The Virginia Department of Agriculture and Consumer Services expanded the Thousand Cankers Disease (TCD) quarantine to include the City of Falls Church. City residents and business owners are asked to not move the following out of the City: all walnut plants and plant parts of walnut including green lumber, logs, stumps, firewood, roots, branches, mulch, and chips.

The quarantine is necessary to prevent the spread of TCD after detecting the disease in both Fairfax and Prince William counties. TCD is a disease strain that attacks walnut trees. This fungus is spread by the walnut twig beetle as it tunnels beneath the bark of a tree and causes small cankers or open wounds on the trunks and branches as a result. As more beetles attack the tree, the number of cankers increases until they coalesce to girdle twigs and branches, restricting movement of nutrients and eventually killing the tree. Neither the beetle nor the fungus is native to the eastern United States. Thinning or dead branches initially occur at the top of the tree, causing it to die from the top down. Trees may be infected for many years before showing symptoms. There is no preventive or curative treatment for the disease.