Disease could kill Ohio’s walnut trees


REYNOLDSBURG, Ohio — In an effort to protect the walnut trees of Ohio, the Ohio Department of Agriculture (ODA) is proposing an exterior state quarantine regulating the transportation of walnut products from areas of 12 states to prevent the introduction of Thousand Cankers Disease (TCD) to Ohio’s walnut trees.

Caused by fungus

Thousand Cankers Disease primarily affects black walnut trees, as well as other species of walnut, and is caused by a fungus transported by the walnut twig beetle. The Walnut Twig Beetle spreads the fungus when it bores into the branches and trunk tissue of walnut trees, which are killed by repeated infections by the fungus.

Thousand Cankers Disease was first found in Colorado in 2003, and has since been detected in 11 other state: parts of Arizona, California, Idaho, Nevada, New Mexico, Oregon, Pennsylvania, Tennessee, Utah, Virginia and Washington.


Walnut materials originating from infested counties within these states will be regulated under the exterior state quarantine. The quarantine would restrict walnut materials from entering Ohio from areas where TCD has become established.

Restricted products originating from or traveling through the regulated areas include walnut nursery stock, unprocessed walnut lumber, or any other walnut material, such as logs, stumps, roots, branches, mulch, wood chips, other products created from walnut trees, and hardwood firewood.

Exemptions to quarantine are nuts, nut meats, hulls, processed lumber (100 percent bark-free, kiln-dried with square edges) and finished wood products without bark, such as walnut furniture, instruments and gun stocks.

What to watch for

Although not yet detected in Ohio, landowners and homeowners are strongly encouraged to watch for signs of TCD on their walnut trees.

Symptoms of TCD vary, but commonly include thinning crowns, yellowing or wilted leaves in the crown, leaves that are smaller than normal and recently dead limbs.

Individuals who see any suspicious signs on their walnut trees are encouraged to contact ODA at 614-728-6270 or by email at plantpest@agri.ohio.gov.


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