@article{ramanathan_gannon_everman_locke_2025, title={Atrazine sensitivity varies among soybean cultivars}, volume={8}, ISSN={["2639-6696"]}, DOI={10.1002/agg2.70032}, abstractNote={Abstract Atrazine carryover from application to a monocot crop may adversely affect soybean ( Glycine max (L.) Merr.) grown in rotation. Here, we tested the hypothesis that genotype selection could reduce atrazine carryover damage to soybean. Five commercially relevant soybean varieties were evaluated for differences in sensitivity to a range of atrazine rates using visual ratings, photosynthetic, and biomass parameters. Visual injury ratings and photosynthetic gas exchange, chlorophyll fluorescence, relative chlorophyll content (SPAD), and aboveground biomass were measured during vegetative stages. Under 9.0 g a.i. ha −1 atrazine, SH 5515 LL exhibited visual injury and aboveground fresh biomass reduction but was unaffected in net photosynthesis rate ( A ) and effective quantum yield of photosystem II (ϕPSII) compared to controls. By 21 days after emergence (DAE), P53A67X recovered in A and ϕPSII, and AG56X8 recovered in SPAD. S52RS86 remained unaffected visually and photosynthetically at this atrazine rate. All genotypes treated with 179.2 g a.i. ha −1 atrazine showed higher injury ratings and lower SPAD, A , and ϕPSII after 7 DAE and lower aboveground biomass 21 DAE except S52RS86, which was similar in SPAD throughout. Atrazine at 358.4 and 716.8 g a.i. ha −1 caused plant death in all genotypes 14 DAE. Visual ratings were strongly correlated with photosynthetic measurements and aboveground biomass at each sampling. Soybean atrazine sensitivity is a function of atrazine concentration in the soil and genotype‐specific tolerance or recovery ability, indicating that growers can select soybean genotypes that reduce risk when atrazine carryover is suspected.}, number={1}, journal={AGROSYSTEMS GEOSCIENCES & ENVIRONMENT}, author={Ramanathan, Shwetha S. and Gannon, Travis W. and Everman, Wesley J. and Locke, Anna M.}, year={2025}, month={Mar} } @article{huddell_needelman_law_ackroyd_bagavathiannan_bradley_davis_evans_everman_flessner_et al._2024, title={Early-season biomass and weather enable robust cereal rye cover crop biomass predictions}, volume={9}, ISSN={["2471-9625"]}, DOI={10.1002/ael2.20121}, abstractNote={AbstractFarmers need accurate estimates of winter cover crop biomass to make informed decisions on termination timing or to estimate potential release of nitrogen from cover crop residues to subsequent cash crops. Utilizing data from an extensive experiment across 11 states from 2016 to 2020, this study explores the most reliable predictors for determining cereal rye cover crop biomass at the time of termination. Our findings demonstrate a strong relationship between early‐season and late‐season cover crop biomass. Employing a random forest model, we predicted late‐season cereal rye biomass with a margin of error of approximately 1,000 kg ha−1 based on early‐season biomass, growing degree days, cereal rye planting and termination dates, photosynthetically active radiation, precipitation, and site coordinates as predictors. Our results suggest that similar modeling approaches could be combined with remotely sensed early‐season biomass estimations to improve the accuracy of predicting winter cover crop biomass at termination for decision support tools.Core Ideas Cereal rye winter cover crop biomass modeled on data from 35 site‐years. We found a strong relationship between early and late‐season biomass. Random forest model with early‐season biomass and weather data performed well. Similar approach could improve decision support tools for cover crop management. }, number={1}, journal={AGRICULTURAL & ENVIRONMENTAL LETTERS}, author={Huddell, Alexandra and Needelman, Brian and Law, Eugene P. and Ackroyd, Victoria J. and Bagavathiannan, Muthukumar V. and Bradley, Kevin and Davis, Adam S. and Evans, Jeffery A. and Everman, Wesley Jay and Flessner, Michael and et al.}, year={2024}, month={Jun} } @article{jones_bradshaw_contreras_cahoon jr_jennings_leon_everman_2024, title={Growth and fecundity of Palmer amaranth escaping glufosinate in cotton with and without grass competition}, volume={38}, ISSN={["1550-2740"]}, DOI={10.1017/wet.2024.68}, abstractNote={Abstract Field experiments were conducted at Clayton and Rocky Mount, NC, during summer 2020 to determine the growth and fecundity of Palmer amaranth plants that survived glufosinate with and without grass competition in cotton. Glufosinate (590 g ai ha −1 ) was applied to Palmer amaranth early postemergence (5 cm tall), mid-postemergence (7 to 10 cm tall), and late postemergence (>10 cm tall) and at orthogonal combinations of those timings. Nontreated Palmer amaranth was grown in weedy, weed-free in-crop (WFIC) and weed-free fallow (WFNC) conditions for comparisons. Palmer amaranth control decreased as larger plants were treated; no plants survived the sequential glufosinate applications in both experiments. The apical and circumferential growth of Palmer amaranth surviving glufosinate treatments was reduced by more than 44% compared to the WFIC and WFNC Palmer amaranth in both experiments. The biomass of Palmer amaranth plants surviving glufosinate was reduced by more than 62% when compared with the WFIC and WFNC in all experiments. The fecundity of Palmer amaranth surviving glufosinate treatments was reduced by more than 73% compared to WFNC Palmer amaranth in all experiments. Remarkably, the plants that survived glufosinate were fecund as WFIC plants only in the Grass Competition experiment. The results prove that despite decreased vegetative growth of Palmer amaranth surviving glufosinate treatment, plants remain fecund and can be fecund as nontreated plants in cotton. These results suggest that a glufosinate-treated grass weed may not have a significant interspecific competition effect on Palmer amaranth that survives glufosinate. Glufosinate should be applied to 5 to 7 cm Palmer amaranth to cease vegetative and reproductive capacities.}, journal={WEED TECHNOLOGY}, author={Jones, Eric A. L. and Bradshaw, Colden L. and Contreras, Diego J. and Cahoon Jr, Charles W. and Jennings, Katherine M. and Leon, Ramon G. and Everman, Wesley J.}, year={2024}, month={Oct} } @article{jones_bradshaw_contreras_cahoon jr_jennings_leon_everman_2024, title={Growth and fecundity of Palmer amaranth escaping glufosinate in soybean with and without grass competition}, volume={38}, ISSN={["1550-2740"]}, DOI={10.1017/wet.2024.29}, abstractNote={Abstract Field experiments were conducted at Clayton and Rocky Mount, North Carolina, during the summer of 2020 to determine the growth and fecundity of Palmer amaranth plants that survived glufosinate with and without grass competition in soybean crops. Glufosinate (590 g ai ha −1 ) was applied at early postemergence (when Palmer amaranth plants were 5 cm tall), mid-postemergence (7–10 cm), and late postemergence (>10 cm) and at orthogonal combinations of those timings. Nontreated Palmer amaranth was grown in weedy (i.e., intraspecific and grass competition), weed-free in-crop (WFIC), and weed-free fallow (WFNC) conditions for comparisons. No Palmer amaranth plants survived the sequential glufosinate applications and control decreased as the plants were treated at a larger size in both experiments. The apical and circumferential growth rate of Palmer amaranth surviving glufosinate was reduced by more than 44% compared with the WFNC Palmer amaranth. The biomass of Palmer amaranth plants that survived glufosinate was reduced by more than 87% compared with the WFNC Palmer amaranth. The fecundity of Palmer amaranth that survived glufosinate was reduced by more than 70% compared with WFNC Palmer amaranth. Palmer amaranth plants that survived glufosinate were as fecund as the WFIC Palmer amaranth in both experiments in soybean fields. The results prove that despite the significant vegetative growth rate decrease of Palmer amaranth that survived glufosinate, plants can be as fecund as nontreated plants. The trends in growth and fecundity of Palmer amaranth that survives glufosinate with and without grass competition were similar. These results suggest that glufosinate-treated grass weeds may not reduce the growth or fecundity of Palmer amaranth that survives glufosinate.}, journal={WEED TECHNOLOGY}, author={Jones, Eric A. L. and Bradshaw, Colden L. and Contreras, Diego J. and Cahoon Jr, Charles W. and Jennings, Katherine M. and Leon, Ramon G. and Everman, Wesley J.}, year={2024}, month={May} } @article{sun_hurley_frisvold_dentzman_ervin_everman_gunsolus_norsworthy_owen_2024, title={How Does Herbicide Resistance Change Farmer's Weed Management Decisions? Evidence from the Roundup Ready Experiment}, volume={14}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy14112720}, abstractNote={Adoption of diverse weed management practices is viewed as essential for slowing the spread of herbicide-resistant (HR) weeds. Yet, adoption of diverse tactics has remained low, while there has been explosive growth of resistant weeds. This study analyzes U.S.-farm-level data to identify factors affecting adoption of diverse weed management practices. This study uses directed acyclic graphs (DAGs) to consider how practice adoption is influenced by different causal pathways between farmer and farm characteristics and farmer awareness of and concern over HR weeds. This study then uses multiple regression analysis to estimate the direct and indirect pathways that influence practice adoption. Respondents relied more heavily on herbicide-based weed control methods than on mechanical or cultural methods. Concern over herbicide resistance increased the number of practices farmers adopted and the percentage of acres where farmers implemented these practices. Practice adoption was negatively associated with increasing levels of farmer risk aversion. Technological optimism—belief that new herbicides would soon be developed to counter HR weeds—discouraged diverse herbicide use practices that combat resistance, but encouraged use of some non-chemical weed control methods. Perceived weed dispersal externalities (from weed mobility) led to more diverse weed management, running counter to hypotheses that greater mobility reduces incentives for individual resistance management.}, number={11}, journal={AGRONOMY-BASEL}, author={Sun, Huichun and Hurley, Terrance and Frisvold, George B. and Dentzman, Katherine and Ervin, David and Everman, Wesley and Gunsolus, Jeffrey and Norsworthy, Jason and Owen, Micheal}, year={2024}, month={Nov} } @article{cahoon_jordan_tranel_york_riggins_seagroves_inman_everman_leon_2024, title={Influence of gender and glyphosate resistance on Palmer amaranth growth and interference with cotton}, volume={10}, ISSN={["2374-3832"]}, url={https://doi.org/10.1002/cft2.20272}, DOI={10.1002/cft2.20272}, abstractNote={Abstract Management of herbicide‐resistant weeds can be improved by understanding the biology of resistant biotypes. While the majority of research has focused on female plants and seed production of Palmer amaranth ( Amaranthus palmeri S. Watson) that are resistant to glyphosate, growth of male plants that are resistant to this herbicide has not been studied in detail. Additionally, interference of male versus female Palmer amaranth plants on cotton ( Gossypium hirsutum ) yield has not been reported. Plant height and biomass of male and female plants from a mixed population of glyphosate‐resistant (GR) and glyphosate‐susceptible (GS) plants was studied in North Carolina when grown season‐long with cotton. Palmer amaranth height was less for GR male plants compared with GS males and both GR and GS females. Biomass of Palmer amaranth female plants was twice that of male plants irrespective of glyphosate resistance. Cotton yield was affected similarly by Palmer amaranth regardless of either gender or glyphosate resistance status. The implications of shorter GR male plants on pollen dispersal and ramifications on management of glyphosate resistance are not known. Results from these trials did not address implications of the height of male plants on fitness of GR resistance. Nonetheless, the finding that GR male plants were shorter in the field than GS male plants warrants a new look at this topic. Similar reductions for cotton yield in presence of both GR and GS biotypes and genders suggest that current yield loss assessments and management decisions do not need to consider these variables in Palmer amaranth populations.}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Cahoon, Charles W. and Jordan, David L. and Tranel, Patrick J. and York, Alan C. and Riggins, Chance and Seagroves, Richard and Inman, Matthew and Everman, Wesley and Leon, Ramon}, year={2024}, month={Jun} } @article{huddell_thapa_marcillo_abendroth_ackroyd_armstrong_asmita_bagavathiannan_balkcom_basche_et al._2024, title={US cereal rye winter cover crop growth database}, volume={11}, ISSN={["2052-4463"]}, DOI={10.1038/s41597-024-02996-9}, abstractNote={AbstractWinter cover crop performance metrics (i.e., vegetative biomass quantity and quality) affect ecosystem services provisions, but they vary widely due to differences in agronomic practices, soil properties, and climate. Cereal rye (Secale cereale) is the most common winter cover crop in the United States due to its winter hardiness, low seed cost, and high biomass production. We compiled data on cereal rye winter cover crop performance metrics, agronomic practices, and soil properties across the eastern half of the United States. The dataset includes a total of 5,695 cereal rye biomass observations across 208 site-years between 2001–2022 and encompasses a wide range of agronomic, soils, and climate conditions. Cereal rye biomass values had a mean of 3,428 kg ha−1, a median of 2,458 kg ha−1, and a standard deviation of 3,163 kg ha−1. The data can be used for empirical analyses, to calibrate, validate, and evaluate process-based models, and to develop decision support tools for management and policy decisions.}, number={1}, journal={SCIENTIFIC DATA}, author={Huddell, Alexandra M. and Thapa, Resham and Marcillo, Guillermo S. and Abendroth, Lori J. and Ackroyd, Victoria J. and Armstrong, Shalamar D. and Asmita, Gautam and Bagavathiannan, Muthukumar V. and Balkcom, Kipling S. and Basche, Andrea and et al.}, year={2024}, month={Feb} } @article{ethridge_chandra_locke_everman_jordan_owen_leon_2023, title={Changes in the herbicide sensitivity and competitive ability of Abutilon theophrasti over 28 years: Implications for hormesis and weed evolution}, volume={79}, ISSN={1526-498X 1526-4998}, url={http://dx.doi.org/10.1002/ps.7604}, DOI={10.1002/ps.7604}, abstractNote={AbstractBACKGROUNDThe potential of weed species to respond to selection forces affecting the evolution of weedy traits such as competitive ability is poorly understood. This research characterized evolutionary growth changes in a single Abutilon theophrasti Medik. population comparing multiple generations collected from 1988 to 2016. A competition study was performed to understand changes in competitive ability, and a herbicide dose–response study was carried out to assess changes in sensitivity to acetolactate synthase‐inhibiting herbicides and glyphosate over time.RESULTSWhen grown in monoculture, A. theophrasti biomass production per plant increased steadily across year‐lines while leaf number decreased. In replacement experiments, A. theophrasti plants from newer year‐lines were more competitive and produced more biomass and leaf area than the oldest year‐line. No clear differences in sensitivity to imazamox were observed among year‐lines. However, starting in 1995, this A. theophrasti population exhibited a progressive increase in growth in response to a sublethal dose of glyphosate (52 g a.e. ha−1), with the 2009 and 2016 year‐lines having more than 50% higher biomass than the nontreated control.CONCLUSIONThis study demonstrates that weeds can rapidly evolve increased competitive ability. Furthermore, the results indicate the possibility of changes in glyphosate hormesis over time. These results highlight the importance of the role that rapid (i.e., subdecadal) evolution of growth traits might have on the sustainability of weed management strategies. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.}, number={10}, journal={Pest Management Science}, publisher={Wiley}, author={Ethridge, Sandra R. and Chandra, Saket and Locke, Anna M. and Everman, Wesley J. and Jordan, David L. and Owen, Micheal D.K. and Leon, Ramon G.}, year={2023}, month={Jun}, pages={4048–4056} } @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{jones_andres_owen_dunne_contreras_cahoon_jennings_leon_everman_2023, title={Confirmation of a five-way herbicide-resistant Amaranthus tuberculatus population in North Carolina}, volume={7}, ISSN={["1365-3180"]}, url={https://doi.org/10.1111/wre.12590}, DOI={10.1111/wre.12590}, abstractNote={AbstractAmaranthus tuberculatus (waterhemp) is a pervasive weed of the Mid‐west and ‐south United States and is not native to North Carolina but infestations in crop fields have been reported recently. Amaranthus tuberculatus has evolved resistance to seven herbicide groups and multiple herbicide‐resistant populations are common where the species is native. The reported A. tuberculatus infestations in North Carolina have not been controlled with herbicides but no formal herbicide resistance characterisation has been conducted to date. Glasshouse dose–response experiments were conducted to determine the susceptibility of a population collected from Surry County, North Carolina to commonly applied postemergence herbicides compared to a herbicide‐susceptible population collected from Story County, Iowa. The Surry County population survived labelled rates of imazethapyr, atrazine, glyphosate, fomesafen, and mesotrione; the Story County population was controlled with these herbicides. Further, 2,4‐D, dicamba, and glufosinate effectively controlled the Surry and Story County populations. Molecular sequencing assays were subsequently conducted to determine if altered target sites facilitated resistance in the acetolactate synthase (ALS), 5‐enolpyruvylshikimate‐3‐phosphate synthase (EPSPS), photosystem II (psbA), and protoporphyrinogen oxidase (PPX2) genes. The Surry County population carried a Trp574Leu and ∆Gly210 mutations in the ALS and PPX2 gene, respectively. No mutations that would confer resistance were found in the EPSPS or psbA gene for either population. The results of both experiments provide evidence that a five‐way herbicide‐resistant A. tuberculatus population has encroached North Carolina. More research is needed to determine the mechanisms of resistance to atrazine, glyphosate, and mesotrione.}, journal={WEED RESEARCH}, author={Jones, Eric A. L. and Andres, Ryan J. and Owen, Micheal D. K. and Dunne, Jeffrey C. and Contreras, Diego J. and Cahoon, Charles W. and Jennings, Katherine M. and Leon, Ramon G. and Everman, Wesley J.}, year={2023}, month={Jul} } @article{jones_austin_dunne_leon_everman_2023, title={Discrimination between protoporphyrinogen oxidase-inhibiting herbicide-resistant and herbicide-susceptible redroot pigweed (Amaranthus retroflexus) with spectral reflectance}, volume={5}, ISSN={["1550-2759"]}, url={https://doi.org/10.1017/wsc.2023.25}, DOI={10.1017/wsc.2023.25}, abstractNote={AbstractThe current assays to confirm herbicide resistance can be time- and labor-intensive (dose–response) or require a skill set/technical equipment (genetic sequencing). Stakeholders could benefit from a rapid assay to confirm herbicide-resistant weeds to ensure sustainable crop production. Because protoporphyrinogen oxidase (PPO)-inhibiting herbicides rapidly interfere with chlorophyll production/integrity; we propose a new, rapid assay utilizing spectral reflectance to confirm resistance. Leaf disks were excised from two PPO-inhibiting herbicide-resistant (target-site [TSR] and non–target site [NTSR]) and herbicide-susceptible redroot pigweed (Amaranthus retroflexus L.) populations and placed into a 24-well plate containing different concentrations (0 to 10 mM) of fomesafen for 48 h. A multispectral sensor captured images from the red (668 nm), green (560 nm), blue (475 nm), and red edge (717 nm) wavebands after a 48-h incubation period. The green leaf index (GLI) was utilized to determine spectral reflectance ratios of the treated leaf disks. Clear differences of spectral reflectance were observed in the red edge waveband for all populations treated with the 10 mM concentration in the dose–response assays. Differences of spectral reflectance were observed for the NTSR population compared with the TSR and susceptible populations treated with the 10 mM concentration in the green waveband and the GLI in the dose–response assay. Leaf disks from the aforementioned A. retroflexus populations and two additional susceptible populations were subjected to a similar assay with the discriminating concentration (10 mM). Spectral reflectance was different between the PPO-inhibiting herbicide-resistant and herbicide-susceptible populations in the red, blue, and green wavebands. Spectral reflectance was not distinctive between the populations in the red edge waveband and the GLI. The results provide a basis for rapidly (∼48 h) detecting PPO-inhibiting herbicide-resistant A. retroflexus via spectral reflectance. Discrimination between TSR and NTSR populations was possible only in the dose–response assay, but the assay still has utility in distinguishing herbicide-resistant plants from herbicide-susceptible plants.}, journal={WEED SCIENCE}, author={Jones, Eric A. L. and Austin, Robert and Dunne, Jeffrey C. and Leon, Ramon G. and Everman, Wesley J.}, year={2023}, month={May} } @article{howell_haug_everman_leon_richardson_2023, title={Low carrier volume herbicide trials and UAAS support management efforts of giant salvinia (Salvinia molesta): a case study}, volume={5}, ISSN={["1939-747X"]}, url={https://doi.org/10.1017/inp.2023.16}, DOI={10.1017/inp.2023.16}, abstractNote={AbstractExpanding the current aquatic herbicide portfolio, reducing total spray volumes, or remotely delivering herbicide using novel spray technologies could improve management opportunities targeting invasive aquatic plants, where options are more limited. However, research on giant salvinia (Salvinia molesta Mitchell) response to foliar herbicide applications at carrier volumes ≤140 L ha−1 is incomplete. Likewise, no data exist documenting S. molesta control with unoccupied aerial application systems (UAAS). Following the recent >100-ha incursion of S. molesta in Gapway Swamp, NC, a case study was developed to provide guidance for ongoing management efforts. In total, three field trials evaluated registered aquatic and experimental herbicides using a 140 L ha−1 carrier volume. Select foliar applications from UAAS were also evaluated. Results at 8 wk after treatment (WAT) indicated the experimental protoporphyrinogen oxidase inhibitor, PPO-699-01 (424 g ai ha−1), in combination with endothall dipotassium salt (2,370 g ae ha−1) provided 78% visual control, whereas control when PPO-699-01 (212 g ai ha−1) was applied alone was lower at 35%. Evaluations also showed diquat (3,136 g ai ha−1) alone, glyphosate (4,539 g ae ha−1) alone, and metsulfuron-methyl (42 g ai ha−1) alone achieved 86% to 94% visual plant control at 8 WAT. Sequential foliar applications of diquat, flumioxazin (210 g ai ha−1), and carfentrazone (67 g ai ha−1) at 6 wk following exposure to in-water fluridone treatments were no longer efficacious by 6 WAT due to plant regrowth. Carfentrazone applications made from a backpack sprayer displayed greater control than applications made with UAAS deploying identical carrier volumes at 2 WAT; however, neither application method provided effective control at 8 WAT. Additional field validation is needed to further guide management direction of S. molesta control using low carrier volume foliar applications.}, journal={INVASIVE PLANT SCIENCE AND MANAGEMENT}, author={Howell, Andrew W. and Haug, Erika J. and Everman, Wesley J. and Leon, Ramon G. and Richardson, Robert J.}, year={2023}, month={May} } @article{howell_leon_everman_mitasova_nelson_richardson_2023, title={Performance of unoccupied aerial application systems for aquatic weed management: Two novel case studies}, volume={37}, ISSN={0890-037X 1550-2740}, url={http://dx.doi.org/10.1017/wet.2023.32}, DOI={10.1017/wet.2023.32}, abstractNote={AbstractUnoccupied aerial application systems (UAAS) are gaining popularity for weed management to increase applicator safety and to deliver herbicide treatments where treatment sites limit ground-based spray equipment. Several studies have documented UAAS application strategies and procedures for weed control in terrestrial settings, yet literature describing remote spray technology for use in aquatics remains limited. Currently, applicators seek guidance for UAAS deployment for aquatic weed management to overcome site access restrictions, deal with environmental limitations, and improve ground-based applicator safety in hazardous treatment scenarios. In the present case studies, we evaluate a consumer-available UAAS to deliver the herbicide, florpyrauxifen-benzyl, as both foliar and directed in-water spray applications. The first case study showed that the invasive floating-leaved plant, yellow floating heart, was controlled 80% to 99% by 6 wk after treatment (WAT) following UAAS foliar herbicide treatments. The second case study demonstrated that UAAS directed in-water herbicide application reduced variable-leaf watermilfoil visible plant material by 94% at 5 WAT. Likewise, directed in-water applications from UAAS eliminated the need to deploy watercraft, which improved overall operational efficiency. Data from both case studies indicate that UAAS can provide an effective and efficient treatment strategy for floating-leaved and submersed plant control among common herbicide treatment scenarios. Future integration of UAAS in aquatic weed control programs is encouraged, especially among smaller treatment sites (≤4 ha) or where access limits traditional spray operations.}, number={3}, journal={Weed Technology}, publisher={Cambridge University Press (CUP)}, author={Howell, Andrew W. and Leon, Ramon G. and Everman, Wesley J. and Mitasova, Helena and Nelson, Stacy A.C. and Richardson, Robert J.}, year={2023}, month={May}, pages={277–286} } @article{ethridge_chandra_everman_jordan_locke_owen_leon_2023, title={Rapid evolution of competitive ability in giant foxtail (Setaria faberi) over 34 years}, volume={71}, ISSN={0043-1745 1550-2759}, url={http://dx.doi.org/10.1017/wsc.2023.1}, DOI={10.1017/wsc.2023.1}, abstractNote={AbstractCompetition between genotypes within a plant population can result in the displacement of the least competitive by more competitive genotypes. Although evolutionary processes in plants may occur over thousands and millions of years, it has been suggested that changes in key fitness traits could occur in as little as decades, with herbicide resistance being a common example. However, the rapid evolution of complex traits has not been proven in weeds. We hypothesized that changes in weed growth and competitive ability can occur in just a few years because of selection in agroecosystems. Seed of multiple generations of a single natural population of the grassy weed giant foxtail (Setaria faberi Herrm.) were collected during 34 yr (i.e., 1983 to 2017). Using a “resurrection” approach, we characterized life-history traits of the different year-lines under noncompetitive and competitive conditions. Replacement-series experiments comparing the growth of the oldest year-line (1983) versus newer year-lines (1991, 1996, 1998, 2009, and 2017) showed that plant competitive ability decreased and then increased progressively in accordance with oscillating selection. The adaptations in competitive ability were reflected in dynamic changes in leaf area and biomass when plants were in competition. The onset of increased competitive ability coincided with the introduction of herbicide-resistant crops in the landscape in 1996. We also conducted a genome-wide association study and identified four loci that were associated with increased competitive ability over time, confirming that this trait changed in response to directional selection. Putative transcription factors and cell wall–associated enzymes were linked to those loci. This is the first study providing direct in situ evidence of rapid directional evolution of competitive ability in a plant species. The results suggest that agricultural systems can exert enough pressure to cause evolutionary adaptations of complex life-history traits, potentially increasing weediness and invasiveness.}, number={1}, journal={Weed Science}, publisher={Cambridge University Press (CUP)}, author={Ethridge, Sandra R. and Chandra, Saket and Everman, Wesley J. and Jordan, David L. and Locke, Anna M. and Owen, Micheal D. K. and Leon, Ramon G.}, year={2023}, month={Jan}, pages={59–68} } @article{ethridge_grieger_locke_everman_jordan_leon_2023, title={Views of RNAi approaches for weed management in turfgrass systems}, volume={7}, ISSN={["1550-2759"]}, url={https://doi.org/10.1017/wsc.2023.37}, DOI={10.1017/wsc.2023.37}, abstractNote={AbstractPublic concern regarding the use of herbicides in urban areas (e.g., golf courses, parks, lawns) is increasing. Thus, there is a need for alternative methods for weed control that are safe for the public, effective against weeds, and yet selective to turfgrass and other desirable species. New molecular tools such as ribonucleic acid interference (RNAi) have the potential to meet all those requirements, but before these technologies can be implemented, it is critical to understand the perceptions of key stakeholders to facilitate adoption as well as regulatory processes. With this in mind, turfgrass system managers, such as golf course superintendents and lawn care providers, were surveyed to gain insight into the perception and potential adoption of RNAi technology for weed management. Based on survey results, turfgrass managers believe that cost of weed management and time spent managing weeds are the main challenges faced in their fields. When considering new weed management tools, survey respondents were most concerned about cost, efficacy, and efficiency of a new product. Survey respondents were also optimistic toward RNAi for weed management and would either use this technology in their own fields or be willing to conduct research to develop RNAi herbicides. Although respondents believed that the general public would have some concerns about this technology, they did not believe this to be the most important factor for them when choosing new weed management tools. The need for new herbicides to balance weed control challenges and public demands is a central factor for turfgrass managers’ willingness to use RNAi-based weed control in turfgrass systems. They believe their clientele will be accepting of RNAi tools, although further research is needed to investigate how a wider range of stakeholders perceive RNAi tools for turfgrass management more broadly.}, journal={WEED SCIENCE}, author={Ethridge, Sandra R. and Grieger, Khara and Locke, Anna M. and Everman, Wesley J. and Jordan, David L. and Leon, Ramon G.}, year={2023}, month={Jul} } @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{jones_leon_everman_2022, title={Biological effects on Palmer amaranth surviving glufosinate}, volume={5}, ISSN={["2639-6696"]}, url={https://doi.org/10.1002/agg2.20315}, DOI={10.1002/agg2.20315}, abstractNote={AbstractPalmer amaranth (Amaranthus palmeri S. Watson) is a difficult weed to manage due to competitive growth, fecundity, and evolved herbicide resistance. Limited information exist on the fecundity of vegetative stage Palmer amaranth surviving glufosinate applied at different timings. In addition, research has not investigated the germination or glufosinate susceptibility of the offspring from these surviving plants. Field experiments were conducted across three locations in 2019 to determine (a) the fecundity of Palmer amaranth plants surviving glufosinate applied at different vegetative growth stages, and (b) if the offspring from the surviving plants exhibited differential germination and susceptibility to glufosinate. Palmer amaranth was treated at three different vegetative sizes (5 cm, 7–10 cm, > 10 cm) and orthogonal combinations of these application timings. The application timings corresponded to early‐, mid‐ and late‐postemergence applications. Palmer amaranth plants surviving the mid‐, late‐, and the mid postemergence followed by late postemergence glufosinate application were fecund. Palmer amaranth plants surviving the mid postemergence followed by late postemergence application produced less seed than the plants surviving the mid postemergence and late postemergence application. Palmer amaranth was controlled with other glufosinate applications resulting in no seed production. Germination was affected across location and glufosinate treatments, but no clear trend/pattern was observed. The offspring from Palmer amaranth plants surviving glufosinate applications were controlled by all glufosinate rates tested. These experiments provide evidence that Palmer amaranth surviving glufosinate in the vegetative stages may remain fecund, but fecundity can vary with application timing. No measurable effect on the offspring germination or susceptibility to glufosinate was apparent.}, number={4}, journal={AGROSYSTEMS GEOSCIENCES & ENVIRONMENT}, author={Jones, Eric and Leon, Ramon G. and Everman, Wesley Jay}, year={2022} } @article{jones_leon_everman_2022, title={Control of pervasive row crop weeds with dicamba and glufosinate applied alone, mixed, or sequentially}, volume={10}, ISSN={["1550-2740"]}, url={https://doi.org/10.1017/wet.2022.80}, DOI={10.1017/wet.2022.80}, abstractNote={AbstractDicamba and glufosinate are among the few effective postemergence herbicides to control multiple herbicide-resistant weeds in southeastern U.S. cotton and soybean production. Field studies were conducted to determine the effect of weed size and the application of dicamba and glufosinate individually, mixed, or sequentially on common ragweed, goosegrass, large crabgrass, ivyleaf morningglory, Palmer amaranth, and sicklepod control. Sequential herbicide treatments were applied 7 d after the initial treatment. The tested weeds sizes predominantly did not affect weed control. Control of broadleaf weed species with sequential herbicide applications never increased compared to the initial herbicide application. Two applications of glufosinate and/or dicamba + glufosinate controlled grasses better than one application. The order of the herbicides in the sequential applications did not affect broadleaf species control, whereas herbicide order was important for the control of grass weeds. Grass weed control was higher when glufosinate was applied before dicamba. Dicamba + glufosinate additively controlled the weeds, except for goosegrass, for which control was less for dicamba + glufosinate compared to glufosinate alone. The results of the experiment provide evidence that dicamba and glufosinate applied individually, mixed, and sequentially are effective on common row crop weeds found in the southeastern United States, but the species present may dictate how the herbicides are applied together.}, journal={WEED TECHNOLOGY}, author={Jones, Eric A. L. and Leon, Ramon G. and Everman, Wesley J.}, year={2022}, month={Oct} } @article{contreras_leon_post_everman_2022, title={Critical period of grass weed control in ALS-tolerant grain sorghum (Sorghum bicolor) is affected by planting date and environment}, volume={4}, ISSN={["2673-3218"]}, DOI={10.3389/fagro.2022.1014801}, abstractNote={Field experiments were conducted at two locations in North Carolina (Clayton and Rocky Mount) to determine the influence of row spacing and planting date on the critical period of weed control (CPWC) of grass weeds in ALS-tolerant grain. Grain sorghum was planted in May and June 2019, with either a 38 or 91 cm row spacing using an ALS-tolerant sorghum variety. Treatments consisted of “weedy” or “weed-free” plots up to 2, 3, 5, and 7 weeks after crop planting (WAP) and two control treatments of weedy and weed-free all season. Selection of grass weed species was achieved by controlling broadleaf weeds with a premix of bromoxynil plus pyrasulfutole at a rate of 264 g a.i. ha-1.Grass weeds were controlled using nicosulfuron at a rate of 69 g of a.i. ha-1. The CPWC was significantly different across locations. Row spacing and planting date factors did not influence the CPWC at Clayton. Planting date was a significant factor for the CPWC at Rocky Mount, however row spacing did not have any effect on the CPWC. Results for the CPWC are presented in terms growing degree days (GDD) from the date of crop sowing. The CPWC for grass weeds in grain sorghum at Clayton was from 368 to 849 GDD. The CPWC at Rocky Mount for May-planted grain sorghum was from 405 to 876 GDD, while the CPWC for June-planted grain sorghum ranged from 228 to 1042 GDD. These results demonstrate that cultural and environmental factors may influence the beginning, duration and end of the CPWC.}, journal={FRONTIERS IN AGRONOMY}, author={Contreras, Diego and Leon, Ramon G. and Post, Angela R. and Everman, Wesley J.}, year={2022}, month={Sep} } @article{ethridge_locke_everman_jordan_leon_2022, title={Crop physiological considerations for combining variable-density planting to optimize seed costs and weed suppression}, volume={70}, ISSN={0043-1745 1550-2759}, url={http://dx.doi.org/10.1017/wsc.2022.62}, DOI={10.1017/wsc.2022.62}, abstractNote={AbstractHigh crop densities are valuable to increase weed suppression, but growers might be reluctant to implement this practice due to increased seed cost. Because it is also possible to lower planting densities in areas with no or low weed interference risk, the area allocated to each planting density must be optimized considering seed cost and productivity per plant. In this study, the growth and yield of maize (Zea mays L.), cotton (Gossypium hirsutum L.), and soybean [Glycine max (L.) Merr.] were characterized in response to low planting densities and arrangements. The results were used to develop a bioeconomic model to optimize the area devoted to high- and low-density plantings to increase weed suppression without increasing seed cost. Physiological differences seen in each crop varied with the densities tested; however, maize was the only crop that had differences in yield (per area) between densities. When a model to optimize low and high planting densities was used, maize and cotton showed the most plasticity in yield per planted seed (g seed−1) and area of low density to compensate for high-density area unit. Maize grown at 75% planting density compared with the high-planting density (200%) increased yield (g seed−1) by 229%, return by 43%, and profit by 79% while decreasing the low-density area needed to compensate for high-density area. Cotton planted at 25% planting density compared with the 200% planting density increased yield (g seed−1) by 1,099%, return by 46%, and profit by 62% while decreasing the low-density area needed to compensate for high-density area. In contrast, the high morphological plasticity of soybean did not translate into changes in area optimization, as soybean maintained return, profit, and a 1:1 ratio for area compensation. This optimization model could allow for the use of variable planting at large scales to increase weed suppression while minimizing costs to producers.}, number={6}, journal={Weed Science}, publisher={Cambridge University Press (CUP)}, author={Ethridge, Sandra R. and Locke, Anna M. and Everman, Wesley J. and Jordan, David L. and Leon, Ramon G.}, year={2022}, month={Nov}, pages={687–697} } @article{basinger_hestir_jennings_monks_everman_jordan_2022, title={Detection of Palmer amaranth (Amaranthus palmeri) and large crabgrass (Digitaria sanguinalis) with in situ hyperspectral remote sensing. I. Effects of weed density and soybean presence}, volume={70}, ISSN={["1550-2759"]}, url={https://doi.org/10.1017/wsc.2021.81}, DOI={10.1017/wsc.2021.81}, abstractNote={AbstractThe utilization of remote sensing in agriculture has great potential to change the methods of field scouting for weeds. Previous remote sensing research has been focused on the ability to detect and differentiate between species. However, these studies have not addressed weed density variability throughout a field. Furthermore, the impact of changing phenology of crops and weeds within and between growing seasons has not been investigated. To address these research gaps, field studies were conducted in 2016 and 2017 at the Horticultural Crops Research Station near Clinton, NC. Two problematic weed species, Palmer amaranth (Amaranthus palmeri S. Watson) and large crabgrass [Digitaria sanguinalis (L.) Scop.], were planted at four densities in soybean [Glycine max (L.) Merr.]. Additionally, these weed densities were grown in the presence and absence of the crop to determine the influence of crop presence on the detection and discrimination of weed species and density. Hyperspectral data were collected over various phenological time points in each year. Differentiation between plant species and weed density was not consistent across cropping systems, phenology, or season. Weed species were distinguishable across more spectra when no soybean was present. In 2016, weed species were not distinguishable, while in 2017, differentiation occurred at 4 wk after planting (WAP) and 15 WAP when weeds were present with soybean. When soybean was not present, differentiation occurred only at 5 WAP in 2016 and at 3 WAP through 15 WAP in 2017. Differentiation between weed densities did occur in both years with and without soybean present, but weed density could be differentiated across more spectra when soybean was not present. This study demonstrates that weed and crop reflectance is dynamic throughout the season and that spectral reflectance can be affected by weed species and density.}, number={2}, journal={WEED SCIENCE}, author={Basinger, Nicholas T. and Hestir, Erin L. and Jennings, Katherine M. and Monks, David W. and Everman, Wesley J. and Jordan, David L.}, year={2022}, month={Mar}, pages={198–212} } @article{joyner_cahoon_everman_collins_taylor_blythe_2022, title={HPPD-resistant cotton response to isoxaflutole applied preemergence and postemergence}, ISSN={["1550-2740"]}, DOI={10.1017/wet.2022.6}, abstractNote={AbstractStudies were conducted in 2019 and 2020 in Lewiston, NC, to determine the crop response of 4-hydroxyphenylpyrivate dioxygenase (HPPD)-resistant cotton to isoxaflutole (IFT) and other cotton herbicides as part of a cotton weed management program that included herbicides applied preemergence, early postemergence (EPOST), and mid-postemergence (MPOST). IFT was applied PRE at 105 g ha−1 alone and in various combinations with acetochlor, diuron, fluometuron, fluridone, fomesafen, pendimethalin, and pyrithiobac. EPOST treatments included IFT at 53 or 105 g ha−1 alone or in combination with glyphosate or glufosinate, or dimethenamid-P + glufosinate. Glyphosate + glufosinate was applied MPOST to all treatments except the nontreated control. Cotton injury from IFT applied PRE was minimal (0% to 3%). Injury following EPOST application of dimethenamid-P + glufosinate ranged from 3% to 5% and 6% to 9% in 2019 and 2020, respectively. In both years, injury from IFT applied PRE followed by IFT applied EPOST never exceeded injury from IFT applied PRE followed by dimethenamid-P + glufosinate. Isoxaflutole applied PRE followed by IFT applied EPOST at 105 g ha−1 resulted in 0% to 2% cotton injury, indicating that IFT can be applied either PRE or EPOST with minimal risk to cotton. Late-season cotton height and cotton lint yield were not affected by any herbicide treatment. The experimental HPPD-resistant cotton cultivar was minimally injured by IFT applied PRE and EPOST, it tolerated standard cotton herbicides, and yield loss was not observed. Given these results, HPPD-resistant cotton and IFT may be integrated into cotton weed management systems with minimal risk for cotton injury and provide an additional effective mechanism of action for managing troublesome weeds in cotton.}, journal={WEED TECHNOLOGY}, author={Joyner, Joshua D. and Cahoon, Charles W. and Everman, Wesley J. and Collins, Guy D. and Taylor, Zachary R. and Blythe, Andrew C.}, year={2022}, month={Feb} } @article{cahoon_jordan_tranel_york_riggins_seagroves_inman_everman_leon_2022, title={In-field assessment of EPSPS amplification on fitness cost in mixed glyphosate-resistant and glyphosate-sensitive populations of Palmer amaranth (Amaranthus palmeri)}, volume={10}, ISSN={["1550-2759"]}, url={https://doi.org/10.1017/wsc.2022.60}, DOI={10.1017/wsc.2022.60}, abstractNote={AbstractComparing fitness of herbicide-resistant and herbicide-susceptible weed biotypes is important for managing herbicide resistance. Previous research suggests there is little to no fitness penalty from amplification of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene (a mechanism of glyphosate resistance) in Palmer amaranth (Amaranthus palmeri S. Watson) in controlled studies in the greenhouse or growth chamber. A field study was conducted in North Carolina at three locations naturally infested with A. palmeri to determine vegetative, reproductive, and germination fitness of plants with and without EPSPS amplification grown season-long with cotton (Gossypium hirsutum L.). Seed number was not correlated with EPSPS copy number. However, when plants were binned into two groups, those having an EPSPS copy number ≥2 (relative to reference genes) and those having an EPSPS copy number <2, plant fresh weight and seed number were 1.4 and 1.6 times greater, respectively, for plants with fewer than 2 EPSPS copies. Amaranthus palmeri height and seed germination, and yield of cotton, did not differ when comparing the two binned groups. These data suggest that A. palmeri plants with EPSPS amplification are relatively less fit in the absence of glyphosate, but this reduced fitness does not translate into differences in interference with cotton.}, journal={WEED SCIENCE}, author={Cahoon, Charles W. and Jordan, David L. and Tranel, Patrick J. and York, Alan C. and Riggins, Chance and Seagroves, Richard and Inman, Matthew and Everman, Wesley and Leon, Ramon}, year={2022}, month={Oct} } @article{spoth_haring_everman_reberg-horton_greene_flessner_2022, title={Narrow-windrow burning to control seeds of Italian ryegrass (Lolium perenne ssp. multiflorum) in wheat and Palmer amaranth (Amaranthus palmeri) in soybean}, volume={9}, ISSN={["1550-2740"]}, url={https://doi.org/10.1017/wet.2022.70}, DOI={10.1017/wet.2022.70}, abstractNote={AbstractNarrow-windrow burning (NWB) is a form of harvest weed seed control in which crop residues and weed seeds collected by the combine are concentrated into windrows and subsequently burned. The objectives of this study were to determine how NWB will 1) affect seed survival of Italian ryegrass in wheat and Palmer amaranth in soybean and 2) determine whether a relationship exists between NWB heat index (HI; the sum of temperatures above ambient) or effective burn time (EBT; the cumulative number of seconds temperatures exceed 200 C) and the post-NWB seed survival of both species. Average soybean and wheat windrow HI totaled 140,725 ± 14,370 and 66,196 ± 6224 C, and 259 ± 27 and 116 ± 12 s of EBT, respectively. Pre-NWB versus post-NWB germinability testing revealed an estimated seed kill rate of 79.7% for Italian ryegrass, and 86.3% for Palmer amaranth. Non-linear two-parameter exponential regressions between seed kill and HI or EBT indicated NWB at an HI of 146,000 C and 277 s of EBT potentially kills 99% of Palmer amaranth seed. Seventy-six percent of soybean windrow burning events resulted in estimated Palmer amaranth seed kill rates greater than 85%. Predicted Italian ryegrass seed kill was greater than 97% in all but two wheat NWB events; therefore, relationships were not calculated. These results validate the effectiveness of the ability of NWB to reduce seed survival, thereby improving weed management and combating herbicide resistance.}, journal={WEED TECHNOLOGY}, author={Spoth, Matthew P. and Haring, Steven C. and Everman, Wesley and Reberg-Horton, Chris and Greene, Wykle C. and Flessner, Michael L.}, year={2022}, month={Sep} } @article{ethridge_locke_everman_jordan_leon_2022, title={Response of Maize, Cotton, and Soybean to Increased Crop Density in Heterogeneous Planting Arrangements}, volume={12}, ISSN={2073-4395}, url={http://dx.doi.org/10.3390/agronomy12051238}, DOI={10.3390/agronomy12051238}, abstractNote={The reduction of row spacing and increase of crop population density are important tools for maximizing crop yield. For this strategy to be effective, the crop population should not create intraspecific crop competition that penalizes yield. Thus, planting arrangements that increase light interception throughout the canopy without increasing row spacing might be needed to maintain yield. In this study, heterogeneous planting arrangements on evenly spaced rows were analyzed for maize (Zea mays L.), cotton (Gossypium hirsutum L.), and soybean (Glycine max (L.) Merr.). Each crop had four planting arrangements: (1) normal density in all rows, considered the control, (2) doubled density in all rows, (3) a sequential arrangement of normal and tripled densities (each in every other row; NTNT), and (4) normal-tripled-tripled-normal (NTTN). Maize and cotton did not exhibit changes in growth and architecture when comparing uniform and variable planting arrangements. Soybeans were more adaptable and increased biomass production by 44% to 45% in variable arrangements. None of the crops showed differences in yield due to planting arrangement, so the use of rows with different densities might not be needed when using high densities to maximize yield.}, number={5}, journal={Agronomy}, publisher={MDPI AG}, author={Ethridge, Sandra R. and Locke, Anna M. and Everman, Wesley J. and Jordan, David L. and Leon, Ramon G.}, year={2022}, month={May}, pages={1238} } @article{jones_cahoon_leon_everman_2022, title={Surveying stakeholder's perception of glufosinate and use in North Carolina}, volume={5}, ISSN={["1550-2740"]}, url={https://doi.org/10.1017/wet.2022.31}, DOI={10.1017/wet.2022.31}, abstractNote={AbstractGlufosinate is among the few remaining effective herbicides for postemergence weed control in North Carolina crops. The evolution of glufosinate resistance in key weeds is currently not widespread in North Carolina, but to better assess the current status of glufosinate effectiveness, surveys were distributed at Extension meetings in 2019 and 2020. The surveys were designed to provide information about North Carolina farmers’ perception of glufosinate and its use. Survey results indicate that many North Carolina farmers (≥26%) apply glufosinate at the correct timing (5- to 10-cm weeds). In addition, North Carolina farmers (≥22%) are applying glufosinate as a complementary herbicide to other efficacious herbicides and to control herbicide-resistant weeds, suggesting that glufosinate is part of a diverse chemical weed management plan. Conversely, survey findings indicated that some farmers (13% to 17%) rely exclusively on glufosinate for weed control. Additionally, 28% to 30% of farmers reported glufosinate control failures, and control failures were observed on several weed species among corn, cotton, and soybean crops. The results of the survey suggest that most North Carolina farmers are currently stewarding glufosinate, but they also support the need for Extension personnel to keep educating farmers on how to correctly use glufosinate to delay the evolution of glufosinate-resistant weeds. Semiannual surveys should be distributed to monitor where glufosinate control failures occur and the weed species not being controlled.}, journal={WEED TECHNOLOGY}, author={Jones, Eric A. L. and Cahoon, Charles W. and Leon, Ramon G. and Everman, Wesley J.}, year={2022}, month={May} } @article{jones_austin_dunne_cahoon_jennings_leon_everman_2022, title={Utilization of image-based spectral reflectance to detect herbicide resistance in glufosinate-resistant and glufosinate-susceptible plants: a proof of concept}, volume={12}, ISSN={["1550-2759"]}, url={https://doi.org/10.1017/wsc.2022.68}, DOI={10.1017/wsc.2022.68}, abstractNote={AbstractGlufosinate is an effective postemergence herbicide, and overreliance on this herbicide for weed control is likely to increase and select for glufosinate-resistant weeds. Common assays to confirm herbicide resistance are dose–response and molecular sequencing techniques; both can require significant time, labor, unique technical equipment, and a specialized skillset to perform. As an alternative, we propose an image-based approach that uses a relatively inexpensive multispectral sensor designed for unmanned aerial vehicles to measure and quantify surface reflectance from glufosinate-treated leaf disks. Leaf disks were excised from a glufosinate-resistant and glufosinate-susceptible corn (Zea mays L.), cotton (Gossypium hirsutum L.), and soybean [Glycine max (L.) Merr.] varieties and placed into a 24-well plate containing eight different concentrations (0 to 10 mM) of glufosinate for 48 h. Multispectral images were collected after the 48-h incubation period across five discrete wave bands: blue (475 to 507 nm), green (560 to 587 nm), red (668to 682 nm), red edge (717 to 729 nm), and near infrared (842 to 899 nm). The green leaf index (GLI; a metric to measure chlorophyll content) was utilized to determine relationships between measured reflectance from the tested wave bands from the treated leaf disks and the glufosinate concentration. Clear differences of spectral reflectance were observed between the corn, cotton, and soybean leaf disks of the glufosinate-resistant and glufosinate-susceptible varieties at the 10 mM concentration for select wave bands and GLI. Leaf disks from two additional glufosinate-resistant and glufosinate-susceptible varieties of each crop were subjected to a similar assay with two concentrations: 0 and 10 mM. No differences of spectral reflectance were observed from the corn and soybean varieties in all wave bands and the GLI. The leaf disks of the glufosinate-resistant and glufosinate-susceptible cotton varieties were spectrally distinct in the green, blue, and red-edge wave bands. The results provide a basis for rapidly detecting glufosinate-resistant plants via spectral reflectance. Future research will need to determine the glufosinate concentrations, useful wave bands, and susceptible/resistant thresholds for weeds that evolve resistance.}, journal={WEED SCIENCE}, author={Jones, Eric A. L. and Austin, Robert and Dunne, Jeffrey C. and Cahoon, Charles W. and Jennings, Katherine M. and Leon, Ramon G. and Everman, Wesley J.}, year={2022}, month={Dec} } @article{glaspie_jones_penner_pawlak_everman_2021, title={Effect of Clay, Soil Organic Matter, and Soil pH on Initial and Residual Weed Control with Flumioxazin}, volume={11}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy11071326}, abstractNote={Greenhouse studies were conducted to evaluate the effects of soil organic matter content and soil pH on initial and residual weed control with flumioxazin by planting selected weed species in various lab-made and field soils. Initial control was determined by planting weed seeds into various lab-made and field soils treated with flumioxazin (71 g ha−1). Seeds of Echinochloa crus-galli (barnyard grass), Setaria faberi (giant foxtail), Amaranthus retroflexus (redroot pigweed), and Abutilon theophrasti (velvetleaf) were incorporated into the top 1.3 cm of each soil at a density of 100 seeds per pot, respectively. Emerged plants were counted and removed in both treated and non-treated pots two weeks after planting and each following week for six weeks. Flumioxazin control was evaluated by calculating percent emergence of weeds in treated soils compared to the emergence of weeds in non-treated soils. Clay content was not found to affect initial flumioxazin control of any tested weed species. Control of A. theophrasti, E. crus-galli, and S. faberi was reduced as soil organic matter content increased. The control of A. retroflexus was not affected by organic matter. Soil pH below 6 reduced flumioxazin control of A. theophrasti, and S. faberi but did not affect the control of A. retroflexus and E. crus-galli. Flumioxazin residual control was determined by planting selected weed species in various lab-made and field soils 0, 2, 4, 6, and 8 weeks after treatment. Eight weeks after treatment, flumioxazin gave 0% control of A. theophrasti and S. faberi in all soils tested. Control of A. retroflexus and Chenopodium album (common lambsquarters) was 100% for the duration of the experiment, except when soil organic matter content was greater than 3% or the soil pH 7. Eight weeks after treatment, 0% control was only observed for common A. retroflexus and C. album in organic soil (soil organic matter > 80%) or when soil pH was above 7. Control of A. theophrasti and S. faberi decreased as soil organic matter content and soil pH increased. Similar results were observed when comparing lab-made soils to field soils; however, differences in control were observed between lab-made organic matter soils and field organic matter soils. Results indicate that flumioxazin can provide control ranging from 75–100% for two to six weeks on common weed species.}, number={7}, journal={AGRONOMY-BASEL}, author={Glaspie, Calvin F. and Jones, Eric A. L. and Penner, Donald and Pawlak, John A. and Everman, Wesley J.}, year={2021}, month={Jul} } @article{mahoney_jordan_hare_leon_roma-burgos_vann_jennings_everman_cahoon_2021, title={Palmer Amaranth (Amaranthus palmeri) Growth and Seed Production When in Competition with Peanut and Other Crops in North Carolina}, volume={11}, ISSN={["2073-4395"]}, url={https://doi.org/10.3390/agronomy11091734}, DOI={10.3390/agronomy11091734}, abstractNote={Palmer amaranth (Amaranthus palmeri S. Wats.) is a highly competitive weed that can be difficult to manage in many cropping systems. Research to date has not quantified the growth and development of A. palmeri in a manner that allows direct comparisons across cropping systems. Research was conducted to compare the growth, development, and seed production of A. palmeri when competing with corn (Zea mays L.), cotton (Gossypium hirsutum L.), peanut (Arachis hypogaea L.), and soybean [Glycine max (L.) Merr.] when emerging with crops or emerging three weeks after crops emerge. Regardless of when A. palmeri emerged, seed production was greatest and similar in cotton and peanut and exceeded that of corn and soybean; seed production in soybean exceeded that of corn. However, seed production was approximately 10-fold greater when A. palmeri emerged with crops compared with emergence three weeks later. These results illustrate the importance of controlling weeds during the first three weeks of the season relative to contributions of A. palmeri to the weed seed bank and is the first report comparing seed production in presence of these crops in a manner allowing a statistical comparison of seed production and highlighting the importance of crop sequence for seed bank management.}, number={9}, journal={AGRONOMY-BASEL}, publisher={MDPI AG}, author={Mahoney, Denis J. and Jordan, David L. and Hare, Andrew T. and Leon, Ramon G. and Roma-Burgos, Nilda and Vann, Matthew C. and Jennings, Katherine M. and Everman, Wesley J. and Cahoon, Charles W.}, year={2021}, month={Sep} } @article{flessner_burke_dille_everman_vangessel_tidemann_manuchehri_soltani_sikkema_2021, title={Potential wheat yield loss due to weeds in the United States and Canada}, volume={35}, ISSN={["1550-2740"]}, DOI={10.1017/wet.2021.78}, abstractNote={AbstractYield losses due to weeds are a major threat to wheat production and economic well-being of farmers in the United States and Canada. The objective of this Weed Science Society of America (WSSA) Weed Loss Committee report is to provide estimates of wheat yield and economic losses due to weeds. Weed scientists provided both weedy (best management practices but no weed control practices) and weed-free (best management practices providing >90% weed control) average yield from replicated research trials in both winter and spring wheat from 2007 to 2017. Winter wheat yield loss estimates ranged from 2.9% to 34.4%, with a weighted average (by production) of 25.6% for the United States, 2.9% for Canada, and 23.4% combined. Based on these yield loss estimates and total production, the potential winter wheat loss due to weeds is 10.5, 0.09, and 10.5 billion kg with a potential loss in value of US$2.19, US$0.19, and US$2.19 billion for the United States, Canada, and combined, respectively. Spring wheat yield loss estimates ranged from 7.9% to 47.0%, with a weighted average (by production) of 33.2% for the United States, 8.0% for Canada, and 19.5% combined. Based on this yield loss estimate and total production, the potential spring wheat loss is 4.8, 1.6, and 6.6 billion kg with a potential loss in value of US$1.14, US$0.37, and US$1.39 billion for the United States, Canada, and combined, respectively. Yield loss in this analysis is greater than some previous estimates, likely indicating an increasing threat from weeds. Climate is affecting yield loss in winter wheat in the Pacific Northwest, with percent yield loss being highest in wheat-fallow systems that receive less than 30 cm of annual precipitation. Continued investment in weed science research for wheat is critical for continued yield protection.}, number={6}, journal={WEED TECHNOLOGY}, author={Flessner, Michael L. and Burke, Ian C. and Dille, J. Anita and Everman, Wesley J. and VanGessel, Mark J. and Tidemann, Breanne and Manuchehri, Misha R. and Soltani, Nader and Sikkema, Peter H.}, year={2021}, month={Dec}, pages={916–923} } @article{sanders_jones_austin_roberson_richardson_everman_2021, title={Remote Sensing for Palmer Amaranth (Amaranthus palmeri S. Wats.) Detection in Soybean (Glycine max (L.) Merr.)}, volume={11}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy11101909}, abstractNote={Field studies were conducted in 2016 and 2017 to determine if multispectral imagery collected from an unmanned aerial vehicle (UAV) equipped with a five-band sensor could successfully identify Palmer amaranth (Amaranthus palmeri) infestations of various densities growing among soybeans (Glycine max [L.] Merr.). The multispectral sensor captures imagery from five wavebands: 475 (blue), 560 (green), 668 (red), 840 (near infrared [NIR]), and 717 nm (red-edge). Image analysis was performed to examine the spectral properties of discrete Palmer amaranth and soybean plants at various weed densities using these wavebands. Additionally, imagery was subjected to supervised classification to evaluate the usefulness of classification as a tool to differentiate the two species in a field setting. Date was a significant factor influencing the spectral reflectance values of the Palmer amaranth densities. The effects of altitude on reflectance were less clear and were dependent on band and density being evaluated. The near infrared (NIR) waveband offered the best resolution in separating Palmer amaranth densities. Spectral separability in the other wavebands was less defined, although low weed densities were consistently able to be discriminated from high densities. Palmer amaranth and soybean were found to be spectrally distinct regardless of imaging date, weed density, or waveband. Soybean exhibited overall lower reflectance intensity than Palmer amaranth across all wavebands. The reflectance of both species within blue, green, red, and red-edge wavebands declined as the season progressed, while reflectance in NIR increased. Near infrared and red-edge wavebands were shown to be the most useful for species discrimination and maintained their utility at most weed densities. Palmer amaranth weed densities were found to be spectrally distinct from one another in all wavebands, with greatest distinction when using the red, NIR and red-edge wavebands. Supervised classification in a two-class system was consistently able to discriminate between Palmer amaranth and soybean with at least 80% overall accuracy. The incorporation of a weed density component into these classifications introduced an error of 65% or greater into these classifications. Reducing the number of classes in a supervised classification system could improve the accuracy of discriminating between Palmer amaranth and soybean.}, number={10}, journal={AGRONOMY-BASEL}, author={Sanders, John T. and Jones, Eric A. L. and Austin, Robert and Roberson, Gary T. and Richardson, Robert J. and Everman, Wesley J.}, year={2021}, month={Oct} } @article{schwartz-lazaro_shergill_evans_bagavathiannan_beam_bish_bond_bradley_curran_davis_et al._2021, title={Seed-shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 3: Drivers of seed shatter}, ISSN={["1550-2759"]}, DOI={10.1017/wsc.2021.74}, abstractNote={AbstractSeed retention, and ultimately seed shatter, are extremely important for the efficacy of harvest weed seed control (HWSC) and are likely influenced by various agroecological and environmental factors. Field studies investigated seed-shattering phenology of 22 weed species across three soybean [Glycine max (L.) Merr.]-producing regions in the United States. We further evaluated the potential drivers of seed shatter in terms of weather conditions, growing degree days, and plant biomass. Based on the results, weather conditions had no consistent impact on weed seed shatter. However, there was a positive correlation between individual weed plant biomass and delayed weed seed–shattering rates during harvest. This work demonstrates that HWSC can potentially reduce weed seedbank inputs of plants that have escaped early-season management practices and retained seed through harvest. However, smaller individuals of plants within the same population that shatter seed before harvest pose a risk of escaping early-season management and HWSC.}, journal={WEED SCIENCE}, author={Schwartz-Lazaro, Lauren M. and Shergill, Lovreet S. and Evans, Jeffrey A. and Bagavathiannan, Muthukumar V and Beam, Shawn C. and Bish, Mandy D. and Bond, Jason A. and Bradley, Kevin W. and Curran, William S. and Davis, Adam S. and et al.}, year={2021}, month={Nov} } @article{moore_jennings_monks_jordan_boyette_leon_mahoney_everman_cahoon_2021, title={Susceptibility of Palmer amaranth accessions in North Carolina to atrazine, dicamba, S-metolachlor, and 2,4-D}, volume={11}, ISSN={["2374-3832"]}, url={https://doi.org/10.1002/cft2.20136}, DOI={10.1002/cft2.20136}, abstractNote={Core Ideas All of the 120 accessions of Palmer amaranth collected in the Coastal Plain of North Carolina were controlled by atrazine and dicamba applied at field use rates in the greenhouse. Reduced sensitivity among accessions was noted when S‐metolachlor and 2,4‐D were applied to Palmer amaranth at field use rates in the greenhouse. Additional research is needed to determine if reduced sensitivity of Palmer amaranth to S‐metolachlor and 2,4‐D is associated with evolved resistance. }, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, publisher={Wiley}, author={Moore, Levi D. and Jennings, Katherine M. and Monks, David W. and Jordan, David L. and Boyette, Michael D. and Leon, Ramon G. and Mahoney, Dennis J. and Everman, Wesley J. and Cahoon, Charles W.}, year={2021}, month={Nov} } @article{frisvold_albright_ervin_owen_norsworthy_dentzman_hurley_jussaume_gunsolus_everman_2020, title={Do farmers manage weeds on owned and rented land differently? Evidence from US corn and soybean farms}, volume={76}, ISSN={["1526-4998"]}, DOI={10.1002/ps.5737}, abstractNote={AbstractBACKGROUNDIt has been frequently argued that growers have less incentive to manage the evolution and spread of herbicide‐resistant weeds on leased than on owned land. This is because resistance management provides long‐term rather than short‐term benefits that operators may be less assured of capturing on land they do not own. Yet, empirical evidence supporting this argument has been lacking.RESULTSThis study reports on results from a large‐scale national survey of weed management and other crop production practices on US agricultural fields. Up to 11 weed management practices were compared across owner‐operated versus renter‐operated fields. Analysis of survey data from corn and soybean fields did not support the hypothesis that adoption of resistance management practices is lower on rented acres. In most instances, there were no statistically significant differences in herbicide use or weed management practices on rented versus owned land. This was true at both national and regional levels of analysis. Where there were significant differences, practices associated with greater herbicide resistance management were, as often as not, more prevalent on rented than owned land.CONCLUSIONSA useful area of future research would be to test for land tenure differences in resistance management using multivariate analysis to control for confounding effects. Unobserved farmer or land characteristics may be confounding results and masking land tenure effects. Results here, however, suggest that these other effects are dominating any obvious disincentive effects of land leasing on resistance management. Of greater concern, the adoption of key resistance management practices was low on both owned and rented land. © 2020 Society of Chemical Industry}, number={6}, journal={PEST MANAGEMENT SCIENCE}, author={Frisvold, George B. and Albright, Joshua and Ervin, David E. and Owen, Micheal D. K. and Norsworthy, Jason K. and Dentzman, Katherine E. and Hurley, Terrance M. and Jussaume, Raymond A. and Gunsolus, Jeffrey L. and Everman, Wesley}, year={2020}, month={Jun}, pages={2030–2039} } @article{hare_jordan_leon_edmisten_post_cahoon_everman_mahoney_inman_2020, title={Influence of timing and intensity of weed management on crop yield and contribution to weed emergence in cotton the following year}, volume={6}, ISSN={["2374-3832"]}, url={https://doi.org/10.1002/cft2.20021}, DOI={10.1002/cft2.20021}, abstractNote={AbstractAdequate weed control is important in protecting crop yield and allowing efficient harvest in North Carolina. Data in the literature are limited with respect to direct comparisons of weed control and yield across multiple crops. Research is also limited in terms of documenting the impact of weed control in one crop on weed populations in the crop planted the following season. Experiments were conducted in North Carolina to determine weed control and yield of corn (Zea mays L.), cotton (Gossypium hirsutum L.), and soybean [Glycine max (L.) Merr.] in the same experiment when herbicides were applied postemergence at different timings (Year 1) and to determine how weed control translated into weed populations and cotton yield the following year (Year 2). Herbicides were applied 2 or 6 wk after planting (WAP); 2 and 4 WAP; 4 and 6 WAP; and 2, 4, and 6 WAP. At Lewiston‐Woodville, common ragweed (Ambrosia artemisiifolia L.) and Texas millet (Urochloa texana L.) were present. At Rocky Mount, Palmer amaranth (Amanthus palmeri S. Wats) and large crabgrass (Digitaria sanguinalis L.) were present. A single postemergence application of herbicide protected yield from weed interference in corn, whereas in most instances multiple herbicide applications were needed in cotton and to a degree in soybean. Weed densities in Year 2 in cotton were negatively correlated with weed control the previous year in corn, cotton, and soybean. Densities of common ragweed and Palmer amaranth 3 WAP in Year 2 were higher in cotton when the preceding crop was cotton or soybean rather than corn when herbicides were not applied; no difference was noted when comparing cotton and soybean. In some instances, sequential applications of herbicides resulted in lower weed densities the following year in cotton. These results demonstrate the importance of timely, sequential herbicide applications for weed control in cotton and soybean and in some instances the positive benefits on weed populations the following year in cotton.}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, publisher={Wiley}, author={Hare, Andrew T. and Jordan, David L. and Leon, Ramon G. and Edmisten, Keith L. and Post, Angela R. and Cahoon, Charles W. and Everman, Wesley J. and Mahoney, Denis J. and Inman, Matthew D.}, year={2020} } @article{basinger_jennings_hestir_monks_jordan_everman_2020, title={Phenology affects differentiation of crop and weed species using hyperspectral remote sensing}, volume={34}, ISSN={["1550-2740"]}, url={https://doi.org/10.1017/wet.2020.92}, DOI={10.1017/wet.2020.92}, abstractNote={AbstractThe effect of plant phenology and canopy structure of four crops and four weed species on reflectance spectra were evaluated in 2016 and 2017 using in situ spectroscopy. Leaf-level and canopy-level reflectance were collected at multiple phenologic time points in each growing season. Reflectance values at 2 wk after planting (WAP) in both years indicated strong spectral differences between species across the visible (VIS; 350–700 nm), near-infrared (NIR; 701–1,300 nm), shortwave-infrared I (SWIR1; 1,301–1,900 nm), and shortwave-infrared II (SWIR2; 1,901–2,500 nm) regions. Results from this study indicate that plant spectral reflectance changes with plant phenology and is influenced by plant biophysical characteristics. Canopy-level differences were detected in both years across all dates except for 1 WAP in 2017. Species with similar canopy types (e.g., broadleaf prostrate, broadleaf erect, or grass/sedge) were more readily discriminated from species with different canopy types. Asynchronous phenology between species also resulted in spectral differences between species. SWIR1 and SWIR2 wavelengths are often not included in multispectral sensors but should be considered for species differentiation. Results from this research indicate that wavelengths in SWIR1 and SWIR2 in conjunction with VIS and NIR reflectance can provide differentiation across plant phenologies and, therefore should be considered for use in future sensor technologies for species differentiation.}, number={6}, journal={WEED TECHNOLOGY}, author={Basinger, Nicholas T. and Jennings, Katherine M. and Hestir, Erin L. and Monks, David W. and Jordan, David L. and Everman, Wesley J.}, year={2020}, month={Dec}, pages={897–908} } @article{schwartz-lazaro_shergill_evans_bagavathiannan_beam_bish_bond_bradley_curran_davis_et al._2021, title={Seed-shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 1: Broadleaf species}, volume={69}, ISSN={["1550-2759"]}, DOI={10.1017/wsc.2020.80}, abstractNote={AbstractPotential effectiveness of harvest weed seed control (HWSC) systems depends upon seed shatter of the target weed species at crop maturity, enabling its collection and processing at crop harvest. However, seed retention likely is influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed-shatter phenology in 13 economically important broadleaf weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to 4 wk after physiological maturity at multiple sites spread across 14 states in the southern, northern, and mid-Atlantic United States. Greater proportions of seeds were retained by weeds in southern latitudes and shatter rate increased at northern latitudes. Amaranthus spp. seed shatter was low (0% to 2%), whereas shatter varied widely in common ragweed (Ambrosia artemisiifolia L.) (2% to 90%) over the weeks following soybean physiological maturity. Overall, the broadleaf species studied shattered less than 10% of their seeds by soybean harvest. Our results suggest that some of the broadleaf species with greater seed retention rates in the weeks following soybean physiological maturity may be good candidates for HWSC.}, number={1}, journal={WEED SCIENCE}, author={Schwartz-Lazaro, Lauren M. and Shergill, Lovreet S. and Evans, Jeffrey A. and Bagavathiannan, Muthukumar V and Beam, Shawn C. and Bish, Mandy D. and Bond, Jason A. and Bradley, Kevin W. and Curran, William S. and Davis, Adam S. and et al.}, year={2021}, month={Jan}, pages={95–103} } @article{schwartz-lazaro_shergill_evans_bagavathiannan_beam_bish_bond_bradley_curran_davis_et al._2021, title={Seed-shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 2: Grass species}, volume={69}, ISSN={["1550-2759"]}, DOI={10.1017/wsc.2020.79}, abstractNote={AbstractSeed shatter is an important weediness trait on which the efficacy of harvest weed seed control (HWSC) depends. The level of seed shatter in a species is likely influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed shatter of eight economically important grass weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to 4 wk after maturity at multiple sites spread across 11 states in the southern, northern, and mid-Atlantic United States. From soybean maturity to 4 wk after maturity, cumulative percent seed shatter was lowest in the southern U.S. regions and increased moving north through the states. At soybean maturity, the percent of seed shatter ranged from 1% to 70%. That range had shifted to 5% to 100% (mean: 42%) by 25 d after soybean maturity. There were considerable differences in seed-shatter onset and rate of progression between sites and years in some species that could impact their susceptibility to HWSC. Our results suggest that many summer annual grass species are likely not ideal candidates for HWSC, although HWSC could substantially reduce their seed output during certain years.}, number={1}, journal={WEED SCIENCE}, author={Schwartz-Lazaro, Lauren M. and Shergill, Lovreet S. and Evans, Jeffrey A. and Bagavathiannan, Muthukumar V and Beam, Shawn C. and Bish, Mandy D. and Bond, Jason A. and Bradley, Kevin W. and Curran, William S. and Davis, Adam S. and et al.}, year={2021}, month={Jan}, pages={104–110} } @article{mahoney_jordan_roma-burgos_jennings_leon_vann_everman_cahoon_2020, title={Susceptibility of Palmer amaranth (Amaranthus palmeri) to herbicides in accessions collected from the North Carolina Coastal Plain}, volume={68}, ISSN={["1550-2759"]}, url={http://dx.doi.org/10.1017/wsc.2020.67}, DOI={10.1017/wsc.2020.67}, abstractNote={AbstractPalmer amaranth (Amaranthus palmeri S. Watson) populations resistant to acetolactate synthase (ALS)-inhibiting herbicides and glyphosate are fairly common throughout the state of North Carolina (NC). This has led farm managers to rely more heavily on herbicides with other sites of action (SOA) for A. palmeri control, especially protoporphyrinogen oxidase and glutamine synthetase inhibitors. In the fall of 2016, seeds from A. palmeri populations were collected from the NC Coastal Plain, the state’s most prominent agricultural region. In separate experiments, plants with 2 to 4 leaves from the 110 populations were treated with field use rates of glyphosate, glufosinate-ammonium, fomesafen, mesotrione, or thifensulfuron-methyl. Percent visible control and survival were evaluated 3 wk after treatment. Survival frequencies were highest following glyphosate (99%) or thifensulfuron-methyl (96%) treatment. Known mutations conferring resistance to ALS inhibitors were found in populations surviving thifensulfuron-methyl application (Ala-122-Ser, Pro-197-Ser, Trp-574-Leu, and/or Ser-653-Asn), in addition to a new mutation (Ala-282-Asp) that requires further investigation. Forty-two populations had survivors after mesotrione application, with one population having 17% survival. Four populations survived fomesafen treatment, while none survived glufosinate. Dose–response studies showed an increase in fomesafen needed to kill 50% of two populations (LD50); however, these rates were far below the field use rate (less than 5 g ha−1). In two populations following mesotrione dose–response studies, a 2.4- to 3.3-fold increase was noted, with LD90 values approaching the field use rate (72.8 and 89.8 g ha−1). Screening of the progeny of individuals surviving mesotrione confirmed the presence of resistance alleles, as there were a higher number of survivors at the 1X rate compared with the parent population, confirming resistance to mesotrione. These data suggest A. palmeri resistant to chemistries other than glyphosate and thifensulfuron-methyl are present in NC, which highlights the need for weed management approaches to mitigate the evolution and spread of herbicide-resistant populations.}, number={6}, journal={WEED SCIENCE}, publisher={Cambridge University Press (CUP)}, author={Mahoney, Denis J. and Jordan, David L. and Roma-Burgos, Nilda and Jennings, Katherine M. and Leon, Ramon G. and Vann, Matthew C. and Everman, Wesley J. and Cahoon, Charles W.}, year={2020}, month={Nov}, pages={582–593} } @article{mahoney_jordan_hare_roma-burgos_jennings_leon_vann_everman_cahoon_2021, title={The influence of soybean population and POST herbicide application timing on in-season and subsequent-season Palmer amaranth (Amaranthus palmeri) control and economic returns}, volume={35}, ISSN={["1550-2740"]}, DOI={10.1017/wet.2020.87}, abstractNote={AbstractOverreliance on herbicides for weed control has led to the evolution of herbicide-resistant Palmer amaranth populations. Farm managers should consider the long-term consequences of their short-term management decisions, especially when considering the soil weed seedbank. The objectives of this research were to (1) determine how soybean population and POST herbicide application timing affects in-season Palmer amaranth control and soybean yield, and (2) how those variables influence Palmer amaranth densities and cotton yields the following season. Soybeans were planted (19-cm row spacing) at a low-, medium-, and high-density population (268,000, 546,000, and 778,000 plants ha–1, respectively). Fomesafen and clethodim (280 and 210 g ai ha–1, respectively) were applied at the VE, V1, or V2 to V3 soybean growth stage. Nontreated plots were also included to assess the effect of soybean population alone. The following season, cotton was planted into these plots so as to understand the effects of soybean planting population on Palmer amaranth densities in the subsequent crop. When an herbicide application occurred at the V1 or V2 to V3 soybean stage, weed control in the high-density soybean population increased 17% to 23% compared to the low-density population. Economic return was not influenced by soybean population and was increased 72% to 94% with herbicide application compared to no treatment. In the subsequent cotton crop, Palmer amaranth densities were 24% to 39% lower 3 wk after planting when following soybean sprayed with herbicides compared to soybean without herbicides. Additionally, Palmer amaranth densities in cotton were 19% lower when soybean was treated at the VE stage compared to later stages. Thus, increasing soybean population can improve Palmer amaranth control without adversely affecting economic returns and can reduce future weed densities. Reducing the weed seedbank and selection pressure from herbicides are critical in mitigating resistance evolution.}, number={1}, journal={WEED TECHNOLOGY}, author={Mahoney, Denis J. and Jordan, David L. and Hare, Andrew T. and Roma-Burgos, Nilda and Jennings, Katherine M. and Leon, Ramon G. and Vann, Matthew C. and Everman, Wesley J. and Cahoon, Charles W.}, year={2021}, month={Feb}, pages={106–112} } @article{acharya_thomas n. o'quinn_everman_mehl_2019, title={Effectiveness of Fungicides and Their Application Timing for the Management of Sorghum Foliar Anthracnose in the Mid-Atlantic United States}, volume={103}, ISSN={["1943-7692"]}, DOI={10.1094/PDIS-10-18-1867-RE}, abstractNote={ Sorghum anthracnose (Colletotrichum sublineola) reduces grain yield up to 50% but suggested management tactics have not yet been developed for the mid-Atlantic United States, where warm, wet conditions favor disease. Under factorial arrangement, five fungicides plus a nontreated control and four application timings were compared for foliar anthracnose control, yield, and profitability of fungicide use in grain sorghum over eight site-years in Virginia and North Carolina. Anthracnose severity was rated at the hard dough stage, and grain yield was determined at harvest. Every percent increase in disease severity resulted in yield losses of 27 to 85 kg/ha. Pyraclostrobin and pyraclostrobin plus fluxapyroxad reduced anthracnose (P < 0.01), and three applications resulted in less disease and greater yield compared with single applications (P < 0.01). However, three applications exceed the labeled maximum application for the fungicides and are not economical. Among single applications, boot or flowering timings reduced disease, and flowering applications resulted in the overall greatest yield. Results suggest that when disease onset occurs at or prior to boot, a single application of pyraclostrobin-containing fungicide at or just prior to flowering reduces anthracnose, protects yield, and increases income. However, when disease is absent or severity is low prior to flowering, fungicide application may not be profitable. }, number={11}, journal={PLANT DISEASE}, author={Acharya, Bhupendra and Thomas N. O'Quinn and Everman, Wesley and Mehl, Hillary L.}, year={2019}, month={Nov}, pages={2804–2811} } @article{basinger_jennings_monks_jordan_everman_hestir_waldschmidt_smith_brownie_2019, title={Interspecific and intraspecific interference of Palmer amaranth (Amaranthus palmeri) and large crabgrass (Digitaria sanguinalis) in sweetpotato}, volume={67}, ISSN={["1550-2759"]}, DOI={10.1017/wsc.2019.16}, abstractNote={AbstractField studies were conducted in 2016 and 2017 in Clinton, NC, to determine the interspecific and intraspecific interference of Palmer amaranth (Amaranthus palmeri S. Watson) or large crabgrass [Digitaria sanguinalis (L.) Scop.] in ‘Covington’ sweetpotato [Ipomoea batatas (L.) Lam.]. Amaranthus palmeri and D. sanguinalis were established 1 d after sweetpotato transplanting and maintained season-long at 0, 1, 2, 4, 8 and 0, 1, 2, 4, 16 plants m−1 of row in the presence and absence of sweetpotato, respectively. Predicted yield loss for sweetpotato was 35% to 76% for D. sanguinalis at 1 to 16 plants m−1 of row and 50% to 79% for A. palmeri at 1 to 8 plants m−1 of row. Weed dry biomass per meter of row increased linearly with increasing weed density. Individual dry biomass of A. palmeri and D. sanguinalis was not affected by weed density when grown in the presence of sweetpotato. When grown without sweetpotato, individual weed dry biomass decreased 71% and 62% from 1 to 4 plants m−1 row for A. palmeri and D. sanguinalis, respectively. Individual weed dry biomass was not affected above 4 plants m−1 row to the highest densities of 8 and 16 plants m−1 row for A. palmeri and D. sanguinalis, respectively.}, number={4}, journal={WEED SCIENCE}, author={Basinger, Nicholas T. and Jennings, Katherine M. and Monks, David W. and Jordan, David L. and Everman, Wesley J. and Hestir, Erin L. and Waldschmidt, Matthew D. and Smith, Stephen C. and Brownie, Cavell}, year={2019}, month={Jul}, pages={426–432} } @article{basinger_jennings_monks_jordan_everman_hestir_bertucci_brownie_2019, title={Large crabgrass (Digitaria sanguinalis) and Palmer amaranth (Amaranthus palmeri) intraspecific and interspecific interference in soybean}, volume={67}, ISSN={["1550-2759"]}, url={https://doi.org/10.1017/wsc.2019.43}, DOI={10.1017/wsc.2019.43}, abstractNote={AbstractField studies were conducted in 2016 and 2017 at Clinton, NC, to quantify the effects of season-long interference of large crabgrass [Digitaria sanguinalis (L.) Scop.] and Palmer amaranth (Amaranthus palmeri S. Watson) on ‘AG6536’ soybean [Glycine max (L.) Merr.]. Weed density treatments consisted of 0, 1, 2, 4, and 8 plants m−2 for A. palmeri and 0, 1, 2, 4, and 16 plants m−2 for D. sanguinalis with (interspecific interference) and without (intraspecific interference) soybean to determine the impacts on weed biomass, soybean biomass, and seed yield. Biomass per square meter increased with increasing weed density for both weed species with and without soybean present. Biomass per square meter of D. sanguinalis was 617% and 37% greater when grown without soybean than with soybean, for 1 and 16 plants m−2 respectively. Biomass per square meter of A. palmeri was 272% and 115% greater when grown without soybean than with soybean for 1 and 8 plants m−2, respectively. Biomass per plant for D. sanguinalis and A. palmeri grown without soybean was greatest at the 1 plant m−2 density. Biomass per plant of D. sanguinalis plants across measured densities was 33% to 83% greater when grown without soybean compared with biomass per plant when soybean was present for 1 and 16 plants m−2, respectively. Similarly, biomass per plant for A. palmeri was 56% to 74% greater when grown without soybean for 1 and 8 plants m−2, respectively. Biomass per plant of either weed species was not affected by weed density when grown with soybean due to interspecific competition with soybean. Yield loss for soybean grown with A. palmeri ranged from 14% to 37% for densities of 1 to 8 plants m−2, respectively, with a maximum yield loss estimate of 49%. Similarly, predicted loss for soybean grown with D. sanguinalis was 0 % to 37% for densities of 1 to 16 m−2 with a maximum yield loss estimate of 50%. Soybean biomass was not affected by weed species or density. Results from these studies indicate that A. palmeri is more competitive than D. sanguinalis at lower densities, but that similar yield loss can occur when densities greater than 4 plants m−2 of either weed are present.}, number={6}, journal={WEED SCIENCE}, author={Basinger, Nicholas T. and Jennings, Katherine M. and Monks, David W. and Jordan, David L. and Everman, Wesley J. and Hestir, Erin L. and Bertucci, Matthew B. and Brownie, Cavell}, year={2019}, month={Nov}, pages={649–656} } @article{sanders_everman_austin_roberson_richardson_2019, title={Weed species differentiation using spectral reflectance and image classification}, volume={11007}, ISSN={["1996-756X"]}, url={http://dx.doi.org/10.1117/12.2519306}, DOI={10.1117/12.2519306}, abstractNote={Advancements in efficient unmanned aerial platforms and affordable sensors has led to renewed interest in remote sensing by agricultural producers and land managers for use as an efficient and convenient method of evaluating crop status and pest issues in their fields. For remote sensing to be employed as a viable and widespread tool for weed management, the accurate detection of distinct weed species must be possible through the use of analytical procedures on the resultant imagery. Additionally, the remote sensing platform and subsequent analysis must be capable of identifying these species across a wide range of heights. In 2017, a field study was performed to identify any weed height thresholds on the accurate detection and subsequent classification of three common broadleaf weed species in the southeastern United States: Palmer amaranth (Amaranthus palmeri), common ragweed (Ambrosia artemisiifolia) and sicklepod Senna obtusifolia) as well as the classification accuracy of image classifications performed on the species scale. Pots of the three species at heights of 5, 10, 15, and 30 cm were randomly arranged in a grid and 5-band multispectral imagery was collected at 15 m. Image analysis was used to identify the spectral reflectance behavior of the weed species and height combinations and to evaluate the accuracy of species based supervised classifications involving the three species. Supervised classification was able to discriminate between the three weed species with between 24-100% accuracy depending on height and species. Palmer amaranth classification accuracy was consistently 100%. Increased height of sicklepod and common ragweed plants did not reliably confer improved accuracy but the species were correctly identified with at least 24% and 60% accuracy, respectively.}, journal={ADVANCED ENVIRONMENTAL, CHEMICAL, AND BIOLOGICAL SENSING TECHNOLOGIES XV}, author={Sanders, J. T. and Everman, W. J. and Austin, R. and Roberson, G. T. and Richardson, R. J.}, year={2019} } @article{ervin_breshears_frisvold_hurley_dentzman_gunsolus_jussaume_owen_norsworthy_al mamun_et al._2019, title={Farmer Attitudes Toward Cooperative Approaches to Herbicide Resistance Management: A Common Pool Ecosystem Service Challenge}, volume={157}, ISSN={["1873-6106"]}, DOI={10.1016/j.ecolecon.2018.11.023}, abstractNote={Dramatic growth in herbicide-resistant (HR) weeds in the United States threatens farm profitability and may undercut environmentally beneficial farming practices. When HR weeds move across farm boundaries due to ecological processes or human action, a common pool resource challenge emerges, requiring farmer cooperation to manage such weeds effectively. We investigate the scope for cooperative management using responses to a national survey on HR weed issues to test a recursive model of three preconditions for collective action: (1) concern about HR weeds migrating from nearby lands; (2) communication with neighbors about HR weeds; and (3) belief that cooperation is necessary for effective resistance management. Results suggest that farmers who relied more on Extension educators regarding weed management, were more likely to satisfy each precondition. Further, concern about weeds resistant to multiple herbicides as well as concern about HR weed mobility positively influence concern about migration and views toward cooperation. Farmer time constraints and "techno-optimism" (a belief that herbicide discoveries will solve resistance problems) detract from the perceived need for cooperative approaches. A different set of factors significantly affect each precondition, suggesting heterogeneity in the underlying casual mechanisms. The findings can help tailor collective action to different socio-ecological settings experiencing HR weed resistance issues.}, journal={ECOLOGICAL ECONOMICS}, author={Ervin, David E. and Breshears, Elise H. and Frisvold, George B. and Hurley, Terrance and Dentzman, Katherine E. and Gunsolus, Jeffrey L. and Jussaume, Raymond A. and Owen, Micheal D. K. and Norsworthy, Jason K. and Al Mamun, Mustofa Mahmud and et al.}, year={2019}, month={Mar}, pages={237–245} } @article{besancon_penner_everman_2018, title={Reduced Translocation Is Associated with Antagonism of Glyphosate by Glufosinate in Giant Foxtail (Setaria faberi) and Velvetleaf (Abutilon theophrasti)}, volume={66}, ISSN={["1550-2759"]}, DOI={10.1017/wsc.2017.72}, abstractNote={Previous reports have underscored antagonism that may result from mixing glyphosate and glufosinate across a wide range of application rates and for various broadleaf and grass weed species, but no investigation has been conducted to characterize glyphosate absorption and translocation when combined with glufosinate. The objectives of this study were to evaluate herbicide efficacy and assess herbicide interaction and physiological response with combinations of glyphosate and glufosinate on common lambsquarters, velvetleaf, and giant foxtail. Greenhouse studies to determine interaction resulted in strong and persistent antagonism between glyphosate at 110 and 220 g ae ha−1and glufosinate at 20 or 40 g ae ha−1in giant foxtail, whereas only transient and reduced antagonism was noted for velvetleaf and common lambsquarters. Combining glyphosate and glufosinate increased the maximum absorption of glyphosate by 9% and 23% in velvetleaf and giant foxtail, respectively, compared with glyphosate alone. In velvetleaf, averaged over time, only 2.6% of the applied radioactivity translocated out of the treated leaf when glufosinate was mixed with glyphosate compared with 9.9% when glyphosate was applied alone. In giant foxtail, 21.6% of the [14C]glyphosate translocated out of the treated leaf when glufosinate was mixed with glyphosate compared with 52.4% when glyphosate was applied alone. Conversely, no change in the radioactive pattern of translocation was noted for common lambsquarters. These results suggest that reduced translocation of glyphosate is the physiological mechanism responsible for the antagonism observed between glyphosate and glufosinate in giant foxtail and, to a lesser extent, in velvetleaf.}, number={2}, journal={WEED SCIENCE}, author={Besancon, Thierry E. and Penner, Donald and Everman, Wesley J.}, year={2018}, pages={159–167} } @article{bagavathiannan_everman_govindasamy_dille_jugulam_norsworthy_2018, title={Weed management in sorghum cultivation}, volume={31}, ISBN={["978-1-78676-120-0"]}, ISSN={["2059-6944"]}, DOI={10.19103/AS.2017.0015.18}, journal={ACHIEVING SUSTAINABLE CULTIVATION OF SORGHUM, VOL 1: GENETICS, BREEDING AND PRODUCTION TECHNIQUES}, author={Bagavathiannan, M. and Everman, W. and Govindasamy, P. and Dille, A. and Jugulam, M. and Norsworthy, J.}, year={2018}, pages={465–482} } @article{besançon_jennings_everman_2017, title={Absorption, Translocation, and Metabolism of Halosulfuron in Cucumber, Summer Squash, and Selected Weeds}, volume={65}, ISSN={1550-2759}, url={http://dx.doi.org/10.1017/WSC.2017.15}, DOI={10.1017/WSC.2017.15}, abstractNote={Greenhouse studies were conducted to investigate the absorption, translocation, and metabolism of foliar-applied [14C]halosulfuron-methyl in cucumber, summer squash, pitted morningglory, and velvetleaf. Cucumber and summer squash were treated at the 4-leaf stage, whereas velvetleaf and pitted morningglory were treated at 10 cm. All plants were collected at 4, 24, 48, and 72 h after treatment (HAT) for absorption and translocation studies and an additional 96-HAT interval was included in the metabolism study. Absorption did not exceed 45% in summer squash, whereas it plateaued around 60% in velvetleaf and cucumber and reached 80% in pitted morningglory 72 HAT. None of the four species translocated more than 23% of absorbed halosulfuron out of the treated leaf. Translocation in cucumber and summer squash was predominantly basipetal, while acropetal movement prevailed in velvetleaf. No significant direction of movement was observed for pitted morningglory. Negligible translocation occurred toward the roots, regardless of plant species. Of the total amount of [14C]halosulfuron-methyl absorbed into the plants at 96 HAT, more than 80% remained in the form of the parent compound in velvetleaf, summer squash, and pitted morningglory, whereas less than 20% was detected in cucumber. Rapid and high herbicide metabolism may explain cucumber tolerance to halosulfuron-methyl, while lack of metabolism contributes to summer squash and velvetleaf susceptibility. Pitted morningglory tolerance may be due to limited translocation associated with some level of metabolism, but further research would be needed to investigate other potential causes.}, number={4}, journal={Weed Science}, publisher={Cambridge University Press (CUP)}, author={Besançon, Thierry. E. and Jennings, Katherine M. and Everman, Wesley J.}, year={2017}, month={Jun}, pages={461–467} } @article{besançon_heiniger_weisz_everman_2017, title={Grain Sorghum and Palmer Amaranth (Amaranthus palmeri) Response to Herbicide Programs and Agronomic Practices}, volume={31}, ISSN={0890-037X 1550-2740}, url={http://dx.doi.org/10.1017/WET.2017.53}, DOI={10.1017/WET.2017.53}, abstractNote={Weed control remains a major challenge for economically viable grain sorghum production in the southeastern United States due to crop sensitivity to weed competition during early growth stages. Field experiments were conducted in 2012 and 2013 to determine the effects of grain sorghum row spacing, population density, and herbicide programs on Palmer amaranth control, crop growth, and grain yield. Treatments included row spacings of 19, 38, and 76 cm; grain sorghum population densities of 99,000, 198,000, 297,000, and 396,000 plants ha−1; and three herbicide programs: (1) a nontreated control, (2)S-metolachlor at 1,410 g ai ha−1plus atrazine at 1,820 g ha−1PRE, and (3)S-metolachlor at 1,070 g ha−1plus atrazine at 1,380 g ha−1PRE followed by 2,4 D at 330 g ha−1POST. Palmer amaranth control benefited from the addition of a POST herbicide and from crop density ≥297,000 plants ha−1. Under weedy conditions, Palmer amaranth density was not affected by narrower row spacing or increased crop density, whereas its dry biomass was reduced by 33% with 19 and 38 compared to 76 cm rows, and by 43% with ≥297,000 vs 99,000 plants ha−1. Row spacing had no effect on light interception by the crop canopy. However, crop density influenced canopy closure with maximum light interception occurring one and a half weeks earlier for density ≥297,000 plants ha−1. Yield increased by 18% for 19 vs 38 and 76 cm rows, whereas grain crop density had no effect. Overall, these results indicate that the combination of row spacing≤30 cm and crop density ≥297,000 plants ha−1provided at least 97% Palmer amaranth control in the absence of POST application and reduced its biomass by 32% in nontreated plots compared to 76 cm row spacing and crop density≤198,000 plants ha−1.}, number={6}, journal={Weed Technology}, publisher={Cambridge University Press (CUP)}, author={Besançon, Thierry E. and Heiniger, Ronnie W. and Weisz, Randy and Everman, Wesley J.}, year={2017}, month={Sep}, pages={781–792} } @article{soltani_dille_burke_everman_vangessel_davis_sikkema_2017, title={Perspectives on Potential Soybean Yield Losses from Weeds in North America}, volume={31}, ISSN={["1550-2740"]}, DOI={10.1017/wet.2016.2}, abstractNote={Weeds are one of the most significant, and controllable, threats to crop production in North America. Monetary losses because of reduced soybean yield and decreased quality because of weed interference, as well as costs of controlling weeds, have a significant economic impact on net returns to producers. Previous Weed Science Society of America (WSSA) Weed Loss Committee reports, as chaired by Chandler (1984) and Bridges (1992), provided snapshots of the comparative crop yield losses because of weeds across geographic regions and crops within these regions after the implementation of weed control tactics. This manuscript is a second report from the current WSSA Weed Loss Committee on crop yield losses because of weeds, specifically in soybean. Yield loss estimates were determined from comparative observations of soybean yields between the weedy control and plots with greater than 95% weed control in studies conducted from 2007 to 2013. Researchers from each US state and Canadian province provided at least three and up to ten individual comparisons for each year, which were then averaged within a year, and then averaged over the seven years. These percent yield loss values were used to determine total soybean yield loss in t ha−1and bu acre−1based on average soybean yields for each state or province as well as current commodity prices for a given year as summarized by USDA-NASS (2014) and Statistics Canada (2015). Averaged across 2007 to 2013, weed interference in soybean caused a 52.1% yield loss. Based on 2012 census data in the US and Canada soybean was grown on 30,798,512 and 1,679,203 hectares with production of 80 million and 5 million tonnes, respectively. Using an average soybean price across 2007 to 2013 of US $389.81 t−1($10.61 bu−1), farm gate value would be reduced by US $16.2 billion in the US and $1.0 billion in Canada annually if no weed management tactics were employed.}, number={1}, journal={WEED TECHNOLOGY}, author={Soltani, Nader and Dille, J. Anita and Burke, Ian C. and Everman, Wesley J. and VanGessel, Mark J. and Davis, Vince M. and Sikkema, Peter H.}, year={2017}, pages={148–154} } @article{besancon_heiniger_weisz_everman_2017, title={Weed Response to Agronomic Practices and Herbicide Strategies in Grain Sorghum}, volume={109}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2016.06.0363}, abstractNote={Core Ideas High sorghum density and narrow row spacing reduce biomass of troublesome weeds. High spatial crop uniformity extends large crabgrass and sicklepod control over time. Optimized crop density and row width may limit the need for postemergence herbicide in sorghum. Sicklepod [Senna obtusifolia (L.) H.S. Irwin & Barneby] and large crabgrass (Digitaria sanguinalis L.) are ranked among the top 10 most common or troublesome weeds in grain sorghum [Sorghum bicolor (L.) Moench] in the southeastern United States. Field studies conducted in North Carolina from 2012 to 2014 investigated the effects of three row widths, four sorghum populations, and three herbicide programs on weed control, density, biomass, and grain yield. Results indicated that 19‐ and 38‐cm rows provided greater sicklepod control 7 and 10 wk after planting (WAP) compared to 76 cm but had no effect on crabgrass control. Under weed‐controlled conditions, sorghum population ≥297,000 plants ha−1 allowed to maintain higher late‐season sicklepod and crabgrass control as compared to lower crop densities. In the weedy control, row spacing had no effect on weed density and biomass, whereas crop population ≥297,000 plants ha−1 reduced sicklepod density and biomass by 38 and 65%, respectively, compared to 99,000 plants ha−1. Effect on crabgrass was less pronounced with density and biomass reduction by 18 and 45%, respectively, for 396,000 plants ha−1 compared to 99,000 plants ha−1. In the absence of water stress, the highest grain yields were obtained with high spatial uniformity, corresponding to 19‐cm rows and sorghum population ≥297,000 sorghum plants ha−1. Our results indicate that increased sorghum density associated with narrow rows may reduce the need for a postemergence (POST) herbicide but underscore the importance of a timely activated preemergence (PRE) treatment to efficiently control sicklepod and crabgrass.}, number={4}, journal={AGRONOMY JOURNAL}, author={Besancon, Thierry and Heiniger, Ronnie and Weisz, Randy and Everman, Wesley}, year={2017}, pages={1642–1650} } @article{soltani_dille_burke_everman_vangessel_davis_sikkema_2016, title={Potential Corn Yield Losses from Weeds in North America}, volume={30}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-16-00046.1}, abstractNote={Crop losses from weed interference have a significant effect on net returns for producers. Herein, potential corn yield loss because of weed interference across the primary corn-producing regions of the United States and Canada are documented. Yield-loss estimates were determined from comparative, quantitative observations of corn yields between nontreated and treatments providing greater than 95% weed control in studies conducted from 2007 to 2013. Researchers from each state and province provided data from replicated, small-plot studies from at least 3 and up to 10 individual comparisons per year, which were then averaged within a year, and then averaged over the seven years. The resulting percent yield-loss values were used to determine potential total corn yield loss in t ha−1 and bu acre−1 based on average corn yield for each state or province, as well as corn commodity price for each year as summarized by USDA-NASS (2014) and Statistics Canada (2015). Averaged across the seven years, weed interference in corn in the United States and Canada caused an average of 50% yield loss, which equates to a loss of 148 million tonnes of corn valued at over U.S.$26.7 billion annually.}, number={4}, journal={WEED TECHNOLOGY}, author={Soltani, Nader and Dille, J. Anita and Burke, Ian C. and Everman, Wesley J. and VanGessel, Mark J. and Davis, Vince M. and Sikkema, Peter H.}, year={2016}, pages={979–984} } @article{gholkar_mueller_rountree_2016, title={Power Tuning HPC Jobs on Power-Constrained Systems}, DOI={10.1145/2967938.2967961}, abstractNote={As we approach the exascale era, power has become a primary bottleneck. The US Department of Energy has set a power constraint of 20MW on each exascale machine. To be able achieve one exaflop under this constraint, it is necessary that we use power intelligently to maximize performance under a power constraint. Most production-level parallel applications that run on a supercomputer are tightly-coupled parallel applications. A naϊve approach of enforcing a power constraint for a parallel job would be to divide the job's power budget uniformly across all the processors. However, previous work has shown that a power capped job suffers from performance variation of otherwise identical processors leading to overall sub-optimal performance. We propose a 2-level hierarchical variation-aware approach of managing power at machine-level. At the macro level, PPartition partitions a machine's power budget across jobs to assign a power budget to each job running on the system such that the machine never exceeds its power budget. At the micro level, PTune makes job-centric decisions by taking the performance variation into account. For every moldable job, PTune determines the optimal number of processors, the selection of processors and the distribution of the job's power budget across them, with the goal of maximizing the job's performance under its power budget. Experiments show that, at the micro level, PTune achieves a performance improvement of up to 29% compared to a naϊve approach. PTune does not lead to any performance degradation, yet frees up almost 40% of the processors for the same performance as that of the naϊve approach under a hard power bound. At the macro level, PPartition is able to achieve a throughput improvement of 5-35% compared to uniform power distribution.}, journal={2016 INTERNATIONAL CONFERENCE ON PARALLEL ARCHITECTURE AND COMPILATION TECHNIQUES (PACT)}, author={Gholkar, Neha and Mueller, Frank and Rountree, Barry}, year={2016}, pages={179–190} } @article{israel_everman_richardson_2015, title={Aminocyclopyrachlor Absorption and Translocation in Three Aquatic Weeds}, volume={63}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-14-00020.1}, abstractNote={Studies were conducted to evaluate 14C-aminocyclopyrachlor absorption and translocation in alligatorweed, waterhyacinth, and waterlettuce. Alligatorweed plants were treated at the seven-node stage, waterhyacinth was treated at the five-leaf stage, and waterlettuce was treated at the eight-leaf stage. All plants were pretreated with nonlabeled aminocyclopyrachlor at 0.14 kg ai ha−1 with 1% (v/v) methylated seed oil (MSO). 14C-aminocyclopyrachlor was then applied to a protected leaf, and plants were harvested at 1, 2, 4, 12, 24, and 96 h after treatment (HAT). Radioactivity was determined in the treated leaf, shoots above treated leaf, shoots below treated leaf, roots, and growing solution. Absorption was rapid in all species and reached a maximum of 73, 72, and 73% of applied radioactivity for alligatorweed, waterhyacinth, and waterlettuce, respectively. In alligatorweed at 96 HAT, 43% of absorbed carbon-14 (14C) was translocated to shoots above the treated leaf and 17% was translocated to lower shoot tissue. In waterhyacinth at 96 HAT, 56% of absorbed 14C remained in the treated leaf, whereas 14 and 13% were found in parts above and below the treated leaf, respectively. In waterlettuce at 96 HAT, 50 and 33% of absorbed radioactivity was located above the treated leaf and in the growing solution, respectively. The low recovery of aminocyclopyrachlor in alligatorweed roots and growing solution might explain regrowth potential after herbicide treatment. These results also indicate that the lack of waterlettuce control with aminocyclopyrachlor is not due to reduced absorption or translocation.}, number={1}, journal={WEED SCIENCE}, author={Israel, Trevor D. and Everman, Wesley J. and Richardson, Robert J.}, year={2015}, pages={248–253} } @article{cahoon_york_jordan_seagroves_everman_jennings_2015, title={Cotton response and Palmer amaranth control with pyroxasulfone applied preemergence and postemergence}, volume={19}, number={1}, journal={Journal of Cotton Science}, author={Cahoon, C. W. and York, A. C. and Jordan, D. L. and Seagroves, R. W. and Everman, W. J. and Jennings, K. M.}, year={2015}, pages={212–223} } @article{cahoon_york_jordan_seagroves_everman_jennings_2015, title={Fluridone carryover to rotational crops following application to cotton}, volume={19}, number={3}, journal={Journal of Cotton Science}, author={Cahoon, C. W. and York, A. C. and Jordan, D. L. and Seagroves, R. W. and Everman, W. J. and Jennings, K. M.}, year={2015}, pages={631–640} } @article{inman_jordan_york_jennings_monks_everman_bollman_fowler_cole_soteres_et al._2016, title={Long-Term Management of Palmer Amaranth (Amaranthus palmeri) in Dicamba-Tolerant Cotton}, volume={64}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-15-00058.1}, abstractNote={Research was conducted from 2011 to 2014 to determine weed population dynamics and frequency of glyphosate-resistant (GR) Palmer amaranth with herbicide programs consisting of glyphosate, dicamba, and residual herbicides in dicamba-tolerant cotton. Five treatments were maintained in the same plots over the duration of the experiment: three sequential POST applications of glyphosate with or without pendimethalin plus diuron PRE; three sequential POST applications of glyphosate plus dicamba with and without the PRE herbicides; and a POST application of glyphosate plus dicamba plus acetochlor followed by one or two POST applications of glyphosate plus dicamba without PRE herbicides. Additional treatments included alternating years with three sequential POST applications of glyphosate only and glyphosate plus dicamba POST with and without PRE herbicides. The greatest population of Palmer amaranth was observed when glyphosate was the only POST herbicide throughout the experiment. Although diuron plus pendimethalin PRE in a program with only glyphosate POST improved control during the first 2 yr, these herbicides were ineffective by the final 2 yr on the basis of weed counts from soil cores. The lowest population of Palmer amaranth was observed when glyphosate plus dicamba were applied regardless of PRE herbicides or inclusion of acetochlor POST. Frequency of GR Palmer amaranth was 8% or less when the experiment was initiated. Frequency of GR Palmer amaranth varied by herbicide program during 2012 but was similar among all herbicide programs in 2013 and 2014. Similar frequency of GR Palmer amaranth across all treatments at the end of the experiment most likely resulted from pollen movement from Palmer amaranth treated with glyphosate only to any surviving female plants regardless of PRE or POST treatment. These data suggest that GR Palmer amaranth can be controlled by dicamba and that dicamba is an effective alternative mode of action to glyphosate in fields where GR Palmer amaranth exists.}, number={1}, journal={WEED SCIENCE}, author={Inman, M. D. and Jordan, D. L. and York, A. C. and Jennings, Katherine and Monks, D. W. and Everman, W. J. and Bollman, S. L. and Fowler, J. T. and Cole, R. M. and Soteres, J. K. and et al.}, year={2016}, pages={161–169} } @article{cahoon_york_jordan_everman_seagroves_culpepper_eure_2015, title={Palmer Amaranth (Amaranthus palmeri) Management in Dicamba-Resistant Cotton}, volume={29}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-15-00041.1}, abstractNote={Cotton growers rely heavily upon glufosinate and various residual herbicides applied preplant, PRE, and POST to control Palmer amaranth resistant to glyphosate and acetolactate synthase-inhibiting herbicides. Recently deregulated in the United States, cotton resistant to dicamba, glufosinate, and glyphosate (B2XF cotton) offers a new platform for controlling herbicide-resistant Palmer amaranth. A field experiment was conducted in North Carolina and Georgia to determine B2XF cotton tolerance to dicamba, glufosinate, and glyphosate and to compare Palmer amaranth control by dicamba to a currently used, nondicamba program in both glufosinate- and glyphosate-based systems. Treatments consisted of glyphosate or glufosinate applied early POST (EPOST) and mid-POST (MPOST) in a factorial arrangement of treatments with seven dicamba options (no dicamba, PRE, EPOST, MPOST, PRE followed by [fb] EPOST, PRE fb MPOST, and EPOST fb MPOST) and a nondicamba standard. The nondicamba standard consisted of fomesafen PRE, pyrithiobac EPOST, and acetochlor MPOST. Dicamba caused no injury when applied PRE and only minor, transient injury when applied POST. At time of EPOST application, Palmer amaranth control by dicamba or fomesafen applied PRE, in combination with acetochlor, was similar and 13 to 17% greater than acetochlor alone. Dicamba was generally more effective on Palmer amaranth applied POST rather than PRE, and two applications were usually more effective than one. In glyphosate-based systems, greater Palmer amaranth control and cotton yield were obtained with dicamba applied EPOST, MPOST, or EPOST fb MPOST compared with the standard herbicides in North Carolina. In contrast, dicamba was no more effective than the standard herbicides in the glufosinate-based systems. In Georgia, dicamba was as effective as the standard herbicides in a glyphosate-based system only when dicamba was applied EPOST fb MPOST. In glufosinate-based systems in Georgia, dicamba was as effective as standard herbicides only when dicamba was applied twice.}, number={4}, journal={WEED TECHNOLOGY}, author={Cahoon, Charles W. and York, Alan C. and Jordan, David L. and Everman, Wesley J. and Seagroves, Richard W. and Culpepper, A. Stanley and Eure, Peter M.}, year={2015}, pages={758–770} } @misc{cahoon_york_jordan_seagroves_everman_jennings_2015, title={Sequential and co-application of glyphosate and glufosinate in cotton}, volume={19}, number={2}, journal={Journal of Cotton Science}, author={Cahoon, C. W. and York, A. C. and Jordan, D. L. and Seagroves, R. W. and Everman, W. J. and Jennings, K. M.}, year={2015}, pages={337–350} } @article{cahoon_york_jordan_everman_seagroves_braswell_jennings_2015, title={Weed Control in Cotton by Combinations of Microencapsulated Acetochlor and Various Residual Herbicides Applied Preemergence}, volume={29}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-15-00061.1}, abstractNote={Residual herbicides are routinely recommended to aid in control of glyphosate-resistant (GR) Palmer amaranth in cotton. Acetochlor, a chloroacetamide herbicide, applied PRE, controls Palmer amaranth. A microencapsulated (ME) formulation of acetochlor is now registered for PRE application in cotton. Field research was conducted in North Carolina to evaluate cotton tolerance and Palmer amaranth control by acetochlor ME alone and in various combinations. Treatments, applied PRE, consisted of acetochlor ME, pendimethalin, or no herbicide arranged factorially with diuron, fluometuron, fomesafen, diuron plus fomesafen, and no herbicide. The PRE herbicides were followed by glufosinate applied twice POST and diuron plus MSMA directed at layby. Acetochlor ME was less injurious to cotton than pendimethalin. Acetochlor ME alone or in combination with other herbicides reduced early season cotton growth 5 to 8%, whereas pendimethalin alone or in combinations injured cotton 11 to 13%. Early season injury was transitory, and by 65 to 84 d after PRE treatment, injury was no longer noticeable. Before the first POST application of glufosinate, acetochlor ME and pendimethalin controlled Palmer amaranth 84 and 64%, respectively. Control by acetochlor ME was similar to control by diuron plus fomesafen and greater than control by diuron, fluometuron, or fomesafen alone. Greater than 90% control was obtained with acetochlor ME mixed with diuron or fomesafen. Palmer amaranth control was similar with acetochlor ME plus a full or reduced rate of fomesafen. Acetochlor ME controlled large crabgrass and goosegrass at 91 and 100% compared with control at 83 and 91%, respectively, by pendimethalin. Following glufosinate, applied twice POST, and diuron plus MSMA, at layby, 96 to 99% control was obtained late in the season by all treatments, and no differences among herbicide treatments were noted for cotton yield. This research demonstrated that acetochlor ME can be safely and effectively used in cotton weed management programs.}, number={4}, journal={WEED TECHNOLOGY}, author={Cahoon, Charles W. and York, Alan C. and Jordan, David L. and Everman, Wesley J. and Seagroves, Richard W. and Braswell, Lewis R. and Jennings, Katherine M.}, year={2015}, pages={740–750} } @article{cahoon_york_jordan_everman_seagroves_2014, title={An Alternative to Multiple Protoporphyrinogen Oxidase Inhibitor Applications in No-Till Cotton}, volume={28}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-13-00078.1}, abstractNote={Glyphosate-resistant (GR) Palmer amaranth is a widespread problem in southeastern cotton production areas. Herbicide programs to control this weed in no-till cotton commonly include flumioxazin applied with preplant burndown herbicides approximately 3 wk before planting followed by fomesafen applied PRE and then glufosinate or glyphosate applied POST. Flumioxazin and fomesafen are both protoporphyrinogen oxidase (PPO) inhibitors. Multiple yearly applications of PPO inhibitors in cotton, along with widespread use of PPO inhibitors in rotational crops, raise concerns over possible selection for PPO resistance in Palmer amaranth. An experiment was conducted to determine the potential to substitute diuron for one of the PPO inhibitors in no-till cotton. Palmer amaranth control by diuron and fomesafen applied PRE varied by location, but fomesafen was generally more effective. Control by both herbicides was inadequate when timely rainfall was not received for activation. Palmer amaranth control was more consistent when programs included a preplant residual herbicide. Applied preplant, flumioxazin was more effective than diuron. Programs with diuron preplant followed by fomesafen PRE were as effective as flumioxazin preplant followed by fomesafen only if fomesafen was activated in a timely manner. Programs with flumioxazin preplant followed by diuron PRE were as effective as flumioxazin preplant followed by fomesafen PRE at all locations, regardless of timely activation of the PRE herbicide. As opposed to flumioxazin preplant followed by fomesafen PRE, which exposes Palmer amaranth to two PPO-inhibiting herbicides, one could reduce selection pressure by using flumioxazin preplant followed by diuron PRE without sacrificing Palmer amaranth control or cotton yield.}, number={1}, journal={WEED TECHNOLOGY}, author={Cahoon, Charles W. and York, Alan C. and Jordan, David L. and Everman, Wesley J. and Seagroves, Richard W.}, year={2014}, pages={58–71} } @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{lindsey_renner_everman_2013, title={Cured Dairy Compost Influence on Weed Competition and on 'Snowden' Potato Yield}, volume={27}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-12-00124.1}, abstractNote={Potatoes are an important global food crop typically produced in high-input systems in temperate zones. Growers that have access to compost may use it to improve soil health and increase tuber yields, but compost may also increase weed competition by increasing early-season water availability and weed growth. A field study at the Michigan State University Montcalm Research farm in 2010 and 2011 investigated the impact of compost on weed competition in potato. Potatoes were grown in field plots with 0, 4,000, or 8,000 kg carbon (C) ha−1of compost under weed-free conditions, and in competition with common lambsquarters, giant foxtail, and hairy nightshade. Compost did not increase biomass or seed production of any weed species. Giant foxtail and hairy nightshade at 5.3 plants per meter of row reduced potato yield by 20%; common lambsquarters reduced yield by 45%. The yield reduction by giant foxtail and hairy nightshade was due to a decrease in tuber bulking, whereas yield reductions from common lambsquarters were a result of lower tuber set and bulking. Potato yield increased 5 to 15% in compost compared to non-compost treatments; tuber specific gravity decreased by 0.3% in composted treatments. Across weed densities, elevated soil potassium levels in the 8,000 kg C ha−1composted treatment may have increased potato yield and decreased tuber specific gravity.}, number={2}, journal={WEED TECHNOLOGY}, author={Lindsey, Alexander J. and Renner, Karen A. and Everman, Wesley J.}, year={2013}, pages={378–388} } @article{lindsey_warncke_steinke_everman_2013, title={Fertilizer and Population Affects Nitrogen Assimilation of Common Lambsquarters (Chenopodium album) and Redroot Pigweed (Amaranthus retroflexus)}, volume={61}, ISSN={["0043-1745"]}, DOI={10.1614/ws-d-12-00094.1}, abstractNote={Weed growth and N assimilation usually increase with N application rate. With the increasing price of N fertilizer, a better understanding N assimilation by weeds is necessary to maximize economic return. Total plant yield is generally independent of population density, except when plants are very small or at very low population density. If plant yield is independent of population density, weed N assimilation may also be independent of population density. However, the effect of weed population density on N assimilation has not been thoroughly investigated. A 2011 controlled-environment study was established in East Lansing, MI, to evaluate the effect of weed population density and N application rate on growth and N assimilation by common lambsquarters and redroot pigweed. Study factors included four weed densities (1, 2, 4, and 8 plants pot−1), three N application rates (0, 67, and 134 kg N ha−1), and two weed species (redroot pigweed and common lambsquarters). Weeds were destructively harvested 3 wk after emergence, and shoot height, biomass, total N concentration, N use efficiency, and N assimilation were measured. Redroot pigweed was taller, had greater shoot biomass, and a greater shoot N assimilation than did common lambsquarters. With similar environmental conditions, redroot pigweed is expected to be more competitive than common lambsquarters. Shoot N assimilation increased with increasing weed population density, indicating that N assimilation was not independent of population density 3 wk after emergence because weeds were small or at low population density.}, number={1}, journal={WEED SCIENCE}, author={Lindsey, Laura E. and Warncke, Darryl D. and Steinke, Kurt and Everman, Wesley J.}, year={2013}, pages={131–135} } @article{lindsey_everman_chomas_kells_2012, title={Evaluation of Application Program and Timing in Herbicide-Resistant Corn}, volume={26}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-12-00012.1}, abstractNote={Field studies were conducted from 2007 to 2009 in East Lansing, MI to evaluate three residual herbicide programs, three POST herbicide application timings, and two POST herbicides in glyphosate- and glufosinate-resistant corn. Herbicide programs included a residual PRE-applied herbicide followed by (fb) POST application (residual fb POST), a residual herbicide tank-mixed with a POST herbicide (residual + POST), and a nonresidual POST. Three POST herbicide application timings included early POST (EP), mid-POST (MP), and late POST (LP) at an average corn growth stage of V3/V4, V4/V5, and V5/V6, respectively. The two POST herbicides evaluated were glyphosate and glufosinate. Control of common lambsquarters and giant foxtail was evaluated 28 d after the LP application. Glyphosate often provided greater weed control than glufosinate. The LP application resulted in greater giant foxtail control compared with the EP application timing, which may be attributed to control of late-emerging weeds. The EP application timing improved common lambsquarters control compared with the LP application timing. The residual + POST program resulted in greater weed control compared with the residual fb POST program in all years. The effect of residual herbicide program, POST herbicide, and POST application timing on corn grain yield varied by year. In 2007, the use of glyphosate resulted in higher grain yield compared with glufosinate. In 2008, corn grain yield was the highest in the PRE fb POST program and with POST applications at EP and MP. To provide the most consistent weed control and minimize the likelihood of grain yield reductions, a PRE fb POST program applied at EP or MP is recommended.}, number={4}, journal={WEED TECHNOLOGY}, author={Lindsey, Laura E. and Everman, Wesley J. and Chomas, Andrew J. and Kells, James J.}, year={2012}, pages={617–621} } @article{min_dietz_everman_chomas_kells_leep_2012, title={Glyphosate-Resistant Alfalfa Response to Harvest Frequency and Weed Management}, volume={26}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-11-00103.1}, abstractNote={Glyphosate-resistant (GR) alfalfa offers growers new options for weed control in alfalfa. One potential benefit of using GR alfalfa is increased longevity of an alfalfa stand under frequent harvests. It was hypothesized that GR alfalfa would have a greater longevity because of removal of weed interference with minimal crop injury. To study GR alfalfa yield, weed invasion, alfalfa stand persistence, and relative forage quality (RFQ), a field experiment with three weed control methods (no herbicide, glyphosate, and hexazinone) under two harvest frequencies (high and moderate) was established in August 2003 at the Michigan State University Agronomy Farm in East Lansing, MI. Forage yield of established alfalfa was not adversely affected by herbicide treatments. There were no differences in weed biomass between alfalfa treated with glyphosate and that treated with hexazinone, except in 2007. Average GR alfalfa stand density decreased approximately 90% (from 236 to 27 plant m−2), and yield decreased approximately 30% (from 11.04 to 7.87 Mg ha−1) during the 7-yr period (2004 to 2010) of the experiment. Stand density of GR alfalfa showed natural thinning during the 7-yr period regardless of harvest intensity or herbicide treatment. In most production years (4 out of 5 yr), relative forage quality of GR alfalfa was higher under a high-intensity harvesting system (4 to 5 harvests yr−1) than it was with a moderate intensity harvesting system (3 to 4 harvests yr−1). Relative forage quality was not affected by weed removal with herbicides in most years. Weed removal and harvest intensity in established GR alfalfa had no effect on stand persistence.}, number={3}, journal={WEED TECHNOLOGY}, author={Min, Doo-Hong and Dietz, Timothy S. and Everman, Wesley J. and Chomas, Andrew J. and Kells, James J. and Leep, Richard H.}, year={2012}, pages={399–404} } @article{everman_mayhew_burton_york_wilcut_2009, title={Absorption, Translocation, and Metabolism of C-14-Glufosinate in Glufosinate-Resistant Corn, Goosegrass (Eleusine indica), Large Crabgrass (Digitaria sanguinalis), and Sicklepod (Senna obtusifolia)}, volume={57}, ISSN={["1550-2759"]}, DOI={10.1614/WS-08-089.1}, abstractNote={Greenhouse studies were conducted to evaluate14C-glufosinate absorption, translocation, and metabolism in glufosinate-resistant corn, goosegrass, large crabgrass, and sicklepod. Glufosinate-resistant corn plants were treated at the four-leaf stage, whereas goosegrass, large crabgrass, and sicklepod were treated at 5, 7.5, and 10 cm, respectively. All plants were harvested at 1, 6, 24, 48, and 72 h after treatment (HAT). Absorption was less than 20% at all harvest intervals for glufosinate-resistant corn, whereas absorption in goosegrass and large crabgrass increased from approximately 20% 1 HAT to 50 and 76%, respectively, 72 HAT. Absorption of14C-glufosinate was greater than 90% 24 HAT in sicklepod. Significant levels of translocation were observed in glufosinate-resistant corn, with14C-glufosinate translocated to the region above the treated leaf and the roots up to 41 and 27%, respectively. No significant translocation was detected in any of the weed species at any harvest timing. Metabolites of14C-glufosinate were detected in glufosinate-resistant corn and all weed species. Seventy percent of14C was attributed to glufosinate metabolites 72 HAT in large crabgrass. Less metabolism was observed for sicklepod, goosegrass, and glufosinate-resistant corn, with metabolites composing less than 45% of detectable radioactivity 72 HAT.}, number={1}, journal={WEED SCIENCE}, author={Everman, Wesley J. and Mayhew, Cassandra R. and Burton, James D. and York, Alan C. and Wilcut, John W.}, year={2009}, pages={1–5} } @article{everman_thomas_burton_york_wilcut_2009, title={Absorption, Translocation, and Metabolism of Glufosinate in Transgenic and Nontransgenic Cotton, Palmer Amaranth (Amaranthus palmeri), and Pitted Morningglory (Ipomoea lacunosa)}, volume={57}, ISSN={["1550-2759"]}, DOI={10.1614/WS-09-015.1}, abstractNote={Greenhouse studies were conducted to evaluate absorption, translocation, and metabolism of14C-glufosinate in glufosinate-resistant cotton, nontransgenic cotton, Palmer amaranth, and pitted morningglory. Cotton plants were treated at the four-leaf stage, whereas Palmer amaranth and pitted morningglory were treated at 7.5 and 10 cm, respectively. All plants were harvested at 1, 6, 24, 48, and 72 h after treatment (HAT). Absorption of14C-glufosinate was greater than 85% 24 h after treatment in Palmer amaranth. Absorption was less than 30% at all harvest intervals for glufosinate-resistant cotton, nontransgenic cotton, and pitted morningglory. At 24 HAT, 49 and 12% of radioactivity was translocated to regions above and below the treated leaf, respectively, in Palmer amaranth. Metabolites of14C-glufosinate were detected in all crop and weed species. Metabolism of14C-glufosinate was 16% or lower in nontransgenic cotton and pitted morningglory; however, metabolism rates were greater than 70% in glufosinate-resistant cotton 72 HAT. Intermediate metabolism was observed for Palmer amaranth, with metabolites comprising 20 to 30% of detectable radioactivity between 6 and 72 HAT.}, number={4}, journal={WEED SCIENCE}, author={Everman, Wesley J. and Thomas, Walter E. and Burton, James D. and York, Alan C. and Wilcut, John W.}, year={2009}, pages={357–361} } @article{everman_clewis_york_wilcut_2009, title={Weed Control and Yield with Flumioxazin, Fomesafen, and S-Metolachlor Systems for Glufosinate-Resistant Cotton Residual Weed Management}, volume={23}, ISSN={["1550-2740"]}, DOI={10.1614/WT-09-007.1}, abstractNote={Field studies were conducted near Clayton, Lewiston, and Rocky Mount, NC in 2005 to evaluate weed control and cotton response to preemergence treatments of pendimethalin alone or in a tank mixture with fomesafen, postemergence treatments of glufosinate applied alone or in a tank mixture withS-metolachlor, and POST-directed treatments of glufosinate in a tank mixture with flumioxazin or prometryn. Excellent weed control (> 91%) was observed where at least two applications were made in addition to glufosinate early postemergence (EPOST). A reduction in control of common lambsquarters (8%), goosegrass (20%), large crabgrass (18%), Palmer amaranth (13%), and pitted morningglory (9%) was observed when residual herbicides were not included in PRE or mid-POST programs. No differences in weed control or cotton lint yield were observed between POST-directed applications of glufosinate with flumioxazin compared to prometryn. Weed control programs containing three or more herbicide applications resulted in similar cotton lint yields at Clayton and Lewiston, and Rocky Mount showed the greatest variability with up to 590 kg/ha greater lint yield where fomesafen was included PRE compared to pendimethalin applied alone. Similarly, an increase in cotton lint yields of up to 200 kg/ha was observed whereS-metolachlor was included mid-POST when compared to glufosinate applied alone, showing the importance of residual herbicides to help maintain optimal yields. Including additional modes of action with residual activity preemergence and postemergence provides a longer period of weed control, which helps maintain cotton lint yields.}, number={3}, journal={WEED TECHNOLOGY}, author={Everman, Wesley J. and Clewis, Scott B. and York, Alan C. and Wilcut, John W.}, year={2009}, pages={391–397} } @article{everman_burke_clewis_thomas_wilcut_2008, title={Critical period of grass vs. broadleaf weed interference in peanut}, volume={22}, ISSN={["1550-2740"]}, DOI={10.1614/wt-07-037.1}, abstractNote={Studies were conducted to evaluate the effects of grass and broadleaf weeds on peanut growth and peanut yield. In separate studies, grass or broadleaf weeds were allowed to compete with peanut for various intervals to determine both the critical timing of weed removal and the critical weed-free period. Hand-weeding and selective herbicides were used at appropriate times to remove and terminate weed growth. These periods were then used to determine the critical period of weed control. The effects of various weedy intervals on peanut yield were also investigated. The critical period of grass weed control was found to be from 4.3 to 9 wk after planting (WAP), whereas the critical period of broadleaf weed control was from 2.6 to 8 WAP. Peanut yields decreased as weed interference intervals for both grass and broadleaf weeds increased, demonstrating the need for control of both grass and broadleaf weeds throughout much of the growing season. Nomenclature: Peanut, Arachis hypogaea L}, number={1}, journal={WEED TECHNOLOGY}, author={Everman, Wesley J. and Burke, Ian C. and Clewis, Scott B. and Thomas, Walter E. and Wilcut, John W.}, year={2008}, pages={68–73} } @article{everman_clewis_thomas_burke_wilcut_2008, title={Critical period of weed interference in peanut}, volume={22}, ISSN={["1550-2740"]}, DOI={10.1614/wt-07-052.1}, abstractNote={Field studies were conducted near Lewiston–Woodville and Rocky Mount, NC to evaluate the effects of mixed weed species on peanut yield. A combination of broadleaf and grass weeds were allowed to interfere with peanut for various intervals to determine both the critical timing of weed removal and the critical weed-free period. These periods were then combined to determine the critical period of weed control in peanut. The effects of various weedy intervals on peanut yield were also investigated. The predicted critical period of weed control, in the presence of a mixed population of weeds, was found to be from 3 to 8 wk after planting (WAP). Peanut yield decreased as weed interference intervals increased, demonstrating the need for weed control throughout much of the growing season in the presence of mixed weed populations. Nomenclature: Peanut, Arachis hypogaea L}, number={1}, journal={WEED TECHNOLOGY}, author={Everman, Wesley J. and Clewis, Scott B. and Thomas, Walter E. and Burke, Ian C. and Wilcut, John W.}, year={2008}, pages={63–67} } @article{clewis_thomas_everman_witcut_2008, title={Glufosinate-resistant corn interference in glufosinate-resistant cotton}, volume={22}, ISSN={["1550-2740"]}, DOI={10.1614/WT-07-085.1}, abstractNote={Studies were conducted at three locations in North Carolina in 2004 to evaluate density-dependent effects of glufosinate-resistant (GUR) corn on GUR cotton growth and lint yield. GUR corn was taller than GUR cotton as early as 11 d after planting, depending on location. A GUR corn density of 5.25 plant/m of crop row reduced late-season cotton height by 38, 43, and 43% at Clayton, Lewiston-Woodville, and Rocky Mount, NC, respectively, compared with weed-free cotton height. GUR corn dry biomass per meter of crop row and GUR corn seed biomass per meter of crop row decreased linearly with increasing GUR corn density at all locations. The relationship between GUR corn density and GUR cotton yield loss was described by the rectangular hyperbola model with the asymptote (a) constrained to 100% maximum yield loss. The estimated coefficient i (yield loss per unit density as density approaches zero) was 7, 5, and 6 at Clayton, Lewiston-Woodville, and Rocky Mount, respectively. Percentage of GUR cotton lint yield loss increased 4, 5, and 8 percentage points at Clayton, Lewiston-Woodville, and Rocky Mount, respectively, with each 500 g increase in weed biomass/m of crop row. The examined GUR corn densities had a significant effect on cotton yield but not as significant as many other problematic grass and broadleaf weeds. Nomenclature: Glufosinate, corn, Zea mays L. ‘Pioneer 34A55LL’ ZEAMX, cotton, Gossypium hirsutum L., ‘FM 958LL’}, number={2}, journal={WEED TECHNOLOGY}, author={Clewis, Scott B. and Thomas, Walter E. and Everman, Wesley J. and Witcut, John W.}, year={2008}, pages={211–216} } @article{everman_medlin_dirks_bauman_biehl_2008, title={The effect of postemergence herbicides on the spectral reflectance of corn}, volume={22}, ISSN={["1550-2740"]}, DOI={10.1614/WT-07-021.1}, abstractNote={Studies were conducted in 2001 and 2002 to determine the effect of POST herbicides on the spectral reflectance of corn. POST corn herbicides evaluated included 2,4-D, atrazine, bromoxynil, dicamba + diflufenzopyr, nicosulfuron, and primisulfuron. Multispectral and hyperspectral data were collected and spectral properties were analyzed using SAS procedures and MultiSpec image analysis. Corn treated with POST applications of atrazine and primisulfuron could not be distinguished from nontreated corn regardless of data type or analysis method used. 2,4-D and dicamba + diflufenzopyr were the most readily distinguished from nontreated corn plots using both hyperspectral and multispectral data.}, number={3}, journal={WEED TECHNOLOGY}, author={Everman, Wesley J. and Medlin, Case R. and Dirks, Richard D., Jr. and Bauman, Thomas T. and Biehl, Larry}, year={2008}, pages={514–522} } @article{thomas_everman_burke_koger_wilcut_2007, title={Absorption and translocation of glyphosate and sucrose in glyphosate-resistant cotton}, volume={21}, ISSN={["0890-037X"]}, DOI={10.1614/WT-06-125.1}, abstractNote={Studies were conducted to evaluate absorption and translocation of 14C-glyphosate in glyphosate-resistant (GR) cotton. Both commercial GR cotton events [glyphosate-resistant event 1, marketed as Roundup Ready®, released 1997 (GRE1), and glyphosate-resistant event 2, marketed as Roundup Ready Flex®, released 2006 (GRE2)] were evaluated at the four-leaf and eight-leaf growth stages. Plants were harvested at 1, 3, 5, and 7 d after treatment (DAT). Glyphosate absorption, as a percentage of applied, increased over time with 29 and 36% absorption at 7 DAT in four-leaf GRE1 and GRE2 cotton, respectively. In eight-leaf cotton, glyphosate absorption (33% at 7 DAT) was not different between events. Glyphosate translocation patterns were not different between events or harvest timings and exhibited a source–sink relation. Observed translocation differences between cotton growth stages were probably due to reduced glyphosate export from the treated leaf of eight-leaf cotton. An additional study compared absorption and translocation of 14C-glyphosate and 14C-sucrose in 5- and 10-leaf GRE2 cotton. Averaged over trials, 14C compounds, and growth stages, cotton absorbed 28% of the applied dose at 14 DAT. On the basis of the percentage of 14C exported out of the treated leaf, glyphosate and sucrose translocation patterns were similar, indicating that glyphosate may be used as a photoassimilate model in GRE2 cotton. Nomenclature: Glyphosate; cotton, Gossypium hirsutum L.}, number={2}, journal={WEED TECHNOLOGY}, author={Thomas, Walter E. and Everman, Wesley J. and Burke, Ian C. and Koger, Clifford H. and Wilcut, John W.}, year={2007}, pages={459–464} } @article{thomas_everman_allen_collins_wilcut_2007, title={Economic assessment of weed management systems in glufosinate-resistant, glyphosate-resistant, imidazolinone-tolerant, and nontransgenic corn}, volume={21}, ISSN={["1550-2740"]}, DOI={10.1614/WT-06-054.1}, abstractNote={Four field studies were conducted in 2004 to evaluate corn tolerance, weed control, grain yield, and net returns in glufosinate-resistant (GUR), glyphosate-resistant (GYR), imidazolinone-tolerant (IT), and nontransgenic (NT) corn with various herbicide systems. No significant differences between hybrid systems were observed for weed control. Limited corn injury (< 5%) was observed for all herbicide treatments. A single early POST (EPOST) system withoutS-metolachlor and sequential POST over the top (POT) herbicide systems, averaged over corn hybrids and PRE and late POST-directed (LAYBY) herbicide options, provide 93 and 99% control of goosegrass, respectively, and at least 83 and 97% control of Texas panicum, respectively. A single EPOST system withoutS-metolachlor, averaged over corn hybrids and LAYBY treatment options, provided at least 88% control of large crabgrass. When averaged over corn hybrid and PRE herbicide options, a sequential POT herbicide system alone provided at least 98, 99, 98, and 100 control of large crabgrass, morningglory species, Palmer amaranth, and common lambsquarters, respectively. The addition of ametryn at LAYBY to a single EPOST system withoutS-metolachlor was beneficial for improving control of morningglory species, common lambsquarters, and Palmer amaranth, depending on location. However, the observed increases (7 percentage points or less) are likely of limited biological significance. Grain yield was variable between hybrids and locations because of environmental differences. Consequently, net returns for each hybrid system within a location were also variable. Any POT system with or without ametryn at LAYBY, averaged over corn hybrid and PRE herbicide options, provided at least 101, 97, 92, and 92% yield protection at Clayton, Kinston, Lewiston, and Rocky Mount, NC, respectively. Net returns were maximized with treatments that provided excellent weed control with minimal inputs.}, number={1}, journal={WEED TECHNOLOGY}, author={Thomas, Walter E. and Everman, Wesley J. and Allen, Jayla and Collins, Jim and Wilcut, John W.}, year={2007}, pages={191–198} } @article{thomas_everman_clewis_wilcut_2007, title={Glyphosate-resistant corn interference in glyphosate-resistant cotton}, volume={21}, ISSN={["1550-2740"]}, DOI={10.1614/WT-06-007.1}, abstractNote={Studies were conducted at three locations in North Carolina in 2004 to evaluate density-dependent effects of glyphosate-resistant (GR) corn on GR cotton growth and lint yield. GR corn was taller than GR cotton as early as 25 d after planting, depending on location. A GR corn density of 5.25 plant/m of crop row reduced late season cotton height by 49, 24, and 28% at Clayton, Lewiston–Woodville, and Rocky Mount, respectively, compared to weed-free cotton height. At Clayton, GR corn dry biomass per m crop row and GR corn seed biomass per m of crop row decreased linearly with increasing corn density. The relationship between GR corn and GR cotton yield loss was described by the rectangular hyperbola model with the asymptote (a) constrained to 100% maximum yield loss. The estimated coefficient i (yield loss per unit density as density approaches zero) was 9, 5, and 5 at Clayton, Lewiston–Woodville, and Rocky Mount, respectively. The examined GR corn densities had a significant effect on cotton yield, but not as significant as many other problematic grass and broadleaf weeds. Nomenclature: Glyphosate; corn, Zea mays L., ZEAMX, ‘DKC 69-71RR’; cotton, Gossypium hirsutum L. ‘FM 989RR’, ‘ST 4892RR’.}, number={2}, journal={WEED TECHNOLOGY}, author={Thomas, Walter E. and Everman, Wesley J. and Clewis, Scott B. and Wilcut, John W.}, year={2007}, pages={372–377} } @article{everman_burke_allen_collins_wilcut_2007, title={Weed control and yield with glufosinate-resistant cotton weed management systems}, volume={21}, DOI={10.1614/W7-06-164.1}, number={3}, journal={Weed Technology}, author={Everman, W. J. and Burke, I. C. and Allen, J. R. and Collins, J. and Wilcut, J. W.}, year={2007}, pages={695–701} } @article{clewis_everman_jordan_wilcut_2007, title={Weed management in north Carolina peanuts (Arachis hypogaea) with s-metolachlor, diclosulam, flumioxazin, and sulfentrazone systems}, volume={21}, ISSN={["1550-2740"]}, DOI={10.1614/WT-06-139.1}, abstractNote={Experiments were conducted at the Upper Coastal Plain Research Station near Rocky Mount and at the Peanut Belt Research Station near Lewiston-Woodville in 2002 and 2003. Peanut injury was minimal (< 5%) with all soil-applied programs. S-Metolachlor PRE alone or in mixture with sulfentrazone, diclosulam, or flumioxazin controlled annual grasses similarly (66 to 87%). The addition of imazapic plus 2,4-DB POST increased annual grass control (> 93%). Sulfentrazone or diclosulam in mixture with S-metolachlor were the best PRE options, with 94% and 92% control of yellow and purple nutsedge, respectively, with flumioxazin being least effective at 70%. Diclosulam and flumioxazin in mixture with S-metolachlor were the best PRE options, with 99% and 93%, respectively for common ragweed control, whereas sulfentrazone was the least effective at 65%. S-Metolachlor in mixture with sulfentrazone, diclosulam, or flumioxazin PRE were similar (87 to 90%) for common lambsquarters control. S-Metolachlor in mixture with sulfentrazone, diclosulam, or flumioxazin provided similar levels of entireleaf, ivyleaf, pitted, and tall morningglory control (87, 86, and 87%, respectively) and better than S-metolachlor alone at 64%. Flumioxazin in mixture with S-metolachlor was the best PRE option for control of Palmer amaranth at 96%, whereas diclosulam with S-metolachlor was the best PRE option for control of eclipta at 100%. The prepackaged mixture of acifluorfen and bentazon plus 2,4-DB POST and imazapic plus 2,4-DB POST were similar for all morningglory species (> 96%) and Palmer amaranth control (93 and 97%, respectively). Peanut treated with S-metolachlor plus diclosulam PRE numerically yielded the highest at 3,210 kg/ha, but were statistically equivalent to S-metolachlor plus flumioxazin PRE at 3,040 kg/ha. Peanut treated with imazapic plus 2,4-DB POST yielded the most at 3,400 kg/ha, while peanut treated with a prepackaged mixture of acifluorfen and bentazon plus 2,4-DB POST yielded less (3,070 kg/ha). Nomenclature: 2,4-DB, acifluorfen, bentazon, diclosulam, flumioxazin, imazapic, S-metolachlor, sulfentrazone, common lambsquarters, Chenopodium album L. CHEAL, common ragweed, Ambrosia artemisiifolia L. AMBEL, eclipta, Eclipta prostrata L. ECLAL, entireleaf morningglory, Ipomoea hederacea var. integriuscula Gray IPOHG, ivyleaf morningglory, Ipomoea hederacea (L.) Jacq. IPOHE, Palmer amaranth, Amaranthus palmeri S. Wats. AMAPA, pitted morningglory, Ipomoea lacunosa L. IPOLA, purple nutsedge, Cyperus rotundus L. CYPRO, tall morningglory, Ipomoea purpurea (L.) Roth PHBPU, yellow nutsedge, Cyperus esculentus L. CYPES, peanut, Arachis hypogaea L., ‘NCV-11’, ‘VA-98R’}, number={3}, journal={WEED TECHNOLOGY}, author={Clewis, Scott B. and Everman, Wesley J. and Jordan, David L. and Wilcut, John W.}, year={2007}, pages={629–635} } @article{everman_clewis_taylor_wilcut_2006, title={Influence of diclosulam postemergence application timing on weed control and peanut tolerance}, volume={20}, ISSN={["0890-037X"]}, DOI={10.1614/WT-05-087R1.1}, abstractNote={Field studies were conducted at Lewiston–Woodville and Rocky Mount, NC in 2001 and 2002 to evaluate weed control and peanut response to POST treatments of diclosulam at various rates and application timings. Diclosulam controlled common ragweed and entireleaf morningglory when applied within 35 d after planting (DAP). Common ragweed 61 cm tall was controlled ≥92% with 4 to 13 g ai/ha diclosulam and larger common ragweed (107 to 137 cm tall) were controlled ≥97% with 27 g/ha diclosulam. Common lambsquarters was controlled 62% or less with all diclosulam POST treatments following metolachlor applied PRE, which provided 48% control. Peanut injury was less than 15% with all diclosulam POST treatments and was transitory. In separate studies, POST diclosulam treatments did not affect peanut yield in a weed-free environment. Peanut yield in weedy environments was reduced as the diclosulam application timing was delayed because of early season weed interference. A linear relationship was observed between yield and application timing with yield decreasing as application timing was delayed. This yield response documents the importance of early season weed management for maximizing peanut yield potential. Virginia peanut varieties were not affected by different POST rates of diclosulam; however, early season peanut injury showed a linear and quadratic relationship with diclosulam rate and was less than 14% at rates as high as 71 g/ha, and was not apparent by late season.}, number={3}, journal={WEED TECHNOLOGY}, author={Everman, Wesley J. and Clewis, Scott B. and Taylor, Zachary G. and Wilcut, John W.}, year={2006}, pages={651–657} } @article{thomas_everman_collins_koger_wilcut_2007, title={Rain-free requirement and physiological properties of cotton plant growth regulators}, volume={88}, ISSN={["1095-9939"]}, DOI={10.1016/j.pestbp.2006.12.002}, abstractNote={Greenhouse studies were conducted to (1) evaluate the rain-free requirement for mepiquat chloride and mepiquat chloride plus cyclanilide with and without surfactant and to (2) evaluate absorption and translocation of cyclanilide, a component of a new cotton plant growth regulator. No significant differences in the number of nodes, leaf area, and plant organ fresh and dry weight were observed with any PGR treatment and rainfall simulation combination. Both plant growth regulators responded similarly to rainfall interval. As rain-free period increased, cotton height was reduced. Based on these data, a rain-free period of 8 h is needed to maximize efficacy, regardless of the use of surfactant. Absorption of cyclanilide ranged from 11 to 15% at 3 and 48 h after treatment, respectively. Averaged over harvest intervals, 18% of the applied cyclanilide remained in the treated leaf while 1.7 and 6.5% of the applied cyclanilide was found in the above and below treated leaf tissue, respectively.}, number={3}, journal={PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY}, author={Thomas, Walter E. and Everman, Wesley J. and Collins, James R. and Koger, Clifford H. and Wilcut, John W.}, year={2007}, month={Jul}, pages={247–251} } @article{porterfield_everman_wilcut_2006, title={Soybean response to residual and in-season treatments of trifloxysulfuron}, volume={20}, ISSN={["1550-2740"]}, DOI={10.1614/WT-05-033R.1}, abstractNote={Experiments were conducted from 1998 to 2000 at Rocky Mount, NC, in weed-free environments to determine soybean tolerance to preplant (PP) applications of trifloxysulfuron and the potential for trifloxysulfuron applied preemergence (PRE) and postemergence (POST) to cotton to injure soybean grown in rotation the following year. Trifloxysulfuron at 3.75 and 7.5 g ai/ha applied PP 2 wk before seeding injured conventional soybean less than 5%, whereas no injury was observed when seeding was delayed 4 or 6 wk after PP treatment. No injury to sulfonylurea-resistant soybean (SR) was observed for any treatment. Soybean yields were not influenced by trifloxysulfuron treatment. Cotton injury was 7% or less with trifloxysulfuron applied PRE or POST at 3.75 and 7.5 g/ha. Trifloxysulfuron at 15 g/ha PRE or POST injured cotton a maximum of 14 to 18%. Trifloxysulfuron did not reduce cotton lint yields regardless of method or rate of application. Both conventional and SR soybean were not injured nor were yields influenced by trifloxysulfuron applied PRE or POST the previous year to cotton.}, number={2}, journal={WEED TECHNOLOGY}, author={Porterfield, Dunk and Everman, Wesley J. and Wilcut, John W.}, year={2006}, pages={384–388} }