Progress 09/01/05 to 05/31/09
Outputs
OUTPUTS: The guiding goal for the USDA Methyl Bromide Transitions (MBT) project was to determine the lethal parameters of dielectric irradiation for eradication of plant pathogens that may infest solid wood packing material (SWPM) used in international trade for global exchange of commerce. Significant laboratory efforts on microwave (MW) and radio-frequency (R-F) dielectric treatment trials were designed and completed during the project duration to collect experimental data with essential interactive dissemination of the research to: 1) Industry Groups; 2) USDA Animal Plant Health Inspection Service (APHIS), PPQ; and 3) the International Forestry Quarantine Research Group (IFQRG) affiliated with the International Plant Protection Committee (IPPC). Interactions with Industry and allied Association Groups included MW and R-F equipment manufacturers, the American Lumber Standard Committee (ALSC) and also the National Wood Pallet and Container Association (NWPCA). During the project activities were completed with more concentrated focused on MW data collection trials that did show 2.45 GHz microwaves will kill with 100% effectiveness several species of cerambycids including the Asian longhorned beetle, pinewood nematodes (PWN), bark beetles and white pine weevils in wood of various species, sizes, and moisture contents. These experimental MW trials showed bark beetles were effective killed to eradicate not only adult but all life stages (eggs, larvae & pupae) to achieve complete sterilization of SWPM. Data to show the most temperature tolerate stage to kill pathogens has been deemed important to the acceptance of any proposed alternative phytosanitary treatment. More strategic focus was placed on 2.45 GHz MW research as opposed to 915 MHz energy irradiation based on the immediate worldwide trend to advance this MW technology. Interest on R-F treating data has intensified with increasing worldwide pressure to replace methyl bromide fumigation under ISPM 15 as an internationally standard for control of invasive pathogens. From preliminary testing data applying R-F this deeper penetration form of dielectric energy has shown the technical feasibility to sterilize infested logs with eradication of emerald ash borers (EAB) in white and green ash. Testing with a 40kW, 18 MHz commercial RF oven and USDA Forest Service cooperation to specially harvest heavily infested 6-inch to 12-inch diameter ash trees permitted three trials applying target cambium temperatures of 50, 55, 60, 65, 70 and 75 degree centigrade-C (20 replicates for each dielectric treatment level). Emergence hole data and collection of adult survivals monitored for each log section shows this especially thermo-tolerant species can be treated reaching high mortality rates below 65 degree C without a hold period in contrast to conventional heat to sterilize wood where ISPM 15 requires a temperature held cycle for 30 minutes. Similar trials with laboratory equipment 2.45 GHz microwaves on ash infested logs also showed positive results to achieve very low survival achieving rapid cambium heating rates to immediately kill EAB thus allowing for an automated systems approach to sanitize infested logs. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
With MBT funding the researchers investigated the use of 2.45 GHz microwave to eradicate pests from solid wood packing material. Applying efficacy data a MW application was prepared through an international & multilateral partnership with an approval review submission to the Technical Panel on Phytosanitary Treatment (TPPT) that advices the Standards Committee. This has resulted in a strong relationship working with the TPPT. The submission was positively received acknowledging MW efficacy that does show satisfactory mortality to kill insect pests and PWN under laboratory conditions. However, they have requested a resubmission (October 2009) to include further verification applying Probit 9 analysis for PWN under simulated operational conditions. We have agreed to resubmission with experimental plans formulated prior to the project termination. To achieve the necessary data under operational conditions we have entered a joint venture with Canadian Researchers (FPInnovations; Vancouver, BC). This scientific cooperation has been initiated to include natural PWN infested sampling and accompanying scale-up trials to be completed prior to the next scheduled IFQRG meeting (September 2009). The Canadian cooperation has been beneficial to obtain access to PWN strains possibly more thermo-tolerant to those native in US forests as the indigenous nematode infestation for experiments that are designed to represent a worst case treating scenario. Presentation of the Penn State University (PSU) and FPInnovations (FPI) scale-up study with updated analyses are planned for exchange and technical discussions with other attending members at the IFQRG meeting (UN FAO, Rome). We anticipate this shall serve to remove the final obstacles to approval of microwave energy (e.g. 2.45 GHz treatment schedule) as the first new alternative phytosanitary treatment for inclusive to ISPM-15. Difficulties were experienced with the first MW review as the alternative treatment submission was submitted before release with developments of submission and criteria as applicable guidance under ISPM-28. Our pending success with the microwave and preliminary experiments using radio frequency to eradicate pests has encouraged us to expand our network research between PSU and FPI to develop a R-F review submission in the next few years. Based on preliminary data with R-F dielectric heating this technology could provide pallet and wooden container manufacturers an even more beneficial (higher efficacy, shorter duration, lower operational cost, reduced health) method as opposed to use of chemical fumigation for phytosanitary treatment. Investigation of microwaves reveals that this form of dielectric heating does have a major limitation on the effective depth of penetration with declining rate of heating beyond wood depths of 14 cm. Radio-frequency does not suffer this same limitation. R-F does provide a very rapid heating rate (16C/min) compared to conventional heating (0.22C/min) to sterilize more tolerant organisms. Deeper penetration with R-F serves an advantage for phytosanitary capacity on SWPM thicknesses that are largely impractical with MW and convection heat applications.
Publications
- Tubajika, K.M, J.J. Janowiak, R. Mack, and K. Hoover. 2007. Efficacy of radio frequency treatment and its potential for control of sapstain and wood decay fungi on red oak, poplar, and southern yellow pine wood species. J. of Wood Science 53 (3):258-263.
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Progress 09/01/07 to 08/31/08
Outputs
OUTPUTS: The project continues to work towards a goal to have microwave irradiation recognized as an alternative to methyl bromide fumigation and conventional heat treatment. Besides microwave (MW) we continue to move forward on radio-frequency (R-F) dielectric heating for phytosanitation application to solid wood packing material (SWPM). During the reporting period we have intensified our efforts to share our experimental results with the International Forestry Quarantine Research Group (IFQRG). Within this period the researchers cooperated with EmiTech SRL to develop a microwave submission for consideration by the Technical Panel for Phyosanitary Treatment (TPPT). During attendance to the Fifth IFQRG meeting (2007) it was agreed that another submission would be necessary for R-F to advance this dielectric method towards approval through the Standards Committee for ISPM 15 inclusion. Other efforts focused to increase replication sampling of microwave (MW)efficacy performance. This effort was taken to determine if the 2.45 GHz MW treating regiment does comply with a Probit 9 Level of Control (LOC) where efficacy is defined at 99.99683% mortality with a 95% statistical confidence. Probit modeling is often preferred to substantiate effectiveness with respect to LOC by regulators who oversee SWPM. Early research to verify conventional heat treating (HT)with pinewood nematodes (Bursaphelenchus xylophilus)includes a Probit 9 compliance for the currently accepted HT treatment with 56 degree centigrade (C) for 30-minute schedule. Probit analyses are well suited to the binary response variable assigning Status 0 (100% morality) or Status 1 if less than 100% mortality. Laboratory efforts have included added MW tests on fresh harvested red pine (Pinus resinosa) logs and then natural infestations of pine bark beetles (Ips spp). Previous efficacy with MW tests was limited n equal to only 56 total adult beetle observations. This give a large confidence interval (CI) of 21 degrees with 65.3 degrees C to achieve a 99% lethal dose (LD99%) control level. To satisfy a Probit 9 additional tests performed to 68 samples this showed a revised LD99% of 66.7C and slightly smaller 13-degree 95% confidence interval. Overlapping confidence intervals observed among life stages (larvae, pupae and adult bark beetles)indicate no statistically difference in the lethal treatment temperature. Combining data (n=116 observations) the LD99% changed slightly 65.2C with only modest confidence interval improvement e.g.12.8 degrees (60.7C-73.5C). This reveals Probit 9 depending on the varability among significant insect pest groups requires very large test replicates to satisfy Probit 9. Results were presented the Sixth IFQRG meeting (September, 2008). Attendance provided in-depth discussions regarding the TPPT's review of Emitech's MW submission. The working group did support and endorsed a 2.45 GHz MW dilectric heating schedule(62C for 120 second duration)for SWPM less than 250 mm thickness. This excludes dunnage until further experiments verify MW irradiation penetration shall provide sufficient dielectric heating results. PARTICIPANTS: The experimental research with MW and R-F continues to involve a number of industrial cooperators and supportive collaboration among several USDA laboratory facilities. Among the USDA facilities active participation includes scientists associated with the Anilmal Plant Health Inspection Service(APHIS)both at the Otis (ANGB, MA)and Brighton, MI locatons. ALso we have maintained an interactive relation with the USDA Forest Service (North Central Laboratory--East Lansing, MI). Also, technical support continues working with PSC, Inc (Cleveland, OH) and Emitech SRL (Molfetta, Italy). Additonal we have maintained and developed new partnerships with other phytosanitatory reseachers in the European Union, New Zealand and Canada. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The results of the on-going research project continue to show promise for a formal approval of 2.45 GHz microwaves as an acknowledged ISPM 15 standard for treatment of solid wood packing materials. Despite this progress on microwaves the alternative approach applying radio-frequency for ISPM 15 shall require additonal attention in the form of experimental test data collection before a technical submission to the TPPT (Technical Panel for Phytosanitation Treatment). MW treating at 2.45 GHz may not receive approval for dielectric heating of dunnage before further efforts and actions are taken. With the granted no-cost time extension approved by USDA Inetgrated Pest Management Program avaliable resources might be better invested to target studies applying optional 915 MHz microwave with penetration better matched to the dielectric properties of wood. This limitation has created a greater awareness that R-F might serve a substantially better and more cost efficient approach to rapidly treat thicker dimension lumber used in shipping containers and heavy transport dunnage versus applying commerical microwave technology design units to handle this type of wood phytosanitation treatment.
Publications
- No publications reported this period
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Progress 09/01/06 to 08/31/07
Outputs
OUTPUTS: During the second year of this 2-year project (IREEDCGP-IPM 112.C Methyl Bromide Transitions) efficacy testing was expanded generating mortality data to determine the most resistant life stage to use for verification of alternative treatment protocols. Experiments with adult cerambycids to compare with pupal and larval life stages were performed with subsequent results reported to the International Forestry Quarantine Research Group (IFQRG). This included a presentation of the IREEDCGP-IPM funded research at the fifth IFQRG meeting at FAO Headquarters. With efforts still in progress this project was granted a no-cost extension for 12-months while the MW approval submission moves forward from the Technical Panel on Phytosanitary Treatments to the Standards Committee. Results were presented on experiments conducted on naturally infested red pine (Pinus resinosa) logs with the pine engraver beetle. The results indicate that effects of microwave (MW) irradiation can be insect
species dependent. Additional testing was completed on several other cerambycid species including Monochamus titillar, Neocyltus scutellaris, and Plectrodera scalator in artificially-infested red pine, northern red oak (Quercus rubra) and aspen (Populus spp), logs, respectively. All experiments used a 2.45 GHz laboratory microwave at 3.2 kW with treatment temperatures of 45, 50 and 55 centigrade. Time to temperature and final temperature (1-minute after exposure) were measured with fiber-optics (core sampling) combined with infrared (IF) thermal scans. Predictive equations (linear regression) were developed to allow use of surface measurements to predict adequate core treatment. Logistic regression showed that mortality could be predicted fairly well by monitoring core temperature but mortality was best predicted monitoring temperature adjacent to the insect. The adult life stage of cerambycids was less tolerant to MW compared to larvae, whereas eggs and pupae were most sensitive.
This series of experiments allowed for comparison to prior treatment data, which showed that artificial infestation overestimates effective lethal temperature. Research will continue to model relationships between surface temperature and temperatures in the cambium and core testing an expanded range of wood species with and without bark. Further dielectric experiments (volumetric heating with microwave and radio-frequency) will continue over the next year to examine the potential for killing the emerald ash borer (EAB) in infested ash roundwood. Currently quarantine restrictions prohibit movement of firewood and significantly hinder the commercial use of EAB-infested ash logs. Experiments were also conducted on the potential for quencher-chelator lanthanide conjugates combined with bleaching agents to serve as fluorescent indicators of the temperatures reached during heat or microwave treatments. Many of the fundamental chemical details have been worked out that can serve as the basis
for a practical time-temperature or microwave indicator.
PARTICIPANTS: The experimental research has involved a number of industrial cooperators and also various personal associated with the USDA Animal Plant Health Inspection Service (APHIS) including their laboratories at Otis, ANGB, MA and Brighton, MI. Additional USDA collaboration includes current involvement with cooperative assistance being provided from the US Forest Service Northern Research Station (East Lansing, MI). Industry assistance with several experiments performed by the Penn State investigators includes technical support from PSC, Inc--A Litzler Company (Cleveland, OH). The investigators have also been interactive with representatives of Emitech SRL (Molfetta, Italy). Working relations have been developed with researchers in Canada, (Adnan Uzunovic PhD; Durability and Protection Building Systems Department FP Innovations - Forintek Division,Vancouver BC; Europe in particular Dr. Roddie Burgess UK Government Center of Forestry and Dr. Micheal Ormsby Senior Risk Analysis,
MAF Biosecurity, Ministry of Agriculture and Forestry (New Zealand). These relations are designed to interactively summarize and support essential data documentation to advance the formal recognition of 2.45 GHz microwave irradiation as an approved ISPM 28 protocol for the phytosanitation of solid wood packing materials. This project is providing valuable experiences for graduate researchers who periodically volunteer their services to participant in the project activities with the preparation of specific experimental trials, insect collection and contribute to the analysis of the scientific results.
TARGET AUDIENCES: Various product manufacturers and end-user groups are being served by the on-going experimental research to investigate and formalize alternative treatments applying microwaves and or dielectric (radio-frequency)methods to sterilize wood. Only two methods are currently recognized by the international community: 1) conventional heat treatment (HT) and 2) chemical fumigation with methyl bromide (MB). HT and MB methods involve both a time consuming approach with increasing costs to assure the proper phytosanitation treatment of wood in the form of solid wood packing material (SWPM) and other wood product commodities. A major industry who will benefit from the completed project includes sawmills (hardwood and softwood producers) were forty percent of more of their product manufacture is converted to pallet, shipping containers and dunnage used for international trade of commerce goods. The pallet industry with the suppliers/users of SWPM will also significantly benefit
from new and more efficient methods for phytosanitation treatment. Worldwide there is an increasing urgency to develop more sensitive environmental measures to better combat the spread of invasive insect pests causing billions of dollar losses with killed urban trees and potential devastation to economically important commercial forests.
Impacts
This work on microwaves has served as the basis for a formal submission to the Technical Panel on Phytosanitary treatments for approval as an alternative treatment for solid wood packing material, providing a viable alternative to methyl bromide fumigation. Once approved, commercial development of microwave chambers and generators can follow.
Publications
- Ray, C., J.J. Janowiak, J. Michaels and H. Bachev. 2007. Economic and environmental assessment of proposed bark-free requirements for wooden pallets in international trade. J. of Forest Product Business Research. 4(6):1-25.
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Progress 09/01/05 to 09/01/06
Outputs
Since the project inception through the Integrated Research, Education, & Extension Competitive Grants Program-Integrated Pest Management IREECGP-IPM 112.C Methyl Bromide Transitions (MBT))a number of activities have been initiated to accomplish the primary research mission to recognize microwave (MW) technology as an approved International Plant protection Convention (IPPC)phytosanitary method combined with compliance verification for treatment of solid wood packing materials (SWPM). These initial efforts have focused on further cooperation with personal of the USDA Animal and Plant Health Inspection Service (APHIS)collecting efficacy data with respect to invasive insect and plant pathogens with SWPM and other wood products with data submission to the United Nations International Forestry Quarantine Research Group (IFQRG). Project investigators were invited to participate (10/2/2006) and present on the status of MW Phyotosanitary Treatment at the Fourth IFQRG Meeting
(Rome, Italy). The meeting concluded with agreement on the potential of both microwaves and radio-frequency (dielectric)irradiation as alternatives to the current accepted approach of conventional heat treatment (HT) and methyl bromide (MB)fumigation for SWPM sterilization. Meeting actions included a recommendation to draft treatment protocols for submission to the IFQRG working group (March, 2007). During this same period efforts have been taken to conduct experiments to evaluate the temperature-dependence of the unimolecular retro Diels-Alder decomposition of non-fluorescent compounds upon heating or microwave irradiation to yield fluorescent products. Yields of fluorescent reaction products, all derivatives of anthracene, increased with MW treatment of wood specimen blocks. Investigation under simulated aging conditions showed the anthracene derivatives are too unstable e.g. susceptible to photooxidation to degrade the fluorescent indicator compound. An alternative approach that is
insensitive to photo-degradation by sunlight exposure is under development. This treating verification approach relies on a fluorescent lanthanide compound such as chelates of the element terbium (Tb) in the +3 oxidative state. Lanthanides based on Tb offer a large gap between the wavelength used for excitation (350 nm) and the wavelength of emission (640 nm)with significant benefit for ready detection of fluorescence against background fluorescence of the wood chemical compounds. Dependence of active fluorescence occurs with either heat- or microwave-activated bleaching of a quencher. Several bleacher agents have been evaluated for rate of activation as a function of irradiation time and temperature elevation. Two bleaching agents were identified to provide a sensitive measure of sterilization heating in the 40-70 degree centigrade temperature range useful relative to MW irradiation previously shown effective for eradication of adult/larvae cerambycid and other insect infestations.
An outline of study has been prepared to examine the cost/benefit aspects with comparison between microwave irradiation to conventional HT or application of MB fumigation.
Impacts
Upon submission of a microwave treatment protocol with review commentary and any essential revisions deemed essential by the IFQRP working group it is anticipated that an irradiation method will move forward to the Technical Panel on Forest Quarantine (TPQP) in the next step towards approval of a recognized microwave-based phytosanitation treatment.
Publications
- No publications reported this period
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