When Polly Augustson isn't caring for children at her Monticello day care, she's caring for trees across the metro.

Augustson and about 20 volunteers spent a sunny Saturday at Powderhorn Park in south Minneapolis, tying red and blue tags to trees to spread awareness about emerald ash borer before it spreads to the park's more than 160 ash trees.

It was the first such event by the Minnesota Tree Care Advisors, hoping to dramatically show park-goers -- many of whom might not be able to distinguish an ash tree from others -- how many trees could be killed off if the destructive insects invade.

"If nothing else, it alerts people," Augustson said. "It would be very devastating to the ecology of Minnesota."

The Minnesota Tree Care Advisor program, a nonprofit housed at the University of Minnesota, trains about 150 volunteers and is ramping up its outreach this year as the invasion of emerald ash borer grows. The group has another tree-tagging event open to the public at 12:30 p.m. Sunday in Van Cleve Park near Dinkytown in Minneapolis.

"There would be a lot of holes in the sky if these trees are gone," said volunteer Lorrie Stromme, who also serves on the Minneapolis Tree Advisory Commission.

Minnesota is a prime target for the tiny beetles with its 998 million ash trees -- 200,000 of which are in Minneapolis -- putting the threat of emerald ash borer on the rise since its discovery in the state in 2009. Last month, the state Department of Agriculture confirmed an infestation at Fort Snelling Golf Course following outbreaks in parts of Minneapolis, Shoreview and St. Paul.

"We know it's anchored in the Twin Cities now," said Gary Johnson, a professor at the University of Minnesota who runs the Tree Care Advisors and teaches urban forestry. "It's here."

However, once the emerald ash borer infects a tree, hope isn't lost. Even a couple years after the pest tunnels into a tree, Johnson said, the tree can be saved with chemical treatments that are less expensive than the costly measure for cities to remove thousands of trees.

Better public education such as Saturday's tags, Johnson said, can help show park users and taxpayers how to identify the pest and show how drastically it could change the tree-lined landscape of Minnesota's parks.

"When they see the visual impact it could have on a park or boulevard it helps," he said. "I'd like to do this at every park" in the metropolitan area.

As parents pushed toddlers on swings and young women in an aerobics class stretched in the shade, the 20 volunteers scattered across the 68-acre park to tie up the tags. Besides details on identifying ash trees and emerald ash borer, the tags have a QR code for smartphone users to scan for more information. The tags will remain on trees for two to three weeks.

For environmental enthusiasts such as Augustson and her husband, Chet, it's the start to what they hope is a broader campaign to ensure Minnesota's parks and streets don't lose their treasured trees.

"It's good to start here and then move out to outlying communities," she said. "It's just the beginning."

Kelly Smith • 612-673-4141 Twitter: @kellystrib