Upon their introduction to forests, invasive insects and fungi can cause widespread devastation. In Tennessee alone, the emerald ash borer has necessitated a quarantine in 63 counties. The beetle’s transportation of choice – firewood – is largely to blame.
“Two of the quarantines we have in Tennessee, for emerald ash borer and thousand cankers disease, both began with infested firewood being brought into the state,” says Katy Kilbourne, plant pathologist at the Tennessee Department of Agriculture (TDA).
See more: Buy It Where You Burn It
And it’s not just out-of-state firewood that presents potential issues. Any time firewood is moved, it provides pests the opportunity to travel farther than they would on their own. “The best thing that you can do is avoid moving firewood,” Kilbourne says. But when the preferable “buy it and burn it” method isn’t possible, particularly for campers looking to transport their own firewood, there are other ways to mitigate risk.
Enter firewood heat-treated by kiln, a special oven that reaches extremely high temperature, killing pests and disease. During these times of quarantine, the U.S. Department of Agriculture issues kiln certifications for the wood that is destined to move across state lines. When that particular quarantine ends, the agency no longer offers such kiln certifications.
For firewood cut and sold within the state, TDA offers kiln certifications of its own. This process entails Kilbourne going over a layout of the kiln, then visiting the site to lay temperature probes to gauge the kiln’s effectiveness after it completes a full run.
“No two kilns, unless they’re store-bought, are going to be identical,” Kilbourne says. The most important factor is that the wood treated in certified kilns reaches 60 degrees Celsius for 60 minutes to kill emerald ash borer adults, larvae and eggs, or 71 degrees Celsius for 75 minutes in order to take care of oak wilt (Ceratocystis fagacearum).
Since the issues surrounding pest-infested firewood have arisen, TDA has worked with various companies to guarantee safe, heat-treated wood, including timber companies producing firewood, firewood producers looking to stay in the game and folks who simply see a good opportunity to start a business.
For those wanting to make merry around a bonfire, look for firewood with a certification stamp on the label to make sure you’re getting kiln-treated products. “I look at it as a value-added product,” Kilbourne says. After all, besides mitigating a potential threat, heat-treated wood simply makes a better fire.
You can find sources for heat-treated firewood online at firewoodscout.org/s/tn.