State plant health officials are advising consumers who bought rhododendrons or azaleas this spring and summer to be on the lookout for signs of a disease that could spread to oaks and kill them.

Plant health staff with the Department of Agriculture, Trade and Consumer Protection have identified Phytophthora ramorum, or P. ramorum, on rhododendrons at a northern Wisconsin nursery. This fungus causes sudden oak death, which has never been found on the landscape in Wisconsin. There is no human health risk.

The find resulted from a July survey of 59 garden centers and nurseries in the state,...