Progress 09/01/19 to 08/31/23
Outputs
Target Audience:Target audience reached during this period include attendees of the American Phytopathological Society (APS) conference and members of the Tennessee Department of Agriculture (TDA). At the APS conference, we presented a poster detailing our research on a lab-scale method to infest, treat, and recover the oak wilt pathogen, Bretziella fagacearum, from oak blocks. Researchers at University of Tennessee (UT) held a plant pathology workshop for TDA titled "Plant Pathogens in the Cross-Hairs: An Update on Applied Research Approaches to Protecting TN Tree Species." In this workshop we presented our research on fumigant efficacy against the oak wilt fungus, B. fagacearum, and pinewood nematode (PWN) in oak and pine logs. During the entirety of this project, we engaged local, national, and international researchers and industries that represent our target audience. We worked closely with USDA APHIS, USFS, and University of Minnesota to determine efficacy of ethanedinitrile (EDN) fumigation on oak logs infested with the oak wilt fungus. We performed two commercial-scale EDN fumigations on pine logs artificially infested with PWN in collaboration with Peeple's Industries Inc., a log exporting company, Ecolab, a company specializing in fumigation and sterilization, and USDA APHIS. We coordinated with Dr. Wemin Ye at the North Carolina Department of Agriculture and Dr. Jon Eisenback at Virginia Tech, who research phytosanitary treatments against PWN, to locate naturally infested pine logs. We presented our research on EDN treatments of oak wilt infested logs at the International Forestry Quarantine Research Group (IFQRG) meeting in 2022, where attendees showed interest in our research and its impact. We worked closely with Dr. Matt Hall of Draslovka, who organized global researchers from the United States, Czech Republic, Australia, New Zealand, and Canada, who focus on EDN efficacy against PWN. We collectively shared data packages to model EDN sorption during fumigation to determine if topping-up EDN concentrations during treatment may help to increase overall efficacy. Changes/Problems:Changes and problems arose during this project primarily due to the lack of 100% efficacy of EDN against the oak wilt fungus and PWN at the large-scale. At the lab-scale, we found EDN treatments that were 100% effective in eradicating the oak wilt fungus (120 g/m3 EDN for 48 hours) and PWN (120 g/m3 EDN for 24 hours). However, these treatments were not as successful once we increased fumigation chamber and log diameter size. In the case of the oak wilt fungus, treatments were only 100% effective when using smaller diameter logs. Increasing the treatment time to 72 hours was also unsuccessful in completely eradicating the oak wilt fungus. EDN was 100% effective against PWN in trials using smaller fumigation chambers (10 or 664 L). We scaled up PWN treatments to perform two experiments using shipping containers that are used in commercial fumigations prior to export. However, EDN was less successful when scaled up to the commercial-scale, even though it was 100% successful at the larger lab-scale. We deduced due to the high sorptivity of EDN that the larger chamber size, and thus load factor, provided enough experimental variance to yield different efficacy in the commercial vs. larger lab-scale experiments. Due to problems we encountered with EDN efficacy, we changed our focus slightly regarding both oak wilt and PWN experiments. We tried to locate pine logs naturally infested with PWN to provide material that possessed lower populations of PWN, which would better represent pine logs encountered in a typical fumigation scenario. For oak wilt, we wanted a method that would allow us to conduct more EDN fumigation replicates without the time constraint of artificially inoculating living oak trees and monitoring disease progression of naturally infested trees to provide adequate material for large-scale testing. We developed a method to artificially infest, treat, and recover the oak wilt fungus from oak blocks. However, our results confirmed that 120 g/m3 EDN for 72 hours was unable to completely eradicate the oak wilt pathogen in waxed blocks, which simulate log fumigations where diffusion occurs primarily through the bark. We found that this treatment was 100% effective in eradicating viable pathogen in unwaxed blocks, which provided additional routes for EDN penetration through the end-grain. What opportunities for training and professional development has the project provided?This project has provided an immeasurable amount of training and professional development. Commercial-scale fumigations provided professional development through coordination with multiple industries and agencies to conduct such large experiments. Large-scale experiments provided a great opportunity to work closely with our collaborators at USDA APHIS, USFS, and University of Minnesota to develop EDN treatments and publish a manuscript on our oak wilt research. Additional training in microbiology techniques was provided through the development of a lab-scale method to artificially infest, treat, and recover the oak wilt fungus from oak blocks. Professional development was also accomplished through presentations on our research to local and international communities. The APS 2023 conference provided a great opportunity to present a poster to the plant pathology community, which widened our perspective on invasive species and effective treatment methods. Presenting our research to local members of the TDA allowed us to focus on the impact of oak and pine wilt disease locally. The IFQRG 2022 meeting allowed us to share our research efforts with an international community solely focused on the control of forest quarantine pests. Working with Dr. Matt Hall and the global team of researchers aided in professional development by giving us an opportunity to work together to solve problems on EDN efficacy against PWN and learn more about what is required for the registration process. How have the results been disseminated to communities of interest?Results have been disseminated to local and international communities of interest through collaborations, presentations, and publications. We collaborated with Ecolab and Peeple's Industries Inc., two companies that fumigate and export logs, respectively. We shared data packages on EDN efficacy with Draslovka and a global team of researchers who are working to develop EDN treatments as a replacement for MB. We presented our research at the IFQRG 2022 meeting, where attendees include scientists, industries, and regulatory agencies who are specifically focused on eliminating the spread of forest pathogens globally. We published our research on EDN efficacy against the oak wilt fungus in oak logs in Forest Products Journal to share our results with interested communities. We shared our research with members of the TDA who are interested in the impact of oak and pine wilt disease locally. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Objective 1.We developed efficacy data for EDN as an alternative fumigant to replace the use of MB against PWN. We fumigated pine logs artificially infested with PWN in commercial-scale shipping containers using 120 g/m3 EDN for 24 hours, a treatment we found 100% effective at the lab-scale. However, we found commercial-scale EDN treatments were unable to eradicate all PWN, with at least 2 out of 4 logs for each container replicate (n=3) possessing live PWN post-treatment. We repeated the commercial-scale treatment which confirmed our results that EDN was unsuccessful in killing all PWN, with at least 2 out of 4 logs for each container replicate (n=4) possessing live PWN post-treatment. After the failures of EDN at the commercial-scale, we investigated why EDN efficacy differed at the larger lab-scale vs. the commercial-scale. We performed large lab-scale fumigations in 664 L chambers containing pine logs artificially infested with PWN using EDN and the current MB treatment for export pine logs. We found that 120 g/m3 EDN for 24 hours and 120 g/m3 MB for 16 hours were 100% effective in eradicating living PWN from the treated logs. We deduced that due to the high sorptivity of EDN either the chamber size or load factor created enough variance in experimental parameters to yield different results on EDN efficacy. Additionally, we determined that the levels of PWN colonization in artificially infested logs is much higher than in naturally infested logs that would be encountered in the real-world, potentially creating too harsh of a test. We also developed efficacy data for EDN as a replacement to MB for treatment of oak logs infested with the oak wilt fungus, B. fagacearum. We performed three experiments using increasingly larger sizes of oak logs to test EDN efficacy against the oak wilt fungus. We first tested smaller (average 12.2 cm diameter, 15.2 cm long) Quercus ellipsoidalis logs naturally infested with B. fagacearum using 120 g/m3 EDN for 24 or 48 hours. Our results detail that 120 g/m3 EDN for 48 hours was 100% effective in eradicating viable B. fagacearum from the treated logs. We repeated this treatment using larger (average 34.4 cm diameter, 41.3 cm long) Quercus rubra logs naturally infested with B. fagacearum. Two chamber replicates (n=3) yielded viable pathogen from at least 1 out of 4 logs post-treatment. However, one chamber replicate yielded a 100% effective treatment, with no viable pathogen found in the four treated logs. Overall, 3 out of 12 treated logs possessed viable B. fagacearum post-treatment. We repeated the experiments using an increased treatment time of 72 hours and larger logs (average 34.7 cm diameter, 91.4 cm long) Q. ellipsoidalis logs artificially infested with the oak wilt fungus. One chamber replicate (n=8) yielded a 100% effective treatment in eliminating viable B. fagacearum. Overall, 11 out of 19 logs possessed viable pathogen after fumigation with 120 g/m3 EDN for 72 hours. Based on our results, we were unable to conclude a truly successful EDN treatment against the oak wilt fungus in oak logs. We developed a lab-scale method to infest, fumigate, and recover the oak wilt fungus from oak blocks. This new method enables generation of B. fagaceraum infested oak samples in the lab, greatly reducing the time and expense requirements to artificially infest or monitor disease progression of naturally infested trees to obtain material for large-scale treatments. We used this method to test efficacy of EDN and the current MB treatment schedule for export oak logs. We conducted experiments using unwaxed and waxed blocks, where all surfaces of the block except the bark-face was coated with wax to simulate log treatment conditions where fumigant penetration occurs through the bark. Our results show that 120 g/m3 EDN for 24 and 72 hours yielded 40.3% and 12.5% average recovery of B. fagacearum post-treatment for waxed blocks. For unwaxed blocks, EDN was 100% effective in eradicating the fungus which can be attributed to increased fumigant penetration through the exposed end-grain. For both waxed and unwaxed blocks, 240 g/m3 MB for 72 hours was 100% effective in eliminating viable B. fagacearum post-treatment. Objective 2 & 5.During this project we collaborated with industry stakeholders and regulatory agencies to develop commercial treatments using EDN. We collaborated with USDA APHIS, Ecolab, Draslovka, and Peeples' Industries Inc. to conduct two commercial-scale container fumigation experiments using pine logs destined for export. We fumigated pine logs artificially infested with PWN using 120 g/m3 EDN for 24 hours, which was not 100% effective in eliminating PWN. This treatment was 100% effective in eradicating PWN in lab-scale treatments, so we repeated these experiments at the larger lab-scale using 664 L chambers. We found that 120 g/m3 EDN for 24 hours was 100% effective in killing PWN in the treated logs at the larger lab-scale, but this treatment was not as successful at the commercial-scale. We concluded that there is enough variance that arises from lab vs. commercial-scale treatments that inhibit the ability of EDN to provide 100% control of PWN, such as chamber size and load factors. Additionally, artificially infested logs possess higher rates of PWN colonization than naturally infested logs that exporters would encounter, thus creating a harsh test to determine efficacy. We collaborated with USDA APHIS, USFS, and University of Minnesota to perform three fumigation experiments using oak logs infested with the oak wilt fungus. We utilized small to large sizes of oak logs and found that 120 g/m3 EDN for 48 hrs was 100% effective in eradicating the oak wilt pathogen in small diameter logs (average 12.2 cm). However, the same treatment was not as successful for larger (average 34.4 cm diameter, 41.3 cm long) logs, with 3 out of 12 logs possessing viable pathogen post-treatment. We increased treatment time to 72 hours and used larger sized logs (average diameter 34.7 cm, 91.4 cm long), and again found viable pathogen in 11 out of 19 treated logs. Since the EDN treatments were not 100% successful in eradicating the oak wilt fungus, we could not conclude an effective treatment against the pathogen. Objective 3.We provided data packages on our EDN fumigations using pine logs infested with PWN to Dr. Matt Hall of Draslovka. Dr. Hall coordinated a group of global researchers who research EDN efficacy on PWN to collectively share our data and model EDN sorption during fumigation to determine if a top-up in EDN concentration during treatment would increase efficacy. The goal of our collaboration was to aid EDN registration status for phytosanitary treatment of logs. Objective 4.The financial impact of replacing MB with EDN for log fumigations has been analyzed by Dr. Chad Hellwinckel at the University of Tennessee. His research details that the costs associated with MB fumigation is slightly higher than it would be if EDN was used as a replacement fumigant for both hardwood and softwood logs. The main reason for the decrease in cost of EDN fumigation is due to base cost of the chemical, with MB being more expensive. Thus, replacing MB with EDN for the treatment of logs would be a financial benefit to log exporters. In addition, the costs associated with MB recapture were analyzed, detailing an increase in overall costs for MB recapture versus the use of EDN as an alternative fumigant treatment. The higher costs of MB recapture are due to additional equipment needed to recapture the gas once the fumigation is completed.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2023
Citation:
Yang, A., Seabright, K., Garrison, T., Taylor, A., Myers, S., Juzwik, J. 2023. Oak Wilt Fungus (Bretziella fagacearum) Survival in Logs Following Fumigation with Ethanedinitrile. Forest Products Journal, 73(3):260266. doi: https://doi.org/10.13073/FPJ-D-23-00016
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2023
Citation:
Seabright, K., Ony, M., Hadziabdic, D., Myers, S., Taylor, A. A lab-scale method to infest, fumigate, and recover the oak wilt fungus from oak blocks. Poster presented at American Phytopathological Society Conference, Denver, Colorado, August 12-16, 2023.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2022
Citation:
Yang, A. Survival of the oak wilt fungus, Bretziella fagacearum, in red oak logs fumigated with ethanedinitrile (EDN). Presented at the International Forest Quarantine Research Group virtual meeting, September 9, 2022.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2022
Citation:
Hall, M., Esfandi, K., Seabright, K., Stejskal, V., Taylor, A., Uzunovic, A. Global collaboration to operationalise fumigant monitoring for EDN. In proceedings of Methyl Bromide Alternatives Outreach Conference, Orlando, Florida, November 2-4, 2022.
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Progress 09/01/21 to 08/31/22
Outputs
Target Audience:Target audience reached during this period included attendees of the International Forestry Quarantine Research Group (IFQRG), consisting of scientists, industries, and policy makers who meet annually to discuss pressing forestry quarantine topics. Two presentations that detailed our work on ethanedinitrile (EDN) log fumigations were given at the conference. Our group presented research on EDN fumigation of large oak logs (Q. rubra and Q. ellipsoidalis) infested with the oak wilt fungus, Bretziella fagacearum. Questions that followed the presentation highlighted the importance of controlling forests pests and pathogens, such as B. fagacearum, to prevent international spread. During this period, we collaborated with a global team of researchers from New Zealand, Australia, Czech Republic, and Canada to detail EDN sorption patterns during log fumigations. The goal was to supply relevant data and model EDN sorption during log fumigation to determine if topping-up during fumigation would be necessary to achieve phytosanitary control of forest pests. The output of this collaboration will be a data package on our findings to aid in the registration of EDN for log fumigation in the United States and other countries. Dr. Matt Hall, a researcher at Draslovka, headed this collaboration and presented our findings at the IFQRG and Methyl Bromide Alternatives Outreach (MBAO) conference. We have collaborated with our group at the USFS Northern Research Station at the University of Minnesota in St. Paul, MN and the USDA APHIS Forest Pest Methods Laboratory in Buzzards Bay, MA to conduct EDN fumigations on oak and pine logs infested with B. fagacearum and pinewood nematode (PWN), respectively. We have also worked with Dr. Jon Eisenback at Virginia Tech and Dr. Wemin Ye at the North Carolina Department of Agriculture to help locate pine logs naturally infested with PWN for additional large-scale commercial fumigations. We have maintained a relationship with our collaborators at Ecolab and Peeple's Industries, two industrial partners that this research could directly influence, who are willing to continue helping with commercial-scale fumigation trials. Changes/Problems:Some changes have been implemented to achieve our goals of this project. We were unable to locate naturally infested pine logs with PWN for EDN treatment, which would have been beneficial to achieve our goals of this project. We were unable to find a completely efficacious treatment using EDN for oak logs infested with the oak wilt fungus. We were able to find an effective EDN treatment of pine logs infested with PWN, but the treatment was ineffective when applied at the commercial-scale container fumigations. We have hypothesized why we observed differences between the lab-scale and commercial-scale, but have not completely resolved this issue of efficacy differences. Since we were unable to determine an effective EDN treatment on commercial-scale logs, we were unable to conduct extension activities to detail protocol and procedures for EDN treatments to log exporters. The development of a method to artificially infest and treat lab-scale oak samples will aid in future research that aims to determine effective treatments against B. fagacearum in oak. What opportunities for training and professional development has the project provided?This project has provided professional development in several ways. It has allowed us to communicate our research to international communities of scientists, industries, and regulatory agencies through conferences, such as IFQRG. The preparation of our presentation and answering audience questions has been a great source of professional development by improving communication skills. Collaboration with the small research team led by Dr. Matt Hall has been a great source of professional development by allowing us to communicate and work closely with researchers from other countries. The ability to collaborate with others who share a similar goal of replacing MB and preventing the spread of invasive pests and pathogens has been beneficial towards progressing our own research and highlighting the importance of this work. In addition to working with other researchers and industries, it has been beneficial to work closely as a group with our team at USDA APHIS and USFS to complete two large-scale fumigation experiments. This has provided professional development by allowing us to perfect our experimental methods and determine ways to improve our research. We have finalized our EDN fumigation treatments of oak logs infested with the oak wilt fungus, and have prepared a manuscript on this research. Drafting a manuscript with our collaborators has been a great source of professional development, requiring close collaboration and improvement on writing skills to detail findings to communities of interest. Finally, this project has enabled professional development by aiding in the development of a new scientific method to artificially infest cut oak blocks with B. fagacearum. The development of this method was accomplished through literature research, dedication to trial and error, and improvement on sterile laboratory techniques to enable small-scale laboratory treatments of the oak wilt fungus in oak. How have the results been disseminated to communities of interest?Results have been communicated to communities of interest, including attendees at the IFQRG and MBAO conferences. Both conferences focus on important forest quarantine issues and share a common goal of finding alternative phytosanitary treatments to replace the use of MB. Attendees for both conferences include researchers, members of regulatory agencies, and industrial partners. In addition, results have been shared with a smaller community of global researchers who aim to aid the registration of EDN for log fumigations in the United States and other countries. What do you plan to do during the next reporting period to accomplish the goals?We plan to accomplish our goals by publishing our research on EDN log fumigations that we have conducted during this project over the next reporting period. One manuscript on EDN fumigation of oak logs infested with B. fagacearum is currently being reviewed by our team with plans to submit soon. Another manuscript on the development of a method to infest cut oak blocks with B. fagacearum for lab-scale treatments has begun, with the experimental portion using EDN completed. Further experimental work has begun, treating infested oak blocks with MB in order to compare efficacy with EDN. Plans to accomplish our goals will include the publication of this manuscript once the experimental work is finalized. Additionally, a manuscript on the development of a method to detect cyanide residue in wood treated with EDN is planned to be drafted and published during the next reporting period.
Impacts
What was accomplished under these goals?
Objective 1. During this period, we made significant progress towards developing efficacy data for EDN against PWN and the oak wilt fungus. We conducted a large-scale (664 L) fumigation trial using loblolly pine (Pinus taeda) logs artificially infested with PWN using 120 g/m3 EDN for 24 hours at 5 °C. Our previous commercial-scale experiments showed that this EDN dosage was not effective in achieving 100 % control of PWN. However, we had previously determined through small-scale log fumigations that dosages of 40-100 g/m3 EDN at 20 °C were effective in eliminating live PWN. We decided to try the same treatment (120 g/m3 EDN for 24 hours) on a larger, lab-scale trial (664 L chamber) to investigate differences in efficacy at the lab-scale and commercial-scale. In addition, we treated PWN infested logs with the current MB schedule (120 g/m3 for 16 hours) to compare efficacy of EDN and MB treatments. We determined that treatments using EDN and MB provided 100 % control of PWN for the large-scale lab experiments. We also conducted a large-scale (664 L) fumigation trial using northern pin oak (Q. ellipsoidalis) logs artificially infested with the oak wilt fungus, B. fagacearum. Our treatments used the highest allowable dosage of EDN (120 g/m3 for 72 hours) to see if we could find an effective treatment. Our previous experiments found that shorter treatment times (24-48 hours) and were unable to achieve 100 % control against B. fagacearum. The extended treatment time reduced the amount of viable B. fagacearum, but was unable to completely eliminate the fungus from the treated logs. We have made significant progress on a method to artificially infest cut oak blocks with B. fagacearum in order to enable lab-scale fumigation treatments of infested oak. Experiments have been conducted using 120 g/m3 EDN for 24 and 72 hours, using B. fagacearum infested oak blocks that were either waxed or unwaxed. Trials are now underway using the MB treatment schedule (240 g/m3 for 72 hours) for oak logs infested with B. fagacearum to compare treatment efficacy of EDN and MB in killing the oak wilt fungus. Objectives 2 & 5. We have collaborated with various industry regulators, commercial fumigators, and log exporters to help develop efficacious treatments of pine and oak logs using EDN. We have maintained our relationship with contacts at Draslovka, Peeple's Industries, and Ecolab, who helped conduct two commercial-scale pine log fumigations last period. We planned to conduct another commercial-scale fumigation using pine logs naturally infested with PWN in order to represent PWN infestation rates more likely encountered in commercial pine logs. Dr. Wemin Ye and Dr. Jon Eisenback, two scientists who also research alternative treatments for logs infested with PWN, helped search for naturally infested pine logs but were unable to locate adequate material for fumigation. We have also collaborated with a global research team led by Dr. Matt Hall of Draslovka to model EDN sorption data from log fumigations to assess treatment requirements to achieve phytosanitary efficacy against log pests. Dr. Hall presented findings from this collaboration at the IFQRG and MBAO conferences, where attendees include researchers and industry regulators who have a collective goal to find alternative phytosanitary treatments to replace the use of MB. The IFQRG conference also enabled us to present our research on EDN treatments of oak logs infested with the oak wilt fungus to scientists and regulatory agencies focused on preventing the spread of diseases caused by forest pests and pathogens. This conference was beneficial in getting feedback on our research and highlighting the importance of an alternative treatment to control the spread of invasive pests and pathogens. Discussions about our research focused on what is necessary to progress EDN registration in other countries and ways to overcome the lack of 100 % efficacy of EDN treatment alone (i.e. systems approach). Objective 3.We have been working with a global research team led by Dr. Matt Hall of Draslovka to prepare data packages on sorption of EDN during log fumigations to aid in the registration of EDN in the United States and other countries. Dr. Hall reached out to us for help in preparing relevant data packages based on our research, in addition to data from collaborators in New Zealand, Australia, Czech Republic, and Canada. Our goal for this collaboration is to model EDN sorption during log fumigation and determine if topping-up the concentration during fumigation would be appropriate to increase phytosanitary efficacy for export log treatments. The ultimate goal is that this information will be provided in a data package to help progress registration of EDN for log treatments. Objective 4. The financial impact of replacing MB with EDN for log fumigations has been analyzed by Dr. Chad Hellwinckel at the University of Tennessee. His research details that the costs associated with MB fumigation is slightly higher than it would be if EDN was used as a replacement fumigant for both hardwood and softwood logs. The main reason for the decrease in cost of EDN fumigation is due to base cost of the chemical, with MB being more expensive. Thus, replacing MB with EDN for the treatment of logs would be a financial benefit to log exporters. In addition, the costs associated with MB recapture were analyzed, detailing an increase in overall costs for MB recapture versus the use of EDN as an alternative fumigant treatment. The higher costs of MB recapture are due to additional equipment needed to recapture the gas once the fumigation is completed.
Publications
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Progress 09/01/20 to 08/31/21
Outputs
Target Audience:During this period, large-scale fumigations were carried out with the help of industry partners who represent a target audience for this research. We have worked closely with companies that perform log fumigations prior to export and shipping companies that ship logs worldwide. Peeple's Industries Inc., a shipping company, helped to carry out this research by providing shipping containers filled with commercial sized southern yellow pine logs destined for export and a location for on-site fumigation. Ecolab Inc., a corporation that specializes in sanitation and fumigation, helped conduct the large-scale experiments by providing licensed fumigators to treat shipping containers filled with commercial sized logs and loblolly pine log sections artificially infested with pinewood nematodes (PWN). Peeple's Industries and Ecolab represent companies that are directly affected by the phase out of methyl bromide (MB) and need an alternative fumigant to replace its use. Both companies are involved in the treatment and exportation of logs, and need a suitable replacement that will be accepted by their industry partners in other countries where logs are exported to. Draslovka, a company that produces the fumigant ethanedinitrile (EDN), has also been involved in this research by providing EDN gas for lab-scale and large-scale experiments. Dr. Wemin Ye, a scientist who evaluates PWN in logs at the North Carolina Department of Agriculture, has been contacted for potential collaboration to obtain naturally infested pine logs. He has previously worked with Peeple's Industries to determine effectiveness of fumigation with MB against PWN in commercial sized logs that are naturally infested. If we can locate naturally infested pine logs, we will conduct another large-scale container fumigation in collaboration with the industry partners we have worked with during this period. Changes/Problems:A few minor changes have been implemented into our plans for the next period. We hope to conduct a large-scale container fumigation of pine logs naturally infested with PWN, which we are currently searching for a source for this material. The reason for the change from artificially infested to naturally infested pine logs is due to the differences in results obtained from the lab-scale vs. large-scale fumigations. Naturally infested pine logs will have lower numbers of PWN present opposed to artificially generated samples, which are produced specifically to have high population densities of PWN. The goal is to then determine an effective treatment using EDN against naturally infested pine logs, which would be representative of infested pine logs encountered in typical export scenarios. Additionally, fumigations with MB will also be conducted with artificially infested pine logs to compare efficacy of EDN and MB treatments for infested pine logs with high densities of PWN. What opportunities for training and professional development has the project provided?Professional development has been accomplished for all persons involved in this research. Two large-scale container fumigations with industry partners has enabled professional development in regards to learning the logistics of log fumigations. This has helped to emphasize the importance of finding a replacement treatment for MB. How have the results been disseminated to communities of interest?Results have been communicated to industries of interest, particularly Ecolab Inc. and Peeple's Industries Inc. Ecolab continues to use MB for quarantine and pre-shipment purposes, and needs a suitable, alternative fumigant to replace its use. Peeple's Industries also continues to use MB for export shipments to countries where they require treatment with MB. Both companies have been continuously involved and updated on the progress and results of all experiments. Results and progress have also been shared with Draslovka, who is working on obtaining EPA approval of EDN for the treatment of logs. What do you plan to do during the next reporting period to accomplish the goals?Plans to reach the projects goals for the next reporting period are to perform additional fumigations, at the large-scale and lab-scale, to determine effective EDN treatments against the oak wilt fungus and PWN in logs. Two large-scale fumigations are in progress and will be conducted in Fall 2021. These fumigations will involve the treatment logs infested with PWN and the oak wilt fungus with EDN at longer time intervals, 48 and 72 hours, respectively. Lab-scale fumigations are currently in progress using artificially infested oak wilt blocks, which provides a method to generate unlimited amounts of samples to be tested in order to determine an effective treatment at the lab-scale. This will also enable experiments to be conducted where parameters, such as temperature, time, load factor, and moisture content, can be varied to help determine effective treatments. Additional plans include to locate pine logs naturally infested with pinewood nematodes with the help of Dr. Ye at the NC Department of Agriculture. The goal is to determine if the treatment of naturally vs. artificially infested pine varies and if an effective treatment can be found using naturally infested material, which would possess lower number of PWN in the logs vs. artificially infested samples prepared in the lab.
Impacts
What was accomplished under these goals?
Objective 1 We have worked to develop efficacy data for EDN against the pinewood nematode and oak wilt fungus as an alternative fumigant to replace the use of MB. We have conducted several lab-scale fumigations using EDN against artificially infested pine blocks with PWN and have determined several successful treatments (40-100 g/m3 EDN for 24 hr) with 100% efficacy. However, large-scale container fumigations of commercial sized logs using the most aggressive treatment that was effective in the lab-scale (100 g/m3 EDN for 24 hr) proved to be unsuccessful. We performed lab-scale fumigations of pine blocks, altering parameters such as EDN dosage, load factors, and end-grain sealing, to determine what can explain the difference in EDN efficacy in the lab-scale vs. large-scale. Results from lab-scale fumigations detailed that increased load factors and exposed surface areas of wood greatly increased the sorption of EDN. We determined that sealing the end-grain with wax and anchor seal greatly reduced EDN sorption into the wood. After 24 hr treatment using 50 g/m3 EDN, blocks sealed on the end with wax and anchor seal displayed an average sorption of 24% and 43%, respectively, compared to 66% sorption by unwaxed blocks. This led to the hypothesis that our infested pine log sections, which are waxed on the ends to prevent drying and mimic the treatment of a large log, have limited EDN sorption due to the sealed end-grain. However, in the large-scale trials, we hypothesized that EDN preferentially sorbed into the exposed end-grain of the nontarget logs rather than the sealed target log sections. For the second large-scale fumigation (April 2021), we sealed the end-grain of the commercial sized pine logs with anchor seal in 2 out of the 4 containers so we could test our hypothesis. However, we again observed differences in lab-scale vs. large-scale experiments, as the anchor seal on nontarget logs in the container fumigations provided no effect in EDN sorption and efficacy against PWN in infested pine logs. We are preparing for additional large-scale fumigations using EDN for pine logs infested with PWN, which will take place in October 2021. For this trial, we will increase the EDN dosage to the maximum limit allowed per the label (120 g/m3 for 72 hr). We plan to conduct another large-scale container fumigation using pine logs naturally infested with PWN if we are able to locate a source for this material. We have also made significant progress on oak wilt treatments, both in the large-scale and lab-scale. A lab-scale experiment using white oak limbs (Quercus alba) naturally infested with the oak wilt fungus determined an effective treatment schedule of 120 g/m3 EDN for 48 hr. We performed a mid-scale experiment using this treatment schedule for oak logs naturally infested with the oak wilt fungus, which showed a treatment effect but did not provide 100% efficacy. These projects have allowed us to collaborate with our partners at the Northern Forest Research Station located at the University of Minnesota in St. Paul. The naturally infested oak logs were obtained from Southeast Purdue Agricultural Center (SEPAC) in Indiana, who helped to identify diseased trees and cut them into log sections to be utilized in fumigations. We are preparing for another mid-scale fumigation of artificially infested oak logs with EDN for November 2021, where we will increase the EDN dosage to the maximum label amount (120 g/m3for 72 hr) to see if this provides effective control. Oak trees have been artificially inoculated at the Governor Knowles State Forest in Grantsburg Wisconsin, and are incubating for preparation of themid-scale fumigation in November 2021. We have developed a novel way to conduct lab-scale fumigations of oak blocks artificially inoculated with the oak wilt fungus, which allows for the production of many lab generated samples for future treatments. We are optimizing this method and performing several lab-scale fumigations to determine an effective treatment that can be used in the larger scale experiments.
Publications
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