Butternut - A New Host for the Walnut Twig Beetle and Thousand Cankers Disease
Posted: February 2, 2012
Walnut twig beetle on black walnut (Juglans nigra L.) Photo:Whitney Cranshaw, Colorado State University, Bugwood.org
"At recent meetings where I have spoken about Thousand Cankers on Black Walnut, I have noted that butternut is not susceptible to the disease. The first article in the [NPDN] newsletter reports it has been clearly shown now that butternut is susceptible. Butternut has severe problems with a couple other fungi anyway but this article presents new information."
Gary W. Moorman, Prof. of Plant Pathology
The Pennsylvania State University, Department of Plant Pathology
NPDN, National Plant Diagnostic Network
NPDN News, Volume 7, Issue 1, January 2012
Butternut - A New Host for the Walnut Twig Beetle and Thousand Cankers Disease
Maryna Serdani, Plant Clinic, Botany and Plant Pathology, Oregon State University
In November 2011, branch samples from a walnut tree with sparse foliage were submitted to the Oregon State University (OSU) Plant Clinic for diagnosis. Additional symptoms included branch die- back, cankers, tiny holes and insect galleries.
The sample originated from a large tree at a private residence in Oregon’s Lane County and was tentatively identified as butternut tree also known as white walnut or oilnut (Juglans cinerea). Nuclear DNA analysis and chloroplast analysis performed by the University of Notre Dame confirmed the host to be J. cinerea and not one of the walnut hybrids (which can closely resemble J. cinerea).
Initial examination of the galleries revealed a small beetle resembling the walnut twig beetle Pityophthorus juglandis. The Oregon Department of Agriculture confirmed its identity to be P. juglandis, the vector of thousand cankers disease (TCD). The OSU Plant Clinic was able to recover Geosmithia morbida, the cause of TCD, from the canker margins. Single-spored cultures of this fungus were sent to Colorado State University for further analysis. This is the first time G. morbida and P. juglandis were detected on butternut in North America. More information will be forthcoming.
TCD and its vector have previously been reported from black walnut (J. nigra) in Oregon as well as eight other western states and three eastern states (Virginia, Tennessee and Pennsylvania). The latter three states fall within the native range of butternut, which includes central and eastern United States and southeastern Canada.
Butternut is a relatively slow grower and is already seriously impacted in its native range by another canker disease (butternut canker) caused by the fungus Ophiognomonia clavigignenti- juglandacearum.
Download the entire NPDN News; Vol.7, Issue 1 January 2012
The Pennsylvania State University, Department of Plant Pathology:
Thousand Cankers Disease on Walnut
