Wehr loses 300 trees to her­bi­cide ap­pli­ca­tion mis­take

Two acres killed off in ef­fort to re­move in­va­sive ground flower

Milwaukee Journal Sentinel - - Front Page - Don Behm

More than 300 hard­wood trees at the Wehr Na­ture Cen­ter died af­ter a weed­killer was sprayed in the woods, and Mil­wau­kee County Parks staff will be cut­ting the trees this win­ter as the first step in restor­ing the land, of­fi­cials said.

Vis­i­tors see the dead canopy of the woods as soon as they drive into the cen­ter’s park­ing lot off Col­lege Av­enue in Franklin. The leaf­less tree­tops ex­tend across two acres east and south of the vis­i­tor cen­ter as tes­ta­ment to us­ing the wrong tool for a job.

Yel­low rib­bons mark ma­ture black wal­nut, sugar maple and ash trees to be logged this win­ter by Parks

Depart­ment foresters. A few of the dead trees will re­main stand­ing for wildlife habi­tat.

Brian Rus­sart of the Mil­wau­kee County Parks Depart­ment said the in­ci­dent was “a learn­ing les­son” for parks staff. That pes­ti­cide will be used in the fu­ture to con­trol in­va­sive weeds only where there are no trees, he said.

Un­in­tended dam­age

Park staff ap­plied a weed­killer, Po­laris AQ, to the leaves of a nui­sance, in­va­sive plant — Lesser celandine — in April 2017, said Brian Rus­sart, nat­u­ral ar­eas co­or­di­na­tor for the parks depart­ment.

Po­laris con­tains the chem­i­cal Imazpyr and it did the job ef­fec­tively. Within a few weeks, parks staff noted the un­wanted celandine was dead.

But a month later, Wehr staff ob­served the hard­wood trees were not grow­ing leaves. They were dy­ing. And they did not leaf out this spring.

“Po­laris re­moved the celandine but killed the for­est we were try­ing to save,” Wehr staff wrote in the Fall 2018 “Wehr Words“news­let­ter.

There is dis­agree­ment among parks depart­ment staff on whether the her­bi­cide should have been sprayed in the woods.

Rus­sart said there were no “red flags” on the pes­ti­cide’s la­bel that would have ruled out its use. “There was no glar­ing fail­ure,” he said.

“We reg­u­larly use her­bi­cides to con­trol in­va­sive species and this was the first time this hap­pened,” he said.

But Wehr staff, in the news­let­ter ar­ti­cle, “For­est of Un­in­tended Con­se­quences,” said the la­bel “cau­tions users about ap­ply­ing near de­sir­able trees.” The rea­son for the cau­tion is that it can be taken up by shal­low roots and flow through a tree.

Wehr staff de­scribed the in­ci­dent as a “bull in a china shop” mo­ment of hu­mans cre­at­ing abrupt change in a nat­u­ral en­vi­ron­ment “that leaves more bro­ken pieces than na­ture can glue back to­gether quickly.”

The woods clos­est to the vis­i­tor cen­ter had been dom­i­nated by black wal­nut. About 25% of the trees are ash and they al­ready had been im­pacted by the Emer­ald ash borer, a de­struc­tive in­sect pest, ac­cord­ing to Rus­sart.

Rus­sart said the in­ci­dent was “a learn­ing les­son” for parks staff. That pes­ti­cide will be used in the fu­ture to con­trol in­va­sive weeds only where there are no trees, he said.

Bri­ana Frank, owner of Tree Health Man­age­ment LLC in Madi­son and a con­sult­ing ar­borist, said she re­ceives calls about un­in­ten­tional dam­age caused by use of her­bi­cides but not any of such a large scale at just one lo­ca­tion.

Donna Gil­son, a spokes­woman for the state Depart­ment of Agri­cul­ture, Trade and Con­sumer Pro­tec­tion, said Fri­day that the county parks staff had con­tacted the depart­ment’s pes­ti­cide reg­u­la­tors this year about the in­ci­dent.

“This was not mis­use, in le­gal terms, since it was ap­plied ac­cord­ing to the la­bel,” Gil­son said. “It was un­for­tu­nate.”

Such large-scale un­in­tended dam­age caused by her­bi­cides does hap­pen oc­ca­sion­ally in Wis­con­sin, she said.

Restora­tion of the for­est

Squir­rels and deer, in­clud­ing a few bucks, walked through the her­bi­cidescarred land­scape on Fri­day. There are scat­tered bare patches of soil beneath the dead trees where no plants grew this sum­mer, not even gar­lic mus­tard, a nui­sance in­va­sive weed.

Parks depart­ment staff will at­tempt to sell black wal­nut and maple lum­ber from the log­ging this win­ter to gen­er­ate rev­enue.

Next spring and sum­mer, staff will mon­i­tor and con­trol in­va­sive weeds be­fore pre­par­ing the soil for plant­ing new trees, shrubs and wild­flow­ers.

“We’ll plan a cli­mate change for­est with south­ern species of trees that might move up here over the next 100 years” due to warm­ing weather pat­terns, Rus­sart said. Among those tree species are Amer­i­can sy­camore and hack­berry.

And parks staff will plant na­tive trees, such as white and bur oak, that likely will put up with a warm­ing cli­mate and stick around here, he said.

“We’ll have a greater di­ver­sity of trees here,” Rus­sart said.

Un­wanted in­va­sive

Lesser celandine was brought to the U.S. from Eura­sia for its showy, or­na­men­tal flow­ers. It is now pro­hib­ited in Wis­con­sin.

This alien forms a rapidly spread­ing ground cover with daisy-like, glossy yel­low flow­ers and kid­ney-shaped to heart-shaped leaves, ac­cord­ing to the Wis­con­sin Depart­ment of Nat­u­ral Re­sources.

It gained a toe-hold at Wehr 10 years ago and even­tu­ally forced out na­tive plants and flow­ers in up to one-third of the woods near the vis­i­tor cen­ter and was spread­ing out­ward.

Dig­ging it up and spray­ing it with the Rodeo brand weed­killer con­tain­ing glyphosate did not stop its spread, parks staff said. So work­ers se­lected Po­laris AQ to stop it.


Dead hard­wood trees unintentionally killed by use of a her­bi­cide at Wehr Na­ture Cen­ter are marked for log­ging this win­ter. More pho­tos at json­line.com.

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