Officials watching for disease that kills oak trees say it hasn’t yet been found in Minnesota

Published 6:26 am Tuesday, October 1, 2019

By Andrew Krueger

MPR News/90.1 FM

Minnesota agriculture officials monitoring for the possible spread of a fungus-like organism that has killed millions of oak trees on the West Coast say it has not yet been found in the state.

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But they remain on the lookout for a disease that could harm the state’s iconic oak trees.

The Minnesota Department of Agriculture put out a call in August to anyone who purchased rhododendrons this year, to be on the lookout for sick plants.

Rhododendrons infected with the organism — called Phytophthora ramorum — were found this year in Iowa, Indiana and Illinois. The shrubs can be a carrier for the disease that causes sudden oak death.

Minnesota did not get a shipment of the infected rhododendrons, but officials asked that anyone in the state who purchased or planted rhododendrons this year to watch for leaves with large, brown blotches, as well as young green stems and shoots that turn brown and shrivel.

Michelle Grabowski, a plant pathologist with the state Department of Agriculture’s Plant Protection Division, said they received more than 40 calls from the public. Those cases were investigated, which led to several site visits.

“We were able to collect samples from those plants, bring them back here to our lab … where we ran the tests,” she said. “And I am very happy to report that Phytophthora ramorum was not found on any of the plants that we sampled here in Minnesota.”