FALCON HEIGHTS  — The Minnesota State Fair opens today under a beautiful canopy of ash trees that have endured for generations.

Behind the scenes, state fair leaders have waged an intensive battle to stave off the emerald ash borer that has destroyed many ash trees across the Twin Cities in recent years, according to a press release.

Officials have managed to keep the beetle at bay at the fairgrounds, but it’s intensive work.

A Minnetonka-based company called Rainbow Treecare developed a kit with stainless steel taps that push into the bark and a pressure tank to force an insecticide, emamectin benzoate, into trees. A bike pump provides the air pressure.

Russell Kennedy, a consulting arborist with Rainbow Treecare, said arborists are intensely tracking each ash tree on the fairgrounds in order to ensure that they’re all healthy.

“The treatment’s been done since 2009 here,” he said. “We haven’t lost a tree to emerald ash borer on the fairgrounds.”

Como Park, a neighborhood right outside the fair’s main entrance, and St. Anthony Park, a neighborhood a few blocks away from the fair, have been hit particularly hard by the ash borer, according to Rachel Coyle, a city forester. St. Anthony Park is where the state first confirmed the bug’s arrival in Minnesota in 2009.

In these neighborhoods, it’s common to see trees with dead branches and sprouts at the base of their canopy, with chain saws not far behind.

Rainbow Treecare treats 600 ash trees at the fair every other year, which costs about $40,000 in addition to treatments.

Fair general manager Jerry Hammer said the cost is worth it because the trees help make the Minnesota fair among the nation’s biggest and most successful.

“There are some fair grounds that are just beautiful around the country, but for the most part, it’s a lot of asphalt, a lot of large exhibit buildings, and some token greenery here or there,” he said. “The kind of park-like setting we have here, trees are just ultra-critical to that, and it’s pretty difficult to look around here and imagine what the fairgrounds would be like, without trees.”