Issue 1, April 20, 2015

Walnut Twig Beetle Detected in Indiana

The walnut twig beetle (WTB), associated with Thousand Cankers Disease (TCD) of Black Walnut, was detected in Indiana for the first time. The walnut twig beetle vectors Geosmithia morbida, the fungus that causes Thousand Cankers Disease. The beetle was detected in a trap at a Franklin County sawmill as part of a 2014 statewide survey for WTB. Additional walnut twig beetles were found during an inspection of walnut logs and lumber at the sawmill.

These beetles bore into the branches of black walnut, and carry fungal spores that are then introduced to the phloem. Small cankers develop under the bark around these galleries.  As feeding areas increase, so does the number and size of the cankers which then begin to girdle the stem or branch. The cankers affect the ability of the tree to transport water and nutrients and it eventually dies.

This is not the first time Thousand Cankers Disease has been associated with Indiana. In 2014, TCD was discovered in Yellowwood State Forest in Brown County in their black walnut plantation. No walnut twig beetles were found associated with this find. The plantation has been quarantined.  Currently, the sawmill is quarantined and is destroying walnut material on the property to prevent the movement of TCD.

Thousand Cankers Disease and the walnut twig beetle have not been found in Illinois. The state of Illinois currently has a quarantine in place that restricts the movement of walnut logs, lumber, and other walnut material into Illinois. Surveys have been conducted for the past 4 years in Illinois and will continue in 2015. You can learn more about TCD at (Kelly Estes)

Kelly Estes

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