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["Dr. Lucky Pittman" <lucky.pittman@murraystate.edu>]

Received this notice from my friend Guy Sternberg, over one of the oak discussion lists this morning.

 

July 26, 2010

 

RE:  Walnut twig beetle and Geosmithia sp. nov. found in Tennessee

 

To Whom It May Concern:

 

This letter is to inform you that a black walnut (Juglans nigra) sample collected by Dr. Scott Schlarbaum, University of Tennessee, and suspected of having thousand cankers disease (TCD), was shipped to me at Colorado State University on July 20, 2010 and arrived July 22nd.   I have a federal  ‘unknown’ permit and a federal permit to receive samples containing Geosmithia within the continental United States. The Tennessee sample sent to me contained one adult male beetle that was verified as Pityophthorus juglandis by Drs. Whitney Cranshaw, Boris Kondratieff and  Don Bright.  Isolations were attempted from the cankers surrounding the beetle galleries in the branch samples and Geosmithia sp nov.  was isolated. The fungus was identified based on morphological features by me.

 

This is a significant discovery because it is the first report of the walnut twig beetle and Geosmithia sp. nov. in the native range of J. nigra.  TCD has killed thousands of walnut trees in the western United States and could potentially be devastating in the eastern United States as well.  The extent of outbreak in the Knoxville area is unknown to me, but Dr. Schlarbaum indicated the affected trees are in an urban area. Judging from the images accompanying the sample, the disease has been present in the region for a number of years and is causing mortality.

 

Based on our experience here in Colorado TCD will be difficult, if not impossible, to stop. Our hope is that the beetle and disease will behave differently in the East.   I believe that there are probably other outbreaks in the East that have not yet been noticed, and I would urge foresters and diagnosticians to be on the lookout for unusual dieback or mortality of walnuts, especially in urban areas.  That is where TCD is likely to occur first because of movement of the beetle in wood (firewood, fresh lumber).  .

 

Since the USDA has no federal quarantine on TCD, and to my knowledge this disease is not on any action  lists,  I will assume unless otherwise notified, that information concerning this outbreak in Tennessee can become public knowledge immediately. Perhaps the state regulatory agencies will be more proactive in dealing with TCD than USDA-APHIS.  My colleague, Dr. Whitney Cranshaw will be giving a lecture on TCD at the International Society of Arboriculture meeting tomorrow, July 27, 2010, and will disclose the new outbreak at that time unless specifically requested not to do so.  I will be lecturing to the NPDN diagnosticians on Thursday and will similarly discuss the new outbreak.

 

If there is any way Dr. Cranshaw or I can help with training, sharing our experiences with TCD, etc., please let us know.  We are hoping to visit the Knoxville area on August 10.

 

Ned Tisserat

Extension Specialist and Professor of Plant Pathology

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In a message dated 7/29/2010 10:17:34 P.M. Central Daylight Time, Strhlfrst@aol.com writes:

Not oak, but deadly serious. Black Walnut Thousand Cankers (KC) blight has jumped the final fail-safe barrier (the habitat gap of the Great Plains) and is now established in central Tennessee. Barring a miracle, this could mean the extinction of Juglans nigra throughout its native range. See report below.

Guy S.

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Thousand cankers disease (TCD) of walnut has been confirmed in Tennesee.  I suggest that you stay in touch with your state department of agriculture colleagues for any updates that may come through APHIS PPQ.  Currently there is no federal quarantine for the pathogen or the insect vector.  According to the attached note from Ted Nisserat at Colorado State University who, along with colleagues confirmed the presence of both Geosmithia sp. and the beetle Pityophthorus juglandisfrom a sample sent by Dr. Scott Schlarbaum (Univ TN), the pathogen has been in the Knoxville area for several years causing decline and mortality.  This is, of course, the first report of the presence of the disease within the native range of J. nigra.   I'll continue to pass along to you any additional information about the find.  If you haven't been thinking about thousand cankers disease in your survey and monitoring activities now might be a good time to revisit that.  I've attached an analysis of the potential impacts of TCD prepared by the Kansas Forest Service and Kansas State University this past March to give you some idea of the scope of effects.     Also attached is the pest alert that we prepared this spring.      Stay tuned.

________________________________________

Noel F. Schneeberger, Forest Health Program Leader
USDA Forest Service
Forest Health and Economics
11 Campus Blvd., Suite 200
Newtown Square, PA 19073
610.557.4121
610.557.4136 (fax)
email:  nschneeberger@fs.fed.us

  

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