Status and impact of walnut twig beetle in urban forest, orchard, and native forest ecosystems

  • Authors: Seybold, Steven; Klingeman, William; Hishinuma, Stacy; Coleman, Tom; Graves, Andrew D.
  • Publication Year: 2019
  • Publication Series: Scientific Journal (JRNL)
  • Source: Journal of Forestry. 117(2): 152-163
  • DOI: 10.1093/jofore/fvy081


The walnut twig beetle, a native phloem-boring bark beetle originating on Arizona walnut, has invaded urban, orchard, and native forest habitats throughout the USA as well as in Italy. Although the beetle has been associated with dead and dying walnut trees indigenous to riparian forests of the Southwest, the primary impact appears to have been on the health of landscape black walnut trees in urban and peri-urban sites in western US states, and in Pennsylvania, Tennessee, and Virginia. This has been reflected in numbers of trees removed and tree removal costs. In addition, trees have been killed in the primary US Juglans germplasm repository in northern California, and low, but measureable, tree mortality has occurred in some English walnut orchards in California’s Central Valley. As assessed under multiple circumstances, tree decline and mortality appear to develop gradually in response to infestations by this beetle.

  • Citation: Seybold, Steven J; Klingeman, William E; Hishinuma, Stacy M; Coleman, Tom W; Graves, Andrew D. 2019. Status and impact of walnut twig beetle in urban forest, orchard, and native forest ecosystems. Journal of Forestry. 117(2): 152-163.
  • Keywords: Pityophthorus juglandis, Juglans californica, Juglans hindsii, Juglans major, Juglans nigra, Juglans regia, tree mortality
  • Posted Date: April 23, 2019
  • Modified Date: October 23, 2019
  • Print Publications Are No Longer Available

    In an ongoing effort to be fiscally responsible, the Southern Research Station (SRS) will no longer produce and distribute hard copies of our publications. Many SRS publications are available at cost via the Government Printing Office (GPO). Electronic versions of publications may be downloaded, printed, and distributed.

    Publication Notes

    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
    • To view this article, download the latest version of Adobe Acrobat Reader.