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Studies Raise Questions about Some Applications of the ISPM-15 Heat Treatment Standard: Is 56/30 Good Enough?
Some studies raise questions about the effectiveness of ISPM-15 heat treatment standards, especially for treating firewood. Should regulators turn up the heat?
By Chaille Brindley
Date Posted: 10/1/2010
Ever since international governments agreed upon the current heat treatment standard for export wood packaging, some scientists have warned that the measure may not be effective enough to kill all wood pests. Despite these concerns, it was largely believed that the standard was sufficient to stop most threats. But there are a number of recent studies that have resurrected the concern for some applications, particularly heat treating of firewood.
Adopted by the International Plant Protection Convention (IPPC), ISPM-15 is a voluntary global standard aimed at stopping the spread of invasive wood pests. This standard requires that solid wood packaging material (ex: pallets, crates and dunnage) be either heat treated at its core to 56 degrees Celsius for 30 minutes or fumigated using methyl bromide.
A number of scientific researchers have pointed to concerns that there are just too many factors that can allow pests to survive despite items being treated according to the existing standard. Factors such as varying amounts of bark, density of the wood, treatment chamber configuration, amount of infestation, moisture of the wood, and treatment schedules can impact the effectiveness of treatment.
Kerry Britton, national pathologist with the USDA Forest Service, said, “We are finding more pests that survive 56/30.”
She pointed to a 2009 study by Scott Myers of the U.S. Animal Plant and Health Inspection Service (APHIS) that discovered a minimum heat treatment of 60 degrees Celsius for 60 minutes or 70 degrees Celsius for 30 minutes internal temperature is needed to allow firewood to move from emerald ash borer (EAB) quarantine areas. Earlier studies observed that the EAB emerged from logs heated to 60 degrees Celsius for 30 minutes, whereas a 65 degrees Celsius treatment proved effective.
Tom Searles, president of the American Lumber Standard Committee (ALSC), which oversees the heat treatment certification process in the United States, said, “I don’t think that firewood data is applicable to pallets.” He pointed to variability in size, stacking patterns and density in firewood that make it much harder to heat treat than wooden pallets. As ISPM-15 has been applied to wood products beyond just packaging material, the likelihood that treatment schedules may need to change for some applications has increased. It sometimes can be difficult to take a standard developed for one class of products and apply it to another, especially if the phytosanitary risks are different.
While it is true that firewood generally lacks the uniformity of pallets and wood packaging and can be much more difficult to effectively treat, some concerns remain even for pallets. Britton said, “ISPM-15 has not been as effective as we had hoped.” She pointed to import data indicating that higher than expected levels of wooden pallets had shown signs of infestation. The big problem is that there is no way to know from current data if this trend has resulted from improper treatment or the existing standard not being effective enough to do the job. Plus, there is not enough data before the widespread adoption of ISPM-15 to truly know how much the threats have truly been eradicated.
ALSC believes the existing standard has been successful. Searles stated, “Our feeling is that until we have scientific evidence showing that 56/30 does not work; we think that 56/30 is adequate to do the job.”
ISPM-15 is truly a mixed bag showing signs of progress while at other points not living up to expectations. In a May 2010 study conducted in New Zealand T.D. Ramsfield found that the existing ISPM-15 heat treatment standard did not sufficiently guarantee mortality for the various wood fungi tested. This research suggested that 70 degrees Celsius for 30 minutes was the minimum temperature required to achieve 99.9% mortality. Searles added that 56/30 was never really designed to eradicate wood fungi.
Although these recent scientific developments indicate that existing standards may need to be tweaked, these findings do not negate the importance of following existing standards or the benefits of ISPM-15 to the world’s forest ecosystems. A group of forest and plant health experts recently met to discuss possible changes to ISPM-15. But it is clear that any modifications, if needed, will take years to usher through the international process.
Dr. Eric Allen, the chairman of the International Forestry Quarantine Research Group (IFQR), said, “I think that ISPM-15 has been effective. What we need to do now is to fine tune it.”
Allen cautioned though that any change must be based on science and practicality. He said, “The big question is, ‘Where do you draw the line? What is the sweet spot (eradicating pests)?’ There needs to be a balance between what is practical, possible and necessary.”
Scientists are still examining what is the real threat by pests that survive 56/30. Just because a pest survives doesn’t mean it still has the ability to reproduce. Also, there is the problem that making treatment requirements too strenuous could discourage compliance and thereby make infestation risks even worse.
Allen said, “We don’t want more non-compliance from cheaters by raising the bar too high and driving the problem under ground.”
Many international countries are just getting accustomed to the existing standard. Any changes could make it hard for them to adapt or even discourage compliance from areas of the world that had previously signed onto the standard.
Searles indicated that any changes in treatment protocols would likely take a year or two at the earliest if needed. Currently, international plant protection authorities are working on developing draft protocols to evaluate any new treatment options. This will be used to validate claims and ensure that any new pest eradication or heating techniques are as effective as existing measures.
EAB Discovered in Tennessee, Quarantine Expanded in NY
By Chaille Brindley
As the emerald ash borer (EAB) continues to spread eastward, authorities have recently made the first discovery of the wood pest in Tennessee. The discovery was made at a truck stop in Knox County near the Loudon County line.
“We knew EAB could potentially reach Tennessee, and we’re prepared to help slow the spread of the infestation and protect our forest resources,” said state Agriculture Commissioner Ken Givens.
Tennessee has issued a quarantine for Knox and Loudon counties prohibiting the movement of firewood, ash nursery stock, ash timber, and other material that can spread the EAB.
The Tennessee Department of Agriculture Division of Forestry estimates that five million urban ash trees in the state are potentially at risk from the EAB. More information on the new quarantine can be found at www.TN.gov/agriculture/eab
Alarmed by the spread of the pest to the Hudson River Valley area, New York officials have expanded existing quarantines to cover 16 additional counties.
New York State Agriculture Commissioner Patrick Hooker, said, “It is quickly becoming evident that the Emerald Ash Borer, which was first detected in New York state last year, is more widespread than originally hoped.”
The EAB has now been confirmed in seven counties in New York: Cattaraugus, Genesee, Greene, Livingston, Monroe, Steuben and Ulster. The expanded quarantine includes the counties where EAB has been confirmed and eleven others that are adjacent to confirmed detections both in New York, Pennsylvania and Canada, including: Allegany, Chautauqua, Chemung, Erie, Niagara, Ontario, Orleans, Schuyler, Wayne, Wyoming and Yates.
The quarantines restrict the intrastate movement of the EAB insect itself, nursery ash, green lumber and any other ash tree material, including logs, stumps, pallets, roots and branches, and wood products within and beyond, as well as into and through the quarantine areas. Because it is difficult to distinguish between species of firewood, all firewood and wood chips and bark mulch are covered by the quarantine.
The U.S. Department of Agriculture’s Animal Plant Health Inspection Service is expected to issue a parallel quarantine for interstate movement in the near future. New York’s Agriculture and Markets’ quarantine goes into effect immediately. For more information on the New York quarantine visit http://www.agmkt.state.ny.us/