@article{freund_kerns_butler_ahmed_gannon_2024, title={Effect of mowing timing and clipping collection practices on azoxystrobin distribution, persistence, and efficacy}, volume={9}, ISSN={["1435-0653"]}, DOI={10.1002/csc2.21365}, abstractNote={Abstract Previous research suggests mowing practices following azoxystrobin application alter pest control and residue fate. Azoxystrobin, an acropetal penetrant quinone outside inhibitor fungicide, is commonly applied in turfgrass and other agricultural settings, protecting desired plants from fungal pathogens by inhibiting fungal growth. Field research was initiated in Raleigh, NC, and repeated in time to assess the effect of post‐application mowing timing and clipping collection practices on azoxystrobin residue persistence in tall fescue ( Schedonorus arundinaceus Schreb.). At trial initiation, azoxystrobin was applied at the maximum single application rate (0.61 kg ai ha −1 ) to tall fescue plots. To determine the effect of initial mowing timing, plots were mowed (9.5 cm) at 0, 1, 2, 3, 7, or 14 days after application (DAA). To determine the effect of clipping removal, plots were mowed at 3, 10, and 17 DAA and clippings were either returned to the canopy or bagged and removed. Concurrently, soil cores (92 cm 2 ) were collected at 3, 7, 14, and 21 DAA and then segmented into remaining aboveground vegetation and soil (0.0‐ to 2.5‐cm depth) for residue analyses. Mowing timing affected azoxystrobin residue in the vegetation and in soil. When clippings were returned to the canopy, 5% more azoxystrobin was detected in the vegetation at 7 and 14 DAA. At 3 and 7 DAA, in the soil, returning clippings resulted in >3% more of the applied azoxystrobin compared to removing clippings. Data from this research may allow for extended fungicide intervals for brown patch suppression and demonstrate the importance of returning clipping to turf systems to retain azoxystrobin residues.}, journal={CROP SCIENCE}, author={Freund, Daniel R. and Kerns, James P. and Butler, E. Lee and Ahmed, Khalied A. and Gannon, Travis W.}, year={2024}, month={Sep} }
 @article{ramanathan_gannon_locke_everman_2023, title={Characterizing atrazine, mesosulfuron-methyl, and topramezone bioavailability in North Carolina soils using greenhouse bioassays}, volume={6}, ISSN={2639-6696}, url={http://dx.doi.org/10.1002/agg2.20371}, DOI={10.1002/agg2.20371}, abstractNote={AbstractHerbicide carryover injury to rotational crops can vary in severity depending on the influence of soil properties on herbicide bioavailability. Greenhouse bioassays were conducted with soybean, radish, and canola to evaluate differences in the bioavailability of three herbicides with carryover risk, atrazine, mesosulfuron‐methyl, and topramezone. Bioassays were conducted in three varying regional soil types with nine herbicide treatment rates including a control. Plant visual injury was evaluated weekly, and aboveground dry biomass was weighed after harvest of soybean 28 days after emergence (DAE) and radish and canola 21 DAE. A log‐logistic dose–response regression model was used to quantify herbicide‐effective concentrations for 30% (EC30), 50% (EC50), and 80% (EC80) visual injury and aboveground dry biomass reduction in each soil type. Relative herbicide‐soil bioavailability was determined through comparisons of herbicide‐effective concentrations among soil types. Pearson correlation revealed that atrazine, mesosulfuron‐methyl, and topramezone EC30 for all species were positively correlated to soil organic matter (OM) content (r = 0.56, 0.48, and 0.40, respectively) and cation exchange capacity (CEC) (r = 0.43, 0.41, and 0.45). Topramezone EC80 for soybean and radish was positively correlated to soil clay content (r = 0.51) and silt content (r = 0.51) and negatively correlated to sand content (r = −0.51) and pH (r = −0.52). Decreased atrazine, mesosulfuron‐methyl, and topramezone bioavailability in soil with high OM and CEC, decreased topramezone bioavailability in coarse‐textured soil and at high soil pH, and differential herbicide sensitivity of crop species can inform grower decisions on herbicide selections and rotational crop plans.}, number={2}, journal={AGROSYSTEMS GEOSCIENCES & ENVIRONMENT}, publisher={Wiley}, author={Ramanathan, Shwetha S. and Gannon, Travis W. and Locke, Anna M. and Everman, Wesley J.}, year={2023}, month={Jun} }
 @article{ramanathan_gannon_maxwell_2023, title={Dose-response of five weed species to indaziflam and oxadiazon}, volume={6}, ISSN={["1550-2740"]}, url={https://doi.org/10.1017/wet.2023.39}, DOI={10.1017/wet.2023.39}, abstractNote={AbstractIndaziflam and oxadiazon are efficacious preemergence herbicides used in warm-season turfgrass because of their persistence and residual activity. It is beneficial to quantify effective concentrations for preemergence control of summer annual weeds and determine whether these concentrations are maintained throughout weed emergence periods. Therefore, greenhouse bioassays were conducted with barnyardgrass, broadleaf signalgrass, doveweed, large crabgrass, and purple nutsedge. Treatments included indaziflam at 0, 4, 8, 12, 17, 21, 25, 29, 33, and 37 g ai ha−1 or oxadiazon at 0, 420, 841, 1,260, 1,681, 2,102, 2,354, 2,942, 3,363, and 3,783 g ha−1. Although preemergence herbicides are not used to control perennial weeds, purple nutsedge was included to investigate the effect of selected herbicides on its growth. Herbicide EC50, EC80, and EC90 for seedling emergence inhibition and shoot and root mass reduction were quantified from log-logistic dose–response curves. Herbicide concentration that remains from a preemergence application during the regional species-specific periodicity of emergence was predicted using first-order kinetics equations. Indaziflam and oxadiazon controlled seedling emergence 14 d after treatment (DAT) in the evaluated annual weeds and shoot and root mass in all species 84 DAT. Indaziflam applied in mid-March at 33 g ha−1 may provide up to 90% seedling emergence inhibition in large crabgrass and signalgrass; up to 80% in barnyardgrass; and up to 50% in doveweed. Oxadiazon applied in mid-March at 3,363 g ha−1 may provide up to 80% seedling emergence inhibition in all species. Indaziflam and oxadiazon may control up to 80% shoot mass and up to 50% root mass, respectively, in purple nutsedge and 80% to 90% shoot or root mass in other species. Such information is useful in evaluating adequacy of herbicide management practices for season-long weed control, and it aids turfgrass managers in applying preemergence herbicides at optimal timing based on target weed species.}, journal={WEED TECHNOLOGY}, author={Ramanathan, Shwetha S. and Gannon, Travis W. and Maxwell, Patrick J.}, year={2023}, month={Jun} }
 @article{frisvold_agme_ervin_allen_askew_bowling_brosnan_elmore_gannon_kaminski_et al._2023, title={Extension event attendance increases adoption of weed management practices by sports field managers}, volume={9}, ISSN={["1550-2740"]}, DOI={10.1017/wet.2023.66}, abstractNote={AbstractData from a national survey of 348 U.S. sports field managers were used to examine the effects of participation in Cooperative Extension events on the adoption of turfgrass weed management practices. Of the respondents, 94% had attended at least one event in the previous 3 yr. Of this 94%, 97% reported adopting at least one practice as a result of knowledge gained at an Extension turfgrass event. Half of the respondents had adopted four or more practices; a third adopted five or more practices. Nonchemical, cultural practices were the most-adopted practices (65% of respondents). Multiple regression analysis was used to examine factors explaining practice adoption and Extension event attendance. Compared to attending one event, attending three events increased total adoption by an average of one practice. Attending four or more events increased total adoption by two practices. Attending four or more events (compared to one event) increased the odds of adopting six individual practices by 3- to 6-fold, depending on the practice. This suggests that practice adoption could be enhanced by encouraging repeat attendance among past Extension event attendees. Manager experience was a statistically significant predictor of the number of Extension events attended but a poor direct predictor of practice adoption. Experience does not appear to increase adoption directly, but indirectly, via its impact on Extension event attendance. In addition to questions about weed management generally, the survey asked questions specifically about annual bluegrass management. Respondents were asked to rank seven sources of information for their helpfulness in managing annual bluegrass. There was no single dominant information source, but Extension was ranked more than any other source as the most helpful (by 22% of the respondents) and was ranked among the top three by 53%, closely behind field representative/local distributor sources at 54%.}, journal={WEED TECHNOLOGY}, author={Frisvold, George B. and Agme, Chandrakant and Ervin, David and Allen, Jennifer and Askew, Shawn and Bowling, Rebecca Grubbs and Brosnan, James and Elmore, Matthew and Gannon, Travis and Kaminski, John and et al.}, year={2023}, month={Sep} }
 @article{stephens_gannon_thiessen_cubeta_kerns_2023, title={In Vitro Fungicide Sensitivity and Effect of Organic Matter Concentration on Fungicide Bioavailability in Take-All Root Rot Pathogens Isolated from North Carolina}, volume={24}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-08-22-0072-RS}, abstractNote={ Take-all root rot (TARR) of ultradwarf bermudagrass is caused by Gaeumannomyces graminis (Gg), Gaeumannomyces graminicola (Ggram), Candidacolonium cynodontis (Cc), and Magnaporthiopsis cynodontis (Mc). Multiple pathogens have recently been associated with this disease, and biological parameters such as fungicide sensitivity have not been explored in ultradwarf bermudagrass. Although fungicides are commonly used to mitigate disease development, high organic matter present in the turfgrass system could limit the bioavailability of fungicides. Fungicide bioavailability can be influenced by organic matter concentration, and the physicochemical properties of fungicides could provide insight into their binding affinity. However, the influence of organic matter content on fungicide bioavailability has not been investigated. Therefore, the in vitro sensitivity of Gg, Ggram, Cc, and Mc to 14 different fungicides across three chemical classes was determined. An in vitro bioavailability assay was developed using three fungicides and three organic matter concentrations. Generally, demethylation inhibitor and quinone outside inhibitor fungicides provided the greatest reduction in mycelial growth, whereas succinate dehydrogenase inhibitors did not reduce mycelial growth. These data can serve as a foundation for TARR pathogen sensitivity to inform in vitro fungicide sensitivity studies and field efficacy trials. Pyraclostrobin and propiconazole have a high affinity to bind to organic matter, which was evident as more fungicide was required to inhibit Gg growth as organic matter concentration increased. This was not observed when evaluating azoxystrobin, which has a lower binding affinity. Understanding how TARR pathogens respond to fungicide in vitro and how organic matter concentration affects in vitro sensitivity will improve fungicide selection for management of TARR. }, number={2}, journal={PLANT HEALTH PROGRESS}, author={Stephens, Cameron M. and Gannon, Travis W. and Thiessen, Lindsey D. and Cubeta, Marc A. and Kerns, James P.}, year={2023}, month={Jul}, pages={162–170} }
 @article{stephens_gannon_cubeta_kerns_2024, title={Influence of fungicide selection and application timing on take-all root rot management under field and greenhouse conditions}, volume={10}, ISSN={["2374-3832"]}, DOI={10.1002/cft2.20261}, abstractNote={Abstract Take‐all root rot (TARR) is a detrimental disease of ultradwarf bermudagrass ( Cynodon dactylon × Cynodon transvaalensis ; UDB) putting greens frequently diagnosed where warm‐season grasses are grown. Since this disease is largely aggregated and variable under field conditions, field research is difficult and often yields inconsistent results. Multiple pathogens have only recently been associated with this disease, so practical management solutions such as fungicide efficacy and fungicide application timing have not been thoroughly investigated. Therefore, the objectives of this research were to determine the influence of fungicide selection and fungicide application timing on take‐all root rot management under field and greenhouse conditions. In general, fungicides from the quinone outside inhibitor and/or demethylation inhibitor chemical classes provided the greatest reduction in take‐all root rot severity. Fungicide applications that were made when soil temperatures were between 77–86°F provided the greatest disease suppression. The in vivo greenhouse method developed in this research proved to be an efficient and consistent method to evaluate management practices such as fungicide efficacy on take‐all root rot. This research improves our understanding of fungicide efficacy and fungicide application timing for take‐all root rot management on ultradwarf bermudagrass.}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Stephens, Cameron M. and Gannon, Travis W. and Cubeta, Marc A. and Kerns, James P.}, year={2024}, month={Jun} }
 @article{polli_gannon_lecompte_rogers_beran_2023, title={Response of soybean, cotton, and tobacco to volatility of 2,4-D and dicamba formulations in humidome}, volume={38}, ISSN={["1550-2740"]}, url={https://doi.org/10.1017/wet.2023.86}, DOI={10.1017/wet.2023.86}, abstractNote={Abstract
	  Dicamba and 2,4-D are postemergence herbicides widely used to control broadleaf weed species in crop and non-crop areas in the United States. Currently, multiple formulations of 2,4-D and dicamba are available on the market. Even though the active ingredient is the same, the chemical formulation may vary, which can influence the volatility potential of these herbicides. Therefore, the objective of this study was to evaluate the response of soybean, cotton, and tobacco plants exposed to vapors of 2,4-D and dicamba formulations alone or mixed in humidomes for 24 h. Humidome studies were conducted in an open pavilion at the Lake Wheeler Turfgrass Field Lab of the North Carolina State University in Raleigh, NC. Dicamba and mixture treatments injured and caused a reduction in the height of soybean. Injury varied from 55% to 70%, and average plant height was 8.8 cm shorter compared with untreated control plants. Treatments with 2,4-D caused the least injury to soybean (≤21%), and differences among formulations were identified (dimethylamine > choline > dimethylamine-monomethylamine). However, soybean height was not affected by 2,4-D treatments. No differences between treatments were observed when herbicides were applied to cotton. The greatest injury to tobacco (23.3%) was caused by dicamba dimethylamine. Overall, the effect of 2,4-D and dicamba vapor was species-specific and formulation-dependent. Additionally, environmental conditions in the humidomes may have played a major role on the outcome of this study.}, journal={WEED TECHNOLOGY}, author={Polli, Estefania G. and Gannon, Travis W. and LeCompte, Mathieu and Rogers, Ronald R. and Beran, Daniel D.}, year={2023}, month={Nov} }
 @article{camacho_faundez-urbina_amoozegar_gannon_heitman_leon_2023, title={Subsurface Lateral Solute Transport in Turfgrass}, volume={13}, ISSN={["2073-4395"]}, url={https://doi.org/10.3390/agronomy13030903}, DOI={10.3390/agronomy13030903}, abstractNote={Turfgrass managers have suspected that runoff-independent movement of herbicides and fertilizers is partially responsible for uneven turfgrass quality in sloped areas. We hypothesized that subsurface lateral solute transport might explain this phenomenon especially in areas with abrupt textural changes between surface and subsurface horizons. A study was conducted to track solute transport using bromide (Br−), a conservative tracer, as a proxy of turfgrass soil inputs. Field data confirmed the subsurface lateral movement of Br− following the soil slope direction, which advanced along the boundary between soil horizons over time. A model based on field data indicated that subsurface lateral movement is a mechanism that can transport fertilizers and herbicides away from the application area after they have been incorporated within the soil, and those solutes could accumulate and resurface downslope. Our results demonstrate that subsurface lateral transport of solutes, commonly ignored in risk assessment, can be an important process for off-target movement of fertilizers and pesticides within soils and turfgrass systems in sloped urban and recreational landscapes.}, number={3}, journal={AGRONOMY-BASEL}, author={Camacho, Manuel E. and Faundez-Urbina, Carlos A. and Amoozegar, Aziz and Gannon, Travis W. and Heitman, Joshua L. and Leon, Ramon G.}, year={2023}, month={Mar} }
 @article{rutland_bowling_russell_hall_patel_askew_bagavathiannan_brosnan_gannon_goncalves_et al._2023, title={Survey of target site resistance alleles conferring resistance in Poa annua}, volume={8}, ISSN={["1435-0653"]}, DOI={10.1002/csc2.21066}, journal={CROP SCIENCE}, author={Rutland, Claudia Ann and Bowling, Rebecca G. and Russell, Eli C. and Hall, Nathan D. and Patel, Jinesh and Askew, Shawn D. and Bagavathiannan, Muthukumar V. and Brosnan, James T. and Gannon, Travis W. and Goncalves, Clebson and et al.}, year={2023}, month={Aug} }
 @article{ramanathan_gannon_everman_locke_2022, title={Atrazine, mesosulfuron‐methyl, and topramezone persistence in North Carolina soils}, volume={114}, ISSN={0002-1962 1435-0645}, url={http://dx.doi.org/10.1002/agj2.21041}, DOI={10.1002/agj2.21041}, abstractNote={AbstractInvestigating the effects of soil properties on herbicide persistence can aid in evaluating the carryover potential of herbicides in soil and the consequent injury risk to rotational crops. Laboratory incubation experiments were conducted to quantify the persistence of atrazine, mesosulfuron‐methyl, and topramezone in five regional soils under aerobic conditions at 23 °C. Additionally, mesosulfuron‐methyl persistence was tested at 7 °C, which is representative of regional average winter soil temperature. Herbicide half‐life was calculated with the logarithmic form of first‐order rate of degradation using linear regression and was correlated with soil properties. Half‐lives of atrazine (37–73 d) and topramezone (15–19 d) varied among soil types at 23 °C. Mesosulfuron‐methyl half‐life varied among soils at 7 °C (8.8–9.8 d) and 23 °C (5.4–5.8 d) and between temperatures. Atrazine and topramezone half‐lives were shortest in Candor sand (4% clay, 1.8% organic matter [OM], pH 5.1) and longest in Portsmouth sandy loam (13% clay, 5.3% OM, pH 4.3). Mesosulfuron‐methyl half‐life was longer at lower soil temperature. Half‐lives of atrazine, mesosulfuron‐methyl, and topramezone were correlated with soil OM content (r = .83, −.53, and .63, respectively) and pH (r = −.86, .55, and −.57). Additionally, atrazine and topramezone half‐lives were positively correlated with soil clay content (r = .83 and .71), and mesosulfuron‐methyl half‐life was negatively correlated with temperature (r = −.97). Correlations between soil OM content, clay content, and pH among soil types may have influenced herbicide persistence.}, note={title = {Atrazine, mesosulfuron-methyl, and topramezone persistence in North Carolina soils}, journal = {Agronomy Journal}}, number={2}, journal={Agronomy Journal}, publisher={Wiley}, author={Ramanathan, Shwetha S. and Gannon, Travis W. and Everman, Wesley J. and Locke, Anna M.}, year={2022}, month={Mar}, pages={1068–1079} }
 @article{camacho_gannon_ahmed_mulvaney_heitman_amoozegar_leon_2022, title={Evaluation of imazapic and flumioxazin carryover risk for Carinata (Brassica carinata) establishment}, volume={5}, ISSN={["1550-2759"]}, url={https://doi.org/10.1017/wsc.2022.27}, DOI={10.1017/wsc.2022.27}, abstractNote={AbstractCarinata (Brassica carinata A. Braun) is a potential crop for biofuel production, but the risk of injury resulting from carryover of soil herbicides used in rotational crops is of concern. The present study evaluated the carryover risk of imazapic and flumioxazin for carinata. Label rates of imazapic (70 g ai ha−1) and flumioxazin (107 g ai ha−1) were applied 24, 18, 12, 6, and 3 mo before carinata planting (MBP). The same herbicides were applied preemergence right after carinata planting at 1X, 0.5X, 0.25X, 0.125X, 0.063X, and 0X the label rate. When either herbicide was applied earlier than 3 MBP, there was no difference in plant density compared with the nontreated control. Carinata damage was <25% when flumioxazin or imazapic was applied at least 6 MBP in Clayton, NC (sandy loam soil), while in Jackson Springs, NC (coarser-textured soil and higher precipitation), at least 12 MPB were needed to lower plant damage to <25%. Preemergence application of 0.063X each herbicide decreased plant density by 40%, with damage reaching >25%. Quantification of herbicide residues in both soils showed that imazapic moved deeper in the soil profile than flumioxazin. This was more evident in Jackson Springs, where 0.68, 3.52, and 7.77 ng of imazapic g−1 soil were detected (15- to 20-cm depth) when the herbicide was applied at 12, 6 and 3 MBP, respectively, while no flumioxazin residues were detected at the same soil depths and times. When residues were 7.78 and 6.90 ng herbicide g−1 soil in the top 10 cm of soil for imazapic and flumioxazin, respectively, carinata exhibited at least 25% damage. Rotational intervals to avoid imazapic and flumioxazin damage to carinata should be between 6 and 12 MBP depending on soil type and environmental conditions, with longer intervals for the former than the latter.}, journal={WEED SCIENCE}, publisher={Cambridge University Press (CUP)}, author={Camacho, Manuel E. and Gannon, Travis W. and Ahmed, Khalied A. and Mulvaney, Michael J. and Heitman, Joshua L. and Amoozegar, Aziz and Leon, Ramon G.}, year={2022}, month={May} }
 @article{rivera-chacon_castillo_gannon_bekewe_2022, title={Harvest frequency and harvest timing following a freeze event effects on yield and composition of switchgrass}, volume={11}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.21202}, abstractNote={AbstractConstant supply of biomass from the field is limited by the seasonality of production of warm‐season grasses in the transition U.S. region. Delaying harvest after occurrence of freeze may be an alternative to extend the biomass supply period of switchgrass (Panicum virgatum L.) in North Carolina. The objectives of this study were to evaluate the effects of harvest frequency (HF) and harvest timing at the end of the growing season (HT) on switchgrass biomass yield, nutrient (N, P, and K) removal, and dry matter (DM) and ash concentrations. Treatments were the factorial combination of two HF (clipped once [1X] or twice [2X] per season) and three HT (before freeze in October, after first freeze in November, and late winter in February). Delaying harvest after occurrence of freeze did not affect total annual biomass yield for the 2X treatment (average of 15.5 Mg ha−1), whereas for 1X yield declined from 14.4 to 10.1 Mg ha−1 when harvest was delayed from October to February. Ash concentration declined from 29 g kg−1 in October to 14 g kg−1 in February. The DM concentration level reached in February was lowest (893 g kg−1) and it would be considered safe for storage of biomass. Nutrient removal was consistently greater for 2X than 1X (ranging from 43 to 137, 3.6 to 25.1, and 54 to 213 kg ha−1 for N, P, K, respectively). Delaying harvest of switchgrass after a freeze event is feasible when clipping twice a year to extend the window of biomass supply.}, journal={AGRONOMY JOURNAL}, author={Rivera-Chacon, Raul and Castillo, Miguel S. and Gannon, Travis W. and Bekewe, Perejitei E.}, year={2022}, month={Nov} }
 @article{allen_ervin_frisvold_brosnan_mccurdy_bowling_patton_elmore_gannon_mccarty_et al._2022, title={Herbicide-Resistance in Turf Systems: Insights and Options for Managing Complexity}, volume={14}, ISSN={["2071-1050"]}, DOI={10.3390/su142013399}, abstractNote={Due to complex interactions between social and ecological systems, herbicide resistance has classic features of a “wicked problem”. Herbicide-resistant (HR) Poa annua poses a risk to sustainably managing U.S. turfgrass systems, but there is scant knowledge to guide its management. Six focus groups were conducted throughout the United States to gain understanding of socio-economic barriers to adopting herbicide-resistance management practices. Professionals from major turfgrass sectors (golf courses, sports fields, lawn care, and seed/sod production) were recruited as focus-group participants. Discussions emphasized challenges of the weed management of turfgrass systems as compared to agronomic crops. This included greater time constraints for managing weeds and more limited chemical control options. Lack of understanding about the proper use of compounds with different modes of action was identified as a threat to sustainable weed management. There were significant regional differences in perceptions of the existence, geographic scope, and social and ecological causes of HR in managing Poa annua. Effective resistance management will require tailoring chemical and non-chemical practices to the specific conditions of different turfgrass sectors and regions. Some participants thought it would be helpful to have multi-year resistance management programs that are both sector- and species-specific.}, number={20}, journal={SUSTAINABILITY}, author={Allen, Jennifer H. and Ervin, David E. and Frisvold, George B. and Brosnan, James T. and McCurdy, James D. and Bowling, Rebecca G. and Patton, Aaron J. and Elmore, Matthew T. and Gannon, Travis W. and McCarty, Lambert B. and et al.}, year={2022}, month={Oct} }
 @article{haug_ahmed_gannon_richardson_2021, title={Absorption and translocation of florpyrauxifen-benzyl in ten aquatic plant species}, volume={69}, ISSN={["1550-2759"]}, DOI={10.1017/wsc.2021.38}, abstractNote={AbstractAdditional active ingredients are needed for use in aquatic systems to respond to new threats or treatment scenarios, enhance selectivity, reduce use rates, and mitigate the risk of herbicide resistance. Florpyrauxifen-benzyl is a new synthetic auxin developed for use as an aquatic herbicide. A study was conducted at North Carolina State University in which 10 µg L−1 of 25% radiolabeled florpyrauxifen-benzyl was applied to the isolated shoot tissue of 10 different aquatic plant species to elucidate absorption and translocation patterns in these species. Extremely high levels of shoot absorption were observed for all species, and uptake was rapid. Highest shoot absorptions were observed for crested floatingheart [Nymphoides cristata (Roxb.) Kuntze] (A192 = 20 µg g−1), dioecious hydrilla [Hydrilla verticillata (L. f.) Royle] (A192 = 25.3 µg g−1), variable watermilfoil (Myriophyllum heterophyllum Michx.) (A192 = 40.1 µg g−1), and Eurasian watermilfoil (Myriophyllum spicatum L.) (A192 = 25.3 µg g−1). Evidence of translocation was observed in all rooted species tested, with the greatest translocation observed in N. cristata (1.28 µg g−1 at 192 h after treatment). The results of this study add to the growing body of knowledge surrounding the behavior of this newly registered herbicide within aquatic plants.}, number={6}, journal={WEED SCIENCE}, author={Haug, Erika J. and Ahmed, Khalied A. and Gannon, Travis W. and Richardson, Rob J.}, year={2021}, month={Nov}, pages={624–630} }
 @article{stephens_gannon_cubeta_sit_kerns_2022, title={Characterization and Aggressiveness of Take-All Root Rot Pathogens Isolated from Symptomatic Bermudagrass Putting Greens}, volume={112}, ISSN={["1943-7684"]}, DOI={10.1094/PHYTO-05-21-0215-R}, abstractNote={ Take-all root rot is a disease of ultradwarf bermudagrass putting greens caused by Gaeumannomyces graminis (Gg), Gaeumannomyces sp. (Gx), Gaeumannomyces graminicola (Ggram), Candidacolonium cynodontis (Cc), and Magnaporthiopsis cynodontis (Mc). Many etiological and epidemiological components of this disease remain unknown. Improving pathogen identification and our understanding of the aggressiveness of these pathogens along with growth at different temperatures will advance our knowledge of disease development to optimize management strategies. Take-all root rot pathogens were isolated from symptomatic bermudagrass root and stolon pieces from 16 different golf courses. Isolates of Gg, Gx, Ggram, Cc, and Mc were used to inoculate ‘Champion’ bermudagrass in an in planta aggressiveness assay. Each pathogen was also evaluated at 10, 15, 20, 25, 30, and 35°C to determine growth temperature optima. Infected plant tissue was used to develop a real-time PCR high-resolution melt assay for pathogen detection. This assay was able to differentiate each pathogen directly from infected plant tissue using a single primer pair. In general, Ggram, Gg, and Gx were the most aggressive while Cc and Mc exhibited moderate aggressiveness. Pathogens were more aggressive when incubated at 30°C compared with 20°C. While they grew optimally between 24.4 and 27.8°C, pathogens exhibited limited growth at 35°C and no growth at 10°C. These data provide important information on this disease and its causal agents that may improve take-all root rot management. }, number={4}, journal={PHYTOPATHOLOGY}, author={Stephens, Cameron M. and Gannon, Travis W. and Cubeta, Marc A. and Sit, Tim L. and Kerns, James P.}, year={2022}, month={Apr}, pages={811–819} }
 @article{stephens_kerns_ahmed_gannon_2021, title={Influence of post-application irrigation and mowing timing on fungicide fate on a United States Golf Association golf course putting green}, volume={6}, ISSN={["1537-2537"]}, DOI={10.1002/jeq2.20249}, abstractNote={AbstractFungicides are routinely applied to golf course putting greens throughout the growing season. Gaining a better understanding of fungicide fate can improve fungicide use and stewardship. Therefore, optimizing fungicide applications with post‐application management practices may enhance fungicide movement and limit potential off‐target effects. Two field studies were initiated on a golf course putting green to evaluate the influence of post‐fungicide application irrigation and mowing timing on fungicide movement into the soil profile and removal in turfgrass clippings. Plots were treated with a single application of either pyraclostrobin, triadimefon, or penthiopyrad and received 0.64 cm post‐application irrigation immediately or 6 h after application or received no post‐application irrigation. Clippings were collected 0, 1, and 3 d after treatment (DAT). Cores were harvested 0, 1, 3, 5, 7, and 14 DAT and dissected into the remaining aboveground vegetation (RAV; verdure/thatch; 0‐to‐2.5‐, 2.5‐to‐5.1‐, and 5.1‐to‐7.6‐cm soil subsections). A small amount of fungicide (<3.6%) was removed with clippings regardless of mowing and irrigation treatment. Post‐application irrigation treatment influenced fungicide movement; however, >50% of fungicide remained restricted to the RAV for the first 3 DAT. Less fungicide remained restricted to the RAV, and more fungicide was detected in deeper soil depths when plots were irrigated immediately after application. Fungicide was only detected at the 5.1‐to‐7.6‐cm depth when plots were irrigated immediately. Applying post‐application irrigation immediately may result in more fungicide moving down to soilborne targets. Irrigating 6 h after application facilitated moderate fungicide movement compared with irrigating immediately but was better than no post‐application irrigation.}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Stephens, Cameron M. and Kerns, James P. and Ahmed, Khalied A. and Gannon, Travis W.}, year={2021}, month={Jun} }
 @article{mcknight_gannon_yelverton_2021, title={Phytoremediation of azoxystrobin and imidacloprid by wetland plant species Juncus effusus, Pontederia cordata and Sagittaria latifolia}, volume={6}, ISSN={["1549-7879"]}, DOI={10.1080/15226514.2021.1932726}, abstractNote={Abstract Azoxystrobin (strobilurin fungicide) and imidacloprid (neonicotinoid insecticide) have been detected in surface waters near treated agricultural, urban, and mixed landscapes. The hazards of pesticide runoff can be prevented through best management practices, including the establishment of diverse wetland plant barriers that can phytoremediate the chemicals in which they come into contact with. In this study, the wetland plant species softrush (Juncus effusus), pickerelweed (Pontederia cordata), and arrowhead (Sagittaria latifolia) were planted in sandy soil containers that were then placed in azoxystrobin or imidacloprid treated water. Every week for 2 months, water samples were collected for pesticide residue analysis using high-performance liquid chromatography (HPLC). At 14, 28, and 56 days after initiation, plants were destructively harvested and analyzed for pesticide residue in soil, above-ground vegetation, and below-ground vegetation. Results from this study report P. cordata reduced greater azoxystrobin (51.7% reduction compared to treated non-planted containers) compared to J. effusus and S. latifolia (24.9% and 28.7% reduction from non-planted containers) at 56 days. However, S. latifolia reduced greater imidacloprid (79.3% reduction compared to non-planted containers) compared to J. effusus and P. cordata (36.0% and 37.1% reduction from non-planted containers) at 56 days. Novelty statement: While research has found that wetland plants can absorb and remediate synthetic chemicals, this practice is only sustainable if used with native plants that require low maintenance and are tolerant to the applied substances. Various previous studies observe plants that are fast-growing, tolerant to environmental conditions, require low-maintenance, and are hardy. However, these plant species are not always suitable for any location and are often considered invasive and/or weed-like. The present research initiates a list of plant species which can be used within the southeastern United States and similar areas to phytoremediate commonly used pesticides azoxystrobin and imidacloprid and prevent off-target movement into sensitive water systems.}, journal={INTERNATIONAL JOURNAL OF PHYTOREMEDIATION}, author={McKnight, Alayne M. and Gannon, Travis W. and Yelverton, Fred}, year={2021}, month={Jun} }
 @article{mcknight_gannon_yelverton_2021, title={Phytoremediation potential of three terrestrial plant species for removal of atrazine, azoxystrobin, and imidacloprid}, volume={6}, ISSN={["1549-7879"]}, DOI={10.1080/15226514.2021.1932724}, abstractNote={Abstract Pesticides can move off-target resulting in contamination of sensitive water bodies and causing adverse effects on inhabiting species. Through best management practices, such as the implementation of vegetative buffer strips, off-target movement of pesticides can be decreased, and compound degradation can be increased via phytoremediation. In this study, blueflag iris (Iris versicolor), broomsedge (Andropogon virginicus) and switchgrass (Panicum virgatum) were planted in soil treated with one of three commonly used pesticides. At 28, 56 and 112 days after treatment (DAT), plants were destructively harvested and analyzed for pesticide residue in soil and above-ground and below-ground vegetation using high-performance liquid chromatography (HPLC). Relative to the amount of pesticide found in planted pots compared to non-planted pots, I. versicolor was found to reduce greater atrazine in soil compared to non-planted pots at 112 DAT by 58.7%. I. versicolor was also the most capable of reducing azoxystrobin, by 86.9% compared to non-planted pots, from the soil at 112 DAT. At the same sampling time, I. versicolor and P. virgatum reduced greater imidacloprid from soil by 62.5% and 64.3% compared to non-planted pots, respectively. This information supports the recommendation for establishment of diverse plant species for optimization of phytoremediation capacities. Novelty statement While research has found that plants can absorb and remediate synthetic chemicals, this practice is only sustainable if used with native plants that require low maintenance and are tolerant to the applied substances. Various previous studies observe plants that are fast-growing, tolerant to environmental conditions, require low-maintenance, and are hardy. However, these plant species are not always suitable for any location and are often considered invasive and/or weed-like. The present research initiates a list of plant species which can be used within the southeastern United States and similar areas to phytoremediate commonly used pesticides atrazine, azoxystrobin, and imidacloprid and prevent off-target movement.}, journal={INTERNATIONAL JOURNAL OF PHYTOREMEDIATION}, author={McKnight, Alayne M. and Gannon, Travis W. and Yelverton, Fred}, year={2021}, month={Jun} }
 @article{maxwell_gannon_2021, title={Post-application irrigation timing affects dislodgeable azoxystrobin foliar residue}, volume={5}, ISSN={["2374-3832"]}, DOI={10.1002/cft2.20098}, abstractNote={AbstractAzoxystrobin is a systemic broad‐spectrum fungicide used extensively in turfgrass. Previous research has shown post‐application irrigation can reduce dislodgeable pesticide residues from turf; however, this management practice has not been evaluated to determine its effect on dislodgeable azoxystrobin residue or if altering post‐application irrigation timing (PAIT) can influence dislodgeable azoxystrobin. Field research was completed to assess the effect of PAIT, sample collection timing within a day and over days on dislodgeable azoxystrobin residue from perennial ryegrass (Lolium perenne L.). Research was completed in Raleigh, NC, to quantify dislodgeable azoxystrobin (0.54 lb a.i. acre–1) from perennial ryegrass foliage prior to and following PAIT (0.25 inch H2O) immediate, 4, or 144 hours after treatment (HAT). Sample collections occurred 1, 2, 3, 6, 12 or 24 days after treatment (DAT) at 7:00 a.m. or 2:00 p.m. EST. From 1 to 6 DAT, treatments irrigated immediately reduced dislodgeable azoxystrobin foliar residue (<0.1–6.8% of applied) more than those irrigated 4 HAT (0.4–10.3%); which were both less than withholding irrigation 144 HAT (1.3–15.5%). Across PAIT more azoxystrobin was dislodged in the morning (1.0–12.7% of applied) compared to the afternoon (0.2–9.0%) from 1 through 6 DAT. This research will enhance turfgrass management practices intended to limit human pesticide exposure and provide information pertaining to azoxystrobin dissipation kinetics in turfgrass systems.}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Maxwell, Patrick J. and Gannon, Travis W.}, year={2021}, month={May} }
 @article{camacho_heitman_gannon_amoozegar_leon_2021, title={Seed germination responses to soil hydraulic conductivity and polyethylene glycol (PEG) osmotic solutions}, volume={462}, ISSN={["1573-5036"]}, url={https://doi.org/10.1007/s11104-021-04857-5}, DOI={10.1007/s11104-021-04857-5}, number={1-2}, journal={PLANT AND SOIL}, author={Camacho, Manuel E. and Heitman, Joshua L. and Gannon, Travis W. and Amoozegar, Aziz and Leon, Ramon G.}, year={2021}, month={May}, pages={175–188} }
 @article{besançon_dayan_gannon_everman_2020, title={Conservation and divergence in sorgoleone production of sorghum species}, volume={49}, url={https://doi.org/10.1002/jeq2.20038}, DOI={10.1002/jeq2.20038}, abstractNote={AbstractSorgoleone‐358 is an important allelochemical of the oily droplets exuded from root hairs of various species in the Sorghum genus. Due to its hydrophobic nature, sorgoleone‐358 can be strongly adsorbed onto soil organic matter, resulting in increased sorgoleone soil persistence. Because of the herbicidal activity of sorgoleone on many small‐seeded weeds, concerns have been raised that sorghum residues may have a detrimental effect on emergence of wheat used as a double crop in the southeastern United States. Laboratory experiments were conducted to evaluate root exudate production and its sorgoleone‐358 content for 36 cultivated sorghum cultivars as well as eight shattercane [Sorghum bicolor (L.) Moench ssp. arundinaceum (Desv.) de Wet & Harlan] accessions and one johnsongrass [S. halepense (L.) Pers.] accession. Using a capillary growing mat system, root exudate was extracted with dichloromethane and subjected to chromatography analysis to determine sorgoleone‐358 content. Root biomass of 7‐ to 12‐d‐old seedlings averaged 18.8 mg g−1 seed, and root exudate production ranged from 0.2 and 4.8 mg g−1 root fresh weight (RFW). The amount of sorgoleone produced varied greatly among sorghum accessions. Sorgoleone‐358 amount in the root exudate averaged 0.5 mg g−1 RFW and varied from 0.13 to 1.05 mg g−1 for shattercane cultivar S7 and cultivated sorghum cultivar 992123, respectively. Regarding volume of root biomass, sorgoleone‐358 levels averaged 0.49 mg g−1 (range, 0.06–1.46 mg g−1) for sorghum cultivar AAS3479 and shattercane cultivar S2, respectively. Segregation of commercial sorghum cultivars according to their maturity group did not show any difference in root biomass and dry extract production, but early‐maturing cultivars produced on average 18% less sorgoleone‐358 compared with medium‐ and late‐maturing cultivars. These results suggest that sorgoleone production may be genetically constitutive because sorghum growing conditions were identical across cultivars.}, number={2}, journal={Journal of Environmental Quality}, publisher={Wiley}, author={Besançon, Thierry E. and Dayan, Franck E. and Gannon, Travis W. and Everman, Wesley J.}, year={2020}, month={Mar}, pages={368–377} }
 @article{inman_vann_fisher_gannon_jordan_jennings_2021, title={Evaluation of dicamba retention in spray tanks and its impact on flue-cured tobacco}, volume={35}, ISSN={["1550-2740"]}, url={http://dx.doi.org/10.1017/wet.2020.73}, DOI={10.1017/wet.2020.73}, abstractNote={AbstractIn recent years, there has been increased use of dicamba due to the introduction of dicamba-resistant cotton and soybean in the United States. Therefore, there is a potential increase in off-target movement of dicamba and injury to sensitive crops. Flue-cured tobacco is extremely sensitive to auxin herbicides, particularly dicamba. In addition to yield loss, residue from drift or equipment contamination can have severe repercussions for the marketability of the crop. Studies were conducted in 2016, 2017, and 2018 in North Carolina to evaluate spray-tank cleanout efficiency of dicamba using various cleaning procedures. No difference in dicamba recovery was observed regardless of dicamba formulation and cleaning agent. Dicamba residue decreased with the number of rinses. There was no difference in dicamba residue recovered from the third rinse compared with residue from the tank after being refilled for subsequent tank use. Recovery ranged from 2% to 19% of the original concentration rate among the three rinses. Field studies were also conducted in 2018 to evaluate flue-cured tobacco response to reduced rates of dicamba ranging, from 1/5 to 1/10,000 of a labeled rate. Injury and yield reductions varied by environment and application timing. When exposed to 1/500 of a labeled rate at 7 and 11 wk after transplanting, tobacco injury ranged from 39% to 53% and 10% to 16% 24 days after application, respectively. The maximum yield reduction was 62%, with a 55% reduction in value when exposed to 112 g ha−1 of dicamba. Correlations showed significant relationships between crop injury assessment and yield and value reductions, with Pearson values ranging from 0.24 to 0.63. These data can provide guidance to growers and stakeholders and emphasize the need for diligent stewardship when using dicamba technology.}, number={1}, journal={WEED TECHNOLOGY}, publisher={Cambridge University Press (CUP)}, author={Inman, Matthew D. and Vann, Matthew C. and Fisher, Loren R. and Gannon, Travis W. and Jordan, David L. and Jennings, Katie M.}, year={2021}, month={Feb}, pages={35–42} }
 @article{maxwell_gannon_2021, title={Formulation, application timing, and postapplication irrigation timing affect dislodgeable azoxystrobin from turfgrass}, volume={113}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.20560}, abstractNote={AbstractAzoxystrobin is a broad‐spectrum strobilurin fungicide used widely in turfgrass systems, including lawns. Previous research has shown that various management practices influence pesticide dislodgement from turfgrass; however, limited research has been performed to determine their effect on azoxystrobin dislodge. A field experiment was conducted in Raleigh, NC, to quantify dislodgeable azoxystrobin (0.61 kg ai ha−1) foliar residue from tall fescue [Lolium arundinaceum (Schreb.) S.J. Darbyshire] across formulations (sprayable or granular), application timings (AM [0700 h Eastern Standard Time] or PM [1400 h Eastern Standard Time]), and postapplication irrigation timings (4 or 48 h after treatment [HAT]). Sample collection occurred 1, 2, 3, 4, 8, or 16 d after treatment (DAT). Evaluated management practices affected dislodgeable azoxystrobin, most notably from 1 to 4 DAT. Sprayable azoxystrobin applied in the PM resulted in greater azoxystrobin dislodged (1.0–8.0% of applied) compared with AM (0.3–5.5%), which were both greater than granular azoxystrobin applied in the AM or PM (<0.1–2.8%) from 1 to 4 DAT. Within sprayable azoxystrobin, five times greater azoxystrobin was dislodged by delaying postapplication irrigation until 48 HAT (1.2–11.8% of applied) compared with irrigation 4 HAT (0.2–1.2%) from 1 to 4 DAT. Information from this study improves our understanding of factors affecting pesticide dislodge and can be incorporated into turfgrass management strategies to minimize potential human pesticide exposure.}, number={2}, journal={AGRONOMY JOURNAL}, author={Maxwell, P. J. and Gannon, T. W.}, year={2021}, month={Mar}, pages={1164–1171} }
 @article{hutchens_gannon_shew_kerns_2019, title={Effect of post-application irrigation on fungicide movement and efficacy against Magnaporthiopsis poae}, volume={122}, ISSN={["1873-6904"]}, DOI={10.1016/j.cropro.2019.04.027}, abstractNote={Management of many crown and root diseases of turfgrasses includes the use of fungicides. The physicochemical properties of the fungicides used vary greatly, but most have low mobility and are not phloem mobile, which results in little active ingredient present in the basal and underground structures of turfgrass plants. Two studies were conducted in a laboratory setting to determine the effects of post-application irrigation amounts (0, 0.3, 0.6, 1.3, and 2.5 cm) on the distribution of 14C myclobutanil and 14C tebuconazole in a soil profile of 90% sand and 10% peat moss by volume. In addition, growth chamber experiments were conducted to examine the effect of post-application irrigation amount on azoxystrobin efficacy against summer patch (Magnaporthiopsis poae) in ‘Penn A-4’ creeping bentgrass (Agrostis stolonifera L.). The creeping bentgrass was treated with azoxystrobin and immediately irrigated with 0, 0.25, 0.3, or 0.6 cm of irrigation. Lastly, an in vitro fungicide sensitivity assay was conducted on three M. poae isolates to determine their sensitivities to two succinate dehydrogenase inhibitors (SDHIs), three demethylation inhibitors (DMIs), and four strobilurins (QoIs) to determine if fungicide concentrations in the soil profile reached levels high enough to suppress fungal growth. In both 14C experiments, more than 54% of the 14C was retained in the top 5 cm of soil for all irrigation treatments. For the 14C myclobutanil experiment, lysimeters treated with 2.5 cm of post-application irrigation resulted in 3.9% of 14C recovered in the 7.6–10.2 cm sampling depth, which was higher than all other irrigation treatments. Post-application irrigation at 2.5 cm in the 14C tebuconazole experiment yielded 6.3% of the 14C at the 7.6–10.2 cm sampling depth and 2.3% at the 10.2–12.7 cm sampling depth—recoveries at both depths were higher with 2.5 cm of irrigation than all other irrigation treatments. No 14C was detected below 12.7 cm for either experiment. Less disease was observed when azoxystrobin received post-application irrigation. Both 0.25 and 0.3 cm of post-application irrigation increased turf quality compared to no irrigation; moreover, 0.25 and 0.6 cm of post-application irrigation increased root length compared to no irrigation. In the in vitro fungicide sensitivity assay, isolates of M. poae were sensitive to all fungicides with only minor sensitivity to the SDHIs. In general, isolates were most sensitive to the QoIs with some variability in isolate sensitivities noted. Isolates of M. poae are sensitive to commonly used fungicides and efficacy is enhanced by post-application irrigation due to improved fungicide distribution into the soil profile.}, journal={CROP PROTECTION}, author={Hutchens, W. J. and Gannon, T. W. and Shew, H. D. and Kerns, J. P.}, year={2019}, month={Aug}, pages={106–111} }
 @misc{ou_gannon_arellano_polizzotto_2018, title={A Global Meta-Analysis to Predict Atrazine Sorption from Soil Properties}, volume={47}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2017.11.0429}, abstractNote={Atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine) is one of the most widely used herbicides worldwide, and groundwater contamination is of concern, especially in heavily used regions and in edaphic conditions prone to leaching. Soil sorption plays an essential role in atrazine environmental fate, yet consistent atrazine risk prediction remains limited. A quantitative meta‐analysis was conducted to characterize the effect of soil properties on atrazine sorption, using 378 previous observations in 48 publications from 1985 to 2015 globally, which included data on soil properties and sorption parameters. A supplemental regional study was conducted to test the derived meta‐analysis models. The meta‐analysis indicated that percentage organic C (OC) was the most important parameter for estimating atrazine sorption, followed by percentage silt, soil pH, and percentage clay. Meta‐analysis and supplemental study models were developed for Freundlich sorption coefficients (Kf) and sorption distribution coefficients (Kd) as a function of OC. The global meta‐analysis models generated positive linear trends for OC with Kf and Kd (R2 = 0.197 and 0.205, respectively). Organic C was highly correlated with Kf and Kd in supplemental experimental study models (R2 = 0.93 and 0.92, respectively), indicating accurate prediction of sorption within the evaluated region. Continental models were investigated, which improved the goodness of fit. Models developed via meta‐analysis may be used to predict atrazine sorption over wide ranges of data, whereas more accurate and refined prediction can be achieved by specific regional models through experimental studies. However, such models could be improved if standardized agroclimatic conditions, soil classification, and other key variables were more widely reported.Core Ideas
Meta‐analysis quantified soil properties governing atrazine sorption.
Organic C content had the highest correlation with atrazine soil sorption.
Meta‐analysis models showed similar trends to independent experimental results.
Continental and supplemental models improved fit compared with global models.
Standard climate and soil taxonomic data should be reported to optimize models.
}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Ou, Ling and Gannon, Travis W. and Arellano, Consuelo and Polizzotto, Matthew L.}, year={2018}, pages={1389–1399} }
 @article{maxwell_gannon_cooper_2018, title={Nonionic Surfactant Affects Dislodgeable 2,4-D Foliar Residue from Turfgrass}, volume={32}, ISSN={["1550-2740"]}, DOI={10.1017/wet.2018.47}, abstractNote={Abstract2,4-dimethylamine salt (2,4-D) is a synthetic auxin herbicide used extensively in turfgrass for selective broadleaf weed control. Previous research has shown that 2,4-D can dislodge from treated turf, notably in the presence of canopy moisture. Practitioners commonly apply 2,4-D in combination with various commercially available surfactants to increase efficacy. Field research was completed to evaluate the effect of surfactant inclusion and sample collection time within a day on dislodgeable 2,4-D residue from perennial ryegrass. Research was initiated May 24, 2016 in Raleigh, NC and repeated in time to quantify dislodgeable 2,4-D following application (2.1 kg ae ha–1) either alone or with a nonionic surfactant (0.5% vol/vol). Sample collection occurred 1, 2, 3, 6, 12 or 24 d after treatment (DAT) at AM [7:00 AM Eastern Standard Time (EST)] and PM (2:00 PM EST) sample timings within a day. 2,4-D applied with surfactant (0.4% to 25.4% of applied) reduced dislodgeable foliar residue compared to 2,4-D applied alone (0.5% to 31.2%) from 1 through 6 DAT, whereas dislodgeable 2,4-D was not detected at 12 and 24 DAT. Regardless of surfactant inclusion or absence, samples collected in the AM resulted in a 5- to 10-fold increase in dislodgeable 2,4-D compared to samples collected in the PM from 1 through 6 DAT, suggesting that 2,4-D dislodgeability may be influenced by conditions favoring canopy moisture development. This research will improve turfgrass management practices and research designed to minimize human 2,4-D exposure.}, number={5}, journal={WEED TECHNOLOGY}, author={Maxwell, Patrick J. and Gannon, Travis W. and Cooper, Richard J.}, year={2018}, month={Oct}, pages={557–563} }
 @article{jeffries_gannon_reynolds_yelverton_silcox_2017, title={Herbicide Applications and Incorporation Methods Affect Dazomet Efficacy on Bermudagrass}, volume={27}, ISSN={["1943-7714"]}, DOI={10.21273/horttech03564-16}, abstractNote={Turfgrass renovations commonly involve changing cultivars or species that are better suited for a given setting. Common bermudagrass [Cynodon dactylon (L.) Pers.] is a perennial turfgrass that is difficult to eradicate before renovations, and poses contaminant concerns for the subsequent stand. Dazomet is a granular soil fumigant that has activity on various pests, including common bermudagrass. Field research was conducted from 2015 to 2016 in Raleigh, NC and College Station, TX to evaluate dazomet treatments including various combinations of soil incorporation (irrigation- or tillage-incorporated) and sealing (tarp or no tarp) methods, application rates [291, 291 followed by (fb) 291, 468, or 583 kg·ha−1], and fluazifop-P [fluazifop (0.4 kg·ha−1)] + glyphosate (2.8 kg·ha−1 acid equivalent) application(s) for established common bermudagrass control. Overall, treatments required fluazifop + glyphosate before dazomet application for acceptable control (>90% cover reduction) at 42 and 46 weeks after initial treatment (WAIT) in Texas and North Carolina, respectively. Soil-incorporation results varied by location, with dazomet application (583 kg·ha−1) fb tillage resulting in ≥88% cover reduction across locations, while acceptable control from irrigation incorporation was only observed in North Carolina. Tarping did not improve efficacy when tillage incorporation at the maximum label application rate provided acceptable control, suggesting practitioners may eliminate this procedure. Information from this research will aid turfgrass managers in developing cost-effective, ecologically sound common bermudagrass eradication programs before renovations.}, number={1}, journal={HORTTECHNOLOGY}, author={Jeffries, Matthew D. and Gannon, Travis W. and Reynolds, W. Casey and Yelverton, Fred H. and Silcox, Charles A.}, year={2017}, month={Feb}, pages={24–29} }
 @article{ou_gannon_polizzotto_2017, title={Impact of soil organic carbon on monosodium methyl arsenate (MSMA) sorption and species transformation}, volume={186}, ISSN={["1879-1298"]}, DOI={10.1016/j.chemosphere.2017.07.147}, abstractNote={Monosodium methyl arsenate (MSMA), a common arsenical herbicide, is a major contributor of anthropogenic arsenic (As) to the environment. Uncertainty about controls on MSMA fate and the rates and products of MSMA species transformation limits effective MSMA regulation and management. The main objectives of this research were to quantify the kinetics and mechanistic drivers of MSMA species transformation and removal from solution by soil. Laboratory MSMA incubation studies with two soils and varying soil organic carbon (SOC) levels were conducted. Arsenic removal from solution was more extensive and faster in sandy clay loam incubations than sand incubations, but for both systems, As removal was biphasic, with initially fast removal governed by sorption, followed by slower As removal limited by species transformation. Dimethylarsinic acid was the dominant product of species transformation at first, but inorganic As(V) was the ultimate transformation product by experiment ends. SOC decreased As removal and enhanced As species transformation, and SOC content had linear relationships with As removal rates (R2 = 0.59–0.95) for each soil and reaction phase. These results reveal the importance of edaphic conditions on inorganic As production and overall mobility of As following MSMA use, and such information should be considered in MSMA management and regulatory decisions.}, journal={CHEMOSPHERE}, author={Ou, Ling and Gannon, Travis W. and Polizzotto, Matthew L.}, year={2017}, month={Nov}, pages={243–250} }
 @article{jeffries_gannon_maxwell_2017, title={Protocols for Quantifying Transferable Pesticide Residues in Turfgrass Systems}, ISSN={["1940-087X"]}, DOI={10.3791/55182}, abstractNote={Plant canopies in established turfgrass systems can intercept an appreciable amount of sprayed pesticides, which can be transferred through various routes onto humans. For this reason, transferable pesticide residue experiments are required for registration and re-registration by the United States Environmental Protection Agency (USEPA). Although such experiments are required, limited specificity is required pertaining to experimental approach. Experimental approaches used to assess pesticide transfer to humans including hand wiping with cotton gloves, modified California roller (moving a roller of known mass over cotton cloth) and soccer ball roll (ball wrapped with sorbent strip) over three treated turfgrass species (creeping bentgrass, hybrid bermudagrass and tall fescue maintained at 0.4, 5 and 9 cm, respectively) are presented. The modified California roller is the most extensively utilized approach to date, and is best suited for use at low mowing heights due to its reproducibility and large sampling area. The soccer ball roll is a less aggressive transfer approach; however, it mimics a very common occurrence in the most popular international sport, and has many implications for nondietary pesticide exposure from hand-to-mouth contact. Additionally, this approach may be adjusted for other athletic activities with limited modification. Hand wiping is the best approach to transfer pesticides at higher mowing heights, as roller-based approaches can lay blades over; however, it is more subjective due to more variable sampling pressure. Utility of these methods across turfgrass species is presented, and additional considerations to conduct transferable pesticide residue research in turfgrass systems are discussed.}, number={121}, journal={JOVE-JOURNAL OF VISUALIZED EXPERIMENTS}, author={Jeffries, Matthew D. and Gannon, Travis W. and Maxwell, Patrick J.}, year={2017}, month={Mar} }
 @article{jeffries_gannon_brosnan_breeden_2017, title={Sprayer Setup Affects Dislodgeable 2,4-D Foliar Residue in Hybrid Bermudagrass Athletic Fields}, volume={31}, ISSN={["1550-2740"]}, DOI={10.1017/wet.2016.22}, abstractNote={2,4-dimethylamine salt (2,4-D) is a selective broadleaf herbicide commonly applied to turfgrass systems, including athletic fields, which can dislodge from treated vegetation. Building on previous research confirming 2,4-D dislodgeability is affected by management inputs, field research was initiated in 2014 and 2015 in North Carolina and Tennessee to quantify the effects of sprayer setup on dislodgeable 2,4-D foliar residue from hybrid bermudagrass, which is the most common athletic field playing surface in subtropical and tropical climates. More specifically, research evaluated dislodgeable 2,4-D foliar residue following spray applications (2.1 kg ae ha−1) at varying carrier volumes (187, 374, or 748 L ha−1) and nozzles delivering varying droplet sizes (fine=extended range [XR], coarse=drift guard, or extra coarse=air induction extended range [AIXR]). Overall, data suggest minimal 2,4-D dislodge occurs via soccer ball roll (3.6 m) outside the day of application; however, increasing carrier volume and droplet size can further decrease dislodgeable 2,4-D foliar residue. At 2 d after treatment (DAT), 3.87% of applied 2,4-D dislodged when applied at 187 L ha−1compared to 2.05% at 748 L ha−1. Pooled over data from 1 to 6 DAT, 1.59% of applied 2,4-D dislodged following XR nozzle application compared to 1.13% with AIXR nozzle. While these are small numerical differences, dislodgeable residue was measured via one soccer ball roll, which is a repeated process within the sport and the additive effect of sprayer setup treatments can be employed by turfgrass managers to reduce potential human 2,4-D human exposure.}, number={2}, journal={WEED TECHNOLOGY}, author={Jeffries, Matthew D. and Gannon, Travis W. and Brosnan, James T. and Breeden, Gregory K.}, year={2017}, pages={269–278} }
 @article{jeffries_gannon_yelverton_2017, title={Zoysiagrass Sod Establishment along Guardrails: Evaluation of Cultivars, Soil Preparation Techniques, and Planting Timings}, volume={57}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2016.09.0740}, abstractNote={Appropriately designed and installed guardrails are structures that enhance motorist safety; however, their inherent design requires additional vegetation management inputs to maintain safe, acceptable driving conditions. Establishing low‐growing, perennial vegetation under guardrails may reduce long‐term management inputs. Field research was initiated 17 Dec. 2012 and 3 Dec. 2013 along guardrails in Chatham, Lee, and Yadkin Counties, NC, to evaluate the effect of establishment timing (December, March, April, or May) and soil preparation technique (tillage alone, tillage + bed preparation, or vegetation strip) on ‘El Toro’ (Zoysia japonica Steud.) and ‘Zeon’ [Zoysia matrella (L.) Merr.] zoysiagrass sod establishment and spread along guardrails. Sod establishment in year 1 was successful (>60% cover) across cultivars, locations, and techniques at December and March timings, with cover ranging from 64 to 90% at 90 wk after initial establishment. April and May timings resulted in inconsistent establishment success and are not recommended for North Carolina. Year 2 sodding generally resulted in unsuccessful establishment, which may be due in part to colder winter and dryer spring–summer conditions compared with year 1. Overall, El Toro sod more readily established and spread than Zeon, suggesting that it is a better species for establishment along guardrails. Tillage alone resulted in equivalent or greater sod establishment and spread than tillage + bed preparation and vegetation stripping, and it also requires fewer equipment and personnel inputs. Results suggest that El Toro sod planted in March following soil tillage is the most promising practice for establishment along North Carolina guardrails; however, water inputs may be required during moisture‐deficient periods following planting.}, number={2}, journal={CROP SCIENCE}, author={Jeffries, Matthew D. and Gannon, Travis W. and Yelverton, Fred H.}, year={2017}, pages={993–1000} }
 @article{jeffries_gannon_brosnan_breeden_2016, title={Comparing Dislodgeable 2,4-D Residues across Athletic Field Turfgrass Species and Time}, volume={11}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0168086}, abstractNote={2,4-dimethylamine salt (2,4-D) is an herbicide commonly applied on athletic fields for broadleaf weed control that can dislodge from treated turfgrass. Dislodge potential is affected by numerous factors, including turfgrass canopy conditions. Building on previous research confirming herbicide-turfgrass dynamics can vary widely between species, field research was initiated in 2014 and 2015 in Raleigh, NC, USA to quantify dislodgeable 2,4-D residues from dormant hybrid bermudagrass (Cynodon dactylon L. x C. transvaalensis) and hybrid bermudagrass overseeded with perennial ryegrass (Lolium perenne L.), which are common athletic field playing surfaces in subtropical climates. Additionally, dislodgeable 2,4-D was compared at AM (7:00 eastern standard time) and PM (14:00) sample timings within a day. Samples collected from perennial ryegrass consistently resulted in greater 2,4-D dislodgment immediately after application (9.4 to 9.9% of applied) compared to dormant hybrid bermudagrass (2.3 to 2.9%), as well as at all AM compared to PM timings from 1 to 3 d after treatment (DAT; 0.4 to 6.3% compared to 0.1 to 0.8%). Dislodgeable 2,4-D did not differ across turfgrass species at PM sample collections, with ≤ 0.1% of the 2,4-D applied dislodged from 1 to 6 DAT, and 2,4-D detection did not occur at 12 and 24 DAT. In conclusion, dislodgeable 2,4-D from treated turfgrass can vary between species and over short time-scales within a day. This information should be taken into account in human exposure risk assessments, as well as by turfgrass managers and athletic field event coordinators to minimize 2,4-D exposure.}, number={12}, journal={PLOS ONE}, author={Jeffries, Matthew D. and Gannon, Travis W. and Brosnan, James T. and Breeden, Gregory K.}, year={2016}, month={Dec} }
 @article{jeffries_gannon_ou_2016, title={Effect of Indaziflam Applications on 'Tifway 419' Bermudagrass Growth}, volume={108}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2015.0352}, abstractNote={Indaziflam {N‐[(1R,S)‐2,3‐dihyrdo‐2,6‐dimethyl‐1H‐inden‐1‐yl]‐6‐(1‐fluorethyl)1,3,5‐triazine‐2,4‐diamine} is a preemergence herbicide for annual weed control in turfgrass systems. Following indaziflam U.S. registration in 2010, sporadic cases of hybrid bermudagrass (HB) injury were reported. Field research was conducted from 2012 to 2014 evaluating indaziflam application rates [16 followed by 16 (28 d), 33, 49, or 65 g a.i. ha−1] and timings (fall‐only, fall‐plus‐spring, or spring‐only) in two environments (reduced sunlight [RS] and full sunlight [FS]) to elucidate their effect on HB growth. In Year 1, differences were not detected, while in Year 2 HB cover varied between environments. In Year 2, HB cover in the RS environment treated with 49 and 65 g ha−1 had 36 and 64% less visual cover 12 wk after initial spring treatment than the FS environment, respectively. Within the RS environment, indaziflam also reduced HB visual cover compared to the nontreated (77% cover). A bioassay study conducted with soil cores collected from field plots suggested HB cover reduction was minimally affected by indaziflam‐soil bioavailability, as perennial ryegrass biomass was not reduced beyond a 2.5‐cm depth. Weather conditions varied between years, with air temperatures ≤0°C occurring more frequently and to a greater magnitude in Year 2. The weather, coupled with reduced solar radiation in the RS environment may have contributed to HB cover reduction in Year 2. Overall, indaziflam applications to established HB in areas with suitable growth conditions were safe; however, unacceptable HB cover reductions were observed in areas with poor growth conditions.

Indaziflam is safe on established bermudagrass grown in appropriate conditions.
Bermudagrass‐indaziflam tolerance decreased when applied in a reduced sunlight setting.
Severe winter climatic conditions exacerbated bermudagrass‐indaziflam injury.

}, number={3}, journal={AGRONOMY JOURNAL}, author={Jeffries, Matthew D. and Gannon, Travis W. and Ou, Ling}, year={2016}, pages={950–956} }
 @article{jeffries_gannon_2016, title={Effect of Soil Organic Matter Content and Volumetric Water Content on 'Tifway 419' Hybrid Bermudagrass Growth Following Indaziflam Applications}, volume={30}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-15-00192.1}, abstractNote={Indaziflam is a cellulose biosynthesis–inhibiting herbicide for PRE annual weed control in turfgrass systems. Since indaziflam's 2010 U.S. registration, sporadic cases of hybrid bermudagrass injury have been reported; however, causes are not well understood. Field research was conducted from 2013 to 2015 on sandy soil to elucidate the effects of soil organic matter content (SOMC) and soil volumetric water content (SVWC) on plant growth following indaziflam application on established or root-compromised (5 cm long) hybrid bermudagrass. The effect of SOMC was evaluated at two levels, 1.4 (low) and 5.5% (high) w/w at the soil surface (0 to 2.5 cm depth), whereas SVWC was evaluated PRE (2 wk before) and POST (6 wk after) indaziflam application at two levels (low or high). Indaziflam was applied (50 or 100 g ai ha−1) at fall-only, fall-plus-spring, and spring-only timings. Regardless of application timing or SVWC, indaziflam applied at 50 g ha−1 to high SOMC did not cause > 10% visual cover reduction on established or root-compromised hybrid bermudagrass. Indaziflam applied to hybrid bermudagrass on low SOMC exacerbated adverse growth effects, most notably when root systems were compromised before application. Overall, PRE indaziflam application SVWC did not affect hybrid bermudagrass growth. Within low SOMC, low POST indaziflam application SVWC caused less visual hybrid bermudagrass cover reduction than did high POST indaziflam application SVWC, whereas both fall-plus-spring and spring-only application timings caused similarly greater reductions than fall-only indaziflam application. Data from this research will aid turfgrass managers to effectively use indaziflam without adversely affecting hybrid bermudagrass growth.}, number={3}, journal={WEED TECHNOLOGY}, author={Jeffries, Matthew D. and Gannon, Travis W.}, year={2016}, pages={677–687} }
 @article{jeffries_gannon_brosnan_ahmed_breeden_2016, title={Factors Influencing Dislodgeable 2, 4-D Plant Residues from Hybrid Bermudagrass (Cynodon dactylon L. x C. transvaalensis) Athletic Fields}, volume={11}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0148992}, abstractNote={Research to date has confirmed 2,4-D residues may dislodge from turfgrass; however, experiments have not been conducted on hybrid bermudagrass (Cynodon dactylon L. x C. transvaalensis), the most common athletic field turfgrass in subtropical climates. More specifically, previous research has not investigated the effect of post-application irrigation on dislodgeable 2,4-D residues from hybrid bermudagrass and across turfgrass species, research has been nondescript regarding sample time within a d (TWD) or conducted in the afternoon when the turfgrass canopy is dry, possibly underestimating potential for dislodgement. The effect of irrigation and TWD on 2,4-D dislodgeability was investigated. Dislodgeable 2,4-D amine was reduced > 300% following irrigation. From 2 to 7 d after treatment (DAT), ≤ 0.5% of applied 2,4-D was dislodged from irrigated turfgrass, while ≤ 2.3% of applied 2,4-D was dislodged when not irrigated. 2,4-D dislodgeability decreased as TWD increased. Dislodgeable 2,4-D residues declined to < 0.1% of the applied at 1 DAT– 13:00, and increased to 1 to 3% of the applied 2 DAT– 5:00, suggesting 2,4-D re-suspended on treated turfgrass vegetation overnight. In conclusion, irrigating treated turfgrass reduced dislodgeable 2,4-D. 2,4-D dislodgeability increased as TWD decreased, which was attributed to non-precipitation climatic conditions favoring turfgrass canopy wetness. This research will improve turfgrass management practices and research designed to minimize human 2,4-D exposure.}, number={2}, journal={PLOS ONE}, author={Jeffries, Matthew D. and Gannon, Travis W. and Brosnan, James T. and Ahmed, Khalied A. and Breeden, Gregory K.}, year={2016}, month={Feb} }
 @article{jeffries_gannon_yelverton_2017, title={Herbicide Inputs and Mowing Affect Vaseygrass (Paspalum urvillei) Control}, volume={31}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-16-00072.1}, abstractNote={Vaseygrass is an invasive, perennial C4-grass commonly found on roadsides in areas with poorly drained soils. Due to its upright growth habit and seedhead production, vaseygrass can impair motorist sightlines and subsequently, require increased management inputs to maintain vegetation at an acceptable height. Two field experiments were conducted from 2012 to 2015 on North Carolina roadsides to evaluate the effect of mowing and mowing timing with respect to applications of various herbicides on vaseygrass control. Both experiments evaluated clethodim (280 g ai ha–1), foramsulfuron+halosulfuron+thiencarbazone-methyl (44+69+22 g ai ha−1), imazapic (140 g ai ha−1), metsulfuron+nicosulfuron (16+59 g ai ha−1), and sulfosulfuron (105 g ai ha−1) with a nonionic surfactant at 0.25% v/v. Experiment one focused on the effect of mowing (routinely mowed or nonmowed) and herbicide application timing (fall-only, fall-plus-spring, or spring-only), while experiment two focused on pre-herbicide application mowing intervals (6, 4, 3, 2, 1, or 0 wk before treatment [WBT]). From experiment one, routine mowing reduced vaseygrass cover in nontreated plots 55% at 52 wk after fall treatment (WAFT), suggesting this cultural practice should be employed where possible. Additionally, routine mowing and herbicide application season affected herbicide efficacy. Treatments providing >70% vaseygrass cover reduction at 52 WAFT included routinely mowed fall-only clethodim and fall-plus-spring imazapic, and fall-plus-spring metsulfuron+nicosulfuron across mowing regimens. Within clethodim, mowing vaseygrass 2 or 1 WBT resulted in the lowest cover at 40 (1 to 2%) and 52 (4 to 6%) wk after treatment (WAT) compared to other intervals, which aligns with current label vegetation height at treatment recommendation. Vaseygrass persisted across all treatments evaluated through 52 WAT, suggesting eradication of this species will require inputs over multiple growing seasons.}, number={1}, journal={WEED TECHNOLOGY}, author={Jeffries, Matthew D. and Gannon, Travis W. and Yelverton, Fred H.}, year={2017}, pages={120–129} }
 @article{gannon_jeffries_ahmed_2017, title={Irrigation and Soil Surfactants Affect Abamectin Distribution in Soil}, volume={57}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2016.05.0320}, abstractNote={Nematodes are microscopic, soil‐dwelling organisms that adversely affect many turfgrass systems, including golf course putting greens. Abamectin controls many nematode species in golf course putting greens; however, high sorption to accumulated organic matter near the soil surface in established turfgrass systems may limit its distribution in soil, thereby limiting its efficacy. Field research was conducted on ‘A1/A4’ creeping bentgrass and ‘Champion’ ultradwarf bermudagrass putting greens to evaluate abamectin distribution in soil following treatment regimens including abamectin application (37 g a.i. ha–1) alone, or tank‐mixed with soil surfactant (Revolution) in tandem with various irrigation timings to promote downward distribution. Laboratory research was also conducted to evaluate 14C‐abamectin soil distribution via treatments comprised of various combinations of simulated irrigation amounts and timings, as well as soil surfactant type (Dispatch or Qualibra) and timing with respect to abamectin application. Abamectin distributed similarly in soil across turfgrass species in field research. At 7 d after treatment (DAT), all irrigation–soil surfactant regimens increased abamectin distribution to the 0‐ to 2.5‐cm soil depth compared with broadcast spray alone; however, no evaluated regimen resulted in >2% of the applied abamectin movement beyond 2.5 cm. In laboratory experiments, 14C‐abamectin soil distribution was affected most by soil surfactant at 3 DAT, with Qualibra increasing distribution (8.2 to 18.4% of applied) to 7.5 cm depth compared with Dispatch or no surfactant. As in field research, irrigation amounts and timings generally affected 14C‐abamectin similarly. This research highlights practices to enhance distribution into the profile, thereby increasing bioavailability and efficacy.}, number={2}, journal={CROP SCIENCE}, author={Gannon, Travis W. and Jeffries, Matthew D. and Ahmed, Khalied A.}, year={2017}, pages={573–580} }
 @article{jeffries_yelverton_ahmed_gannon_2016, title={Persistence in and Release of 2,4-D and Azoxystrobin from Turfgrass Clippings}, volume={45}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2016.03.0081}, abstractNote={Research has shown that pesticide residue in clippings from previously treated turfgrass may become bioavailable as grass decomposes, adversely affecting off‐target organisms. We conducted a field study to quantify 2,4‐D (2,4‐dichlorophenoxyacetic acid) and azoxystrobin (methyl(E)‐2‐{2[6‐(2‐cyanophenoxy)pyrmidin‐4‐yloxy]phenyl}‐3‐methoxyacrylate) residues in turfgrass clippings collected from hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt–Davy], tall fescue [Lolium arundinaceum (Schreb.) S.J. Darbyshire], and zoysiagrass (Zoysia japonica Steud.). A subsequent greenhouse experiment was conducted to measure pesticide release from clippings into water. 2,4‐D (1.6 kg a.i. ha−1) and azoxystrobin (0.6 kg a.i. ha−1) were applied to field plots at 32, 16, 8, 4, 2, 1, or 0 d before collection of the clippings. Clippings were collected from each experimental unit to quantify pesticide release from clippings into water. Both 2,4‐D and azoxystrobin were detected when turfgrass was treated over the 32‐d experimental period, suggesting that clipping management should be implemented for an extended period of time after application. Pesticide residue was detected in all water samples collected, confirming 2,4‐D and azoxystrobin release from turfgrass clippings; however, pesticide release varied between compounds. Two days after clippings were incorporated in water, 39 and 10% of 2,4‐D and azoxystrobin were released from clippings, respectively. Our research supports the currently recommended practice of returning clippings to the turfgrass stand when mowing because removal of 2,4‐D and azoxystrobin in clippings may reduce pest control and cause adverse off‐target impacts.Core Ideas
2,4‐D and azoxystrobin residues were detected in clippings 32 d after treatment.
2,4‐D and azoxystrobin were released from turfgrass clippings into water.
Pesticide release from turfgrass clippings into water varied between compounds.
}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Jeffries, Matthew D. and Yelverton, Fred H. and Ahmed, Khalied A. and Gannon, Travis W.}, year={2016}, pages={2030–2037} }
 @article{jeffries_gannon_2016, title={Soil Organic Matter Content and Volumetric Water Content Affect Indaziflam-Soil Bioavailability}, volume={64}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-16-00039.1}, abstractNote={Indaziflam is a cellulose biosynthesis-inhibiting herbicide for annual weed control in various agricultural systems. Sporadic cases of unacceptable injury to desirable plants have been reported after indaziflam application, which may have been due to conditions favoring increased indaziflam–soil bioavailability. Research was conducted from 2013 to 2015 on a sandy soil to elucidate the effects of soil organic matter content (SOMC) and soil volumetric water content (SVWC) on indaziflam–soil bioavailability. Indaziflam was applied (50 or 100 g ha–1) at fall only, fall plus spring, and spring only timings to plots in a factorial arrangement of SOMC, pre–indaziflam application (PrIA) SVWC, and post–indaziflam application (PoIA) SVWC. After application, field soil cores were collected for a subsequent greenhouse bioassay experiment, where foliage mass reduction of perennial ryegrass seeded from 0 to 15 cm soil depth was used as an indicator of indaziflam–soil bioavailability throughout the profile. Significant edaphic effects were observed at 0 to 2.5, 2.5 to 5, and 5 to 7.5 cm depths, with increased bioavailability at low compared with high SOMC. Pre–indaziflam application SVWC did not affect bioavailability, whereas PoIA high SVWC increased indaziflam–soil bioavailability at 2.5 to 7.5 cm depth compared with PoIA low SVWC. Low SOMC–PoIA high SVWC decreased perennial ryegrass foliage mass 40 and 37% at 5 to 7.5 cm depth from cores collected 10 and 14 wk after treatment, respectively, whereas reductions from all other SOMC–PoIA SVWC combinations were < 12% and did not vary from each other. Pearson's correlation coefficients showed a moderate, positive relationship between perennial ryegrass mass reductions at 0 to 2.5, 2.5 to 5, 0 to 5, and 0 to 10 cm depths and hybrid bermudagrass cover reduction, which suggests conditions favoring increased indaziflam–soil bioavailability can adversely affect plant growth. Data from this research will aid land managers to use indaziflam effectively without adversely affecting growth of desirable species.}, number={4}, journal={WEED SCIENCE}, author={Jeffries, Matthew D. and Gannon, Travis W.}, year={2016}, pages={757–765} }
 @article{jeffries_gannon_yelverton_2017, title={Tall Fescue Roadside Right-of-Way Mowing Reduction from Imazapic}, volume={109}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2016.04.0246}, abstractNote={Core Ideas
Imazapic provided 100% tall fescue seedhead suppression through 56 d after treatment.
Imazapic reduced tall fescue mowing requirements by two cycles across 23‐ and 30‐cm intervention heights.
Imazapic application to tall fescue mown at 30‐cm intervention height required one mowing event through 70 d after treatment.
Tall fescue [Lolium arundinaceum (Schreb.) S.J. Darbyshire] is commonly established along roadside rights‐of‐way in adapted zones due to its tolerance of drought, heat, and wear; however, its upright growth habit coupled with seedhead production can impair motorist vision. Field research was conducted in 2013 and 2014 to quantify tall fescue mowing requirements following imazapic {(±)‐2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl]‐5‐methyl‐3‐pyridinecarboxylic acid}, an herbicide commonly used for plant growth regulation, application (53 g a.i. ha−1) alone, as well as tank‐mixed with clopyralid (3,6‐dichloro‐2‐pyridinecarboxylic acid) + triclopyr {[(3,5,6‐trichloro‐2‐pyridinyl)oxy]acetic acid} (158 + 473 g a.i. ha−1). Plots were mown at a 23‐ or 30‐cm foliage intervention height following treatment. Nontreated‐mown and nontreated‐nonmown controls were included for comparisons. Evaluated herbicide treatments caused 0 to 20% tall fescue injury, which recovered following mowing. Additionally, imazapic provided 100% tall fescue seedhead suppression through 56 days after treatment (DAT). Imazapic reduced tall fescue mowing requirements at both intervention heights through 70 DAT. Two mowing cycles were reduced across intervention heights in 2013, while three and two cycles were reduced at 23 and 30 cm heights, respectively, in 2014. Lastly, imazapic + clopyralid + triclopyr application increased tall fescue cover 84 DAT. This information will allow vegetation managers to more efficiently allocate resources to maintain clear motorist sightlines on tall fescue roadside rights‐of‐way.}, number={4}, journal={AGRONOMY JOURNAL}, author={Jeffries, Matthew D. and Gannon, Travis W. and Yelverton, Fred H.}, year={2017}, pages={1765–1770} }
 @article{mahoney_gannon_jeffries_polizzotto_2015, title={Arsenic Distribution and Speciation in a Managed Turfgrass System Following Monosodium Methylarsenate Application}, volume={55}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2015.03.0163}, abstractNote={ABSTRACTMonosodium methylarsenate (MSMA) is an organic arsenical herbicide commonly used in certain warm‐season turfgrasses. Recently, concerns about MSMA use have arisen because of the release of As into the environment, although the fate of applied As is not well quantified for realistic management scenarios. Greenhouse lysimeter experiments were conducted to determine As distribution and speciation over time following an MSMA application to established bermudagrass [Cynodon dactylon (L.) Pers.]. At 1 wk after treatment (WAT), up to 65% of As from MSMA was detected in bermudagrass clippings and the remaining aboveground vegetation. Elevated soil and porewater As concentrations were detected to 5 cm depth but increases were not observed below this depth. Mass balance calculations revealed that As partitioned into the soil over time, with 91% of the applied As residing in the upper 5 cm of soil solids by 8 WAT. Arsenate was the dominant As species by 2 WAT and thereafter in porewater and soil. Results indicate that turfgrass management plans could be altered to minimize potential off‐target contamination from MSMA by returning clippings following mowing events and using MSMA in a herbicide rotation.}, number={6}, journal={CROP SCIENCE}, author={Mahoney, Denis J. and Gannon, Travis W. and Jeffries, Matthew D. and Polizzotto, Matthew L.}, year={2015}, pages={2877–2885} }
 @article{gannon_jeffries_brosnan_breeden_tucker_henry_2015, title={Preemergence herbicide efficacy for crabgrass (Digitaria spp.) control in common bermudagrass managed under different mowing heights}, volume={50}, number={4}, journal={HortScience}, author={Gannon, T. W. and Jeffries, M. D. and Brosnan, J. T. and Breeden, G. K. and Tucker, K. A. and Henry, G. M.}, year={2015}, pages={546–550} }
 @article{gannon_jeffries_2014, title={Dislodgeable 2,4-D from athletic field turfgrass}, volume={79}, number={3}, journal={European Journal of Horticultural Science}, author={Gannon, T. W. and Jeffries, M. D.}, year={2014}, pages={116–122} }
 @article{jeffries_mahoney_gannon_2014, title={Effect of Simulated Indaziflam Drift Rates on Various Plant Species}, volume={28}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-14-00004.1}, abstractNote={Indaziflam is a PRE herbicide for control of annual grass and broadleaf weeds in numerous settings, including managed roadsides, railroads, and noncroplands. There is a need for new and improved PRE herbicides for herbaceous vegetation management along roadsides; however, off-target crop injury via spray drift is a concern because of the close proximity of roadside applications to the wide array of crops grown throughout the southeastern United States where indaziflam is used. Greenhouse research was conducted to evaluate the effect of PRE and POST simulated indaziflam spray drift rates on the growth of cotton, bell pepper, soybean, squash, tobacco, and tomato. Simulated indaziflam spray drift rates were 100, 20, 10, 5, or 2.5% of a 73 g ai ha−1 application rate, whereas other herbicide treatments included for comparative purposes were applied at 10% of a typical North Carolina roadside vegetation management application rate. These included sulfometuron (4 g ai ha−1), aminocyclopyrachlor + metsulfuron (11 + 3.5 g ai ha−1), clopyralid + triclopyr (21 + 63 g ai ha−1), or aminopyralid (12 g ai ha−1). In general, plant growth responses varied among herbicides and application timings. Across all evaluated parameters, indaziflam at the 10% simulated drift rate adversely effected plant growth similarly or less than all other herbicides when applied PRE (squash and tomato), POST (bell pepper and soybean), and PRE or POST (cotton and tobacco). No clear trends were observed regarding indaziflam application timing, as PRE squash and tomato, and POST bell pepper and soybean applications were safer than their respective alternative timing, and no significant differences were detected between timings on cotton or tobacco. Across application timings, plant susceptibility to indaziflam-simulated spray drift rates ranked cotton < tobacco < tomato < squash < pepper < soybean. Finally, it should be noted that the lowest simulated indaziflam drift rate (2.5%) caused greater than 20% root mass reduction on cotton (POST), bell pepper (PRE and POST), soybean (PRE and POST), squash (PRE), and tomato (POST). Although this research supports indaziflam use along roadsides, it still poses an off-target plant injury risk. Future research should evaluate techniques to minimize spray drift from roadside pesticide applications.}, number={4}, journal={WEED TECHNOLOGY}, author={Jeffries, Matthew D. and Mahoney, Denis J. and Gannon, Travis W.}, year={2014}, pages={608–616} }
 @article{matteson_mahoney_gannon_polizzotto_2014, title={Integrated Field Lysimetry and Porewater Sampling for Evaluation of Chemical Mobility in Soils and Established Vegetation}, ISSN={["1940-087X"]}, DOI={10.3791/51862}, abstractNote={Potentially toxic chemicals are routinely applied to land to meet growing demands on waste management and food production, but the fate of these chemicals is often not well understood. Here we demonstrate an integrated field lysimetry and porewater sampling method for evaluating the mobility of chemicals applied to soils and established vegetation. Lysimeters, open columns made of metal or plastic, are driven into bareground or vegetated soils. Porewater samplers, which are commercially available and use vacuum to collect percolating soil water, are installed at predetermined depths within the lysimeters. At prearranged times following chemical application to experimental plots, porewater is collected, and lysimeters, containing soil and vegetation, are exhumed. By analyzing chemical concentrations in the lysimeter soil, vegetation, and porewater, downward leaching rates, soil retention capacities, and plant uptake for the chemical of interest may be quantified. Because field lysimetry and porewater sampling are conducted under natural environmental conditions and with minimal soil disturbance, derived results project real-case scenarios and provide valuable information for chemical management. As chemicals are increasingly applied to land worldwide, the described techniques may be utilized to determine whether applied chemicals pose adverse effects to human health or the environment.}, number={89}, journal={JOVE-JOURNAL OF VISUALIZED EXPERIMENTS}, author={Matteson, Audrey R. and Mahoney, Denis J. and Gannon, Travis W. and Polizzotto, Matthew L.}, year={2014}, month={Jul} }
 @article{mahoney_gannon_jeffries_matteson_polizzotto_2015, title={Management considerations to minimize environmental impacts of arsenic following monosodium methylarsenate (MSMA) applications to turfgrass}, volume={150}, ISSN={["1095-8630"]}, DOI={10.1016/j.jenvman.2014.12.027}, abstractNote={Monosodium methylarsenate (MSMA) is an organic arsenical herbicide currently utilized in turfgrass and cotton systems. In recent years, concerns over adverse impacts of arsenic (As) from MSMA applications have emerged; however, little research has been conducted in controlled field experiments using typical management practices. To address this knowledge gap, a field lysimeter experiment was conducted during 2012-2013 to determine the fate of As following MSMA applications to a bareground and an established turfgrass system. Arsenic concentrations in soil, porewater, and aboveground vegetation, were measured through one yr after treatment. Aboveground vegetation As concentration was increased compared to nontreated through 120 d after initial treatment (DAIT). In both systems, increased soil As concentrations were observed at 0-4 cm at 30 and 120 DAIT and 0-8 cm at 60 and 365 DAIT, suggesting that As was bound in shallow soil depths. Porewater As concentrations in MSMA-treated lysimeters from a 30-cm depth (22.0-83.8 μg L(-1)) were greater than those at 76-cm depth (0.4-5.1 μg L(-1)). These results were combined with previous research to devise management considerations in systems where MSMA is utilized. MSMA should not be applied if rainfall is forecasted within 7 DAIT and/or in areas with shallow water tables. Further, disposing of MSMA-treated turfgrass aboveground vegetation in a confined area - a common management practice for turfgrass clippings - may be of concern due to As release to surface water or groundwater as the vegetation decomposes. Finally, long-term MSMA use may cause soil As accumulation and thus downward migration of As over time; therefore, MSMA should be used in rotation with other herbicides.}, journal={JOURNAL OF ENVIRONMENTAL MANAGEMENT}, author={Mahoney, Denis J. and Gannon, Travis W. and Jeffries, Matthew D. and Matteson, Audrey R. and Polizzotto, Matthew L.}, year={2015}, month={Mar}, pages={444–450} }
 @article{lewis_jeffries_gannon_richardson_yelverton_2014, title={Persistence and Bioavailability of Aminocyclopyrachlor and Clopyralid in Turfgrass Clippings: Recycling Clippings for Additional Weed Control}, volume={62}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-13-00119.1}, abstractNote={The synthetic auxin herbicides, aminocyclopyrachlor and clopyralid, control dicotyledonous weeds in turf. Clippings of turfgrass treated with synthetic auxin herbicides have injured off-target plants exposed to herbicide-laden clippings. Labels of aminocyclopyrachlor and clopyralid recommend that clippings of treated turfgrass remain on the turf following a mowing event. Alternative uses for synthetic auxin-treated turfgrass clippings are needed because large quantities of clippings on the turf surface interfere with the functionality and aesthetics of golf courses, athletic fields, and residential turf. A white clover bioassay was conducted to determine the persistence and bioavailability of aminocyclopyrachlor and clopyralid in turfgrass clippings. Aminocyclopyrachlor and clopyralid were each applied at 79 g ae ha−1 to mature tall fescue at 56, 28, 14, 7, 3.5, and 1.75 d before clipping collection (DBCC). Clippings were collected, and the treated clippings were recycled onto adjacent white clover plots to determine herbicidal persistence and potential for additional weed control. Clippings of tall fescue treated with aminocyclopyrachlor produced a nonlinear regression pattern of response on white clover. Calculated values for 50% response (GR50) for visual control, for normalized difference vegetative index (NDVI), and for reduction in harvested biomass were 20.5, 17.3, and 18.7 DBCC, respectively, 8 wk after clippings were applied. Clippings of tall fescue treated with clopyralid did not demonstrate a significant pattern for white clover control, presumably because clopyralid was applied at a less-than-label rate. The persistence and bioavailability of synthetic auxin herbicides in clippings harvested from previously treated turfgrass creates the opportunity to recycle clippings for additional weed control.}, number={3}, journal={WEED SCIENCE}, author={Lewis, Dustin F. and Jeffries, Matthew D. and Gannon, Travis W. and Richardson, Robert J. and Yelverton, Fred H.}, year={2014}, pages={493–500} }
 @article{gannon_hixson_keller_weber_knezevic_yelverton_2014, title={Soil Properties Influence Saflufenacil Phytotoxicity}, volume={62}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-13-00171.1}, abstractNote={Saflufenacil, a pyrimidinedione herbicide, is used for contact and residual broadleaf weed control in various crops. Bioactivity of saflufenacil in soil was tested in greenhouse and laboratory studies on 29 soils representing a wide range of soil properties and geographic areas across the United States. A greenhouse bioassay method was developed using various concentrations of saflufenacil applied PPI to each soil. Whole canola plants were harvested 14 d after treatment, and fresh and dry weights were recorded. Nonlinear regression analysis was used to determine the effective saflufenacil doses for 50% (ED50,), 80% (ED80), and 90% (ED90) inhibition of total plant fresh weight. Bioactivity of saflufenacil in soil was strongly correlated to soil organic (R= 0.85) and humic matter (R= 0.81), and less correlated to cation exchange capacity (R= 0.49) and sand content (R= −0.32). Stepwise regression analysis indicated that organic matter was the major soil constituent controlling bioactivity in soil and could be used to predict the bioactivity of saflufenacil. Saflufenacil phytotoxicity was found to be dependent on soil property; therefore, efficacy and crop tolerance from PRE and PPI applications may vary based on soil organic matter content and texture classification.}, number={4}, journal={WEED SCIENCE}, author={Gannon, Travis W. and Hixson, Adam C. and Keller, Kyle E. and Weber, Jerome B. and Knezevic, Stevan Z. and Yelverton, Fred H.}, year={2014}, pages={657–663} }
 @article{mahoney_jeffries_gannon_2014, title={Weed Control with Liquid Carbon Dioxide in Established Turfgrass}, volume={28}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-14-00003.1}, abstractNote={In recent years, increasing implementation of biological, cultural, and mechanical weed-control methods is desired; however, many of these techniques are not viable in established turfgrass systems. The use of freezing or frost for weed control has previously been researched; however, is not well elucidated. Field and greenhouse experiments were conducted to evaluate liquid carbon dioxide (LCD) for weed control in established turfgrass systems. LCD was applied with handheld prototypes that were modified to reduce the amount of LCD required for weed control. Common annual and perennial turfgrass weeds included common chickweed, corn speedwell, goosegrass, large crabgrass, smooth crabgrass, Virginia buttonweed, and white clover. Turfgrass tolerance was evaluated on the following species: hybrid bermudagrass, Kentucky bluegrass, tall fescue, and zoysiagrass. The final modification allowed for lower output (0.5 kg LCD min−1) when compared with the initial prototype (3 kg LCD min−1). In general, weed control increased as LCD increased. When comparing weed species life cycles, annuals were controlled more than perennials (P < 0.0001) at 14 and 28 d after treatment (DAT). Further, exposure time affected control as white clover, Virginia buttonweed, and large crabgrass control was greater (18, 14, 15%, respectively) from the longer exposure time (30 vs. 15 s), although equivalent amounts of LCD (30 kg m−2) were applied. These data also suggest that plant maturity affects control, as large crabgrass control in one- to two- and three- to four-leaf stages (> 90%) was greater than in the one- to two-tiller stage (< 70%). Turfgrass injury at 7 DAT was unacceptable (> 30%) on all species, but declined to 0% by 28 DAT. These data suggest that LCD has the potential to provide an alternative for weed control of select species where synthetic herbicides are not allowed or desired.}, number={3}, journal={WEED TECHNOLOGY}, author={Mahoney, Denis J. and Jeffries, Matthew D. and Gannon, Travis W.}, year={2014}, pages={560–568} }
 @article{lewis_roten_everman_gannon_richardson_yelverton_2013, title={Absorption, Translocation, and Metabolism of Aminocyclopyrachlor in Tall Fescue (Lolium arundinaceum)}, volume={61}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-12-00189.1}, abstractNote={Synthetic auxin herbicides are commonly used in forage, pasture, range, and turfgrass settings for dicotyledonous weed control. Aminocyclopyrachlor (AMCP) is a newly developed pyrimidine carboxylic acid with a chemical structure and mode of action similar to the pyridine carboxylic acids—aminopyralid, clopyralid, and picloram. Injury to sensitive dicotyledonous plants has been observed following exposure to monocotyledonous plant material previously treated with pyridine compounds. The absorption, translocation, and metabolism of AMCP has been documented in susceptible broadleaf weeds; however, no information is available, to our knowledge, regarding AMCP fate in tolerant Poaceae, which may serve as the vector for off-target plant injury. Based on this premise, research was conducted to characterize absorption, translocation, and metabolism of AMCP in tall fescue.14C-AMCP was applied to single tiller tall fescue plant foliage under controlled laboratory conditions at North Carolina State University (Raleigh, NC). Radiation was quantified in leaf wash, treated leaf, foliage, crown, roots, and root exudates at 3, 12, 24, 48, 96, and 192 h after treatment (HAT).14C-AMCP was rapidly absorbed by tall fescue, reaching 38 and 68% at 3 and 48 HAT, respectively. Translocation of14C-AMCP was limited to the foliage, which reached maximum translocation (34%) at 96 HAT. Most of the recovered14C-AMCP remained in the leaf wash, treated leaf, or foliage, whereas minimal radiation was detected in the crown, roots, or root exudates throughout the 192-h period. No AMCP metabolism was observed in tall fescue through the 192 HAT. These data suggest AMCP applied to tall fescue can remain bioavailable, and mishandling treated plant material could result in off-target injury.}, number={3}, journal={WEED SCIENCE}, author={Lewis, Dustin F. and Roten, Rory L. and Everman, Wesley J. and Gannon, Travis W. and Richardson, Robert J. and Yelverton, Fred H.}, year={2013}, pages={348–352} }
 @article{jeffries_yelverton_gannon_2013, title={Annual Bluegrass (Poa annua) Control in Creeping Bentgrass Putting Greens with Amicarbazone and Paclobutrazol}, volume={27}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-12-00144.1}, abstractNote={Amicarbazone is a photosystem II–inhibiting herbicide recently registered for annual bluegrass control in established turf systems that include creeping bentgrass. However, research to date reveals potential issues with creeping bentgrass tolerance to amicarbazone. Currently, the plant-growth regulator paclobutrazol is widely adopted by turf managers for chemical annual bluegrass suppression in creeping bentgrass putting greens. Field experiments were conducted throughout North Carolina in the spring of 2010 and 2011 to assess treatment regimens that included amicarbazone (49, 65, or 92 g ai ha−1) and paclobutrazol (70, 140, or 280 g ai ha−1) applied alone, as tank-mixtures, or used in tandem, at varying rates and sequential timings for annual bluegrass control in creeping bentgrass putting greens. In general, regimens including both compounds provided greater annual bluegrass control and acceptable turfgrass tolerance compared with stand-alone applications of amicarbazone at 8 and 12 wk after initial treatment (WAIT). When comparing regimens that included amicarbazone at 49 or 65 g ha−1, creeping bentgrass tolerance was greater for the higher application rate applied less frequently. These results indicate amicarbazone usage on creeping bentgrass greens may be beneficially affected with the incorporation of paclobutrazol to treatment regimens because annual bluegrass control with the combination was equal to or greater than stand-alone amicarbazone applications, and creeping bentgrass tolerance was superior 8 and 12 WAIT.}, number={3}, journal={WEED TECHNOLOGY}, author={Jeffries, Matthew D. and Yelverton, Fred H. and Gannon, Travis W.}, year={2013}, pages={520–526} }
 @article{matteson_gannon_jeffries_haines_lewis_polizzotto_2014, title={Arsenic Retention in Foliage and Soil after Monosodium Methyl Arsenate (MSMA) Application to Turfgrass}, volume={43}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2013.07.0268}, abstractNote={Monosodium methyl arsenate (MSMA) is a commonly used herbicide for weed control in turfgrass systems. There is concern that arsenic from applied MSMA could leach to groundwater or run off into surface water, thereby threatening human and ecosystem health. The USEPA has proposed a phase-out of the herbicide but is seeking additional research about the toxicity and environmental impacts of MSMA before establishing a final ruling. Little research has systematically investigated MSMA in field-based settings; instead, risks have been inferred from isolated field measurements or model-system studies. Accordingly, the overall goal of this study was to quantify the fate of arsenic after MSMA application to a managed turfgrass system. After MSMA application to turfgrass-covered and bareground lysimeters, the majority of arsenic was retained in turfgrass foliage and soils throughout year-long experiments, with 50 to 101% of the applied arsenic recovered in turfgrass systems and 55 to 66% recovered in bareground systems. Dissolved arsenic concentrations from 76.2-cm-depth pore water in the MSMA-treated soils were consistently <2 μg L, indistinguishable from background concentrations. As measured by adsorption isotherm experiments, MSMA retention by the sandy soil from our field site was markedly less than retention by a washed sand and a clay loam. Collectively, these results suggest that under aerobic conditions, minimal arsenic leaching to groundwater would occur after a typical application of MSMA to turfgrass. However, repeated MSMA application may pose environmental risks. Additional work is needed to examine arsenic cycling near the soil surface and to define arsenic speciation changes under different soil conditions.}, number={1}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Matteson, Audrey R. and Gannon, Travis W. and Jeffries, Matthew D. and Haines, Stephanie and Lewis, Dustin F. and Polizzotto, Matthew L.}, year={2014}, pages={379–388} }
 @article{jeffries_gannon_rufty_yelverton_2013, title={Effect of Selective Amicarbazone Placement on Annual Bluegrass (Poa annua) and Creeping Bentgrass Growth}, volume={27}, ISSN={["0890-037X"]}, DOI={10.1614/wt-d-13-00015.1}, abstractNote={Growth chamber experiments were conducted to assess the effects of foliage-only, soil-only, and foliage-plus-soil placements of amicarbazone on annual bluegrass and creeping bentgrass growth. Evaluated herbicide treatments included amicarbazone at 49 or 147 g ai ha−1, as well as bispyribac-sodium at 74 g ai ha−1for comparative purposes. Data from this research agree with previous reports of amicarbazone plant uptake. Amicarbazone is absorbed via above- and belowground pathways; however, plant growth is inhibited more by root uptake. Compared to foliage-only amicarbazone placement, soil-only placement more than doubled reductions in aboveground biomass and root mass 56 d after treatment (DAT), whereas no differences were detected between placements including soil contact. Across all evaluated parameters in this research, amicarbazone (49 g ha−1) impacted creeping bentgrass growth similarly to bispyribac-sodium, whereas annual bluegrass growth was inhibited more by amicarbazone, suggesting it provides a more efficacious chemical option for end-user applications.}, number={4}, journal={WEED TECHNOLOGY}, author={Jeffries, Matthew D. and Gannon, Travis W. and Rufty, Thomas W. and Yelverton, Fred H.}, year={2013}, pages={718–724} }
 @article{hoyle_yelverton_gannon_2013, title={Evaluating Multiple Rating Methods Utilized in Turfgrass Weed Science}, volume={27}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-12-00126.1}, abstractNote={Turfgrass weed scientists commonly use visual ratings (VR) to assign a numerical value to a turfgrass or weed response. These ratings lack quantifiable numerical values and are considered subjective. Alternatives to VR, including line intersect analysis (LIA) and digital image analysis (DIA), have been used to varying extents in turfgrass research. Alternatives can be expensive, labor intensive, and can require extensive calibration and increased time for data acquisition. Minimal research has been conducted evaluating rating methods used in turfgrass weed science. Trials were conducted in 2007 and 2008 to evaluate ratings methods used to quantify large crabgrass populations as influenced by tall fescue mowing height (2.5, 5.1, 7.6, and 10.2 cm). Percent large crabgrass cover was assessed utilizing VR, LIA, and DIA to determine if differences existed among evaluation methods. Pairwise comparisons, Pearson's correlation, and linear regression were performed to compare evaluations. All rating methods were significantly correlated to one another. Differences of large crabgrass cover estimates existed between LIA and DIA data at all mowing heights and between VR and DIA data at the 7.6 and 10.2 cm mowing heights in 2007. Authors believe that shadows produced by the turf canopy at higher (≥ 7.6 cm) mowing heights increased DIA estimates of large crabgrass cover. At trial initiation in 2007, researchers did not capture calibration images because the methodology to eliminate a shadow influence using a standard digital image had not been published. Additional DIA calibration in 2008 corrected for canopy shadows, and no differences were observed in large crabgrass cover between all evaluation methods indicated by nonsignificance pairwise comparisons and estimated regression parameters. These data indicate VR are no different than LIA or DIA in estimating large crabgrass cover as affected by tall fescue mowing height.}, number={2}, journal={WEED TECHNOLOGY}, author={Hoyle, Jared A. and Yelverton, Fred H. and Gannon, Travis W.}, year={2013}, pages={362–368} }
 @article{gannon_hixson_weber_shi_yelverton_rufty_2013, title={Sorption of Simazine and S-Metolachlor to Soils from a Chronosequence of Turfgrass Systems}, volume={61}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-12-00173.1}, abstractNote={Pesticide sorption by soil is among the most sensitive input parameters in many pesticide-leaching models. For many pesticides, organic matter is the most important soil constituent influencing pesticide sorption. Increased fertility, irrigation, and mowing associated with highly maintained turfgrass areas result in constant deposition of organic material, creating a soil system that can change drastically with time. Changes in soil characteristics could affect the environmental fate of pesticides applied to turfgrass systems of varying ages. Sorption characteristics of simazine andS-metolachlor were determined on five soils from bermudagrass systems of increasing ages (1, 4, 10, 21, and 99 yr) and compared to adjacent native pine and bare-ground areas. Surface soil (0 to 5 cm) and subsurface soil (5 to 15 cm) from all sites were air-dried and passed through a 4-mm sieve for separation from plant material. Using a batch-equilibrium method, sorption isotherms were determined for each soil. Data were fit to the Freundlich equation, andKd(soil sorption coefficient) andKoc(organic carbon sorption coefficient) values were determined. Sorption and soil system age were directly related to organic matter content in the soil. Sorption of both herbicides increased with age of the soil system and was greatest on the surface soil from the oldest bermudagrass soil system. Herbicide sorption decreased at greater soil depths with lower organic matter. Greater amount of14C–simazine sorbed to subsurface soil of the oldest turfgrass system compared to14C–S-metolachlor. Results indicate that as bermudagrass systems age and accumulate higher organic matter levels increased herbicide sorption may decrease the leaching potential and bioavailability of simazine andS-metolachlor.}, number={3}, journal={WEED SCIENCE}, author={Gannon, Travis W. and Hixson, Adam C. and Weber, Jerome B. and Shi, Wei and Yelverton, Fred H. and Rufty, Thomas W.}, year={2013}, pages={508–514} }
 @article{gannon_yelverton_2011, title={Application Placement Equipment for Bahiagrass (Paspalum notatum) Suppression along Roadsides}, volume={25}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-10-00074.1}, abstractNote={Experiments were initiated during 2003 and 2004 to evaluate application placement equipment for plant growth regulator (PGR) applications along bahiagrass roadsides. Recently designed equipment combine low-volume application and pesticide placement technology. Application placement equipment conceal the image of a traditional spray application. Evaluated application placement equipment included a wet-blade mower (Burch Wet Blade) and rotary-wick applicator (Weedbug™) compared with a traditional broadcast spray. Wet-blade mowers are designed to mow and simultaneously apply a pesticide solution to a cut stem or leaf in a single pass, whereas rotary-wick applicators are designed to wick a solution onto foliage. Evaluated PGRs included imazapic (9, 35, or 53 g ha−1) and sulfometuron-methyl (26 g ha−1). Bahiagrass injury varied with application placement equipment and was greater with rotary-wick applications in 2003, compared with foliar broadcast applications and the wet-blade mower. Bahiagrass seedhead suppression ranged from 31 to 60% with application placement equipment in July 2003 compared with 93% for a broadcast spray. In 2004, rotary wick- or broadcast-applied PGRs provided excellent (> 90%) seedhead suppression. Although application placement equipment may have advantages to broadcast-spray applications, evaluated equipment did not enhance bahiagrass suppression along roadsides in North Carolina compared with a foliar broadcast spray. Additional research is needed to determine if this type of application may provide consistent results with other species and compounds.}, number={1}, journal={WEED TECHNOLOGY}, author={Gannon, Travis W. and Yelverton, Fred H.}, year={2011}, pages={77–83} }
 @article{gannon_yelverton_2008, title={Effect of simulated rainfall on tall fescue (Lolium arundinaceum) control with glyphosate}, volume={22}, ISSN={["1550-2740"]}, DOI={10.1614/WT-07-158.1}, abstractNote={Field experiments were conducted to determine the effect of simulated rainfall after glyphosate application on tall fescue control. Three glyphosate formulations, three simulated rainfall amounts, two application rates, and three rain-free periods were evaluated. Glyphosate formulations evaluated included Roundup Original®, Roundup Pro®, and Roundup ProDry®. Herbicide drying periods, or rain-free intervals, included 15, 30, or 60 min. Simulated rainfall amounts were 0, 0.25, or 0.64 cm. Application rates of glyphosate were 3.4 or 6.7 kg ae/ha. Averaged across glyphosate formulation and simulated rainfall amount, excellent (≥ 90%) tall fescue control was observed when no simulated rainfall occurred within 60 min after application, whereas good (≥ 80%) tall fescue control was observed when 30 rain-free min were provided. Although current glyphosate labels are vague about rainfastness, these data indicate that critical rain-free periods may be as short as 30 min when higher application rates are used.}, number={3}, journal={WEED TECHNOLOGY}, author={Gannon, Travis W. and Yelverton, Fred H.}, year={2008}, pages={553–557} }
 @article{hixson_gannon_yelverton_2007, title={Efficacy of application placement equipment for tall fescue (Lolium arundinaceum) growth and seedhead suppression}, volume={21}, ISSN={["1550-2740"]}, DOI={10.1614/WT-06-108.1}, abstractNote={Field research was conducted to evaluate plant growth-regulator efficacy for tall fescue growth and seedhead suppression applied using application placement equipment. Specially designed equipment outfitted with fluid application systems applies low-volume plant growth regulator directly on plant foliage, reducing opportunity for drift and visible application. Wet-blade mowers are equipped to apply plant growth regulators and mow in a single pass, whereas rotary-wick applicators simply wipe chemicals directly on uncut vegetation. Therefore, a wet-blade, rotary-wick, and broadcast sprayer system were chosen to apply imazapic at three rates (9, 35, and 53 g ai/ha), and a mefluidide + chlorsulfuron tank mix at 7 + 140 g ai/ha to tall fescue roadsides for vegetative growth and seedhead suppression. Experiments were conducted during the spring and summer of 2004 in central and western North Carolina. Tall fescue was slightly injured and discolored by all treatments but fully recovered by 2 mo after treatment. Imazapic suppressed new vegetative growth 3 mo after treatment compared with the nonmowed–nontreated control (16.1 cm of growth) and the mowed–nontreated control (21.1 cm) when applied with the rotary-wick applicator (8.5 cm) and broadcast sprayer (6.2 cm). However, differences in vegetative height primarily occurred when application placement equipment treatments were compared with nontreated vegetation as opposed to mowed–nontreated plants. Although mowed–nontreated and wet-blade–treated plots had more new vegetative growth, nonmowed–nontreated plots still consistently had the greatest vegetative height. Seedhead suppression ranged from 87 to 100% when compared with the nonmowed–nontreated control, with wet-blade treatments consistently providing the least-effective seedhead suppression. Overall, application placement equipment did not improve plant growth-regulator efficacy when compared with the foliar broadcast spray. Nomenclature: Chlorsulfuron; imazapic; mefluidide; tall fescue, Lolium arundinaceum (Schreb.) S.J. Darbyshire, ‘Kentucky 31’}, number={3}, journal={WEED TECHNOLOGY}, author={Hixson, Adam C. and Gannon, Travis W. and Yelverton, Fred H.}, year={2007}, pages={801–806} }
 @article{gannon_yelverton_mcelroy_2006, title={Allelopathic potential of centipedegrass (Eremochloa ophiuroides)}, volume={54}, ISSN={["0043-1745"]}, DOI={10.1614/WS-05-179R.1}, abstractNote={Abstract Laboratory and greenhouse experiments were conducted to determine the allelopathic potential of centipedegrass. Germination and growth of indicator species were evaluated in soil leachates, leaf debris, and aqueous leaf extracts of centipedegrass. Centipedegrass soil leachates did not inhibit annual bluegrass, goosegrass, henbit, large crabgrass, or perennial ryegrass germination compared with the nonfertilized control. Incorporated centipedegrass leaf debris did not reduce lettuce germination, shoot weight, or root weight compared with the control. However, shoot and root dry weights of radish were reduced with increasing rates of centipedegrass leaf debris. Six and 9 mg debris g−1 soil reduced radish shoot weight by 49 and 64%, respectively, compared with the control. Aqueous leaf extracts of centipedegrass reduced lettuce germination; however, radicle and hypocotyl length were similar to the control. These data do not conclusively suggest centipedegrass has widespread allelopathic activity; however, significant reductions in shoot and root weight of radish with increasing centipedegrass leaf debris demonstrate a pattern of inhibition of one species against another, which fulfills a requirement of allelopathic interactions. Nomenclature: Annual bluegrass, Poa annua L. POAAN; goosegrass, Eleusine indica (L.) Gaertn. ELEIN; henbit, Lamium amplexicaule L. LAMAM; large crabgrass, Digitaria sanguinalis (L.) Scop. DIGSA; centipedegrass, Eremochloa ophiuroides (Munro) Hack.; lettuce, Lactuca sativa L.; perennial ryegrass, Lolium perenne L.; radish, Raphanus sativus L.}, number={3}, journal={WEED SCIENCE}, author={Gannon, TW and Yelverton, FH and McElroy, JS}, year={2006}, pages={521–525} }
 @article{mcelroy_breeden_yelverton_gannon_askew_derr_2005, title={Response of four improved seeded bermudagrass cultivars to postemergence herbicides during seeded establishment}, volume={19}, ISSN={["1550-2740"]}, DOI={10.1614/WT-04-303R2.1}, abstractNote={Herbicides and herbicide prepackaged mixtures registered for use on established bermudagrass turf may cause significant injury to recently seeded bermudagrass cultivars, delaying full establishment. Research was conducted to evaluate the use of 12 herbicide treatments applied at onset of uniform stolon development (4 to 8 wk after seeding) to recently seeded ‘Princess 77,’ ‘Riviera,’ ‘Savannah,’ and ‘Yukon’ bermudagrass cultivars. In general, Yukon was more susceptible to herbicide injury than other cultivars. Atrazine at 1.1 kg ai/ha injured all cultivars 55 to 59% 14 d after initial treatment (DAIT), which lead to reduced bermudagrass cover 21 DAIT. Triclopyr + clopyralid at 0.63 + 0.21 kg ae/ha, respectively, injured Savannah and Yukon greater than other broadleaf weed herbicides (2,4-D + mecoprop + dicamba or 2,4-D + clopyralid + dicamba). Foramsulfuron did not injure or reduce bermudagrass cover of any cultivar evaluated at any rating date. The only adverse effect of trifloxysulfuron was a reduction in Riviera and Yukon ground cover at 21 DAIT. MSMA applied sequentially and quinclorac treatments did not injure or reduce ground cover of Savannah or Princess 77. MSMA applied sequentially and/or quinclorac injured and reduced ground cover of Riviera and Yukon; however, both cultivars completely recovered from MSMA or quinclorac injury by 42 DAIT. Nomenclature: clopyralid, 2,4-D, dicamba, foramsulfuron, mecoprop, MSMA, triclopyr, trifloxysulfuron, quinclorac; common bermudagrass, Cynodon dactylon (L.) Pers. #3 CYNDA, ‘Princess 77’, ‘Riviera’, ‘Savannah’, ‘Yukon.’ Additional index words: Seeded establishment, stolon development, turfgrass tolerance. Abbreviations: DAIT, days after initial treatment; NTEP, National Turfgrass Evaluation Program.}, number={4}, journal={WEED TECHNOLOGY}, author={McElroy, JS and Breeden, GK and Yelverton, FH and Gannon, TW and Askew, SD and Derr, JF}, year={2005}, pages={979–985} }
 @article{burnell_yelverton_neal_gannon_mcelroy_2004, title={Control of silvery-thread moss (Bryum argenteum Hedw.) in creeping bentgrass (Agrostis palustris Huds.) putting greens}, volume={18}, ISSN={["1550-2740"]}, DOI={10.1614/WT-03-082R1}, abstractNote={Field experiments were conducted to evaluate chemicals for silvery-thread moss control and bentgrass turfgrass quality. Treatments included iron (Fe)-containing products, nitrogen fertilizers, Ultra Dawn dishwashing detergent (UD) at 3% (v/v), and oxadiazon. In general, greater silvery-thread moss control was achieved with Fe-containing products. Ferrous sulfate at 40 kg Fe/ha plus ammonium sulfate at 30 kg N/ha, a combined product of ferrous oxide, ferrous sulfate, and iron humates (FEOSH) at 125 kg Fe/ha, and a combined product of iron disulfide and ferrous sulfate (FEDS) at 112 kg Fe/ha reduced silvery-thread moss populations 87, 81, and 69%, respectively, 6 wk after initial treatment (WAIT). UD reduced silvery-thread moss populations 57% 6 WAIT. The addition of oxadiazon to Fe-containing treatments did not improve silvery-thread moss population reduction. Other experiments evaluated two formulations of chlorothalonil, each applied at two rates, chlorothalonil with zinc at 9.5 and 17.4 kg ai/ha and chlorothalonil without zinc at 9.1 and 18.2 kg/ ha, and two spray volumes (2,038 and 4,076 L/ha). Greater silvery-thread moss population reduction was observed at Jefferson Landing in 1999 compared with Elk River in 1999 and 2000. Rainfall events at Elk River in 1999 and 2000 within 24 h after application and no rain at Jefferson Landing may account for variation in performance of products between sites. However, no difference in chlorothalonil formulation, rate, or spray volume was observed in any location or year. These data indicate that Fe-containing fertilizers or chlorothalonil can be used to reduce silvery-thread moss populations in creeping bentgrass putting greens.}, number={3}, journal={WEED TECHNOLOGY}, author={Burnell, KD and Yelverton, FH and Neal, JC and Gannon, TW and McElroy, JS}, year={2004}, pages={560–565} }
 @article{gannon_yelverton_cummings_mcelroy_2004, title={Establishment of seeded centipedegrass (Eremochloa ophiuroides) in utility turf areas}, volume={18}, ISSN={["0890-037X"]}, DOI={10.1614/WT-03-112R1}, abstractNote={Experiments were conducted to evaluate safety and effectiveness of herbicides during establishment of seeded centipedegrass. Centipedegrass tolerance to herbicides was evaluated at seeding and early postemergence. Imazapic at 105 g ai/ha, sulfometuron at 53 g ai/ha, or metsulfuron at 21 or 42 g ai/ha applied at seeding reduced centipedegrass ground cover compared with the nontreated. Imazapic at 18 or 35 g/ha or applications of atrazine or simazine at seeding did not reduce centipedegrass ground cover compared with the nontreated. Applications of chlorsulfuron plus mefluidide (7 + 140 g ai/ha) or metsulfuron at 21 or 42 g/ha applied 6 wk after seeding (WAS) centipedegrass (one-leaf to one-tiller growth stage) caused 20, 16, and 83% phytotoxicity, respectively, 56 d after treatment (DAT). Imazapic, sulfometuron, atrazine, or simazine applied 6 WAS caused <15% phytotoxicity 56 DAT. When large crabgrass and centipedegrass were seeded together, large crabgrass emergence was reduced 41% when atrazine (1,100 g ai/ha) was applied at seeding. Centipedegrass tiller production was reduced with increasing amounts of crabgrass. However, centipedegrass tiller production and ground cover were higher when atrazine was applied because of reduced interspecific interference from large crabgrass. These data indicate that centipedegrass can be established more quickly if appropriate herbicides are used at seeding or shortly after seeding.}, number={3}, journal={WEED TECHNOLOGY}, author={Gannon, TW and Yelverton, FH and Cummings, HD and McElroy, JS}, year={2004}, pages={641–647} }