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New Insecticide Gets Ash Borer Results05-27-08 | News

New Insecticide Gets Ash Borer Results

A pesticide called emamectin benzoate is generating smiles among landscapers for its ability to squash emerald ash borer infestation. The brilliant green beetle is one of the most dangerous tree pests in the U.S. today.
Photos: David Cappaert, Michigan State University, Bugwood.org

Michigan State University scientists are seeing a new insecticide halt and kill emerald ash borer on its own ravaged campus. The chemical, called emamectin benzoate, became available to certified applicators for the first time this year. The verdict: this stuff saves trees.

It costs about $200 to treat a 16-inch diameter tree with emamectin benzoate. One formulation is being sold by the Arborjet company of Woburn, Mass. Research shows that other insecticide formulas based on Imidacloprid are effective against the beetle too. Results using the new chemical, however, are generating some buzz in the landscaping community.

Imidacloprip-based formulas have also shown results against the ash borer. Some formulations are injected into the trunk, others into the soil, and some are sprayed on trees, as seen here.

Campus Trials

Paul Swartz, the campus arborist for MSU Grounds Maintenance, said the MSU campus lost about 15 ash trees to the emerald ash borer last year, and will lose even more this year because of spreading.

If the trees are beyond salvation, they are removed.

The emerald ash borer has killed more than 30 million trees in Michigan since 2002 and also has killed trees across Ohio and Indiana.

MSU Grounds Maintenance is currently injecting emamectin benzoate, sold under the brand name Tree-age, into ash trees on campus.

He said the process involves injecting the insecticide through four small needles directly into the tree, and the larvae of the emerald ash borer die when they eat the treated wood. The chemical is supposed to be effective for two years, he said.

Several companies market chemicals that can be directly injected into ash trees to provide lasting protection against burrowing beetles. This injector is made for use with ArborSystems Imidacloprid-based treatment for emerald ash borer and can be directly inserted without using a drill.

Good Results

“It’s pretty much considered the best on the market,” Swartz said.

“This beetle has the potential to kill every ash tree in North America,” said Robin Usborne, communications manager for the MSU College of Agriculture and Natural Resources. “It looks hopeful, but more study is needed.”

Swartz said there are some noticeably dead ash trees on Harrison and Grand River avenues that weren’t previously protected from the emerald ash borer by insecticides.

Most ash trees have no known resistance to the ash borer because the trees in the area did not evolve with them, Usborne said, and because of that the trees can’t protect themselves from it.

Robert Haack, a research entomologist for the United States Department of Agriculture Forest Service, said the emerald ash borer is native to Asia, and can be found in China, Korea, Japan, and parts of Mongolia and Russia.

He said the beetle was discovered in Michigan in 2002, but is estimated to have been in the state, undetected, for several years, possibly a decade. It did not become a problem until recently because it took several years for the population to grow from a small number of beetles.

The larvae of the emerald ash borer feeds on the tissue between the wood and the bark of trees where there is water and mineral conduction, he said.

“Once it feeds into the tissue, the tree doesn’t repair itself,” Haack said. “Thousands of larvae are each eating easily a couple feet.”

With so many of the beetles doing damage, there is no way to save the trees once they are infested, he said.

Source: The State News (Mich.), www.arborjet.com