The search for a signature Minnesota wine grape worthy of royalties rivaling the Honey Crisp apple has led to theft and intrigue.

Somebody pilfered promising grapevines recently from the University of Minnesota's test fields at the Minnesota Landscape Arboretum in Chanhassen.

"We have a lot of time and money invested in these vines,'' said Peter Moe, operations manager for the arboretum. "The plants that were stolen were one of a kind.''

After suspecting theft at the horticultural research center for two years, plant breeder Peter Hemstad kept close records and on Oct. 20 reported that vines had been cut from six plants, said Carver County Sheriff Bud Olson.

Hemstad "had just identified these plants as having good qualities in early October. They were stolen three weeks later,'' Moe said. The woody cuttings that were stolen could be rooted to produce new plants and sold as a new variety.

Because the 10-acre arboretum test field has thousands of vines, officials suspect the thief is someone who knows the project and is likely an experienced grape grower.

Olson said his department's investigation is looking at current and former arboretum employees and anyone else who had access to the field work. Olson is treating the incident as a felony theft of valuable intellectual property. "It's a trade secret type of crime,'' he said.

In research, "you do hundreds and hundreds of crosses and evaluate the vines," Moe said. "It is illegal and damaging to us to have someone steal that material.''

At the arboretum, the university makes wine to test grapes harvested at the research vineyards. It counts on royalties from the sale of vines to help pay for the research, Moe said.

The test fields are not open to the public. "We have an opening in the fence where somebody pried up the bottom of the fence to make space to crawl under,'' Moe said.

The stolen plants were four- or five-year-old seedlings that this year produced a substantial crop of good-tasting grapes, Moe said.

"The real value of the theft is what the grapes and what that vine could produce in royalties,'' Olson said. The Honey Crisp apple developed by the university has brought the state more than $8 million in royalty revenues, Olson said.

The university is developing grapevines that are winter-hardy and don't have to be moved to the ground and covered to survive the cold, Moe said. "Laying them down is very labor-intensive and not economical.''

Grapes have a good growing season in Minnesota. In hot weather, vines can put on 6 or 8 feet of growth a year, Moe said.

The legal way to get access to university grapevines is to buy them from nurseries licensed by the university and pay a royalty. There are now 28 wineries operating in Minnesota, Moe said.

Laurie Blake • 612-673-1711