Walnut Quarantine Expansion Looming

thousand cankers disease in black walnut

We’ve discussed the explosive expansion of the Walnut Twig Beetle’s territory in North America as well as the terrible disease it carries on this blog before. In short, the species is believed to be native to the continent but has expanded its range dramatically over the past decades. The beetle feeds on, and therefore carries the spores of, a fungus with a particular predilection for Black Walnut.

Although Western species of Walnut have fairly robust immunity to the fungus, it wreaks havoc on otherwise healthy Black Walnut trees (Juglans nigra), which are found throughout much of the eastern United States.

The beetles interaction with Black Walnut of the east results in the devastating Thousand Cankers Disease and the eventual death of the tree. The fungus and the beetle have developed a symbiotic relationship whereby the twig beetle feeds on the fungus as it grows on an infected Walnut tree. As a winged, flying insect, the beetle then flies to the next tree, carrying the fungus to its next host and so on.

Although researchers are unclear as to why and how the beetle’s range has expanded over the later part of the twentieth century, it is clear that the beetle has most recently been detected in Butler County Ohio for the past several seasons.

This has resulted in the addition of Butler county to the growing number of places throughout the east with quarantines preventing the transportation or removal of Black Walnut timber.

Growing Quarantined Regions

Butler County has already been quarantined!
There are currently 16 states with some sort of quarantine on the transportation of Black Walnut within their boundaries.

While most of these quarantines refer specifically to bringing Black Walnut timber into the state from outside areas, there are also states with restrictions on moving Black Walnut timber from one county to another within the same state. These states are Ohio, Virginia, Tennessee and Pennsylvania. Of these states, both Tennessee and Virginia have multiple-county quarantines.

In Virginia, you the quarantine includes both counties with an active infestation of Thousand Cankers disease as well as a “buffer” zone of counties around the infected region (marked in the figure below in blue).


States with county specific limits on the transportation of Black Walnut timber currently include Ohio, Virginia, Pennsylvania and Tennessee.

Counties throughout the Eastern United States with an active quarantine and restrictions on the removal and transportation of Black Walnut timber are as follows:

  • In Ohio: Butler County
  • In Pennsylvania: Bucks County
  • In Tennessee: Anderson, Blount, Jefferson, Knox, Loudon, Sevier, Union, Campbell, Claiborne, Cocke, Grainger, Hamblen, McMinn, Monroe, Morgan, Rhea, Roane, and Scott counties
  • In Virginia: Chesterfield, Fairfax, Goochland, Hanover, Henrico, Powhatan, Prince William, King William, New Kent and King and Queen counties.
If the trajectory of quarantining the infested area follows a similar trajectory to quarantines on invasive species and pests in the past, it is likely that the quarantine zones within regions with a singular county quarantined will grow. In other words, owners of Black Walnut timber in the hot zone for Walnut Twig Beetle may soon lose the right to harvest their timber. That’s why our company is urging residents of neighboring counties to consider a select harvest of their Black Walnut.

Specifically, the Ohio counties of Preble, Montgomery, Warren, Clermont and Hamilton are at risk of quarantine.

What a Quarantine Means in Practice

Most states have enacted interstate quarantines meaning they have disallowed outside Black Walnut from being transported into their boundaries. Intrastate quarantines at the county level are different and have the potential of evoking much harsher restrictions on what a landowner may or may not do with their timber.

In places with county-wide restrictions, Black Walnut is forbidden from being moved out of the county in which it has grown, making it very difficult and in many cases impossible for a landowner to market their timber to buyers.

Effectively this limits a landowner to selling their Black Walnut trees and timber to mills with a physical presence in their county. Unfortunately in many of the quarantines counties, there are no such mills.

The Case for Harvesting Your Walnut Timber

With Black Walnut prices at all time highs and the threat of increasing quarantine ones looming, this is arguably an excellent time to consider harvesting your Black Walnut.

No one knows how far Thousand Cankers Disease will spread, and what sorts of quarantines and restrictions on harvesting will follow. What is clear is that if you own timber, especially Walnut timber near the active quarantine, you should strongly consider going over your options with one of our professional timber buyers. Schedule your assessment today.

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