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Posts Tagged: walnut twig beetle

A Sign of the Times: Why This Black Walnut Tree Is Dying

Forest entomologists Steve Seybold (right) and Jackson Audley stand by a 150-year-old black walnut tree on the 100 block of E Street. It is dying of thousand cankers disease. (Photo by Kathy Keatley Garvey)

If you've ever walked into the courtyard on the 100 block of E Street in downtown Davis, Calif., you've probably noticed the massive black walnut tree near Sophia's Thai Bar and Kitchen. It's about 150 years old, 50 feet in height, and measures about five feet in diameter. And it's dying. What's...

Forest entomologists Steve Seybold (right) and Jackson Audley stand by a 150-year-old black walnut tree on the 100 block of E Street. It is dying of thousand cankers disease. (Photo by Kathy Keatley Garvey)
Forest entomologists Steve Seybold (right) and Jackson Audley stand by a 150-year-old black walnut tree on the 100 block of E Street. It is dying of thousand cankers disease. (Photo by Kathy Keatley Garvey)

Forest entomologists Steve Seybold (right) and Jackson Audley stand by a 150-year-old black walnut tree on the 100 block of E Street. It is dying of thousand cankers disease. (Photo by Kathy Keatley Garvey)

Walnut twig beetles tunnel into branches and trunks of walnut (Juglans) where they create galleries for mating and reproduction. In association with a canker producing fungus, Tthey cause a disease known as thousand cankers disease. This tree is in downtown Davis, Calif. (Photo by Kathy Keatley Garvey)
Walnut twig beetles tunnel into branches and trunks of walnut (Juglans) where they create galleries for mating and reproduction. In association with a canker producing fungus, Tthey cause a disease known as thousand cankers disease. This tree is in downtown Davis, Calif. (Photo by Kathy Keatley Garvey)

Walnut twig beetles tunnel into branches and trunks of walnut (Juglans) where they create galleries for mating and reproduction. In association with a canker producing fungus, Tthey cause a disease known as thousand cankers disease. This tree is in downtown Davis, Calif. (Photo by Kathy Keatley Garvey)

This massive, 150-year-old black walnut tree on the 100 block of E Street, Davis, is dying of thousand cankers disease. (Photo by Kathy Keatley Garvey)
This massive, 150-year-old black walnut tree on the 100 block of E Street, Davis, is dying of thousand cankers disease. (Photo by Kathy Keatley Garvey)

This massive, 150-year-old black walnut tree on the 100 block of E Street, Davis, is dying of thousand cankers disease. (Photo by Kathy Keatley Garvey)

Jackson Audley: A Case Study with the Walnut Twig Beetle

The walnut twig beetle is about the size of a grain of rice. (Photo by Kathy Keatley Garvey)

So tiny and so destructive. It's about the size of a grain of rice but it's a killer. That's the walnut twig beetle, Pityophthorus juglandis, which in association with a newly described fungus, Geosmithia morbida, causes thousand cankers disease, wreaking havoc on native black walnut...

The walnut twig beetle is about the size of a grain of rice. (Photo by Kathy Keatley Garvey)
The walnut twig beetle is about the size of a grain of rice. (Photo by Kathy Keatley Garvey)

The walnut twig beetle is about the size of a grain of rice. (Photo by Kathy Keatley Garvey)

Pursuit of a Tiny Beetle Leads to Coveted Honor

The walnut twig beetle is about the size of a grain of rice. In association with a newly described fungus, it causes thousand cankers disease of walnut and butternut trees. (Photo by Kathy Keatley Garvey)

Her research pursuit of a tiny beetle that is wreaking havoc on walnut and butternut trees throughout the United States has led to a major honor. UC Davis entomology doctoral student Stacy Hishinuma has received and accepted a position in the USDA Pathways Internship Program with the Region 5...

The walnut twig beetle is about the size of a grain of rice. In association with a newly described fungus, it causes thousand cankers disease of walnut and butternut trees. (Photo by Kathy Keatley Garvey)
The walnut twig beetle is about the size of a grain of rice. In association with a newly described fungus, it causes thousand cankers disease of walnut and butternut trees. (Photo by Kathy Keatley Garvey)

The walnut twig beetle is about the size of a grain of rice. In association with a newly described fungus, it causes thousand cankers disease of walnut and butternut trees. (Photo by Kathy Keatley Garvey)

Posted on Monday, April 27, 2015 at 8:42 PM

The Scholar and the Walnut Twig Beetle

Kristina Tatiossian and the ceramic mosaic of a walnut twig beetle. (Photo by Kathy Keatley Garvey)

Most people have never seen the walnut twig beetle, a tiny insect that spreads a fungal pathogen that kills walnut trees.  No wonder. The insect, measuring about 1.5 millimeters long, is much smaller than a grain of rice.  Now, however, they can see a teddy-bear-sized version, thanks to...

Kristina Tatiossian and the ceramic mosaic of a walnut twig beetle. (Photo by Kathy Keatley Garvey)
Kristina Tatiossian and the ceramic mosaic of a walnut twig beetle. (Photo by Kathy Keatley Garvey)

Kristina Tatiossian and the ceramic mosaic of a walnut twig beetle. (Photo by Kathy Keatley Garvey)

The poster that Kristina Tatiossian created. (Photo by Kathy Keatley Garvey)
The poster that Kristina Tatiossian created. (Photo by Kathy Keatley Garvey)

The poster that Kristina Tatiossian created. (Photo by Kathy Keatley Garvey)

National trapping guidelines for walnut twig beetle released

Walnut twig beetle is native to California, the southwestern U.S. and Mexico.
The University of California Statewide Integrated Pest Management Program has just published trapping guidelines for the detection of the walnut twig beetle. This tiny beetle, only several millimeters long, is the vector of the fungus that causes thousand cankers disease.

“The disease has killed thousands of black walnut trees in California’s landscape and is threatening commercial walnut trees as well,” said Mary Louise Flint, UC Cooperative Extension specialist in the Department of Entomology at UC Davis and UC Statewide IPM Program.

Thousand cankers disease has now moved into the eastern U.S., where it threatens valuable stands of black walnut timber east of the Mississippi. Once in trees, the beetle and fungus cause gradual decline and eventual death by killing the vital phloem tissue beneath the bark.

The guidelines and trapping methods were developed by a team of entomologists from UC Davis and the USDA Forest Service Pacific Southwest Research Station in Davis. In 2010 and 2011, the scientific team discovered and patented an aggregation pheromone for the beetle and conducted scientific trials in northern California.

Late in the summer of 2011, they demonstrated the efficacy of the pheromone as a flight trap bait for detecting new populations of the beetle in Tennessee, Virginia and Utah.  The demonstration-research project was extended to Pennsylvania in 2012. The bait lures both male and female beetles into a small plastic funnel trap. The team worked with a commercial partner, Contech Enterprises, Inc., to develop the technology.

When cankers accumulate, the crown of the tree dies and the tree attempts to resprout branches from the stem.
The trapping guidelines were developed for federal and state detection specialists who are trying to identify where the beetle populations occur in the eastern U.S. Early detection of the vector is the key to the potential local eradication or effective management of the disease.

As the eastern black walnut resource is valued at over $500 billion, the stakes are high for containing thousand cankers disease if it is introduced into key timber-producing states like Indiana and Missouri.

The study team is also using the traps and pheromone in research in California to learn more about biology and potential management strategies for the beetle in commercial walnut orchards and wildland areas.

The trapping guidelines are presented in a full-length document with color photographs and details on identifying the beetle, a short version for use in the field, and two video clips that demonstrate how to set up and service the traps.  Find them at  http://www.ipm.ucdavis.edu/thousandcankers.

In addition to Flint, members of the UC Davis and USDA scientific team and authors of guidelines are Steven J. Seybold, insect chemical ecologist, USDA Forest Service, based at Pacific Southwest Research Station in Davis; Paul L. Dallara, postdoctoral research scientist in the Department of Entomology at UC Davis; and Stacy M. Hishinuma, graduate student, Department of Entomology at UC Davis.

Inset map (red counties) is the historic (pre-1960) distribution of the beetle; the main map (blue counties) is the current distribution of the beetle. (Map courtesy of Dr. Andrew D. Graves, USDA Forest Service, Forest Health Protection, Albuquerque, New Mexico)

Posted on Friday, June 15, 2012 at 8:32 AM

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