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ODA, nurseries ready for new way to detect P. ramorum

Changes ahead in inspection of nurseries for pathogen that causes sudden oak death

At the end of the month, most Oregon nurseries will no longer have to face a federally-required program each year specifically designed to detect Phytophthora ramorum, the pathogen that causes sudden oak death. After a decade of requiring all nurseries with plants susceptible to P. ramorum to undergo inspection, sampling, testing, and certification by the Oregon Department of Agriculture, only those nurseries with a history of problems related to the disease will receive that level of scrutiny.

“In the past, all 600 or so Oregon nurseries that shipped host material out of the state had to be inspected and tested every year,” says ODA’s Dan Hilburn, Director of Plant Programs. “Each nursery had to have an ODA inspector go in and collect at least 40 plant samples, which had to be processed in a laboratory. That whole process would typically take a week or more to get results. What we found, year after year, was that most of the nurseries were perfectly clean and stay that way, one year after another. A few of the nurseries have problems, and they tend to continue to be problems year after year.”

As a result, the US Department of Agriculture has changed its protocol effective March 31. The end result is that ODA inspectors will spend more time in problem nurseries, working to clean them up, and less time on nurseries that have never had problems and are unlikely to have them in the future.

Hilburn says this is a better use of limited resources.

“Instead of treating everybody alike and wasting time in places that don’t need the extra attention, we are using a risk-based process that focuses on nurseries with a history of problems.”

All nurseries receive routine annual inspections anyway. If ODA discovers P. ramorum during routine inspections in a nursery that has not had problems before, that nursery will be added to the list of those required to undergo the mandatory federal certification program, complete with extra inspection, sampling, and testing. That group of nurseries remain on the list until they stay clean for three years.

ODA has employed a team of five seasonal workers in the past that was dedicated to visit all nurseries with P. ramorum host material and collect the samples. With a limited number of nurseries now required to participate in the federal program, only two seasonal ODA surveyors are needed. The change also lightens the work load on ODA’s pathology laboratory, which processes the plant samples.

“It’s been a long time coming and we think this is now a good situation,” says Gary McAninch, manager of ODA’s Nursery Program. “This allows us to concentrate our efforts where we know the disease is present. We can assist those nurseries in producing plants that don’t have the disease and help them to keep the pathogen from spreading to other places. Those nurseries that don’t have a history of the disease will no longer be under such a large regulatory burden.”

The nursery industry, which remains the state’s top agricultural commodity in value and sales, is also very pleased with USDA’s revised regulation.

"Oregon nurseries have unmatched quality, and ship clean plants," says Jeff Stone, executive director of the Oregon Association of Nurseries. "Any regulatory scheme should reward good behavior, work with those who have a problem to fix it, allow states and the federal government to manage their inspection resources in a cost effective manner. The USDA deserves a lot of credit for getting this right.”

ODA’s Hilburn also credits nursery growers themselves for being patient with the extra inspection, especially when only a handful of P. ramorum problems are detected each year.

“We’ve learned a lot in 10 years about the points in the production cycle where sudden oak death can enter. No plants start out infected at the beginning of the production cycle. Everything is clean. But over time, P. ramorum can find a way in, especially at those nurseries whose practices leave them somewhat vulnerable.”

Recycling water in a nursery sounds like a good thing. But if that water is recycled without being treated, it could spread the pathogen. Likewise, recycling pots without cleaning them in between use can introduce disease– not just P. ramorum, but a host of plant infections. Purchasing plants from another nursery at the cheapest price might save money, but could be risky.

“Those are things the nurseries can address by changing their practices,” says Hilburn. “Most nurseries are doing a fine job with those issues. Nurseries that aren’t, we can help get them to a point where if they address those critical control points, the chances of getting sudden oak death are reduced.”

Another change in the federal regulation of P. ramorum is expected to save time and expense. Nurseries that are positive for the pathogen are required to notify all states receiving their plant material in advance. This allows the receiving states to conduct their own inspection once the plants arrive. In the past, the notification by nurseries has been done through faxes and email to each individual receiving state. Now those nurseries have the option of notifying via a web-based system that is a one-click, streamlined process.

The new federal regulation has no impact on the natural spread of P. ramorum in Curry County. There are no nurseries in the affected area. ODA and other agencies have adopted a policy of slowing the spread of the disease in the county instead of trying to eradicate it. The hope is to buy time while research continues on how to control or eliminate sudden oak death in the natural environment.

In the meantime, Oregon nurseries are embracing the change in regulation this year. For those that are on the list to still receive the focused P. ramorum inspection, the effort will concentrate on getting off the list in three years. Those who can now bypass the requirement are able to work to maintain their clean status.

Despite the revised system, P. ramorum and sudden oak death still demand serious attention.

“As a disease problem of nursery stock, it’s a minor issue,” says Hilburn. “But as a quarantine pest, it’s still an issue because other states don’t want it. We hope this new system will be a better deal for everyone.”

For more information, contact Dan Hilburn at (503) 986-4663.

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