Janesville49.2°

Janesville tree owners on offensive against borer

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Marcia Nelesen
August 31, 2014

JANESVILLE—The emerald ash borer continues its relentless attack on city trees, but officials and some residents appear to be armed and on the offensive.

More effective chemicals to fight the borer have led to better weapons in tree owners' hands, all agree.

Cullen Slapak, Janesville parks director, said the borer probably has been in Janesville for five years or more, meaning the infestation is nearing the top of a curve when a large number of untreated trees succumb quickly.

The city has opted to treat many of its ash trees in its developed areas. He believes from his contact with the public that many residents are opting to do the same.

Researchers believe treating trees also helps slow the spread of the bugs, Slapak said.

The number of infected trees in the city has increased, especially in a corridor along East Milwaukee Street and four to five blocks to the north and south and a smaller area on the west side, Slapak said.

“If homeowners are wanting to treat their trees, next spring would be an ideal time to do it,” Slapak said.

Tree owners might miss the opportunity if they don't act then, he said.

Professionals do not recommend treating trees if more than 40 percent of the canopy already shows dieback from the borer.

The city in 2013 set aside $100,000 to fight the bug and hire a forester.

But an inventory by a summer intern in 2013 showed 435 ash trees on city property and another 2,025 on street terraces, many fewer than had been estimated. The department was able to return some of the money to the general operating budget.

Seven city workers are now certified to treat public trees, lowering the cost to treat an average-sized tree from several hundred dollars to about $75. Workers can treat trees in about 10 minutes, Slapak said.

Treatment methods include injections, soil drenches and bark sprays, depending on the size of the tree.

Last fall, the city treated 205 trees on developed city property and has had good success, Slapak said. He plans to treat another 45 trees either in fall or spring.

“I think when we first started, it was doom and gloom,” Slapak said, with staff believing the only option available was to cut all ash trees.

Treatments continue to show good results, and researchers are finding they protect trees longer than the one year promised.

“If you have a tree that you think is valuable, I would definitely encourage people to treat it,” Slapak said.

“If you do choose to take a tree down … look at replanting something.”

Professionals recommend residents stay away from maple trees because the city has a large number of maples. A diverse tree population protects the canopy from being devastated by one bug.

Janesville cut about 80 of its ash trees in 2013. Another four trees since then were felled. The trees removed were past their primes, were damaged or growing into lines, Slapak said.

In Rockport Park's undeveloped areas, workers are selectively cutting trees growing close to the trails and allowing people to remove the wood.

Slapak plans to log ash trees from the Janesville Schools Outdoor Lab this winter and offer the wood for sale for reuse.

Workers earlier this year planted 106 trees paid for with an Urban Forestry Grant. The city matched the $25,000 grant for a total of $50,000.

That grant is almost depleted and Slapak is ready to apply for another one for 2015.

Staff also continues to plant hundreds of hardwood seedlings the city gets free from the state Department of Natural Resources.

Many of the seedlings don't survive, but even if only one-quarter grow, they would develop into a forest in 25 to 50 years, Slapak said.

Residents who do not treat their trees should remove them and chop the wood into small pieces, Slapak said. Residents can bring the wood to the demolition landfill, but that might change if and when hundreds of trees start coming in.

The city set aside $42,000 to deal with the ash borer in 2014, and Slapak expects to ask the city council for the same in 2015. He also plans to hire another summer intern rather than contracting with a forester.

If the city gets another grant, Slapak said he might recommend the council use some of the money to help residents buy terrace trees.



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