Source: UNIVERSITY OF TENNESSEE submitted to NRP
WEED MANAGEMENT IN AGRONOMIC FIELD CROPS IN TENNESSEE
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1015408
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Feb 15, 2018
Project End Date
Feb 14, 2023
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIVERSITY OF TENNESSEE
2621 MORGAN CIR
KNOXVILLE,TN 37996-4540
Performing Department
Plant Sciences
Non Technical Summary
Natural (i.e., not-managed) ecosystems are highly diverse with many different species often present. Managed systems often have much lower levels of plant richness. Humans have chosen to conduct these bio-diversity reduction programs due to the greatly increased productivity of agriculture or other benefits of management. The absolute human carrying capacity of agricultural systems far-exceeds the natural flora and fauna. As our human population continues to increase, more food and other desirable plants will be needed to meet our demands. Stewards of a given land area select those plants that are "good" (crops) and those that are "bad" (weeds). The subjective nature of this decision, and the dynamic use of land imparts unique challenges to land managers. Plant species that are "crops" in one situation can become "weeds" in a different landscape setting. As weeds respond to control measures, there will always be a struggle to optimize the beneficial plants and reduce the negative effects of weeds. In the last few years, huge challenges have emerged that radically change weed management for many row crop farmers.Herbicides have been an extraordinarily effective means to reduce weed growth. Weed populations have responded in two ways. Firstly, new and different weed species have been "introduced" into a given area following herbicide applications. This phenomenon is called a "weed shift". Many of our most troublesome weeds are not native to Tennessee but introduced from other parts of the country or the world. These new weedy species are often not controlled by given management schemes (both with and without herbicides). The second phenomenon is when weeds that were previously controlled by a given herbicide become less susceptible to that particular herbicide and are thus no longer controlled, and this is termed "herbicide-resistance".Weeds respond to a variety of external stimuli. Tillage systems can affect various plant species (Teasdale et al. 1991). Given the problem of soil erosion in Tennessee, a major emphasis of our research is to control weeds while minimizing soil disturbance. No-tillage systems favor perennial weeds or those that germinate from a shallow depth (Teasdale et al. 1991). Annual row crops often have a critical weed free period early in the growing season where weed control must be effective in order to maintain maximum yield (Knezevic et al. 2002).A major change in the last 20 years has been the development and widespread adoption of glyphosate-resistant (GR) crops (Shaner 2000). Glyphosate can now be used for selective, post-emergence weed control in GR varieties of soybeans, cotton, canola and maize (Shaner 2000). In many production systems, most farmers are using GR crops and exclusively glyphosate for their weed control. This system is low cost, simple and effective. However, several weed species have developed resistance to glyphosate, including horseweed (Mueller et al 2003.), palmer amaranth (Steckel 2007), and goosegrass (Mueller et al. 2011). These GR weeds were not unexpected given previous examples of resistance (Owen and Zelaya 2005, Heap 1997).
Animal Health Component
80%
Research Effort Categories
Basic
10%
Applied
80%
Developmental
10%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
21323001140100%
Knowledge Area
213 - Weeds Affecting Plants;

Subject Of Investigation
2300 - Weeds;

Field Of Science
1140 - Weed science;
Goals / Objectives
Integrated Weed ManagementThe primary objective of this component is to determine the most effective weed control strategy for a given land use pattern. Success must be defined by a given scenario that is effective (controls weeds to an acceptable level), economical, and environmentally sustainable. All three of these pillars of success must be met from a given series of practices. Results of this research will be used to provide management recommendations for control of weed species. Implied in this objective are research efforts to determine not only what interventions are needed for weed management but also efforts to learn why these tactics are effective..New Herbicides and Herbicide Resistant CropsThe primary objective of this component is to determine the efficacy, environmental safety and economic feasibility of potential new herbicides, as well as new uses for established herbicides. A secondary objective will be to evaluate herbicide resistant crops. The overall goal of this project is to provide Tennessee producers with cutting edge information on the management of weeds with new herbicides as well as new technology.
Project Methods
Test systems will be conducted using established scientific methods to design the research, conduct the tests under the highest standards of ethical conduct, collect the appropriate data, examine that data using approved statistical methods and then report that data in high impact refereed journals and other various outlets. Laboratory methods will utilize modified Good Laboratory Procedures to maintain data quality to verify that analytical methods are accurate, sensitive and precise.

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:The only way for TN producers to apply dicamba to Xtend crops is to attend a 35 minute training module that was developed by and used research provided from Dr. Mueller and Steckel's weed science programs. Over 4,500 TN herbicide applicators took the training in 2020. Changes/Problems:In 2020, 95% of the 1.6 million acres of soybean and 90% of the 270,000 acres of cotton were planted to Xtend varieties. If they were not trained in dicamba then the Enlist system is the other option. Figuring $9/A for Engenia and $12/A for Enlist One. Conservatively would cost $7.50/acre more using Enlist One in soybean (figuring 2.5 apps). 1.6 million x $7.50 x .95 =$11,400,000 270,000 x $7.5 x .90 = $1,822,500 Total weed control savings for TN applicators $13,222,500 who took dicamba training The 2020 Weed Control Manual has been updated. There were 6000 copies printed and distributed to pesticide applicators. Applicators were then able to make wise herbicide choices based on UT weeds recommendations. What opportunities for training and professional development has the project provided?The development of Glyphosate-Resistant weeds have caused producers to substantially alter their weed control programs. Depending on what weeds are not controlled, training from TN has been essential for farmers to make the correct decisions on how to proceed. The unfortunate off-target movement of dicamba has also made the need to training of applicators and others a paramount importance. The importance of good herbicide stewardship is again shown to be an important aspect to the safe and effective use of herbicides. How have the results been disseminated to communities of interest?These data have helped lay the foundation for several weed control sections of the TN Weed Control Manual, and for all the recommendations contained therein. Refereed publications have also been produced to disseminate our research findings to the largest possible readership. What do you plan to do during the next reporting period to accomplish the goals?Due to all the issues with dicamba drift in recent years, stakeholders requested research to help characterize what environmental parameters effected volatility of labeled dicamba formulations in Xtend crops compared to older dicamba formulations. Our research group has been recognized as a preeminent source of information on the research topic of dicamba volatilization under field conditions.

Impacts
What was accomplished under these goals? Junglerice from several locations was screened for glyphosate-resistance and ACCase resistance. Preliminary results show low level Glyphosate resistance, but also antagonism by dicamba, and also slight reduction of control due to the use of drift reducing nozzles. Other projects addressed optimum herbicide use strategies in field crops. Dicamba emissions after application were affected by the treated surface, with the order from least to most emissions being dead plants < tilled soil < green plant material. In fact, dicamba emissions were > 300% when applied to green plants compared to other surfaces. These data suggest that field studies where dicamba applications are made to bare ground may underestimate what may occur under normal field use conditions when post-emergent applications are made and the crop canopy is nearly 100% green material.

Publications

  • Type: Other Status: Published Year Published: 2020 Citation: Sosnoskie L, Hayes R, Steckel. L. 2020 Field bindweed (Convolvulus arvensis): all tied up. Weed Tech 34: DOI: https://doi.org/10.17?wet.2020.61
  • Type: Other Status: Published Year Published: 2020 Citation: Sosnoskie L, Hanson B, Steckel. L. 2020 Hophornbean copperleaf (Acalypha ostryifolia Riddell) Weed Tech 34:305-307.
  • Type: Other Status: Published Year Published: 2020 Citation: Oseland E, Bish M, Steckel L, Bradley K. 2020. Identification of environmental factors that reduce the likely hood of off-target movement of dicamba. Pest Mgt Sci. DOI: 10.1002/ps.5887
  • Type: Other Status: Published Year Published: 2020 Citation: Perkins, C, Gage K, Norsworthy J, Young B, Bradley K, Bish M, Hager, A, Steckel L. 2020. Efficacy of residual herbicides as influenced by cover-crop residue for control of Amaranthus palmeri and A. tuberculatus in soybean. Weed Tech 34:DOI: https://doi.org/10.1017?wet.2020.77
  • Type: Other Status: Published Year Published: 2020 Citation: Mueller T, Steckel L. 2020 Dicamba emissions under field conditions as affected by surface conditions. Weed Tech. 34:DOI: https://doi.org/10.1017/wet.2020.106
  • Type: Other Status: Published Year Published: 2020 Citation: Mueller T, Kincer, D, Steckel L. 2020 Atrazine residues in flooded and non-flooded soil and effects on soybean. Weed Tech. 34: DOI: https://doi.org/10.1017/wet.2020.107
  • Type: Other Status: Published Year Published: 2020 Citation: Noguera, M, Rangani G, Heiser J, Bararpour, T, L. E. Steckel, Betz M, Porri A, Lerchl J, Zimmermann S. Nichols R, Roma-Burgos, N. 2020. Functional PPO2 mutations: co-occurrence in one plant or the same ppo2 allele of herbicide-resistant Amaranthus palmeri in the US Mid-south. Pest Mgt Sci. http://DOI: 10.1002/ps.6111


Progress 10/01/18 to 09/30/19

Outputs
Target Audience:Landscape scale loading of dicamba could impact all inhabitants of a geographic area where dicamba is used. However, homeowners located adjacent to dicamba applications areas, or conservation areas could be affected. Agricultural producers that either use herbicides to improve their operations, or those nearby could be affected. Another interested group is the technical staff at US EPA, who has had keen interest in this research for use in their regulatory decisions. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The development of Glyphosate-Resistant weeds have caused producers to substantially alter their weed control programs. Depending on what weeds are not controlled, training from TN has been essential for farmers to make the correct decisions on how to proceed. The unfortunate off-target movement of dicamba has also made the need to training of applicators and others a paramount importance. The importance of good herbicide stewardship is again shown to be an important aspect to the safe and effective use of herbicides. The unfortunate off-target movement of dicamba has also made the need to training of applicators and others a paramount importance. The importance of good herbicide stewardship is again shown to be an important aspect to the safe and effective use of herbicides. The federal labels mandate mandatory yearly training, and our research was instrumental in the herbicides being used in the most effective way, that still minimizes off target movement. In 2019, 2600 training sessions were conducted in Tennessee, and off target complaints of soybean injury was reduced from 126 (2018) to 22 (2019). While other factors were also involved, the training effort was a major factor in decreasing dicamba off target movement problems to injury sensitive plants. How have the results been disseminated to communities of interest?These data have helped lay the foundation for the Palmer amaranth control section of the TN Weed Control Manual, and for all the recommendations contained therein. Many refereed publications have also been produced to disseminate our research findings to the largest possible readership. What do you plan to do during the next reporting period to accomplish the goals?Due to all the issues with dicamba drift in 2017 and beyond, stakeholders requested research to help characterize what environmental parameters effected volatility of labeled dicamba formulations in Xtend crops compared to older dicamba formulations. The first study examined if adding Roundup PM to Engenia increased the volatility in a field setting. The results showed that Roundup PM did not affect Engenia volatility. Moreover, the research showed that with/without Roundup PM Engenia could be detected departing from the field surface for up to 36 hours after application. In a separate study that evaluated if dicamba volatility was effected by being applied to green plants compared to soil it was found that volatility was increased when dicamba was applied to 12" tall weeds compared to tilled soils or dead plant material. This dicamba data was disseminated via utcrops.com and was widely cited throughout the nation. Our research group has been recognized as a preeminent source of information on the research topic of dicamba volatilization under field conditions.

Impacts
What was accomplished under these goals? Johnsongrass and barnyardgrass from several locations was screened for glyphosate-resistance. The johnsongrass we evaluated did turn out to be resistant to glyphosate. The GR-johnsongrass populations were found in Shelby and Fayette counties. The barnyardgrass was controlled with the maximum rate of glyphosate applied alone. However, when glyphosate was tank-mixed with any other herbicide (Flexstar, dicamba, etc) the barnyardgrass was not controlled.This means that farmers will need to use alternative strategies to get the same weed control. This will result in lower yields due to incomplete weed control, and/or greater weed control expenses due to more herbicide use. Additional studies under field and laboratory conditions showed that adding glyphosate to dicamba formulations caused more secondary movement. This increased vapor movement was apparently strongly associated with the glyphosate addition lowering the pH of the spray mixture.Off target movement of dicamba causes plant damage to sensitive plants such as soybeans, trees, gardens, etc. This chemical trespass causes problems for home owners that experience plant damage. By changing how the farmers use dicamba products, we have provided them to tools to make intelligent decisions on herbicide stewardship. Our data is also used by the US EPA as they consider how to best use these products based on the label or directions for use that are written and approved by USEPA.

Publications

  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Whalen D. M. Bish, B, Young, L. Steckel, J. Norsworthy, A. Hager, S. Conley, D. Reynolds and K. Bradley. Evaluation of cover crop sensitivity to residual herbicides applied in the previous soybean crop. Weed Technol. 33:312-320.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Mueller, T.C., L.E. Steckel. 2019. Dicamba volatility in humidomes as affected by temperature and herbicide treatment. Weed Technol. 33:541-546.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Steckel, L.E., L.M. Sosnoskie, S.J. Steckel. 2019. Common evening-primrose (Oenothera biennis L.). Weed Technol. 33:757-760.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Copeland, J.D., G.B. Montgomery, L.E. Steckel. 2019. Evaluation of the time-of-day effect of herbicides applied POST on protoporphyrinogen IX oxidase-resistant and  susceptible Palmer amaranth (Amaranthus palmeri). Weed Technol. 33:651-657.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Mueller, T.C., L.E. Steckel. 2019. Spray mixture pH as affected by dicamba, glyphosate and spray additives. Weed Technol. 33:547-554.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Rowsey G (2019) Glyphosate lowers pH or dicamba mixtures, says study. AgFax Weed Solutions. Aug 2019. https://agfaxweedsolutions.com/2019/08/16/glyphosate-lowers-ph-of-dicamba-spray-mixtures-says-study/
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: UTIA. Research suggests glyphosate lowers pH of dicamba spray mixtures below acceptable levels. Lancaster Farming. 16 Aug 2019. https://www.lancasterfarming.com/news/ag_science/research-suggests-glyphosate-lowers-ph-of-dicamba-spray-mixtures-below/article_15b78e6d-efe6-51b8-8129-6d4f23833965.html
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Rowsey G (2019) Research suggests glyphosate lowers pH of dicamba spray mixtures below acceptable levels. Phys.org. 15 Aug 2019. https://phys.org/news/2019-08-glyphosate-lowers-ph-dicamba-mixtures.html
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: UTIA. Research shows temperature, glyphosate increase probability for dicamba volatility. Phys.org. 13 Jun 2019. https://phys.org/news/2019-06-temperature-glyphosate-probability-dicamba-volatility.html
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: UTIA. Research shows temperature, glyphosate increase probability for dicamba volatility. EurekAlert! online. 13 Jun 2019. https://www.eurekalert.org/pub_releases/2019-06/uoti-rst061319.php
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: UTIA. Research shows temperature, glyphosate increase probability for dicamba volatility. Science News. 13 Jun 2019. https://www.sciencedaily.com/releases/2019/06/190613121029.htm
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: UTIA. Research shows temperature, glyphosate increase probability for dicamba volatility. Soybean South. 13 Jun 2019. https://soybeansouth.com/departments/feature/research-shows-temperature-glyphosate-boost-probability-of-dicamba-volatility/
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: UTIA. Research shows temperature, glyphosate increase probability for dicamba volatility  both factors found to be contributors in dicamba movement. SeedQuest. 13 Jun 2019. https://www.seedquest.com/news.php?type=news&id_article=107629
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Rowsey G (2019) Dicamba: High temperatures plus glyphosate increase chances of volatility AgFax Weed Solutions. Jun 2019. https://agfaxweedsolutions.com/2019/06/13/dicamba-high-temperatures-plus-glyphosate-increase-chances-of-volatility/
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Tips for weed control in cotton. October 16, 2019. https://www.farmprogress.com/weeds/tips-weed-control-cotton?NL=DFP-01&Issue=DFP-01_20191016_DFP-01_514&sfvc4enews=42&cl=article_1&utm_rid=CPG02000000696310&utm_campaign=43214&utm_medium=email&elq2=26200a8c38ca4857b99797e55a358251 UTIA. Research suggests glyphosate lowers pH of dicamba spray mixtures below acceptable levels. L Steckel and TC Mueller in article. EurekAlert! online. 15 Aug 2019. https://www.eurekalert.org/pub_releases/2019-08/uoti-rsg081519.php
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Rowsey G (2019) Glyphosate lowers pH or dicamba mix too much, study shows. Delta Farm Press. 16 Aug 2019. https://www.farmprogress.com/herbicide/glyphosate-lowers-ph-dicamba-mix-too-much-study-shows
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Rowsey G (2019) Research shows temperature, glyphosate increase probability for dicamba volatility. Cotton Grower. 16 Jun 2019. https://www.cottongrower.com/crop-inputs/weed-management/research-shows-temperature-glyphosate-increase-probability-for-dicamba-volatility/
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Steckel L (2019) Reports of Palmer amaranth escapes in XTend crops continue to mount. Soybean South magazine. 26 Sept 2019. https://soybeansouth.com/departments/feature/reports-of-palmer-amaranth-escapes-in-xtend-crops-continue-to-mount/
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bomgardner MM (2019) Palmer amaranth, the king of weeds, cripples new herbicides. 3 Aug 2019. Chemical and Engineering News Vol 97 Issue 31. https://cen.acs.org/business/specialty-chemicals/Palmer-amaranth-king-weeds-cripples/97/i31
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Steckel L (2019) Houston, we have a problem Soybean South. 26 Sept 2019. https://soybeansouth.com/departments/feature/houston-we-have-a-problem/
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Rowsey G, L Steckel (2019). Tennessee: Where do we stand with weeds (link to podcast). AgFax. 24 Jun 2019. agfax@bellsouth.net. http://news.utcrops.com/2019/06/call-of-the-week-weeds-weeds-weeds/#new_tab
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Rowsey G, L Steckel (2019). Tennessee: Management options for grass weeds (link to podcast). AgFax. 14 Jun 2019. agfax@bellsouth.net. http://news.utcrops.com/2019/06/call-of-the-week-controlling-grass-weeds/#new_tab
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Steckel L (2019) Reports of sketchy Palmer amaranth control with Engenia and XtendiMax. MidAmerica Farmer Grower magazine. July 5, 2019. Vol. 39 No. 27. Pp 4, 8.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Steckel L (2019) Questions on grass control in cotton. MidAmerica Farmer Grower Vol. 39 No. 23. June 7, 2019. P 12.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Steckel L, Mueller T (2019) Does adding glyphosate to low-volatile dicamba formulations increase volatility? MidAmerica Farmer Grower Vol. 39 No. 18. May 3, 2019. P 10.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Steckel L (2019) Destroying a poor stand of corn and planting back to corn. MidAmerica Farmer Grower Vol. 39 No. 17. April 26, 2019. P 5 .
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Smith R (2019) Tennessee weed tour showcases cover crops, new mixes. Delta Farm Press magazine. 2 Jul 2019. https://www.farmprogress.com/weeds/tennessee-weed-tour-showcases-cover-crops-new-mixes
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Steckel L (2019) Starting this fall paraquat training will be required for all paraquat-containing products. MidAmerica Farmer Grower Vol. 39 No. 14. April 5, 2019. P 9.


Progress 02/15/18 to 09/30/18

Outputs
Target Audience:Target audience is row crop producers and all citizens of TN Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The development of Glyphosate-Resistant weeds has caused producers to substantially alter their weed control programs. Depending on what weeds are not controlled, training from TN has been essential for farmers to make the correct decisions on how to proceed. The unfortunate off-target movement of dicamba has also made the need to training of applicators and others a paramount importance. The importance of good herbicide stewardship is again shown to be an important aspect to the safe and effective use of herbicides. Data generated from this research was central to state-wide training efforts which were mandated by the newly revised labels of the USEPA for dicamba products. How have the results been disseminated to communities of interest?These data have helped lay the foundation for the Palmer amaranth control section of the TN Weed Control Manual, and for all the recommendations contained therein. Many refereed publications have also been produced to disseminate our research findings to the largest possible readership. A webinar was requested and hosted by the American Chemical Society in June of 2018 that had nation-wide audience participation. What do you plan to do during the next reporting period to accomplish the goals?Due to all the issues with dicamba drift in 2018, stakeholders requested research to help characterize what environmental parameters effected volatility of labeled dicamba formulations in Xtend crops (those that are resistant to dicamba) compared to older dicamba formulations. This dicamba data was disseminated via utcrops.com and was widely cited throughout the nation. Our research group has been recognized as a preeminent source of information on the research topic of dicamba volatilization under field conditions

Impacts
What was accomplished under these goals? Substantial new data was generated to examine the behavior of dicamba and 24D under field and laboratory conditions. These new research areas have been challenging to get meaningful data that is helpful in explaining the broad acre off target movement of dicamba to injure soybeans that have not been transgenically altered to be resistant to dicamba. This dicamba environmental fate area was a main focus of our efforts this year. Cover crops can be a valuable tool for resource management, and projects were conducted to establish weed control systems utilizing cover crops that are effective and economical. We evaluated a cover crop blend of vetch and cereal rye for Palmer amaranth control. We found moreover, there is a difference on how well some herbicides provide residual control when used in a heavy cover crop. In summary, Dual Magnum was not as effective PRE used in a heavy cover crop as other herbicides tested Moreover, research examining heavy cover crop would indicate that integrating this level of cover crop with herbicides can reduce the need for at least one Liberty Post application resulting in a net savings (including cover crop seed price) of $18.00/acre. Johnsongrass, ryegrass, goosegrass and barnyardgrass from several locations was screened for glyphosate-resistance. While these studies are ongoing, it was shown that grass weeds are increasingly being found to be resistant to glyphosate. The new dicamba resistant crop varieties may actually be hastening the development of grass species weeds, since the dicamba treatments provide no grass control. Research to examine optimum systems for weed control of broadleaf crops continues, since glyphosate resistant palmer pigweed, horsetail and others remain key driver weeds that are causing producers to change their cropping systems in response to their presence. Other topic areas of research include the fate of herbicides in soil, with special emphasis on agronomic priorities. Herbicides examined include atrazine and pyroxasulfone. As auxin-type herbicides are increasingly used by US farmers, our research group also has begun projects to remove the auxin herbicides from application equipment, since there is little published work in this area.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Parker ET, Owen MDK, Bernards ML, Curran WS, Steckel LE and Mueller TC. 2018. A Comparison of Symmetrical and Asymmetrical Triazine Herbicides for Enhanced Degradation in three midwestern soils. Weed Sci 66:673-679.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Korres NE, Norsworthy JK, Young BG, Reynolds DB, Johnson WG, Conley SP, Smeda RJ, Mueller TC, Spaunhorst DJ, Gage KL, Loux M, Kruger GR, Bagayathiannan MV. 2018. Seedbank Persistence of Palmer Amaranth (Amaranthus palmeri) and Waterhemp (Amaranthus tuberculatus) across Diverse Geographical Regions in the United States. Weed Sci 66:446-456.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Umphres AM, Steckel LE, and Mueller TC. 2018. Control of Protoporphyrinogen Oxidase Inhibiting Herbicide Resistant and Susceptible Palmer Amaranth (Amaranthus palmeri) with Soil-Applied Protoporphyrinogen Oxidase-Inhibiting Herbicides. Weed Technol. 32:95-100.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Mueller TC. 2017. Effect of Pyroxasulfone Formulation on Dissipation from a Winter Wheat Field in Tennessee. Weed Technol. 31:822-827
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Schwartz, L.M., J.K. Norsworthy, L.E. Steckel and D.O. Stephenson. 2018. A midsouthern consultants' survey on weed management practices in soybean. Weed Technol 32:116-125. Published online: Dec 04, 2017.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Nandula, V., G. Montgomery, D. A. Giacomini, M. Jugula, J. Ray, J. Bond, L. Steckel and P. Tranel. 2018. Glyphosate-resistant Echinochloa colona from Mississippi and Tennessee: confirmation nd resistance mechanisms. Weed Sci. 66:603-610.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Copeland, J.D., D. A. Giacomini, P.J. Tranel, G. B. Montgomery and L. E. Steckel. 2018. Distribution of PPX2 mutations conferring PPO-inhibiting resistance in Palmer amaranth populations of Tennessee. Weed Technol. 32: 592-596. Published Nov. 9, 2018.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Schroeder, J., M. Barrett, L. Steckel, et al. 2018. Managing wicked herbicide-resistance: Lessons from the field. Weed Technol. 32:489-497. Published Aug. 2018.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Schroeder, J., M. Barrett, L. Steckel, et al. 2018. Managing herbicide resistance: Listening to the perspective of practitioners. Procedures for conducing listening sessions and an evaluation of the process. Weed Technol. 32:489-497. Published Aug. 2018.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Steckel, L.E. 2017. Off-target dicamba in Tennessee: an Extension perspective. Proc. South Weed Sci. Soc. 70:165.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Steckel, L.E. 2018. Southern Extension weed specialist concerns. Abstr. Weed Sci. Soc. Am. 57:303.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Steckel, L.E. 2018. Restrictions and regulations are overwhelming at the farm level-developing a more freindly approach. Abstr. Weed Sci. Soc. Am. 57: 285.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Mueller, TC and LE Steckel. 2018 Dicamba Volatility Under Field and Laboratory Conditions. Proc. South Weed Sci. Soc. 70:267
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Mueller TC and LE Steckel. 2018 Diamba Volatility under Field and Controlled Conditions. Abstr. Weed Sci. Soc. Am. 57: 388
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Mueller TC, P Sayer, C. Hay, Silva, B. Bruss; 2018. Comparison of 2,4-D Amine and 2,4-D Choline Volatility under Field Conditions. Abstr. Weed Sci. Soc. Am. 57:390
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Mueller TC and LE Steckel 2018. Air Sampler Demonstration and Discussion: Lessons Learned. Abstr. Weed Sci. Soc. Am. 57: 391