Pathogens Sudden Oak Death Pathogen Found in Minnesota for the First Time

The sudden oak death pathogen was identified from a sample the researchers collected from a plant at a Hennepin County nursery in Minnesota in July, and which was later confirmed by the Minnesota Department of Agriculture Plant and Seed Laboratory.

Minnesota/USA – University of Minnesota researchers detected the pathogen that causes sudden oak death in Minnesota for the first time. Sudden oak death is a tree disease that has devastated forests on the West Coast for decades and is expanding east with no cure. Early detection and containment are the best available tools to slow the spread of the disease.

Researchers in the University’s Minnesota Invasive Terrestrial Plants and Pests Center identified the sudden oak death pathogen, Phytophthora ramorum, while working on a multi-year project to detect a variety of invasive forest pathogens with the potential to damage Minnesota's landscapes and cause significant economic loss. This project was supported by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources.

“Because Minnesota has a short growing season and ships in plants from other states, it is critical to monitor nurseries and Christmas tree farms for various plant diseases,” said Nick Rajtar, a postdoctoral associate in the Department of Plant Pathology, College of Food, Agricultural and Natural Resource Sciences. “We have always had the sudden oak death pathogen on our radar. This early detection shows our biosurveillance methods are working and can reduce the potential impacts of this pathogen — and many others — to cause damage to our natural resources in the state.”

The pathogen was identified from a sample the researchers collected from a plant at a Hennepin County nursery in July, and later confirmed by the Minnesota Department of Agriculture (MDA) Plant and Seed Laboratory. The plant has since been destroyed, and this appears to be an isolated incident.

“The MDA visited the site in September and collected samples from susceptible plant hosts, water and soil — all samples tested negative for P. ramorum,” said Michelle Grabowski, a plant pathologist with the Minnesota Department of Agriculture. “The MDA reported the detection to state officials and will continue to monitor the site.”

The researchers will continue their statewide monitoring of nurseries and Christmas tree farms for the sudden oak death pathogen and other diseases before they cause significant damage across the state.

“We are very fortunate here in Minnesota to have nursery owners who are interested in keeping new diseases out and allow us to survey and sample their plants to detect new pathogens and prevent them from being established,” said Robert Blanchette, a professor in the College of Food, Agricultural and Natural Resource Sciences, who leads the project.

The team will continue to work closely with growers, the Minnesota Department of Agriculture and Minnesota Department of Natural Resources.

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