Harrisburg, PA – Agriculture Secretary Russell Redding announced that the department has lifted a quarantine in place since August 2014, because Thousand Cankers Disease no longer threatens Pennsylvania’s black walnut trees. Pennsylvania leads the nation in production and exports of hardwood lumber, and the disease was once thought to be a significant threat to the state’s $36 billion hardwoods industry.
“Quarantines are excellent tools to help protect our agriculture industry and our economy from disease and pests,” said Sec. Redding. “When science demonstrates that the disease is no longer a threat, restrictions on commerce are no longer necessary. We remain vigilant against invasive species and disease threats, but the quarantine as a tool has done its job.”
Thousand Cankers Disease is caused when walnut twig beetles, which carry a fungus called Geosmithia morbida, tunnel beneath the bark of walnut trees, causing small cankers to form. Over time, repeated beetle attacks and resulting cankers disrupt the movement of water and nutrients throughout the tree, causing branches and limbs to die and eventually killing the tree.
Several peer-reviewed, published research studies have shown that despite the presence of the beetles and fungus, native black walnuts in Pennsylvania have been largely unaffected by the disease. Black walnut constitutes about one percent of Pennsylvania’s hardwood forests and is highly sought after for furniture and other valuable products, as well as the nuts it produces.
Efforts to control walnut twig beetles using parasitic wasps are still underway and the department will continue to monitor the presence of the insects, fungus and disease in Pennsylvania.
The quarantine restricted movement of materials from walnut trees, living or dead, including nursery stock, green lumber and firewood, as well as roots, branches, mulch and other debris. It applied to Bucks, Chester, Delaware, Lancaster, Montgomery and Philadelphia counties. Affected businesses in those counties will be notified of the action this month.
The Pennsylvania Department of Agriculture also issued a quarantine in 2007 prohibiting the movement of firewood of all types and species into Pennsylvania unless it is labeled as "kiln-dried" and/or is USDA-certified. This quarantine, still in effect, is designed to help slow the spread of nonnative, invasive forest pests and diseases that are often moved long distances hidden in firewood.
Campers and homeowners can help protect Pennsylvania's urban, suburban and forested areas from nonnative invasive forest pests and diseases by the following:
• Buy and burn locally cut firewood,
• Burn any firewood already brought from another area. Don’t leave it behind or take it with you.
The repealed Thousand CankerDisease quarantine order can be found in the Pennsylvania Bulletin.