Progress 01/15/15 to 10/14/19
Outputs
Target Audience:Citrus growers, Crop consultants, Agricultural machinery industry. Growers are seeking novel ways to effectively mitigate the negative production effects from citrus greening (i.e. HLB). Early trials using thermotherapy techniques showed promise in suppressing the bacterial effects of HLB and enhancing renewed tree growth and fruit production. This project centered around a large-scale trial where high-temperature steam "cooked" individual trees for varying durations to see if this thermotherapy technique could achieve economic feasibility. If positive trial results were observed, equipment manufacturers would be encouraged to design and build cost-effective treatment systems to apply the thermotherapy treatment. Changes/Problems:Hurricane Irma affected our experiments and measurements. We asked for a no-cost extension. What opportunities for training and professional development has the project provided?Graduate students and postdocs have had training opportunities and developed the mobile thermotherapy system, the sensing system and the thermodynamic model. They presented their work in international conferences. Several graduate and undergraduate students, and postdocs worked on this project and evaluated the thermal treatments, and participated in the preparation of oral and poster presentations. For example, one graduate student has had training opportunities and has worked on RNA methods and interpretation as well as professional development presenting results at regional and international meetings. Two postdocs have had one on one training opportunities and developed experimental design, data analysis, and presentation skills while studying conditions that induce movement of Candidatus Liberibacter asiaticus between the roots and canopy to better guide application timing. Furthermore, we demonstrated the developed mobile thermotherapy system, presented our results, demonstrated EPN application techniques (among other activities) to growers and stakeholders. How have the results been disseminated to communities of interest?As part of the extension effort to inform citrus industry members, master gardeners, and homeowners about research outcomes and HLB management we presented material from this project at several conferences (see journal and conference publications), trade shows, workshops, and field days; trade journal articles were written explaining the results too. We also handed out HLB identification and management informational documents at many events. As an example: Extension Publications Ampatzidis, Y. 2018. Agricultural engineering technologies to improve citrus production, Citrus Show, Fort Pierce, Florida, Jan-24, 2018. Ampatzidis Y. 2018. Smart Machines, UAV and Precision Farming Technologies, 2018 Citrus Innovation and Technology Show. Arcadia, Florida, April-5, 2018. Ampatzidis Y. 2018. Agricultural and Biological Engineering Technology Applied to Citrus Crops, 2018. Citrus Health Forum, NFREC, Quincy Fl., April 19, 2018. Ampatzidis Y. 2018. New Technologies in Agriculture for Specialty Crops, 2018. Citrus Engineering Conference, Panel Session, Lake Alfred, FL, June 6, 2018. Ampatzidis Y. 2018. Smart and Precision Agriculture, 2018. LaBelle Rotary Club, LaBelle Fl, September 17, 2018. Ampatzidis Y. 2017. UF Citrus Field day, Immokalee, FL, USA, Nov-2, 2017. Dewdney, M., Johnson, E., Thapa, N., and Danyluk, M. 2018. Thermotherapy's effects on fruit drop, yield and quality. Citrus Industry 99(12): 12-15. Ehsani, R., Dewdney, M.M., and Johnson, E.G. 2016. Controlling HLB with thermotherapy: What we have learned so far? Citrus Industry 97(9): 26-28. Ehsani, R. and Pertiwi, C. 2015. Tenting and supplementary heat for thermotherapy of HLB trees. Citrus Industry 96(8): 8, 10, 12. Thapa, N., Johnson, E.G., and Dewdney, M.M. 2019. Effect of thermotherapy on fruit yield. Citrus Expo. Fort Myers, Florida. Thapa, N., Johnson, E.G., and Dewdney, M.M. 2019. HLB and steam thermotherapy. Citrus Expo. Fort Myers, Florida. Johnson, E. G. 2018. What's going on below ground? Citrus Growers' workshop. Sebring, FL. September 25, 2018 Johnson, E. G. 2018. Effect of HLB on citrus root density. Citrus nutrient management for trees affected by HLB. Immokalee, FL. February 2, 2018. Johnson, E. G. 2017. Root Health of HLB-affected citrus. Citrus Show. Ft. Pierce, FL. January 26. Johnson, E. G. 2017 Rootstocks, root lifespan, and yield: What do they tell us about managing root health with HLB. Citrus Production School. Arcadia, FL. February 28. Johnson, E. G. 2017. Citrus Root Health and HLB Management. Citrus Institute. April 4. Johnson, E. G. 2017. Citrus Root Health Management. Citrus Expo. August 17. Johnson, E. G. 2016. Root Health in Florida Citrus Trees. Ridge Citrus School. October 25. Johnson, E. G. 2016. Video of root responses to HLB using minirhizotrons. UF/IFAS/CREC extension booths. First displayed at the Citrus Expo August. Ehsani, R., Trotochaud, J. and Souri, S. 2016. Heat therapies. Citrus Expo. Fort Myers, Florida. Ehsani, R. 2016. Heat therapy overview. The Citrus Show. Fort Pierce, Florida. (revised) Ehsani, R. 2016. Comparison of heat therapy methods. The Citrus Show. Fort Pierce, Florida. (revised) Ehsani, R. 2016. On-going heat therapy work. The Citrus Show. Fort Pierce, Florida. (revised) Ehsani, R. 2015. Heat therapy overview. Citrus Expo. Fort Myers, Florida. Ehsani, R. 2015. Comparison of heat therapy methods. Citrus Expo. Fort Myers, Florida. Ehsani, R. 2015. On-going heat therapy work. Citrus Expo. Fort Myers, Florida. Ehsani, R. and Trotochaud, J. 2015. Technical specifications. Citrus Expo. Fort Myers, Florida. Outside with thermotherapy vehicle. Ehsani, R. and Trotochaud, J. 2015. Typical operation. Citrus Expo. Fort Myers, Florida. Outside with thermotherapy vehicle. We have organized a "thermotherapy workshop" at the 131st Annual Florida State Horticultural Society (FSHS) Conference, in Fort Lauderdale, FL., on June 10-12, 2018. Please see "publication section" for the full list of oral presentations. Example of talks are: Abdulridha J., Ampatzidis Y, Ehsani R., Dai A., Thompson K., Xu Y., 2018. Automated mobile heat thermotherapy system for HLB-infected citrus plants. 131st Annual Florida State Horticultural Society (FSHS) Conference, Fort Lauderdale, FL., June 10-12, 2018. Souri S., Abdulridha J., Ehsani R., Schueller J., and Ampatzidis Y, 2018. The effect of root heat treatment on PMS, LAI, and stomata conductance in HLB infectedtrees. 131st Annual Florida State Horticultural Society (FSHS) Conference, Fort Lauderdale, FL., June 10-12, 2018. Abdulridha J., Ampatzidis Y., Kakarla S.C., and Ehsani R., 2018. Mobile heat thermotherapy system for treating HLB-infected citrus trees utilizing hot water and steam. ASABE Annual International Meeting, July 29 - August 1, Detroit, Michigan, USA. Dai A., Thompson K., Xu Y., Ehsani R., and Ampatzidis Y., 2018. Development and Experiment of a Monitoring System for Steam Treatment of Citrus Greening. ASABE Annual International Meeting, July 29 - August 1, Detroit, Michigan, USA. Duncan, L.W., Fluty, J.Q., El-Borai, F.F.E. 2018. Does management of plant parasitic nematodes FritzRoka, Megan Dewdney, Evan Johnson, Naweena Thapa, Reza Ehsani, Yiannis Ampatzidis, Jaafar Abdulridha. Economic Feasibility of Thermotherapy as a Strategy to Mange HLB Infected Trees. Annual meetings of the Florida State Horticultural Society, Fort Lauderdale, FL. June 13, 2018. Some extension EDIS publications are: Document title EDIS numbera Number distributedb Huanglongbing (HLB; citrus greening) Leaf and Fruit Symptom Identification PP327 4153 Huanglongbing (HLB; Citrus Greening) and Nutrient Deficiency Identification PP328 5440 Citrus Greening (Huanglongbing; HLB) Blight and Tristeza Comparison Identification Sheet PP263 2602 Citrus Greening (Huanglongbing): A Serious Threat to the Florida Citrus Industry CH198 4621 Scouting for Citrus Greening (Huanglongbing; HLB) HS1147 297 Citrus canker & greening (HLB) Handling Protocols for Master Gardener Plant Clinics HS1117 592 The Effects of Huanglongbing on Florida Oranges FSHN11-08 592 TAP Sampling for Asian Citrus Psyllid (ACP) Field Sheet ENY-887 4925 TAP Sampling for Asian Citrus Psyllid (ACP) Field Sheet (Spanish) ENY-890 315 Citrus Pest Identification Sheet -- 4646 aUniversity of Florida Institute of Food and Agriculture Systems (UF/IFAS) Electronic Data Information System (EDIS) bFrom January 2015 to September 2019 What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Obj 1: A mobile thermotherapy system was designed and developed to provide heat treatment to individual citrus trees infected with HLB disease. Computational Fluid Dynamics was utilized to develop a model to simulate the heat distribution inside the canopy cover. Based on previous studies, the system was designed to produce heat inside a canopy cover that covered a whole citrus tree, raising the internal temperature to 54oC and treating the tree for 90 s. The system was able to increase the heat inside the canopy cover using different heat sources by either releasing steam or a combination of steam and hot water. A series of experiments were conducted to assess the uniformity of heat distribution within the tree canopy. Results indicated that the uniformity of heat is similar with both treatment types, while the average time for the entire treating process was 63% shorter when using HWST compared to ST. A thermodynamic model was developed to simulate the heat distribution inside the phloem, where the HLB bacterial live, based on the outside treatment temperatures. The heat transfer model was developed by a comparative analysis of the experimental data; ANSYS software was used to simulate the heat transfer in the phloem. The simulation results were consistent with the experimental results, with an average relative error of less than 5%. Initial experiments showed that the temperature in the phloem was 10-40% lower than the temperature on the bark. Obj 2-4: Our results showed that there was no prolonged reduction of CLas from the leaves and roots post-treatment, when compared to the control trees as well as to the pre-treatment bacterial titers. Overall, there was no consistent trend of CLas titer reduction for different treatments, nor for the seasonal application of thermotherapy, within and between the two groves used in the experiment. From the root density sampling, the seasonal patterns of growth can be observed with the fall root flush being the major root growth of the year leading to higher root densities in the winter compared to the summer. Most thermotherapy treatments had a drop in fibrous root density that increased with treatment severity immediately after thermotherapy application. The leaf drop and flush stimulation caused by thermotherapy treatment likely disrupted this root flush causing more severe effects on root health than other seasonal treatments, especially compared to the winter treatment. Longer term response showed a positive reaction of the root system to thermotherapy treatment in the spring (May), which aligns with the season that resulted in the most consistent early canopy titer reductions. However, this effect was fading 2 years after treatment before a yield response was observed. For all treatments, yield was significantly lower than the untreated trees, although the yield started to recover from the second year. Over the four years, there was no improvement from the heat treatment on the overall yield. Moreover, the fruit quality, such as % acidity, °Brix, and Brix:Acid ratio, also remained comparable among the treated and untreated trees so there was no benefit in that regard either. Soil and root samples were taken in 70 orchards on the Florida central ridge and processed to recover nematodes. We found no evidence use of EPNs, nematicides or thermotherapy had a beneficial impact on the growth or fruit production of trees with HLB. The lack of tree response to these treatments supports the possibility that root loss due to HLB represents a limiting factor in root health management. A caveat to this possibility is that although oxamyl produced a significant reduction of ectoparasitic nematodes, the EPN treatments were ineffective in reducing root weevil populations to acceptable levels. However, the experiments were designed at a time of extremely limited availability of affordable EPN projects. More frequent application of EPNs in smaller surface areas (e.g., at the crown of the root system) has the potential to provide good control of root weevils at an affordable cost. No effects of tree recovery/response nor a consistent response of Phytophthora nicotianae populations was observed after treatment. This showed that root disease pressure did not affect and was not effected by canopy thermotherapy and the negative impacts of canopy stress on the root system. Obj 5: We built and tested a heating tunnel equipped with steam and air flowmeters and thermocouples into the heating tunnel. Determination of heating and cooling transients of the heating tunnel indicated that under 'ideal' heating conditions, direct steam heating is too fast (within 5 s) and resulted in defoliation of the trees after a few days. Mimicking grove conditions require mixing air and steam to decrease the rate of heating. Determination of residual catalase and peroxidase activity of orange tree leaves heated to 45, 50 or 55 °C. At 45 °C both enzymes were stable and catalase activity increased in response to stress. At 50 °C catalase was stable and peroxidase activity decreased moderately. At 55 °C both enzymes inactivated moderately. The rate of cooling has a significant impact in leaf survival after thermal treatments. Rapid cooling with water reduces the level of defoliation. The grafting experiment of the treated bud-sticks was conducted to determine the effect of steam treatment on the CLas population in the bark tissue. The number of grafts that survived the steam treatment was inversely proportional to the temperature and duration of exposure to the steam. There was no CLas DNA detected from the leaf samples of the treated scions at the temperature time combinations of 55°C for 90s and 55°C for 120s, except for two samples. Treatment at 60°C for 30s was lethal to the treated bud-sticks. Following the grafting experiment with the RNA-based assay, it was shown that higher temperatures and longer exposure of the plant tissues to the steam treatment reduced the CLas population in the woody tissue. Obj 6: A laboratory-scale horticultural oil (HO) thermotherapy application technology unit was developed and refined through graduate student research efforts to effectively apply the thermotherapy. Two prototypes were developed. Experiments were conducted to have spray treatments including four variables namely heat-condition (i.e., heat and no-heat), HO concentration (i.e., 0.5 and 1.0 %), two nozzle types and application pressure. Each treatment was replicated four times on pear psylla bioassays. Mortality was evaluated at 3, 6, 12, 24 and 48 h after spray application. HO combined with thermotherapy achieved as high as 100 % pear psylla mortality during early hours after spray application. Overall, HO combined with thermotherapy caused a rapid kill of pear psylla. Overall, affirmative results suggest that we can potentially use HO-based thermotherapy as an environment friendly insect-pest management in tree-fruit production. However, further field studies are warranted to refine the application parameters, determine the treatment applicability in orchard conditions and evaluate the treatment efficacy and possible phytotoxic effects. Obj 7: We conducted a 3-year cost-benefit analysis. Treatment #6 was administered during the fall and applied 55-degree Celsius steam for 120 s. A small grower survey provided representative values for annual delivered-in fruit prices and harvest costs. After 3-years, Treatment #6 earned $1.80 per tree more than what was earned from untreated trees. The positive earnings, however, were based only on yield differences. When the initial cost of application, $7 per tree, is considered, even the numerically best thermotherapy treatment did not achieve positive economic outcome.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Bahlol, H. Y., R. Sinha, G.A. Hoheisel, R. Ehsani and L. R. Khot. 2018. Efficacy evaluation of horticultural oil based thermotherapy for pear psylla management. Crop Protection, 113: 97-103. https://doi.org/10.1016/j.cropro.2018.07.015
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Bahlol, H.Y., R. Sinha, L.R. Khot, G.-A. Hoheisel and R. Ehsani. 2019. Efficacy evaluation of horticultural oil based thermotherapy for pear psylla management. BIOAg Symposium, Center for Sustaining Agriculture and Natural Resources, Washington State University, Pullman, WA. February 7, 2018. (Received Best Graduate Poster Award).
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bahlol, H.Y., R. Sinha, L. R. Khot, G.-A. Hoheisel and R. Ehsani. 2018. Horticultural oil based thermotherapy for Pear psylla management. Research News Flash, 114th Annual Meeting & NW Hort Expo, Yakima, WA. December 3, 4 & 5, 2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Bahlol, H.Y., G.-A. Hoheisel and L.R. Khot. 2017. Thermotherapy with HMO for pear psylla management. CPAAS Agricultural Technology Day, July 31, 2017 (Poster Presentation)
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Bahlol, H., G.-A. Hoheisel, R. Ehsani and L. Khot. 2017. Thermotherapy with horticulture mineral oil for pear psylla management. Presentation No. 1701562, 2017 ASABE Annual International Meeting, Spokane, WA, 17-19 July 2017 (Poster Presentation).
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Nalavade, P., G.-A. Hoheisel, L. R. Khot and R. Ehsani. 2016. Development and feasibility evaluation of HMO based thermotherapy technique for effective pear psylla management. Abstract # 2460369. 2016 ASABE Annual International Meeting, Orlando, FL. July 17- 20, 2016
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Dai, Andong, and Xu, Yunjun. "Path Control of a Heat Treatment Truck Considering Driver-Vehicle Interaction." Proceedings of the ASME 2018 Dynamic Systems and Control Conference. Vol.3, Atlanta, Georgia, USA. September 30October 3, 2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Merchan, C. A., Xu, Y., Ehsani, R., and Trotochaud, J., The Design of an Automation Process for the Steam Treatment of Citrus Trees, presented at the 2016 ASABE Annual International Meeting, Orlando, July 17-20, 2016.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Dai, A., Garcia, E., Xu, Y., and Ehsani, R. Semi-Automated Thermotherapy for Citrus Trees with HLB Disease, 2017 ASABE Annual International Meeting, July 16-19, 2017, Spokane, Washington USA Poster
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Dai, K. Thompson, Y. Xu, R. Ehsani and Y. Ampatzidis, "Development and Experiment of a Monitoring System for Steam Treatment of Citrus Greening" 2018 ASABE Annual International Meeting, Detroit Michigan, July 29 - August 1, 2018 Poster
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Cimowski, S., Yang, D., Reyes-De-Corcuera J.I. Thermotherapy: Time-Temperature Thresholds to Prevent Orange Tree Defoliation. Oral presentation given at the Florida State Horticultural Society Meeting, Ft. Lauderdale, FL, June 12, 2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Cimowski, S., Jackson, J. Yang, D., Reyes-De-Corcuera J.I. Use of Chlorophyll Fluorescence as an Indicator of the Extent of Heat Treatment of Citrus Trees to Combat HLB. Poster presented at the International Annual Meeting of the ASABE, Detroit, MI, August 1, 2018
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Thapa, N., Johnson E. G., and Dewdney, M. M. 2019. Determining the viability of Candidatus Liberibacter asiaticus (CLas) via grafting results and RNA-based assay. Florida Phytopathological Society. Lake Alfred, Florida.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Thapa, N., Johnson E. G., Ehsani, R. and Dewdney, M. M. 2018. Seasonal variation in yield and root response to steam-generated supplementary heat thermotherapy. Florida Society of Horticultural Sciences.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Thapa, N., Johnson E. G., and Dewdney, M. M. 2017. Steam-generated Thermotherapy: How does the canopy and roots of infected Citrus trees respond to it? Florida Phytopathological Society. Quincy, Florida.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Thapa, N., Johnson E. G., and Dewdney, M. M. 2017. Canopy and root response of CLas-infected citrus trees to steam generated thermotherapy. Journal of Citrus Pathology, Vol. 5. 40-41. Orlando, Florida.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Johnson, E. G., Graham, J. H., Orrock, J., Commerford, S. L., Dewdney, M. M., Thapa, N. The role of early root infection and damage in Huanglongbing. Citrus Research International Symposium. South Africa. August 22, 2016
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Thapa N., Johnson, E. G., and Dewdney, M. M. 2019. Determining the viability of Candidatus Liberibacter asiaticus via graft- and RNA-based assays. The American Phytopathological Society. Cleveland, Ohio.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Thapa, N., Johnson, E. G., and Dewdney, M. M. 2019. Assessing CLas viability to determine the efficacy of steam-generated thermotherapy. Journal of Citrus Pathology, Vol. 6, pp. 73-74.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Thapa, N., Johnson, E. G., and Dewdney, M. M. 2019. Assessing CLas viability to determine the efficacy of steam-generated thermotherapy. Posters and Pastries Research Symposium. CREC, Florida.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
J. D. Veloso Dos Santos, M. M. Murata, K. Gerberich, D. B. Bright, E. G. Johnson. 2018. Limited movement of Candidatus Liberibacter asiaticus in split-root citrus provides a model system for local and systemic effects of Huanglongbing. Phytopathology. 108(10): S127.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Thapa, N., Johnson, E. G., and Dewdney, M. M. 2018. Selection of reference genes to develop an RNA-based viability assay in response to thermotherapy. Phytopathology, Vol. 108, No. 10: S1.164.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Thapa, N., Johnson, E. G., and Dewdney, M. M. 2018. Effect of thermotherapy on CLas population within the treated HLB-affected trees. Poster and Pastries Research Symposium. CREC, Florida.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Gerberich, K.M. Commerford, S.L., Ehsani, R., Dewdney, M.M., Johnson, E.G. 2017. Root response of Huanglongbing-affected citrus trees to steam thermotherapy. Phytopathology, Vol. 107: S5.49.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Thapa, N., Commerford, S.L., Ehsani, R., Johnson, E.G. and Dewdney, M.M. 2017. Canopy and root response of HLB-affected citrus trees to steam-generated thermotherapy. Phytopathology, Vol. 107, No. 12: S5.51.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Thapa, N., Commerford, S. L., Johnson, E. G., and Dewdney, M. M. 2017. Canopy and root response of HLB-affected citrus trees to steam generated thermotherapy. Poster and Pastries Research Symposium. CREC, Florida.
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Thapa, N., Commerford, S. L., Ehsani, R., Johnson, E. and Dewdney, M., 2016. Canopy and root response of HLB-affected citrus trees to steam-generated thermotherapy. Phytopathology, Vol. 106, No. 12: S4.77.
- Type:
Other
Status:
Published
Year Published:
2015
Citation:
Johnson, E.G. The challenges of managing citrus Huanglongbing: A question of delivery to phloem and roots. Seminar at UCF Nanotechnology Center, July 2, 2015
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Ghatrehsamani S., Czarnecka E., Verner L., Gurley W.B., Ehsani R., Ampatzidis Y., 2019. Evaluation of Mobile Heat Treatment System for Treating In-field HLB-affected Trees by Analyzing Survival Rate of Surrogate Bacteria. Agronomy, 9(9), 540.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Ghatrehsamani S., Abdulridha J., Balafoutis T., Zhang X., Ehsani R., Ampatzidis Y., 2019. Development and Evaluation of a Mobile Thermotherapy Technology for In-field Treatment of HLB-Infected Trees. Biosystems Engineering, 182 (June 2019), 1-15.
- Type:
Other
Status:
Published
Year Published:
2019
Citation:
Ghatrehsamani S., Czarnecka E., Verner F.L., Gurley W.B., Ehsani R., and Ampatzidis Y., 2019. Evaluation of Mobile Heat Treatment System for Treating In-field HLB-affected Trees by Analyzing Biosensor Survival Rate. University Of Florida Graduate Student Research Day, hosted by the Organization for Graduate Student Advancement and Professional Development (OGAP), Gainesville, April 2nd, 2019. First Place Poster Award at the Graduate Student Research Poster contest in the Engineering category.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Ghatrehsamani S., and Ampatzidis Y., 2019. Evaluation of heat transfer inside the phloem of a tree during heat treatment of HLB-infected citrus tree by CFD. ASABE Annual International Meeting, July 7-10, Boston, Massachusetts, USA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Abdulridha J., Ampatzidis Y, Ehsani R., Dai A., Thompson K., Xu Y., 2018. Automated mobile heat thermotherapy system for HLB-infected citrus plants. 131st Annual Florida State Horticultural Society (FSHS) Conference, Fort Lauderdale, FL., June 10-12, 2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Souri S., Abdulridha J., Ehsani R., Schueller J., and Ampatzidis Y, 2018. The effect of root heat treatment on PMS, LAI, and stomata conductance in HLB infected trees. 131st Annual Florida State Horticultural Society (FSHS) Conference, Fort Lauderdale, FL., June 10-12, 2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Roka F., Dewdney M., Johnson E., Thapa N., Ehsani R., Ampatzidis Y., Abdulridha J., 2018. Economic Feasibility of Thermotherapy as a Strategy to Mange HLB Infected Trees. 131st Annual Florida State Horticultural Society (FSHS) Conference, Fort Lauderdale, FL., June 10-12, 2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Abdulridha J., Ampatzidis Y., Kakarla S.C., and Ehsani R., 2018. Mobile heat thermotherapy system for treating HLB-infected citrus trees utilizing hot water and steam. ASABE Annual International Meeting, July 29 August 1, Detroit, Michigan, USA.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2019
Citation:
SIMULATION OF INTERACTIVE HEAT AND CANOPY OF INFECTED TREE INSIDE MOBILE HEAT TREATMENT CANOPY COVER. CASE STUDY: HLB-AFFECTED CITRUS TREE.Ghatrehsamani S.,2019. University of Florida
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Duncan, L.W., Fluty, J.Q., El-Borai, F.F.E.. 2018. Does management of plant parasitic nematodes modulate citrus response to thermotherapy? 131st Annual Florida State Horticultural Society (FSHS) Conference, Fort Lauderdale, FL., June 10-12, 2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Trotochaud, J., and Reza Ehsani.2016. Commercial-scale thermotherapy for combating citrus greening (Huanglongbing). ASABE Annual International Meeting in Orlando, Florida, USA. Paper No. 2455891.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Al-Jumaili, A. and R. Ehsani. 2015. Mobile batch heat treatment system for treating HLB-infected citrus trees. ASABE Annual International Meeting in New Orleans, LA, USA. Paper No. 152190319.
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
Dewdney, M. M. E. G. Johnson, N. Thapa, M. D. Danyluk. 2018. Thermotherapys effects on fruit drop, yield and quality. Citrus Industry 99(12): 12-15.
|
Progress 01/15/18 to 01/14/19
Outputs
Target Audience:Citrus growers, Crop consultants, Agricultural machinery industry. Growers are seeking novel ways to effectively mitigate the negative production effects from citrus greening (i.e. HLB). Early trials using thermotherapy techniques showed promise in suppressing the bacterial effects of HLB and enhancing renewed tree growth and fruit production. This project centered around a large-scale trial where high-temperature steam "cooked" individual trees for varying durations to see if this thermotherapy technique could achieve economic feasibility. If positive trial results were observed, equipment manufacturers would be encouraged to design and build cost-effective treatment systems to apply the thermotherapy treatment. Changes/Problems:We have struggled to identify an appropriate RNA target for CLas viability in the host. This has delayed our work on the second part of Objective 5 where we planned to calculate the D/Z values for CLas. We are testing another method for RNA primer design and hope to have this resolved in the next month to initiate the experimental work. Hurricane Irma directly affected the trial block. It may not be possible to disentangle hurricane impacts from differences in thermotherapy treatments. What opportunities for training and professional development has the project provided?One graduate student and one postdoc have had training opportunities and developed the mobile thermotherapy system and the thermodynamic model. They presented their work in international conferences. One graduate student and one part time undergraduate student continued working on this project year applying the thermal treatments, measuring of chlorophyll fluorescence and participating in the preparation of oral and poster presentations. The undergraduate student gave a local oral presentation at the College's undergraduate research symposium. In part because of the research experience, the undergraduate student is now pursuing a M.S. degree. One graduate student has had training opportunities and has worked on RNA methods and interpretation as well as professional development presenting results at regional and international meetings. Two postdocs have had one on one training opportunities and developed experimental design, data analysis, and presentation skills while studying conditions that induce movement of Candidatus Liberibacter asiaticus between the roots and canopy to better guide application timing. Furthermore, we demonstrate EPN application techniques to grower-cooperators. How have the results been disseminated to communities of interest?The effects of thermal treatments were presented at the Annual International Meeting of the American Institute of Agricultural and Biological Engineers and at the annual meeting of the Florida State Horticultural Society. Furthermore, we demonstrate EPN application techniques to grower-cooperators. Several presentations were given at grower events. Examples are: Y. Ampatzidis. Agricultural engineering technologies to improve citrus production, Citrus Show, Fort Pierce, Florida, Jan-24, 2018. Y. Ampatzidis. Smart Machines, UAV and Precision Farming Technologies, 2018 Citrus Innovation and Technology Show. Arcadia, Florida, April-5, 2018. Y. Ampatzidis. Agricultural and Biological Engineering Technology Applied to Citrus Crops, 2018. Citrus Health Forum, NFREC, Quincy Fl., April 19, 2018. Y. Ampatzidis. New Technologies in Agriculture for Specialty Crops, 2018. Citrus Engineering Conference, Panel Session, Lake Alfred, FL, June 6, 2018. Y. Ampatzidis. Smart and Precision Agriculture, 2018. LaBelle Rotary Club, LaBelle Fl, September 17, 2018. E. G. Johnson. What's going on below ground?. 2018. Citrus Growers' workshop. Sebring, FL. September 25, 2018 E. G. Johnson. Effect of HLB on citrus root density. 2018. Citrus nutrient management for trees affected by HLB. Immokalee, FL. February 2, 2018 We organized a "thermotherapy workshop" at the 131st Annual Florida State Horticultural Society (FSHS) Conference, in Fort Lauderdale, FL., on June 10-12, 2018. Please see "publication section" for the full list of oral presentations. Example of talks are: Abdulridha J., Ampatzidis Y, Ehsani R., Dai A., Thompson K., Xu Y., 2018. Automated mobile heat thermotherapy system for HLB-infected citrus plants. 131st Annual Florida State Horticultural Society (FSHS) Conference, Fort Lauderdale, FL., June 10-12, 2018. Souri S., Abdulridha J., Ehsani R., Schueller J., and Ampatzidis Y, 2018. The effect of root heat treatment on PMS, LAI, and stomata conductance in HLB infectedtrees. 131st Annual Florida State Horticultural Society (FSHS) Conference, Fort Lauderdale, FL., June 10-12, 2018. Abdulridha J., Ampatzidis Y., Kakarla S.C., and Ehsani R., 2018. Mobile heat thermotherapy system for treating HLB-infected citrus trees utilizing hot water and steam. ASABE Annual International Meeting, July 29 - August 1, Detroit, Michigan, USA. Dai A., Thompson K., Xu Y., Ehsani R., and Ampatzidis Y., 2018. Development and Experiment of a Monitoring System for Steam Treatment of Citrus Greening. ASABE Annual International Meeting, July 29 - August 1, Detroit, Michigan, USA. Duncan, L.W., Fluty, J.Q., El-Borai, F.F.E. 2018. Does management of plant parasitic nematodes FritzRoka, Megan Dewdney, Evan Johnson, Naweena Thapa, Reza Ehsani, Yiannis Ampatzidis, Jaafar Abdulridha. Economic Feasibility of Thermotherapy as a Strategy to Mange HLB Infected Trees. Annual meetings of the Florida State Horticultural Society, Fort Lauderdale, FL. June 13, 2018. What do you plan to do during the next reporting period to accomplish the goals?We plan to continue developing the thermodynamic model to better explain the heat therapy's effects and to help equipment designers to further develop the proposed system. We plan to complete root tracings of minirhizotrons at the main field sites to improve our understanding of seasonal and time-temperature combinations effects on root health. While spring treatments have seen an increase in root biomass, minirhizotron scanning and analysis allows quantification of root growth and lifespan. All scans in the first site have been completed and we are near completion in the second field site. Preliminary analysis of traced roots in these scans has been done and a final thorough analysis will be completed by October. Last year, hurricane Irma directly affected the trial block; we want to collect field data during this growing period to further evaluate the heat therapy to treat HLB-infected citrus trees.
Impacts
What was accomplished under these goals?
Obj. 1: A new central control box is designed for the mobile thermotherapy system, which is more compact; the connection between the control box and the circuitry is more robust, and its working condition can be better monitored. Ten new water-proof thermal sensors are designed too. Furthermore, a thermodynamic model was developed to simulate the heat distribution inside the tent (canopy cover). Several field experiments were conducted to evaluate the mobile thermotherapy system and the thermodynamic model. Biosensors were utilized in these experiments to evaluate bacterial survival rate after heat treatment. Obj. 2: The third year of post treatment yield was collected from the first field trial site and the second year of yield data was collected from the second experimental site. Although the spring treatment showed promise with recovery of functional root mass after treatment, this was not reflected in fruit yields in year 3. The 2 year recovery in root health also lapsed during this year, showing a regression back to the pretreatment impairment of the root system. Yield in 2015/16, first year after thermotherapy treatment, tree yields were consistently lower and statistically significant from untreated control trees. Yield losses were observed across all levels of thermotherapy treatments and across the three treatment periods. Losses ranged from 2.5 to 5.9 pound-solids per tree. Yield differences across thermotherapy treatments were not statistically different. Treatments ranged from 55 to 60 C and between 0 and 120 seconds of duration. The timing of treatment did not produce significant yield effects. Obj. 3: In 2018, most of the lab work was focused on developing an RNA-based viability assay in response to thermotherapy. Bacterial viability is usually determined by the ability of the bacterial cells to actively grow and form the colonies in media. However, CLas is a fastidious, yet non-culturable bacterium. This makes it impossible to use classical bacteriological techniques to measure the viability of CLas post-treatments. Therefore, a molecular approach to determine CLas viability was tested. The hypothesis of this study is that the RNA expression patterns in CLas changes with the exposure to different levels of heat treatment (different temperature-time combinations). Our overall objective was to develop an RNA-based viability assay for CLas to measure lethality of high temperatures. Along with the goal of developing viability assay, grafting of the treated branches on healthy rootstocks, was also done to evaluate the effect of steam treatment on CLas survival. Comparison of expression pattern of CLas 16S rRNA at different treatment levels of temperature-time combinations showed significant differences amongst the treatments, particularly for 3 hours post treatment (3HPT) samples (p ≤ 0.0005). There is 3.3-fold decrease of CLas 16S rRNA at untreated control (UTC) in 3HPT samples showing RNA degradation under normal conditions. Obj. 4: In the two main field trial sites there was a good distribution of trees with and without damaging Phytophthora root rot prior to treatment. No effects on tree recovery/response nor a consistent response of Phytopthora populations was observed after treatment. Except in the most extreme cases where Phytophthora is already severely damaging the tree is it expected that a Phytophthora dependent response of the tree to thermotherapy would occur. Obj. 5: Nematode management results. Sample intensity was reduced in the second year following thermotherapy to avoid over-sampling the root systems. Sampling occurred 60-75 days after the final spring and fall oxamyl applications. Each sample consisted of 8 cores (2.5 cm dia. X 30 cm depth) per tree which were combined. Nematodes were recovered from the soil by centrifugal floatation and citrus roots were recovered by sieving from a known weight of soil, dried at room temperature and weighed. At the Black, Buffum East and Buffum West sites, ectoparasitic nematode densities in plots treated with oxamyl twice in 2015, 4 times in 2016 and 2017 and three times in 2018 were 96% 80% and 87% less abundant (P<0.001), respectively, than those in untreated control plots, following the spring treatments. Thermotherapy treatments (2017) had no residual effects on nematode control. Average yield of fruit at Buffum West was 14% higher in trees treated with thermotherapy but the result was not significant. The percentage of total fruit lost to dropping was reduced by 33% and 30% in the thermotherapy and oxamyl treatments, respectively, but again the trends were not significant. Fruit yield was significantly (P=0.001) correlated with the number of dropped fruit (r=0.53) and the trunk girth (r=0.69), but not with root weight. Obj. 6: A laboratory-scale application technology unit was developed to apply horticultural oil (HO)-based thermotherapy. Spray treatments included four variables namely heat-condition (i.e., heat and no-heat), HO concentration (i.e., 0.5 and 1.0 %), two nozzle types (N1: VisiFlo® ConeJet nozzles, TeeJet® Technologies, N2: D2/DC13 disc-core nozzles TeeJet® Technologies) and application pressure (i.e., 344.7 [50] and 689.5 [100] kPa [psi]). Each treatment was replicated four times on pear psylla bioassays. Mortality was evaluated at 3, 6, 12, 24 and 48 h after spray application. HO combined with thermotherapy achieved as high as 100 % pear psylla mortality during early hours after spray application. The overall mean pear psylla mortality using HO under heat condition (63.7±2.4 % [mean±std. error]) was significantly higher compared to HO applications under no-heat condition (43.6±1.8 %). Higher HO concentration (i.e., 1.0 %) under heat condition had significantly higher mortality (60.2±2.3 %) compared to HO applications under heat condition at lower concentration (47.1±2.0 %). Pear psylla mortality was significantly affected by nozzle type under heat conditions, and nozzle N1 (with comparatively higher spray coverage on water sensitive papers) had significantly higher (74.4±3.1 %) pear psylla mortality compared to nozzle N2 (52.9±3.3 %). The interaction between thermotherapy and each of the HO concentrations and nozzles on psylla mortality was significant at α=0.05. Overall, HO combined with thermotherapy caused a rapid kill of pear psylla. Obj. 7: First year results showed a statistically significant yield decline when Valencia orange trees were subjected to steam-generated thermotherapy. A multi-year cost-benefit analysis is necessary to assess whether the costs of applying thermotherapy and first-year yield losses will be offset by yield gains in the subsequent years. Even if treated trees respond positively with higher fruit yields, the magnitude of the yield gains have to be evaluated in the context of a grower's individual discount rate, which incorporates his/her degree of risk aversion and desired rates of returns. Yield differences in years 2 and 3 were not statistically different than the untreated control. Therefore, the value of yield losses experienced in the first year after treatment were never recouped, not to mention the cost of thermotherapy application, which was estimated to be $7 per tree. We conducted a 3-year cost-benefit analysis on Treatment #6, which was the "best" treatment as measured by numerical differences from the untreated control. Treatment #6 was administered during the fall and applied 55-degree Celsius steam for 120 s. A small grower survey provided representative values for annual delivered-in fruit prices and harvest costs. After 3-years, Treatment #6 earned $1.80 per tree more than what was earned from untreated trees. The positive earnings, however, were based only on yield differences. When the initial cost of application, $7 per tree, is considered, even the numerically best thermotherapy treatment did not achieve positive economic outcome.
Publications
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
Cimowski, S., Yang, D., Reyes-De-Corcuera J.I. Thermotherapy: Time-Temperature Thresholds to Prevent Orange Tree Defoliation. Oral presentation given at the Florida State Horticultural Society Meeting, Ft. Lauderdale, FL, June 12, 2018.
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
Cimowski, S., Jackson, J. Yang, D., Reyes-De-Corcuera J.I. Use of Chlorophyll Fluorescence as an Indicator of the Extent of Heat Treatment of Citrus Trees to Combat HLB. Poster presented at the International Annual Meeting of the ASABE, Detroit, MI, August 1, 2018
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
Duncan, L.W., Fluty, J.Q., El-Borai, F.F.E.. 2018. Does management of plant parasitic nematodes modulate citrus response to thermotherapy? 131st Annual Florida State Horticultural Society (FSHS) Conference, Fort Lauderdale, FL., June 10-12, 2018.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Bahlol, H. Y., R. Sinha, G.⿿A. Hoheisel, R. Ehsani and L. R. Khot*. 2018. Efficacy evaluation of horticultural oil based thermotherapy for pear psylla management. Crop Protection, 113: 97-103. (5-Year IF: 1.936).
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
Bhalol*, H.Y., R. Sinha, L. R. Khot, G.-A. Hoheisel and R. Ehsani. 2018. Horticultural oil based thermotherapy for Pear psylla management. Research News Flash, 114th Annual Meeting & NW Hort Expo, Yakima, WA. December 3, 4 & 5, 2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Dai, A., and Xu, Y., ⿿Path Control of a Heat Treatment Truck Considering Driver-Vehicle Interaction, 2018 ASME Dynamic Systems and Control Conference, Atlanta, GA, Oct. 2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Dai, A., Thompson, K., Xu, Y., Ehsani, R., and Ampatzidis, Y., ⿿Development and Experiment of a Monitoring System for Steam Treatment of Citrus Greening, 2018 ASABE Annual International Meeting, Detroit, Michigan, July 2018.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
J. D. Veloso Dos Santos, M. M. Murata, K. Gerberich, D. B. Bright, E. G. Johnson. 2018. Limited movement of Candidatus Liberibacter asiaticus in split-root citrus provides a model system for local and systemic effects of Huanglongbing. Phytopathology. 108(10): S127.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
N. Thapa, E. G. Johnson, M. M. Dewdney. 2018. Selection of reference genes to develop an RNA-based viability assay in response to thermotherapy. Phytopathology. 108(10): S1.164.
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
N. Thapa, E. G. Johnson, R. Ehsani, M. M. Dewdney. 2018. Seasonal variation in yield and root response to steam-generated supplementary heat thermotherapy. Abstract booklet of 131st Annual meeting of the Florida State Horticultural Society: 31.
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
Roka, F., M. M. Dewdney, E. G. Johnson, N. Thapa, R. Ehsani. 2018. Economic feasibility of thermotherapy as a strategy to manage HLB infected trees. Abstract booklet of 131st Annual meeting of the Florida State Horticultural Society: 32.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Dewdney, M. M. E. G. Johnson, N. Thapa, M. D. Danyluk. 2018. Thermotherapy⿿s effects on fruit drop, yield and quality. Citrus Industry 99(12): 12-15.
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
Abdulridha J., Ampatzidis Y, Ehsani R., Dai A., Thompson K., Xu Y., 2018. Automated mobile heat thermotherapy system for HLB-infected citrus plants. 131st Annual Florida State Horticultural Society (FSHS) Conference, Fort Lauderdale, FL., June 10-12, 2018.
- Type:
Other
Status:
Published
Year Published:
2018
Citation:
Souri S., Abdulridha J., Ehsani R., Schueller J., and Ampatzidis Y, 2018. The effect of root heat treatment on PMS, LAI, and stomata conductance in HLB infected trees. 131st Annual Florida State Horticultural Society (FSHS) Conference, Fort Lauderdale, FL., June 10-12, 2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Abdulridha J., Ampatzidis Y., Kakarla S.C., and Ehsani R., 2018. Mobile heat thermotherapy system for treating HLB-infected citrus trees utilizing hot water and steam. ASABE Annual International Meeting, July 29 ⿿ August 1, Detroit, Michigan, USA.
|
Progress 01/15/17 to 01/14/18
Outputs
Target Audience:Citrus growers, Crop consultants, Agricultural machinery industry Changes/Problems:We transfered the the principal investigator role from Dr. Ehsani to Dr. Ampatzidis. Dr. Reza Ehsani turned in his resignation letter to the University of Florida on June 30, 2017. Hurricane Irma directly affected several trial blocks. It may not be possible to disentangle hurricane impacts from differences in thermotherapy treatments. Objective 5: Further studies on the effects of thermal inactivation of lipoxygenase activity revealed that the activity of that enzyme is too small even in untreated samples to make the assay practical. Therefore, we decided to focus on the measurement of chlorophyll fluorescence using a portable device that would be suitable for in-filed use. What opportunities for training and professional development has the project provided?One graduate student and one part time undergraduate student were trained this year to perform enzyme activity assays (peroxidase, catalase, and lipoxygenase) and in the measurement of chlorophyll fluorescence as well as on enzyme kinetics and on the kinetics of enzyme inactivation. Two graduate students and one part time graduate student were trained this year to develop a mobile heat thermotherapy system to treat HLB-infected citrus trees. At UCF, two graduate students have trained from January to August of 2017, and two graduate students trained from August to December of 2017 to develop an automated data collection system for the mobile heat therapy system. How have the results been disseminated to communities of interest?Several presentations were given at grower events. Y. Ampatzidis. Mobile heat therapy system for HLB-infected citrus trees. Citrus field day at the Southwest Florida Research and Education Center, Immokalee, Fl, November 2, 2017. M. M. Dewdney, O. Batuman, E. G. Johnson, and A. Levy. The pathogen and how it influences current management. Lake Alfred, FL. April 21, 2017. E. G. Johnson. Root Health of HLB-affected citrus. Citrus Show. Ft. Pierce, FL. January 26, 2017 E. G. Johnson. Rootstocks, root lifespan, and yield: What do they tell us about managing root health with HLB. Citrus Production School. Arcadia, FL. February 28, 2017. E. G. Johnson. Citrus Root Health and HLB Management. Citrus Institute. April 4, 2017. E. G. Johnson. Citrus Root Health Management. Citrus Expo. August 17, 2017. Additionally, the effects of thermal treatments on lipoxygenase activity were presented at the Annual International Meeting of the American Institute of Agricultural and Biological Engineers. At the University of Central Florida, several presentation were given: Task 1: Finalize the modification of the sensing systems Task 2: Install the sensing system in the heat treatment truck Task 3: Conduct field experiments with PD's group Task 4: Implement the valve control systems (the controller will be driven by the sensed temperature profile) What do you plan to do during the next reporting period to accomplish the goals?Objective #1: We plan to further develop and in-field evaluate the performance of the mobile heat thermotherapy system (root and canopy). We plan to submit at least 2-3 refereed publications. Objective #2: We plan to continue collecting data from both sites 1 and 2 to access and evaluate heat treatments. Objective #3: The goal is to develop a model for correlating survivability of the bacteria in the canopy with different time, temperature and equipment configurations in the field. This approach will involve close collaboration with the field steam-treatment team to obtain precise data related to temperature profiles during treatment of young flushes, mature leaves, stems and branches, and temperature profiles under the bark at the phloem layer of branches and the main trunk where CLas resides. Survivability of CLcre under laboratory conditions that simulate the temperature profiles of specific regions of the canopy will be determined using colony size and abundance at various serial dilutions from treated liquid cultures followed by growth on agar plates. These types of studies will provide a surrogate-based model for predictions regarding the impact of the heat treatments on CLas viability. Objective #4: We will continue pest management treatments and evaluate effects of thermotherapy on pest-managed/non-managed trees for a second year. Objective #5: We will repeat the study on the effects of heating orange tree leaves in water to confirm the time-temperature combinations that do not defoliate the trees. These experiments will be done with hot water. Then we will do the experiments using the steam heating tunnel. Based on the results from next year's experiments we will determine the function that allows calculating the treatment time at any given temperature that does not cause defoliation and corroborate the chlorophyll fluorescence values that will enable growers to rapidly assess the extent of thermal treatment in the field. Objective 6: In 2017-2018 season, WSU team will evaluate reduced concentrations of HO and pertinent Pear Psylla mortality as well as the smothering of eggs/larvae for such treatment combinations. Efforts will also be focused on experimenting viability of the technology for Pear Psylla mortality control on actual tree canopies. Objective #7: We plan to finalize statistical analysis of yield and fruit quality data from the 2015/16 and 2016/17 seasons. We will harvest trial blocks for a third year in March 2018 and include yield and fruit quality data analysis into the economic model. Draft a paper, or a subsection of a larger paper, to describe the economic impact of thermotherapy on HLB management over a three-year period. Survey growers who have been utilizing thermotherapy from a variety of vendors and document their costs and estimated benefits from thermotherapy.
Impacts
What was accomplished under these goals?
Obj 1: The design (layout) of the mobile thermotherapy system was modified. The system now utilizes steam and hot water. The CPU of the system is contained within the cab of the truck with a display for real time system monitoring. This system is self-contained within the truck and allows the driver to implement a more precise treatment of the citrus tree. Obj 2: Based on the hypothesis that heat treatment (thermotherapy) can reduce Las titer in the infected trees, the responses of canopy and root system are being studied, along with the movement of bacteria within the tree, post-treatment. Roots were assessed for Las titer on the same trees, as roots are an untreated reservoir. Results from the summer 2017 showed an overall reduction of Las titer in the roots when compared to the UTC but in the canopy, the effect on the titer was inconsistent. In the fall 2017, the canopy titer decreased during the first month post-treatment compared to the UTC, but it increased in the second and third months. In contrast, the titer decreased in the roots compared to the UTC overall. In the winter 2017, the titer fell in all treatments as it did in the UTC. In the roots, the titer decreased in all treatments but not the UTC. In the spring timing, the titer in the canopy decreased in the first month but rose in the second and third months in a similar pattern to the UTC although in the 60°C/30s treatment was lower than the UTC. In the roots, there was a titer decrease in the third month post-treatment compared to UTC. Obj 3: An attempt was made to employ changes in mRNA populations, that were assumed to occur in response to heat stress, as a measure of bacterial cell viability. Preliminary analysis of real-time quantitative PCR of a variety of cDNAs synthesized from total RNA from the surrogate organism for CLas, C. Liberibacter crescens (CLcre), suggest that the heat stress regulon is already turned on to significant levels under normal growth temperatures (20-28°C) and is not further induced transcriptionally at higher temperatures. Plans for 2018 include developing a model of survivability in the canopy of a citrus tree by assessing survivability of CLcre in the laboratory under conditions that mimic actual temperature profiles obtained during steam-heat treatment in the field. In close collaboration with the steam-heat treatment team, 3-D temperature profiles during field treatments will be obtained from various components of the canopy including new flushes and stems, mature leaves, lateral branches, and the main trunk at standard heights and circumferences within the canopy. This type of thermal modeling of the canopy should facilitate detailed predictions of CLas viability resulting from various temperature, time and equipment configurations. Obj 4: Root densities and Phytophthora nicotianae populations were assessed before and after treatment. A good distribution of no Phytophthora root rot, mild root rot, and severe root rot were found within the trial allowing for analysis of how treatment affects root disease severity and how root rot affects the ability of the tree to respond to thermotherapy. Additionally, immediate damage to the roots to canopy thermotherapy and the subsequent leaf flush were monitored using minirhizotrons. The recovery and possible improvement of the fibrous root system continue to be monitored in the first rep of objective 2 field trial and these measurements are being repeated in the 2nd rep of the objective 2 field trial. A site has been selected to test the effects of root thermotherapy treatment on Phytophthora populations. The 5 field sites (described in year 1 report) were treated to manage root herbivores. Sites at Ona and Wauchula (infested by Diaprepes root weevils) received treatments of entomopathogenic nematodes (EPNs; Nemasys R, BASF) which are formulated Steinernema riobrave. This formulation is produced using fermentation technology which greatly reduced the production cost and permitted treatment of a larger surface area beneath the trees in 2016 and 2017 than in 2015. Each application consisted of 25 infective juvenile nematodes per cm2 soil surface. Nematodes were applied via the orchard micro-jet irrigation systems. 20 trees in each orchard received no EPNs by installing on-off valves on the individual micro-jet. Nematicides were not applied in 2017 to avoid accelerated microbial degradation which occurs with repeated application of soil applied carbamates. Populations of ectoparasitic nematodes treated six times previously remained below damage thresholds in 2017 until late in the year. Therefore the oxamyl treatments will be reinitiated in spring 2018. Obj 5: Initial experiments were completed and a full experiment was initiated. Gene expression was chosen to monitor CLas activity. Multiple bacterial genes were tested for appropriate gene expression levels and plant genes were selected as reference genes to standardize expression data. Infected branches from field trees were collected for treatment. Leaves were removed from the branches and a bark strip was collected for pretreatment bacterial activity (RNA) assessment. 13 branches per treatment were steamed at 8 temperature-time combinations in a steam chamber. Branches were then grafted into rootstocks to monitor bacterial populations and symptom expression for 1 year after treatment. Additionally, we selected chlorophyll fluorescence as the method to determine the impact of thermal treatment on the defoliation of citrus trees. We found that after treatment, when Fv/Fm values are greater than 0.5 =/- 0.1 the leaves do not die and fall off the trees. Obj 6: In 2016-17 project period, a lab scale application technology unit was developed to apply HO-based thermotherapy for effective management of Pear Psylla, one of the major pests in Pacific Northwest pear orchards. Experiments were conducted on pear-leaf bioassay to quantify efficacy of HO-based thermotherapy treatments to control adult Pear Psylla. Treatments included four parameters as thermotherapy (heat, and no heat), HO (0.5%, and 1% HO), two nozzle types and two pressure settings. Selected commercial nozzles generated very fine to fine and fine droplets, respectively at tested pressures. Two spray application pressures were 50(3.44), and 100(6.89) Psi (Bar). Each treatment was replicated four times. Evaluated was the efficacy of treatments in terms of mortality (%) at 3, 6, 12, 24 and 48 h after the application. Among the tested combinations, Pear Psylla mortality was significantly affected by thermotherapy, concentration of HO, and nozzle type. The combination of 1% HO thermotherapy when applied as very fine spray droplets had highest mortality (90.25 ± 18.95% [mean± std. dev.]). Overall, thermotherapy treatments achieved higher mortality than other treatments over the 48 h study period. Obj 7: A multi-year cost-benefit analysis is necessary in order to assess whether the costs of applying thermotherapy and first-year yield losses will be offset by yield gains in the subsequent years. The average on-tree value of Valencia oranges during 2015/16 was estimated to be $1.37 per pound-solids. This estimate is based on an average on-tree value of $8.96 per 90-pound box and 6.55 pound-solids per box as of April 1st (FASS, 2017). Given the average on-tree fruit value and estimated yield losses of between 2.5 and 5.85 pound-solids per tree, financial losses during the first year after thermotherapy treatment ranged from $4.40 to nearly $6 per tree. Costs of applying thermotherapy treatments are dependent on the equipment, which is evolving rapidly. One commercial applicator treated individual trees and charged $7 per tree. Another company is developing a multi-tree applicator and claims to have reduced its cost to $1 per tree. In either case, a grower has to see between a $6 and $13 financial gain in subsequent years to offset the costs of thermotherapy.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
N. Thapa, S. L. Commerford, R. Ehsani, E. G. Johnson, M. M. Dewdney. 2017. Canopy and root response of HLB-affected citrus trees to steam-generated thermotherapy. International Research Congress on Huanglongbing. Orlando, FL.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
N. Thapa, S. L. Commerford, R. Ehsani, E. G. Johnson, M. M. Dewdney, 2017. Steam-generated thermotherapy: How does canopy and root of HLB-affected citrus trees respond to it?. Florida Phytopathological Society, Quincy, FL
- Type:
Other
Status:
Published
Year Published:
2017
Citation:
E. G. Johnson. Citrus Huanglongbing in the roots: The hidden half of a systemic disease. 2017. Georgia Association of Plant Pathologists meeting.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Andong Dai, Emmanuel Garcia, Yunjun Xu, Reza Ehsani, Semi-Automated Thermotherapy for Citrus Trees with HLB Disease, 2017 ASABE Annual International Meeting, July 16-19, 2017, Spokane, Washington USA
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Jia Z., Ehsani R., Zheng J., Xu L., Zhou H., Ding R., 2017. Heating characteristics and field control effect of rapid citrus huanglongbing steam heat treatment. Transactions of the Chinese Society of Agricultural Engineering, Volume 33, Number 11, 1 June 2017, pp.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Bahlol*, H., G.-A. Hoheisel, R. Ehsani, and L. Khot. 2017. Thermotherapy with horticulture mineral oil for pear psylla management. Presentation No. 1701562, 2017 ASABE Annual International Meeting, Spokane, WA, 17-19 July 2017 (Poster Presentation).
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
2. Yang, D., Reyes-De-Corcuera J.I. Determination of the thermotherapy kinetics for citrus leaves. Presented at the International Annual Meeting of the ASABE, Spokane, WA, August 17, 2017
- Type:
Other
Status:
Published
Year Published:
2017
Citation:
Pradens Pierre-Louis, Master Thesis, Mechanical and Aerospace Engineering, UCF
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2018
Citation:
Ampatzidis Y., Derival M., Kakarla S.C., and Albrecht U., 2018. Evaluation of HLB-Infected Citrus Rootstocks Using Ground Penetrating Radar. 14Th International Conference on Precision Agriculture (ICPA), June 24-27, Montreal, Canada.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2018
Citation:
Dai A., Thompson K., Xu Y., Ehsani R., and Ampatzidis Y., 2018. Development and Experiment of a Monitoring System for Steam Treatment of Citrus Greening. ASABE Annual International Meeting, July 29 August 1, Detroit, Michigan, USA.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2018
Citation:
Abdulridha J., Ampatzidis Y., Kakarla S.C., and Ehsani R., 2018. Mobile heat thermotherapy system for treating HLB-infected citrus trees utilizing hot water and steam. ASABE Annual International Meeting, July 29 August 1, Detroit, Michigan, USA.
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Progress 01/15/16 to 01/14/17
Outputs
Target Audience:Citrus growers, Crop consultants, Agricultural machinery industry Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Five PhD and three masters graduate students and two part time post doctoral researchers are being trained through this grant. The efforts have been supplemented by involving another PhD researcher working partly on this project. Besides review of organic pest management practices and hands-on training experiences, year-1 & 2 activities have aided students towards training on effective project management with focus on problem identification, research methodologies development, experimental design, data collection & analysis, and report writing. How have the results been disseminated to communities of interest?The PI's involved in this project gave 12presentations at growers events, farm shows, workshops, and field days as well as at professional meetings. The following is the list of presentations given: Alizadeh, A., S. Souri, Z. Jia, K. Migliaccio, R. Ehsani. Investigating the effect of thermotherapy on physiological factors in HLB-Infected citrus. ASABE Annual International Meeting, Orlando, July 17-20, 2016. Ehsani, R. In-field short-time heat treatment system for managing HLB-affected citrus. 59th Biennial Citrus Engineering Symposium. Laker Alfred, FL. June. 21, 2016. Ehsani, R. Thermotherapy: Putting the latest results to work for you. 25rd Annual Citrus Expo Seminar Program. Ft. Myers, FL. Aug. 17, 2016. Ehsani, R. Citrus greening management with thermotherapy. Heat treatment extension seminar. Immokalee IFAS center, FL. April 26, 2016 Johnson, E. G., J. H. Graham, J. Orrock, S. L. Commerford, M. Dewdney, N. Thapa. The role of early root infection and damage in Huanglongbing. Citrus Research International Symposium. South Africa. August 22, 2016 Johnson, E. G., J. H. Graham, J. Orrock, S. L. Commerford, M. Dewdney, N. Thapa. The role of early root infection and damage in Huanglongbing. Stellenbosch University. August 26, 2016. Merchan, Carlos A., Xu, Yunjun, R. Ehsani, and Trotochaud, Joseph. The Design of an automation process for the steam treatment of citrus trees. ASABE Annual International Meeting, Orlando, July 17-20, 2016. Nalavade, P., L. Khot, G.-A. Hoheisel and R. Ehsani. Efficacy of thermotherapy and horticultural mineral oils for the control of pear psylla. Presentation at the 2016 ASABE Annual International Meeting to be held at Orlando, Florida during July 17 - 20, 2016. Thapa, N., S. L. Commerford, R. Ehsani, E. G. Johnson, M. M. Dewdney. Canopy and root response of HLB-affected citrus trees to steam-generated thermotherapy. Annual meeting of the American Phytopathological Society, Tampa FL, July 30 - August 3, 2016. Trotochaud, J., R. Ehsani. Development and field trials of thermotherapy systems for combating citrus greening (Hunaglongbing). ASABE Annual International Meeting, Orlando, July 17-20, 2016. Johnson, E. G. Root health in Florida citrus trees. Ridge Citrus School. October 25, 2016 Johnson, E. G. Video of root responses to HLB using minirhizotrons. UF/IFAS/CREC extension booths. First displayed at the Citrus Expo August 2016. What do you plan to do during the next reporting period to accomplish the goals?Objective #1: We plan to complete the installation of the sensor system, continue modifications to the new heat treatment system, and evaluate the performance of the new sensor system that is installed on the machine under field conditions. We plan to complete and submit at least one refereed publication on the activities conducted under this objective. Objective #2: We will continue the heat treatment of the trees at the second site as scheduled and will collect data from both sites 1 and 2 as mentioned in the project proposal. Objective #3: Our plan is to identify RNA biomarkers of lethality associated with high temperatures in Lcre. Total RNA has been isolated from cultures grown at various temperatures. This RNA will be analyzed by real-time PCR to assess the expression levels of genes associated with heat shock and cell death. Once an RNA expression profile of Lcre under severe heat stress has been constructed, this information will be used to probe key transcripts in Las present in citrus samples that have been treated at various temperatures. The underlying assumption is that Lcre can serve as a surrogate for constructing a RNA expression profile that correlates with a lethal condition existing in Las present in the field. Objective #4: In the third year, we will continue pest management treatments and initiate and evaluate effects of thermotherapy on infested/non-infested trees and pest-managed/non-managed trees. The first thermotherapy treatments will be applied in January 2017 to 10 oxamyl-treated and 10 non-treated trees at sites 4-6. Ten additional replicate trees of each nematicide treatment will receive thermotherapy after an additional year of nematode management. Treatment of trees in blocks 1-3 will occur later in the year, after further attempts (sampling adult weevils, examining roots of declining trees) to confirm significant herbivory and EPN treatment effects on the weevil populations. Objective #5: Our goal is to complete chlorophyll l fluorescence tests and steam-air heating experiments and then determine the kinetics of lipoxygenase thermal inactivation. We will present results at the ASABE Annual meeting and submit for publication in refereed journal. Objective #6: We are planning to carry out a lab experiment using two organic compounds (pectins and PEGs) with variable temperature and nozzle size to modify the plant surface in order to evaluate the plant-derived and other organic compounds for the following objectives (a) The heat transfer capacity of these materials from source to the target at the required value. (b) The contact between insect and leaf, i.e. the barrier between insects and plants. Objective #7: The plan for 2017 is to input second year yield data into the economic model and compute a net economic change over two years since thermotherapy was initiated. Then, the production data collected from commercial groves where thermotherapy has been performed will be analyzed.
Impacts
What was accomplished under these goals?
Objective 1: Changes were made to the thermotherapy system, some sensors were reselected, and the layout was redesigned. Currently, new sensors and valves are being installed on the thermotherapy truck, and the GUI is being reprogrammed. A total of 16 thermal sensors will be installed inside of the tent from the top to bottom. In the new design, the tree covering tent is located at the side of the truck so that it can cover the canopy when operating. Operators will monitor the surface temperature of a tree under heat therapy. Operator will be able to monitor whether every essential part of the system such as water tank and water pump is working properly. Objective 2: The second site for the second heat treatment trial was selected. A split-plot randomized complete block design field trial was laid out with the main plots at three month intervals to determine optimum time-of-year to reduce Las titer with the subplots at six temperature-time combinations with three blocks per time of year. Last year's experimental site received the last two seasonal treatments (winter and spring) during the reporting period. Leaf and root samples were collected based on the proposed plan in the project proposal. Results from the summer showed an overall reduction of Las titer in the root and canopy for all treatments when compared to the control. There was significant difference among the treatments for the root samples but not the leaves. Preliminary data from the winter treatment showed significantly lower Las titer in the canopy than the control after 2-months post treatment for all the temperature-time combinations. In the roots, Las titer decreased significantly for 55°C/0s, 55°C/90s and 60°C/30s, after 3 months of treatment compared to the control, suggesting Las movement from root to shoot along with the stored carbohydrates. The spring treatment resulted in a decrease in bacterial titer one-month post-treatment, but the titer in leaves increased in the second month. The 60°C/30s treatment significantly reduced Las titer compared to other treatments two months after thermotherapy. For the roots, all the treatments, except 55°C/0s, showed significantly lower Las titers in the 1st and 2nd months, post-treatment. For each season, there was a significant) interaction between the treatments and time after thermotherapy for the roots. Variations in Las titer within the control group were observed, regardless of the season which indicates an influence of natural physiological and environmental factors in bacterial movement in-tree. Seasonality and physiological state of the tree seem to play a critical role for Las distribution and movement within a particular tree. Physical damage to the canopy from heat stress may alter phloem flow and bacterial movement between roots and the treated canopy. Objective 3: The viability of Las titer was tested in the leaves of Las titer-infected citrus plants. The samples were treated and collected for PMA viability assay using real-time PCR. However, the high variability in the distribution and viability of Las titer in infected citrus plants makes it impractical to routinely use PMA viability assays due to the large number of samples required to obtain statistically significant differences between control and heat-treated samples. These inherent difficulties in measuring the viability and survival of Las titer in the field caused us to turn to surrogate systems to estimate the effect of various heat treatment regimens on survivability of the bacteria. Klebsiella oxytoca (Koxy) was used as a biological indicator of heat treatment effectiveness citrus trees. The large range in survivability of Koxy positioned in the canopy suggests that the tent apparatus created a nonuniform thermal profile. In general, most killing occurred in the upper and outer portions of the canopy. Also, nonuniformity was evident in the left quadrant nearest the viewer in the mid- to lower-portions of the canopy. Additionally, bacterial titers near control levels were recovered from packets placed under the tree bark, suggesting that the bark of the inner trunk served as an efficient thermal barrier under these conditions. Objective 4: As part of the larger experiment in objective 2, fibrous root densities and Phytophthora nicotianae populations were assessed before and after treatment. A good distribution of no Phytophthora root rot, mild root rot, and severe root rot were found within the trial allowing for analysis of how treatment affects root disease severity and how root rot affects the ability of the tree to respond to thermotherapy. As the effects of Phytophthora on the efficacy of thermotherapy for HLB are determined additional field trials using Phytophthora control measures (fungicides) may be initiated. The 6 field sites (described in year 1 report) were treated to manage root herbivores. Sites 1-3received treatments of entomopathogenic nematodes (Nemasys-G, BASF) which are formulated Steinernema riobrave. Bi-weekly monitoring of ground traps revealed no adult weevils in orchards 1 and 3 and therefore net effects of EPN treatments could not be measured. Sites 4-6 (infested by plant parasitic nematodes) were treated with oxamyl insecticide/nematicide (Vydate-L, DuPont) at an annual rate of 3 gallons per acre, divided into either 3 or 4 applications, dictated by specific grove operations. Nematicide treatments reduced the combined ectoparasite densities by 84%, 62%, 93% at the sites 4, 5, and 6, respectively. Objective 5: Preliminary experiments have been initiated to determine time-temperature combinations for the inactivation of CLas. Plant material is being prepared and optimal temperature and time ranges are being investigated. Construction and testing of the heating tunnel, incorporation of steam and air flowmeters and thermocouples into it are underway as well as determination of heating and cooling transients of the heating tunnel, assessment of thermal uniformity (temperature distributions of the tunnel, assessment of heating transients of citrus leaves, testing of temperatures in mid-rib of citrus leaves. Determination of residual catalase and peroxidase activity of orange leaves heated to 45, 50 and 55°C. At 45°C both enzymes were stable and catalase activity increased in response to stress. At 50°C catalase was stable and peroxidase activity decreased moderately. At 55°C both enzymes inactivated moderately. Enzyme activity was very variable which prevented determining the kinetic order of inactivation. Therefore, another enzyme needs to be used to determine the extent of heat treatment. Determination of chlorophyll fluorescence after heating trees to 45, 50 and 55°C revealed that the disruption of the photosystem does not follow first- or second-order kinetics. Leaves started to die after 2 min of heating at 55°C. Objective 6: Steam generator and associated instrumentation needed to conduct laboratory and field experiments at the WSU site have been procured and tested during this project period.We observed that 1% HMO at 40°C and without heat achieved complete mortality immediately 3 h after treatment, while 0.5% HMO at 40°C and without heat achieved it at 36 h after treatment. It clearly represents the mode of action of HMO by volatizing into fumes, which might have disrupted respiration of adult pear psylla, suffocated them. Moreover, different levels of concentrations indicate different extent of HMO fumes to present adequate suffocation over the time. Consequently, higher HMO concentration may have achieved complete mortality earlier compared to lower HMO concentration. Objective 7: Developed a spreadsheet template in which thermotherapy costs and value fruit yield changes resulting from thermotherapy can be inputted. No results to report. Full economic impact of thermotherapy will not come until the second or third year of the project.
Publications
- Type:
Journal Articles
Status:
Submitted
Year Published:
2017
Citation:
1.Jia, Z, R. Ehsani, S. Buchanon, J. Zheng, H. Zhou, M. b. Mail, and A. Toudeshki. Comparison of three sources of heat as a source of heat for thermotherapy of HLB-infected citrus. Applied Engineering in Agriculture.
- Type:
Other
Status:
Published
Year Published:
2016
Citation:
Ehsani, R., M. Dewdney and E. Johnson. 2016. Controlling HLB with thermotherapy: what have learned so far. Citrus Industry. 97(9) 26-28.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Trotochaud, J., R. Ehsani. 2016. Development and field trials of thermotherapy systems for combating citrus greening (Hunaglongbing). ASABE Annual International Meeting, Orlando, July 17-20, 2016.Paper Number: 2455891
- Type:
Other
Status:
Published
Year Published:
2016
Citation:
Garcia, Emmanuel, Dai, Andong, Xu, Yunjun, and Ehsani, Reza, Semi-Automated Thermotherapy for Citrus Trees with HLB Disease, submitted to the 2017 ASABE Annual International Meeting, Spokane, WA, Jul 16-19, 2017
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