Tara Costanzo M.S. defense
Tuesday, June 19, 2012, 10:00 AM
Forestry Building, Room 212

Tara Costanzo will defend her M.S. thesis, "Developing a Kiln Treatment Schedule for Sanitizing Black Walnut Wood of the Walnut Twig Beetle."

Tara's advisor is Dr. Kurt Mackes.

Abstract

Geosmithia morbida is a fungus that causes numerous cankers on branches and trunks of walnut tree species (Juglans spp.), hence the common name “Thousand Cankers Disease” (TCD), with the result being widespread morbidity and ultimately tree mortality. This fungus is vectored by the walnut twig beetle (Pityophthorus juglandis Blackman, 1928), which feed aggressively on the bark.

Subsequently cankers develop around the beetle galleries in the phloem. TCD is currently a major concern in Colorado. If the fungus expands from Colorado and other western states to the native range of black walnut (J. nigra), it could have devastating impacts on the nut and timber production industries.

Black walnut wood is valuable for wood products because of its strength properties and rich dark color. Developing a protocol for heat treating black walnut lumber and logs with bark intact is important so that they can be sanitized and safely utilized.

The purpose of this research was to determine whether the International Plant Protection Convention (IPPC) International Standards for Phytosanitary Measures (ISPM-15) standards and United States Department of Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), Plant Protection and Quarantine (PPQ) Treatment T314-a/c regulations are sufficient to kill live beetles in the bark.

The thermotolerance of the walnut twig beetles was evaluated by subjecting walnut twig beetle populations at all stages including eggs, larvae, pupae, and adults, to a series of time and temperature regimes. This experiment was conducted from October 2011 to February 2012 by heating walnut twig beetle-infested black walnut wood in a laboratory oven.

The heat-treatments were developed based on the ISPM-15 standards and USDA APHIS PPQ Treatment T314-a/c regulation standards based on internal wood temperature. The treatments ranged from 107.6°F to 159.8°F (42°C to 71.1°C, respectively) and lasted between 30 and 120 minutes. The ability of adult beetles to emerge was used to evaluate if the treatment was successful.

Results from the emergence trials showed that adults were able to survive up to 118.4°F (48°C) but no survival of any stage of beetle development was detected at 122.2°F (50.1°C) when heated for 30 minutes. Overall results suggest that walnut twig beetle survival is variable depending on heating conditions, and an internal wood temperature of 132.8°F (56°C) for 30 minutes should be considered the minimum for safe treatment of walnut lumber and wood with intact bark.

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Event Contact: Sonya Le Febre can be reached at (970) 491-1907

Sponsored by the Department of Forest & Rangeland Stewardship.