Staff Reports
The Indiana Department of Natural Resources has intercepted plants in Columbus containing a fungal pathogen that kills oak trees through sudden oak death (SOD), the first time the pathogen has been detected in a decade.
Inspectors from the DNR Division of Entomology & Plant Pathology detected SOD (Phytophthora ramorum) in several varieties of rhododendrons being sold in Columbus, Noblesville, South Bend, and Sullivan and Tippecanoe counties.
SOD has killed large tracts of oaks on the West Coast, according to the department, but it has not been established in the Midwest, to date.
The pathogen can kill standing oak trees, which could happen if pathogen-positive rhododendrons were planted within about 6 feet of a standing oak, according to the department.
The pathogen can travel in more than a hundred species of host plant material. It causes some browning of the leaves in the host plant but does not kill it.
For a list of plants that can carry the pathogen, visit aphis.usda.gov/plant_health/plant_pest_info/pram/downloads/pdf_files/usdaprlist.pdf.
Anyone who has purchased rhododendrons in the last four weeks in Columbus, or the other communities, is asked to call 866-NO-EXOTIC (663-9684) or call the local county extension office at 1-888-EXT-INFO (1-888-398-4636) for instructions.
The Indiana Department of Natural Resources is destroying all rhododendrons from the source nursery, Park Hill Plants (Oklahoma), and any other host plants that were co-mingled with them.
In addition, the department is quarantining the sale of four other common pathogen-host plants (viburnum, azalea, cameilia, and pieris) for further testing to determine if they contain SOD.
Testing will determine if other species are infested and require destruction, the department said.
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For a list of plants that can carry the pathogen, visit aphis.usda.gov/plant_health/plant_pest_info/pram/downloads/pdf_files/usdaprlist.pdf.
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