September 19, 2023

Disease no longer threatens Eastern Black Walnut

Harrisburg, Pennsylvania – Agriculture Secretary Russell Redding today announced that the department has lifted a quarantine in place since August 2014 because thousand cankers disease no longer threatens Pennsylvania black walnut trees. Pennsylvania leads the nation in hardwood production and export, and the disease was once considered a significant threat to the state’s $36 billion hardwood industry. dollars.

“Quarantines are great tools to help protect our agriculture industry and economy from disease and pests,” Sec said. Redding. “When science demonstrates that disease is no longer a threat, trade restrictions are no longer necessary. We remain vigilant against invasive species and disease threats, but quarantine as a tool has done its job. “

Thousand canker disease is caused when walnut twig beetles, which carry a fungus called Morbid Geosmithy, tunnel under 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 published, peer-reviewed research studies have shown that despite the presence of the beetles and fungi, native Pennsylvania black walnut trees have been largely unaffected by 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 ongoing, and the department will continue to monitor the insects, fungi, and diseases in Pennsylvania.

The quarantine restricted the movement of materials from walnut trees, living or dead, including nursery stock, green wood 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 labeled as “kiln-dried” and/or USDA certified. This quarantine, still in effect, is designed to help slow the spread of invasive non-native forest pests and diseases that are often carried long distances hidden in firewood.

The invasive spotted lantern is an example of such a pest. A 34-county quarantine remains in effect, prohibiting the transportation of items containing the insect or its eggs. Items covered include, but are by no means limited to firewood, since the insect moves around and lays its eggs on all items outdoors.

Campers and homeowners can help protect Pennsylvania’s urban, suburban, and forest areas from invasive non-native forest pests and diseases by:

  • Buy and burn locally cut firewood,
  • Burn any firewood already brought from another region. Don’t leave it behind or take it with you.

The repealed thousand canker quarantine order can be found in the Pennsylvania Bulletin.

For more information about programs, funding, and initiatives to protect and grow Pennsylvania agriculture, visit

MEDIA CONTACT: Shannon Powers – 717.603.2056, [email protected]