Thousand Cankers Disease

Research Issue

[photo:] Thousand Cankers Disease-symptomatic eastern black walnut.  Source:  J. Juzwik, U.S. Forest Service.Thousand Cankers Disease (TCD) is a recently discovered disease that is killing walnut, butternut and wingnut trees (species Juglans) in the United States and Italy. It is caused by a fungus, Geosmithia morbida. The walnut twig beetle (Pityophthorus juglandis) is believed to infect individual trees with the fungus as it burrows into the bark to feed. Native to Arizona, New Mexico and Mexico, this beetle appears to have “jumped” hosts from the disease-tolerant Arizona walnut to the highly susceptible eastern black walnut (J. nigra). By moving infested walnut wood from the western USA, people have helped the disease spread to eastern states. There is widespread concern that TCD may cause disastrous losses of highly valuable black walnut trees in eastern North America.
Removal and proper disposal of infested walnut wood is currently the main treatment option for TCD. State quarantines are trying to prevent the movement of the fungus, the insect, and walnut wood to states that do not yet have TCD. The US Forest Service is part of a multi-agency partnership that is guiding and tracking research on TCD. Efforts to manage the disease are detailed in the National Response Framework for Thousand Cankers Disease on Walnut developed in 2011.

Our Research

[photo:] Geosmithia morbida canker on eastern black walnut branch.  Source: J. Juzwik, U.S. Forest Service.Northern Research Station scientists and their university partners have been studying TCD since 2011. Research on the walnut twig beetle that spreads TCD have examined how far the insect can fly in 24 hours and how cold tolerant it is. Field and laboratory studies have documented that the beetle can reproduce with equal success in black walnut and butternut trees (which are part of the walnut family). This raises concerns that butternut may also be susceptible to TCD in the eastern United States.

In field studies in Indiana and Missouri, our researchers found no walnut twig beetles in black walnut trees that were under stress. However, in companion studies, insects (that were not walnut twig beetles) from stressed trees in Indiana, Missouri, and Ohio were found to be carrying the TCD-causing fungi. This means that the fungi is present in the Midwestern U.S., even if it is not yet infecting black walnut trees there. Subsequent studies have confirmed that the G. morbida fungi is already found on non-walnut twig beetles in Illinois, Minnesota and North Carolina.

[photo:] Walnut twig beetle in nuptial gallery on eastern black walnut stem. We have also conducted basic laboratory research on the genetic makeup of the G. morbida fungus. After analyzing samples of the fungus from forests in 12 states, we concluded that it was introduced to different regions on several occasions and from several sources. We have also mapped the first draft genome of G. morbida.

Additional research is counting the number of cankers on black walnut trees with TCD and documenting other fungus species that are found in cankers on these trees. We are also trying to determine just how quickly the disease progresses and spreads inside individual trees.

Expected Outcomes

Our goals are to:

  1. develop and share scientific knowledge on G. morbida and the other insects associated with TCD,
  2. figure out a way to treat and save trees suffering from TCD, and
  3. provide management guidelines for plant regulatory officials, natural resource managers, growers of walnut for timber and nuts, and others to prevent the spread of TCD to new areas of the U.S.

Research Results

Hefty, Andrea R.; Seybold, Steven J.; Aukema, Brian H.; Venette, Robert C. 2017. Cold Tolerance of Pityophthorus juglandis (Coleoptera: Scolytidae) From Northern California. Environmental Entomology

Kees, Aubree M.; Hefty, Andrea R.; Venette, Robert C.; Seybold, Steven J.; Aukema, Brian H. 2017. Flight Capacity of the Walnut Twig Beetle (Coleoptera: Scolytidae) on a Laboratory Flight Mill. Environmental Entomology

Hefty, Andrea R.; Coggeshall, Mark V.; Aukema, Brian H.; Venette, Robert C.; Seybold, Steven J. 2016. Reproduction of walnut twig beetle in black walnut and butternut. HortTechnology. 26: 727-734.

Juzwik, Jennifer; McDermott-Kubeczko, M.; Stewart, T. J.; Ginzel, M. D. 2016. First report of Geosmithia morbida on ambrosia beetles emerged from thousand cankers-diseased Juglans nigra in Ohio. Plant Disease. 100(6): 1238.

Schuelke, Taruna A.; Westbrook, Anthony; Broders, Kirk; Woeste, Keith; MacManes, Matthew D. 2016. De novo genome assembly of Geosmithia morbida, the causal agent of thousand cankers disease. PeerJ. 4(15): e1952. http://dx.doi.org/10.7717/peerj.1952. 11 p.

Juzwik, Jennifer; Banik, Mark T.; Reed, Sharon E.; English, James T.; Ginzel, Matthew D. 2015. Geosmithia morbida found on weevil species Stenominus pallidus in Indiana. Plant Health Progress. 16(1): 7-10.

Reed, Sharon E.; Juzwik, Jennifer; English, James T.; Ginzel, Matthew D. 2015. Colonization of artificially stressed black walnut trees by ambrosia beetle, bark beetle, and other weevil species (Coleoptera: Curculionidae) in Indiana and Missouri. Environmental Entomology. 44(6): 1455-1464.

Zerillo, Marcelo M.; Ibarra Caballero, Jorge; Woeste, Keith; Graves, Andrew D.; Hartel, Colleen; Pscheidt, Jay W.; Tonos, Jadelys; Broders, Kirk; Cranshaw, Whitney; Seybold, Steven J.; Tisserat, Ned. 2014. Population structure of Geosmithia morbida, the causal agent of thousand cankers disease of walnut trees in the United States. PLoS ONE. 9(11): e112847.

Utley, Curtis; Nguyen, Tivonne; Roubtsova, Tatiana; Coggeshall, Mark; Ford, Tim M.; Grauke, L.J.; Graves, Andrew D.; Leslie, Charles A.; McKenna, James; Woeste, Keith; Yaghmour, Mohammad A.; Seybold, Steve; Bostock, Richard M.; Tisserat, Ned. 2013. Susceptibility of walnut and hickory species to Geosmithia morbida. Plant Disease. 97:601-607.

Van Sambeek, Jerry; Juzwik, Jenny. 2010. What's killing my walnuts -- how to find help. Walnut Council Bulletin. 37(1): 10-12.

Research Participants

Principal Investigators

  • Mark Coggeshall, U.S. Forest Service, Northern Research Station, W. Lafayette, IN
  • Jennifer Juzwik, U.S. Forest Service, Northern Research Station, St. Paul, MN
  • James McKenna, U.S. Forest Service, Northern Research Station, W. Lafayette, IN
  • Steven Seybold, U.S. Forest Service, Pacific Southwest Research Station, Davis, CA
  • Rob Venette, U.S. Forest Service, Northern Research Station, St. Paul, MN
  • Keith Woeste, U.S. Forest Service, Northern Research Station, W. Lafayette, IN

Graduate Students

Research Partners

  • Last modified: August 10, 2018