First case of deadly tree disease confirmed in MN

University of Minnesota researchers have confirmed the state’s first case of a tree disease responsible for sudden oak death.

With no known cure, the pathogen is always fatal in some tree species like oak, while others can just be carriers.

“We discovered sudden oak death on a rhododendron in a nursery in Hennepin County in July, and it appears to be an isolated incident,” said Nick Rajtar, a researcher in the university’s plant pathology department. “As far as we can tell, there was only one rhododendron at the nursery that tested positive for sudden oak death.”

During a follow-up visit in September, neither the university or the Minnesota Department of Agriculture found any remaining evidence of sudden oak death at the nursery. Rajtar said because Minnesota has a short growing season, the infected plant was more than likely shipped in from another state.

The university continued further testing on what was discovered in July before announcing the confirmation earlier this week. Rajtar said while the incident appears isolated, early detection is key.

“This is a really worrying pathogen because it is wreaking havoc on the West Coast,” Rajtar said. “It’s responsible for killing some 45 to 50 million trees out there, and it’s making its way east."

Rajtar said the disease can be spread from tree to tree through water or over land. It causes large bleeding cankers on oak trees and interrupts the flow of water and nutrients, leading to death. He said the cankers are what distinguishes sudden oak death from oak wilt.

“I would say it’s extremely unlikely that anyone would probably encounter this right now when they’re out,” Rajtar said. “I’ve been searching for it for five years and this is the first time we found it.”

For anyone who thinks they might have found the disease in the wild, Rajtar recommends reaching out to the Department of Agriculture or the university.