SALEM, Ore. — The discovery of a bacterial disease, Xylella fastidiosa, has convinced Oregon’s farm regulators to order a quarantine restricting shipments of susceptible plants from nine counties.
The pathogen causes symptoms similar to drought stress and often kills affected plants, as no treatments are available, said Helmuth Rogg, director of the Oregon Department of Agriculture’s plant program area.
A pear nursery in Hood River County first reported disease symptoms earlier this year, which researchers from Washington State University found were caused by Xylella fastidiosa, he said.
The Oregon Department of Agriculture was initially unable to replicate these results but eventually confirmed the bacteria’s presence after refining its test procedures, Rogg said.
The agency then found that pear trees from the National Clonal Germplasm Depository in Corvallis were infected with the bacteria and that pear scion wood from that facility had been sent to 22 sites in the state, he said.
ODA is now trying to trace the disease’s source and where else infected plant material may have been shipped.
It’s also issued an emergency quarantine for the nine counties where the pear tree scions were shipped: Benton, Hood River, Jackson, Lane, Linn, Marion, Multnomah, Washington and Yamhill. Violating the quarantine is punishable by fines of up to $10,000.
While the bacteria has so far been associated with pear trees, the quarantine prohibits shipments of any host plant material, including oak, maple, blackberry, caneberry, blueberry and stone fruit, said Rogg.
That restriction remains in place until either the counties are found free of the disease or the bacteria’s presence is determined not to exist at a particular nursery production site, he said.
If ODA nursery inspectors do detect the bacteria, affected plants must be destroyed and the surrounding 10 meters around them will be surveyed for further evidence of the pathogen.
Insects that suck sap from plants, such as the glassy-winged sharpshooter in California, are known vectors for the bacteria’s spread, Rogg said.
Disease caused by Xylella fastidiosa has devastated olive orchards in Italy and threatens California wine producers, he said.
Oregon’s climate has traditionally been considered too cold to harbor the bacteria, which is likely why it hasn’t been found in the state until now, he said. With the prospect of warming temperatures, however, the concern is that Xylella fastidiosa will be able to survive here.
The recent discovery will postpone shipments of plant material to Europe until ODA and the USDA’s Animal and Plant Health Inspection Service are able to demonstrate the existence of pest-free areas or production sites, Rogg said.
Cort Brazelton, whose family runs the Fall Creek Farm &Nursery near Lowell, said he’s optimistic that ODA’s efforts will allow his company to ship blueberry plants to Europe next year.
“We feel confident we’ll be able to comply with all the requirements,” he said.
Brazelton said he’s happy to follow additional steps to ensure that Xylella fastidiosa doesn’t spread to customers in Europe.
“You’d always rather have no barriers but it’s important that individual counties that don’t want pathogens have reasonable protocols so that they don’t come in,” he said. “We do have to comply with the higher global standards because we ship all over the world.”