Threat to oak trees possible locally
A plant disease that has decimated oak forests in California, Oregon and parts of Europe has been detected in rhododendrons and lilacs sold during the spring and early summer at Walmart and Rural King in 17 states, including southeastern Ohio.
Anyone who bought the plants is being urged to destroy them by following very specific directions.
Sudden oak death disease is caused by a type of mold, Phytophthora ramorum, spread through spores. The spores typically are dispersed from the host plant by rain splatter and are aerially transferred to infect new plants.
“If it gets out and blows into the forest, it can really do some damage,” said Marcus McCartney at the Ohio State University extension office in Washington County. “This is an urgent priority. This is bad.”
McCarthy compared the damage potential of sudden oak death disease to that of the emerald ash borer, which has killed nearly all the ash trees in the region’s forests.
The infected plants were rhododendrons and lilacs sold at Walmart and Rural King outlets in southeastern Ohio between March 1 and June 1 of this year, including at the Marietta Walmart. McCartney said it is not yet clear how many of the plants sold were actually infected, or whether outlets in West Virginia were among those that received the infected plants.
The extension will come and examine any plant a homeowner is concerned about, and it can run diagnostic tests to determine the problem, he said. Anyone who bought a rhododendron or lilac from either of the two store chains during the period in question should contact the extension office immediately, he said, especially if the plants look unhealthy.
“Twig die-back, necrotic brown or yellow leaves, wilting are symptoms,” he said.
The disease can kill an oak tree within a year, he said.
Any plant that is infected must be dug up, roots and all, double-bagged and disposed of through trash collection that will bury it in a municipal landfill – the plants cannot be mulched, composted or recycled, the OSU extension said. Any garden tools that come in contact with it have to be disinfected by soaking in a 10 percent solution of bleach for at least 30 minutes.
Oaks, in addition to providing $26 billion of value to the Ohio forest industry, are a crucial feature of southeastern Ohio woods, offering habitat to birds, insects and other plants, soil stability through their massive root systems, and regal aesthetics to both wild and urban landscapes.
McCartney said he didn’t have information that would account for the time lapse between the sale of the infected plants and the reports of the disease. He said a conference is scheduled for today to discuss the matter in greater detail.
Sudden oak death disease is spread by airborne dispersion of spores aided by rainfall splash on leaves. The spores also live in soil moisture and are resistant to freezing. Even if all the infected plants are identified and eradicted, he said, the presence of the disease will trigger a monitoring effort that could last for years, he said.
“It would be nice if Walmart and Rural King were able to tell us how many of the plants they sold, who they sold them to and where they live,” McCartney said. “We could monitor the site and check back to see if it makes its way out.”
Attempts to reach Walmart and Rural King Tuesday were unsuccessful.
Sudden oak death disease has killed more than a million trees in the past decade in California and Oregon, according to information from the University of California integrated pest management program. Nurseries normally monitor for the disease and treat susceptible plants with an appropriate fungicide. McCartney said the USDA has not disclosed which nursery shipped the infected plants, although it is known to be in the western U.S.
He encouraged anyone who has a plant with a problem to call the extension office.
“If you’ve got a new shrub or tree and it doesn’t look right, get hold of the extension office. We’ll come and take a look at it, there’s a $20 charge for the diagnostic, they’ll culture it and know exactly what it is,” he said. Often, such plants are just suffering from transplant shock, but they might also have a disease the specialists at the extension office need to know about.
“If it gets out, if it blows into the forest, this could do some real damage,” he said. “It’s really important to get the community’s help on this.”
McCartney can be reached at 740-376-7431 or by email at firstname.lastname@example.org.
Michael Kelly can be contacted at email@example.com.
Disposing of an infected plant:
• Dig up the plant, roots and all and double-bag it.
• Place it in garbage container for municipal landfill pickup.
• Do not drop it off for mulching, recycling or composting.
• Clean any garden tools such as trowels or shovels that have come in contact with the plant, using a 10 percent solution of bleach for 30 minutes.
•Plants that may be infected: Rhododendrons or lilacs purchased from Walmart or Rural King since March.
Sources: The Ohio State University Extension office, Washington County, USDA, Ohio Department of Agriculture