replaced those with ash (trees),? she said. ?Now we?re seeing whole streets where we again have to take out all their trees because they?re dying.?