@article{moursi_youssef_poole_castro-bolinaga_chescheir_richardson_2023, title={Drainage water recycling reduced nitrogen, phosphorus, and sediment losses from a drained agricultural field in eastern North Carolina, USA}, volume={279}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2023.108179}, abstractNote={An experimental study was conducted to evaluate the effect of drainage water recycling (DWR) on reducing nitrogen (N), phosphorus (P), and sediment losses from agricultural fields to downstream surface water bodies. The two-year study (May 2019-April 2021) was conducted at an agricultural field in eastern North Carolina, U.S.A. A reservoir existed at the site was used to store subsurface drainage and surface runoff water during wet periods and provide supplemental irrigation during dry periods of the crop growing season. On average, the reservoir retained 14% of received inflow, with a higher flow reduction in the dry year (2019–2020; 29%) than the wet year (2020–2021; 8%). The hydraulic retention time (HRT) for the reservoir was 33.8 days for the dry year and 12.4 days for the wet year. The reservoir significantly reduced the loadings of N by 47%, P by 30% and sediment by 87%. Nitrogen load reduction was primarily driven by nitrate assimilation, the dominant form of N in the reservoir. Phosphorus load reduction was attributed to Orthophosphate assimilation as the reservoir released more particulate P than received. Reductions in both water flow and species concentration contributed to nutrient load reductions. Results suggested the removal efficiency of the reservoir would be highest during the summer and early fall months when the reservoir has a smaller water volume (due to irrigation), longer HRT, and warmer temperature. This study clearly demonstrated the potential of DWR for significantly reducing N, P, and sediment losses from agricultural land to receiving surface water. Further research is needed to investigate the physical, chemical, and biological processes that occur in the storage reservoir and affect the fate and transport of nutrients and sediment. The understanding of these processes will enable optimizing the treatment efficiency of DWR, which maximizes the system’s benefits and reduces construction cost.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Moursi, Hossam and Youssef, Mohamed A. and Poole, Chad A. and Castro-Bolinaga, Celso F. and Chescheir, George M. and Richardson, Robert J.}, year={2023}, month={Apr} }
 @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{haug_howell_sperry_mudge_richardson_getsinger_2023, title={Simulated herbicide spray retention of commonly managed invasive emergent aquatic macrophytes}, volume={5}, ISSN={["1550-2740"]}, url={https://doi.org/10.1017/wet.2023.26}, DOI={10.1017/wet.2023.26}, abstractNote={AbstractInvasive emergent and floating macrophytes can have detrimental impacts on aquatic ecosystems. Management of these aquatic weeds frequently relies upon foliar application of aquatic herbicides. However, there is inherent variability of overspray (herbicide loss) for foliar applications into waters within and adjacent to the targeted treatment area. The spray retention (tracer dye captured) of four invasive broadleaf emergent species (water hyacinth, alligatorweed, creeping water primrose, and parrotfeather) and two emergent grass-like weeds (cattail and torpedograss) were evaluated. For all species, spray retention was simulated using foliar applications of rhodamine WT (RWT) dye as a herbicide surrogate under controlled mesocosm conditions. Spray retention of the broadleaf species was first evaluated using a CO2-pressurized spray chamber overtop dense vegetation growth or no plants (positive control) at a greenhouse (GH) scale. Broadleaf species and grass-like species were then evaluated in larger outdoor mesocosms (OM). These applications were made using a CO2-pressurized backpack sprayer. Evaluation metrics included species-wise canopy cover and height influence on in-water RWT concentration using image analysis and modeling techniques. Results indicated spray retention was greatest for water hyacinth (GH, 64.7 ± 7.4; OM, 76.1 ± 3.8). Spray retention values were similar among the three sprawling marginal species alligatorweed (GH, 37.5 ± 4.5; OM, 42 ± 5.7), creeping water primrose (GH, 54.9 ± 7.2; OM, 52.7 ± 5.7), and parrotfeather (GH, 48.2 ± 2.3; OM, 47.2 ± 3.5). Canopy cover and height were strongly correlated with spray retention for broadleaf species and less strongly correlated for grass-like species. Although torpedograss and cattail were similar in percent foliar coverage, they differed in percent spray retention (OM, 8.5± 2.3 and 28.9 ±4.1, respectively). The upright leaf architecture of the grass-like species likely influenced the lower spray retention values in comparison to the broadleaf species.}, journal={WEED TECHNOLOGY}, author={Haug, Erika J. and Howell, Andrew W. and Sperry, Benjamin P. and Mudge, Christopher R. and Richardson, Robert J. and Getsinger, Kurt D.}, year={2023}, month={May} }
 @article{wersal_sartain_getsinger_madsen_skogerboe_nawrocki_richardson_sternberg_2022, title={Improving chemical control of nonnative aquatic plants in run-of-the-river reservoirs}, volume={7}, ISSN={["1939-747X"]}, DOI={10.1017/inp.2022.18}, abstractNote={AbstractCurrent dam discharge patterns in Noxon Rapids Reservoir reduce concentration and exposure times (CET) of herbicides used for aquatic plant management. Herbicide applications during periods of low dam discharge may increase herbicide CETs and improve efficacy. Applications of rhodamine WT dye were monitored under peak (736 to 765 m3 s−1) and minimum (1.4 to 2.8 m3 s−1) dam discharge patterns to quantify water-exchange processes. Whole-plot dye half-life under minimal discharge was 33 h, a 15-fold increase compared with the dye treatment during peak discharge. Triclopyr concentrations measured during minimum discharge within the treated plot ranged from 214 ± 25 to 1,243 ± 36 µg L−1 from 0 to 48 h after treatment (HAT), respectively. Endothall concentrations measured during minimum discharge in the same plot ranged from 164 ± 78 to 2,195 ± 1,043 µg L−1 from 0 to 48 HAT, respectively. Eurasian watermilfoil (Myriophyllum spicatum L.) occurrence in the treatment plot was 66%, 8%, and 14% during pretreatment, 5 wk after treatment (WAT), and 52 WAT, respectively. Myriophyllum spicatum occurrence in the nontreated plot was 68%, 71%, and 83% during pretreatment, 5 WAT, and 52 WAT, respectively. Curlyleaf pondweed (Potamogeton crispus L.) occurrence in the treatment plot was 29%, 0%, and 97% during pretreatment, 5 WAT, and 52 WAT, respectively. Potamogeton crispus increased from 24% to 83% at 0 WAT to 52 WAT, respectively, in the nontreated plot. Native species richness declined from 3.3 species per point to 2.1 in the treatment plot in the year of treatment but returned to pretreatment numbers by 52 WAT. Native species richness did not change during the study in the nontreated reference plot. Herbicide applications during periods of low flow can increase CETs and improve control, whereas applications during times of high-water flow would shorten CETs and could result in reduced treatment efficacy.}, journal={INVASIVE PLANT SCIENCE AND MANAGEMENT}, author={Wersal, Ryan M. and Sartain, Bradley T. and Getsinger, Kurt D. and Madsen, John D. and Skogerboe, John G. and Nawrocki, Justin J. and Richardson, Rob J. and Sternberg, Morgan R.}, year={2022}, month={Jul} }
 @article{howell_hofstra_heilman_richardson_2022, title={Susceptibility of native and invasive submersed plants in New Zealand to florpyrauxifen-benzyl in growth chamber exposure studies}, volume={15}, ISSN={["1939-747X"]}, url={https://doi.org/10.1017/inp.2022.22}, DOI={10.1017/inp.2022.22}, abstractNote={AbstractInvasive aquatic plants constantly threaten freshwaters and associated environs globally. Water resource managers frequently seek new control tactics to combat invasive macrophytes, especially when the availability of herbicides registered for submersed plant control is limited. The synthetic auxin herbicide, florpyrauxifen-benzyl, recently registered (2018) for aquatic site applications in the United States, has shown success in controlling several invasive aquatic weeds. Studies were conducted to evaluate responses of native and invasive submersed plants to florpyrauxifen-benzyl under growth chamber conditions to provide insight on the selectivity of varying herbicide concentrations in New Zealand. Florpyrauxifen-benzyl concentrations evaluated ranged from 0.01 to 107.86 µg ai L−1, encompassing the maximum use concentration (48 µg L−1) for submersed plant applications. Dose–response metrics indicated the New Zealand native species watermilfoil [Myriophyllum triphyllum Orchard] was highly sensitive to florpyrauxifen-benzyl following a 21-d static exposure, having a dry weight 50% effective concentration (EC50) value of 1.2 µg L−1. The invasive species oxygen-weed [Lagarosiphon major (Ridley) Moss] and Canadian waterweed (Elodea canadensis Michx.) were less sensitive, with dry weight EC50 values of 35.4 and >107.86 µg L−1, respectively. Brazilian waterweed (Egeria densa Planch.) was most tolerant to the tested concentrations, as EC50 values were not achieved. Overall, results indicate florpyrauxifen-benzyl demonstrates potential for controlling L. major, with further large-scale screening required to confirm control among field site applications. As the native species (M. triphyllum) was most sensitive to florpyrauxifen-benzyl compared with the invasive plant evaluated (I/N ratio indicated >31.3 times more sensitive), any targeted concentration used for invasive plant control for field applications would likely injure the native M. triphyllum plants. Future studies should investigate additional native and invasive species for management guidance and consider how exposure times influence plant response using similar florpyrauxifen-benzyl concentrations tested in the present study.}, number={3}, journal={INVASIVE PLANT SCIENCE AND MANAGEMENT}, author={Howell, Andrew W. and Hofstra, Deborah E. and Heilman, Mark A. and Richardson, Robert J.}, year={2022}, month={Sep}, pages={133–140} }
 @article{haug_ahmed_gannon_richardson_2021, title={Absorption and translocation of florpyrauxifen-benzyl in ten aquatic plant species}, volume={69}, ISSN={["1550-2759"]}, DOI={10.1017/wsc.2021.38}, abstractNote={AbstractAdditional active ingredients are needed for use in aquatic systems to respond to new threats or treatment scenarios, enhance selectivity, reduce use rates, and mitigate the risk of herbicide resistance. Florpyrauxifen-benzyl is a new synthetic auxin developed for use as an aquatic herbicide. A study was conducted at North Carolina State University in which 10 µg L−1 of 25% radiolabeled florpyrauxifen-benzyl was applied to the isolated shoot tissue of 10 different aquatic plant species to elucidate absorption and translocation patterns in these species. Extremely high levels of shoot absorption were observed for all species, and uptake was rapid. Highest shoot absorptions were observed for crested floatingheart [Nymphoides cristata (Roxb.) Kuntze] (A192 = 20 µg g−1), dioecious hydrilla [Hydrilla verticillata (L. f.) Royle] (A192 = 25.3 µg g−1), variable watermilfoil (Myriophyllum heterophyllum Michx.) (A192 = 40.1 µg g−1), and Eurasian watermilfoil (Myriophyllum spicatum L.) (A192 = 25.3 µg g−1). Evidence of translocation was observed in all rooted species tested, with the greatest translocation observed in N. cristata (1.28 µg g−1 at 192 h after treatment). The results of this study add to the growing body of knowledge surrounding the behavior of this newly registered herbicide within aquatic plants.}, number={6}, journal={WEED SCIENCE}, author={Haug, Erika J. and Ahmed, Khalied A. and Gannon, Travis W. and Richardson, Rob J.}, year={2021}, month={Nov}, pages={624–630} }
 @article{harms_thum_gettys_markovich_french_simantel_richardson_2021, title={Hybridization between native and invasive Nymphoides species in the United States}, volume={23}, ISSN={["1573-1464"]}, url={https://doi.org/10.1007/s10530-021-02558-9}, DOI={10.1007/s10530-021-02558-9}, number={10}, journal={BIOLOGICAL INVASIONS}, publisher={Springer Science and Business Media LLC}, author={Harms, Nathan E. and Thum, Ryan A. and Gettys, Lyn A. and Markovich, Ian J. and French, Anna and Simantel, Leah and Richardson, Rob}, year={2021}, month={Oct}, pages={3003–3011} }
 @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{reinhardt piskackova_reberg-horton_richardson_jennings_franca_young_leon_2021, title={Windows of action for controlling palmer amaranth (Amaranthus palmeri) using emergence and phenology models}, volume={61}, ISSN={["1365-3180"]}, url={https://doi.org/10.1111/wre.12470}, DOI={10.1111/wre.12470}, abstractNote={AbstractAmaranthus palmeri S. Watson is a competitive weed native to North America with many herbicide‐resistant biotypes that have been spreading around the world. Due to its fast growth, farmers need to optimise control timing to reduce the risk of escapes. This study tracked A. palmeri emergence and phenology using days or growing degree days (GDD, Tbase = 15°C; thermal time or hydrothermal time). While A. palmeri has been observed emerging throughout the summer growing season, this study found that 90% of total season A. palmeri emerged before July in the absence of a crop canopy. Using thermal time, emergence could be predicted in different locations and years: reaching 10%, 50% and 90% at 77, 278 and 593 GDD from January 1, respectively. From the time of emergence, 10% of A. palmeri were 10 cm tall after 148 GDD, showed first signs of inflorescence by 212 GDD, and open florets by 419 GDD. Also, 50% of A. palmeri plants had reached the respective stages by 244, 394 and 796 GDD. Using the probability of A. palmeri to reach different phenological stages over time as a function of emergence prediction, critical control windows were determined based on thresholds for risk of escapes. Many tactics and times of action are important for managing this weed. Information about A. palmeri biology indicates these actions could be timed more effectively using weather data and predictive models.}, number={3}, journal={WEED RESEARCH}, author={Reinhardt Piskackova, Theresa A. and Reberg-Horton, Samuel Chris and Richardson, Robert J. and Jennings, Katie M. and Franca, Lucas and Young, Bryan G. and Leon, Ramon G.}, year={2021}, month={Jun}, pages={188–198} }
 @article{piskackova_reberg-horton_richardson_jennings_leon_2020, title={Incorporating environmental factors to describe wild radish (Raphanus raphanistrum) seedling emergence and plant phenology}, volume={68}, ISSN={["1550-2759"]}, url={https://doi.org/10.1017/wsc.2020.64}, DOI={10.1017/wsc.2020.64}, abstractNote={AbstractWild radish (Raphanus raphanistrum L.) is a weed found globally in agricultural systems. The facultative winter annual nature of this plant and high genetic variability makes modeling its growth and phenology difficult. In the present study, R. raphanistrum natural seedbanks exhibited a biphasic pattern of emergence, with emergence peaks occurring in both fall and spring. Traditional sigmoidal models were inadequate to fit this pattern, regardless of the predictive environmental variable, and a corresponding biphasic model (sigmoidal + Weibull) was used to describe emergence based on the best parameters. Each best-fit chronological, thermal, and hydrothermal model accounted for at least 85% of the variation of the validation data. Observations on phenology progression from four cohorts were used to create a common model that described all cohorts adequately. Different phenological stages were described using chronological, thermal, hydrothermal, daylength-dependent thermal time, and daylength-dependent hydrothermal time. Integrating daylength and temperature into the models was important for predicting reproductive stages of R. raphanistrum.}, number={6}, journal={WEED SCIENCE}, publisher={Cambridge University Press (CUP)}, author={Piskackova, Theresa Reinhardt and Reberg-Horton, S. Chris and Richardson, Robert J. and Jennings, Katie M. and Leon, Ramon G.}, year={2020}, month={Nov}, pages={627–638} }
 @article{piskackova_reberg-horton_richardson_jennings_leon_2020, title={Integrating emergence and phenology models to determine windows of action for weed control: A case study using Senna obtusifolia}, volume={258}, ISSN={["1872-6852"]}, DOI={10.1016/j.fcr.2020.107959}, abstractNote={The success of integrated weed management strategies is contingent on the accuracy of control actions in both time and space. While emphasis has been given to spatial accuracy, timing accuracy has been largely neglected. Weed control timing must consider not only the total duration of weed interference with the crop, as done by the traditional critical period of weed control (CPWC) based on yield protection only, but also weed growth, size, and susceptible phenological stages. In this study, we expand upon the idea of using weed emergence models for timing weed control by integrating them with phenology probability models for key weed growth stages to optimize timing of control actions, here referred as Critical Control Windows (CCW). Combining the CCW with thresholds for yield loss due to weed interference and thresholds for weed survival risk makes it possible determining the frequency with which control actions should be implemented to maintain crop yield and weed populations at desired levels. Using Senna obtusifolia as a study case, vegetative and reproductive phenological stages were modeled as a function of seedling emergence for different cohorts. Chronological and thermal-time models provided robust predictions of S. obtusifolia phenology. CCW did not always coincided with CPWC for several crops when considering 10-cm tall plants as the threshold for control. In general, for summer row crops, CCW required 2 postemergence control actions and sometimes 1 action outside the CPWC. The results of the present research illustrate how predictive models can be used to develop CCW that will complement the traditional CPWC. These two concepts when used complementary can increase not only timing accuracy, but also efficiency of weed control.}, journal={FIELD CROPS RESEARCH}, author={Piskackova, Theresa A. Reinhardt and Reberg-Horton, Chris and Richardson, Robert J. and Jennings, Katie M. and Leon, Ramon G.}, year={2020}, month={Nov} }
 @article{patel_jernigan_richardson_ferguson_buckner_2019, title={Autonomous Robotics for Identification and Management of Invasive Aquatic Plant Species}, volume={9}, url={https://doi.org/10.3390/app9122410}, DOI={10.3390/app9122410}, abstractNote={Invasive aquatic plant species can expand rapidly throughout water bodies and cause severely adverse economic and ecological impacts. While mechanical, chemical, and biological methods exist for the identification and treatment of these invasive species, they are manually intensive, inefficient, costly, and can cause collateral ecological damage. To address current deficiencies in aquatic weed management, this paper details the development of a small fleet of fully autonomous boats capable of subsurface hydroacoustic imaging (to scan aquatic vegetation), machine learning (for automated weed identification), and herbicide deployment (for vegetation control). These capabilities aim to minimize manual labor and provide more efficient, safe (reduced chemical exposure to personnel), and timely weed management. Geotagged hydroacoustic imagery of three aquatic plant varieties (Hydrilla, Cabomba, and Coontail) was collected and used to create a software pipeline for subsurface aquatic weed classification and distribution mapping. Employing deep learning, the novel software achieved a classification accuracy of 99.06% after training.}, number={12}, journal={Applied Sciences}, publisher={MDPI AG}, author={Patel, Maharshi and Jernigan, Shaphan and Richardson, Rob and Ferguson, Scott and Buckner, Gregory}, year={2019}, month={Jun}, pages={2410} }
 @article{bishop_willis_cope_richardson_2020, title={Biomass of the Cyanobacterium Lyngbya wollei Alters Copper Algaecide Exposure and Risks to a Non-target Organism}, volume={104}, ISBN={1432-0800}, DOI={10.1007/s00128-019-02755-2}, abstractNote={Nuisance algal infestations are increasing globally in distribution and frequency. Copper-based algaecides are routinely applied to control these infestations, though there is an ever-present concern of risks to non-target species. This research evaluated risks associated with a commonly applied chelated copper algaecide (Captain® XTR; SePRO Corporation) to a sentinel non-target species (Daphnia magna) and further assessed alteration of the exposure and toxicity when a nuisance mat-forming cyanobacterium, Lyngbya wollei, was present in exposures. Aqueous copper concentrations in treatments with algae significantly decreased within 1 h after treatment and averaged 57.5% of nominal amended Cu through the experiment duration. The 48 h LC 50  values were 371 µg Cu/L with no algae present in exposures and increased significantly to 531 µg Cu/L when L. wollei was simultaneously exposed. This research provides information on the short-term fate of copper and hazard assessment by incorporating targeted binding ligands, as present in operational treatments.}, journal={BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY}, author={Bishop, West M. and Willis, Ben E. and Cope, W. Gregory and Richardson, Robert J.}, year={2020}, pages={228–234} }
 @article{howell_richardson_2019, title={Correlation of consumer grade hydroacoustic signature to submersed plant biomass}, volume={155}, ISSN={["1879-1522"]}, DOI={10.1016/j.aquabot.2019.02.001}, abstractNote={Invasive macrophytes, such as non-native Hydrilla verticillata, negatively affect lentic systems of the Southeastern United States by impeding recreational activities and power generation as well as disrupting intrinsic ecological function. Expenditures associated with aquatic weed management include costs accompanied with monitoring, mapping, and implementing control measures. Traditional biomass sampling techniques have been widely utilized to assess the extent and abundance of submersed aquatic vegetation (SAV) incursions, but often require significant labor inputs which limits repeatability, the scale of sampling, and the rapidness of processing. Advances in consumer available hydroacoustic technology and data post-processing platforms offer the opportunity to estimate SAV biomass at scale with reduced labor and economic requirements. Research was conducted at two North Carolina reservoirs to compare acoustically derived cloud-based biovolume estimations from an over-the-counter echosounder, to in situ hydrilla biomass measurements. Temporal patterns, spatial developments, and hydrilla biomass prediction models are presented. Biomass and biovolume measurements were positively correlated at both the Shearon Harris and Roanoke Rapids study locations. The most robust predictive equation employed generalized additive models (GAMs) from the Shearon Harris dataset which, described environmental parameters with the lowest error and greatest agreement compared to other verified models. Each biovolume to biomass relationship supported the initial hypothesis that as biovolume increases, SAV biomass increases in a positive, non-linear trend. Implications from this study may prove useful for comparing seasonal growth patterns, littoral occupancy, and herbicide treatment effects on a spatiotemporal level.}, journal={AQUATIC BOTANY}, author={Howell, Andrew W. and Richardson, Robert J.}, year={2019}, month={Apr}, pages={45–51} }
 @article{howell_richardson_2019, title={Estimating standing biomass of exotic macrophytes using sUAS}, volume={11008}, ISSN={["1996-756X"]}, DOI={10.1117/12.2519199}, abstractNote={With the advent of sUAS, research scientists and plant managers are capable of obtaining unique, fast, and low-cost quantitative data, which delivers many repeatable survey options. Benefits of autonomous sUAS platforms include minimal training, reduced human safety concerns, and creation of graphic outputs which may be readily viewed by any stakeholder who was not actively involved in the survey or management activity. Research conducted in the Wellington Region, New Zealand was used to evaluate consumer-grade sUAS technologies to map and estimate standing biomass of Manchurian Wild Rice (MWR), an exotic semi-aquatic grass which promotes flooding, and displacement of native flora and fauna. The goal of this research was to improve the speed and resolution of current survey strategies used to assess MWR among a lowland pasture site using unmanned systems and photogrammetry techniques. Image collection and data processing was conducted in a manner to provide a theoretic biomass estimation of remaining MWR following seasonal growth and herbicide applications. Post-processing methods and theories discussed attempt to identify and quantify MWR biomass using supervised imaging analysis, plant height modeling, and biomass collected in situ. The use of unmanned systems to map, monitor, and manage MWR is encouraged for future applications.}, journal={AUTONOMOUS AIR AND GROUND SENSING SYSTEMS FOR AGRICULTURAL OPTIMIZATION AND PHENOTYPING IV}, author={Howell, Andrew W. and Richardson, Robert J.}, year={2019} }
 @article{haug_harris_richardson_2019, title={Monoecious Hydrilla verticillata development in complete darkness}, volume={154}, ISSN={["1879-1522"]}, DOI={10.1016/j.aquabot.2018.12.005}, abstractNote={Hydrilla verticillata is one of the most problematic invasive submersed aquatic weeds in the United States. A study was conducted in growth chambers to look at aspects of development of monoecious Hydrilla verticillata in complete darkness. A single tuber was placed in each of forty-eight growth chambers. Following differential blackout intervals of zero, two, four, six, eight, or ten weeks, plants in each treatment group were dissected into above ground (shoot) and below ground (tuber) material. Plant section length, dry weight, and non-structural carbohydrate content were determined. Shoot lengths increased by 32.1 cm following ten weeks of dark exposure, as compared to the zero-darkness exposure controls. Despite the increase in total shoot length, total dry weight decreased from 34.6 mg (zero-darkness) to 25.4 mg after ten weeks of dark exposure. During this time, tuber dry weight declined from 34.6 mg (zero-darkness) to 5.8 mg and shoot dry weight increased from 0 mg (zero-darkness) to 20 mg. Starch was the most prominent non-structural carbohydrate present in plants throughout the experiment. Starch levels were highest in plants prior to germination (31% of dry weight) and declined significantly and steadily over the course of the 10-week dark development experiment to an average of 20% of dry weight. The results of this study indicate that monoecious hydrilla has a high elongation and development potential over long periods of time in darkness. This adaptation is advantageous in overcoming light blocking management techniques and in allowing the species to occupy a larger area of the profundal zone.}, journal={AQUATIC BOTANY}, author={Haug, Erika J. and Harris, Jon T. and Richardson, Robert J.}, year={2019}, month={Mar}, pages={28–34} }
 @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{bishop_richardson_willis_2018, title={Comparison of Partitioning and Efficacy Between Copper Algaecide Formulations: Refining the Critical Burden Concept}, volume={229}, ISSN={["1573-2932"]}, DOI={10.1007/s11270-018-3958-z}, number={9}, journal={WATER AIR AND SOIL POLLUTION}, author={Bishop, West M. and Richardson, Robert J. and Willis, Ben E.}, year={2018}, month={Sep} }
 @article{bishop_willis_richardson_cope_2018, title={The presence of algae mitigates the toxicity of copper-based algaecides to a nontarget organism}, volume={37}, ISSN={0730-7268}, url={http://dx.doi.org/10.1002/ETC.4166}, DOI={10.1002/ETC.4166}, abstractNote={AbstractCopper‐based algaecides are routinely applied to target noxious algal blooms in freshwaters. Standard toxicity testing data with copper suggest that typical concentrations used to control algae can cause deleterious acute impacts to nontarget organisms. These “clean” water experiments lack algae, which are specifically targeted in field applications of algaecides and contain competing ligands. The present research measured the influence of algae on algaecide exposure and subsequent response of the nontarget species Daphnia magna to copper sulfate and an ethanolamine‐chelated copper algaecide (Captain®). Significant shifts (p < 0.05) in D. magna 48‐h median lethal concentration (LC50) values were found when algae were present in exposures along with a copper salt or a chelated copper formulation. Copper sulfate 48‐h LC50 values shifted from 75.3 to 317.8 and 517.8 μg Cu/L, whereas Captain increased from 353.8 to 414.2 and 588.5 μg Cu/L in no algae, 5 × 105, and 5 × 106 cells/mL algae treatments, respectively. Larger shifts were measured with copper sulfate exposures, although Captain was less toxic to D. magna in all corresponding treatments. Captain was more effective at controlling Scenedesmus dimorphus at most concentrations, and control was inversely proportional to toxicity to D. magna. Overall, incorporating target competing ligands (i.e., algae) into standard toxicity testing is important for accurate risk assessment, and copper formulation can significantly alter algaecidal efficacy and risks to nontarget organisms. Environ Toxicol Chem 2018;37:2132–2142. © 2018 SETAC}, number={8}, journal={Environmental Toxicology and Chemistry}, publisher={Wiley}, author={Bishop, West M. and Willis, Ben E. and Richardson, Robert J. and Cope, W. Gregory}, year={2018}, month={Jun}, pages={2132–2142} }
 @article{bishop_richardson_2018, title={Influence of PhoslockA (R) on legacy phosphorus, nutrient ratios, and algal assemblage composition in hypereutrophic water resources}, volume={25}, DOI={10.1007/s11356-017-0832-2}, abstractNote={Acceleration of eutrophication in freshwater resources can result in prolific growth of nuisance algae, notably cyanobacteria. In this research, we evaluated the ability of an in situ P binding technology (Phoslock®) to alter available water column and sediment P, and the subsequent impact on nutrient ratios and algal assemblage composition. Two golf course irrigation ponds with legacy nutrient loads and chronic cyanobacterial blooms were treated with Phoslock and monitored for 2 years post-treatment. Phoslock significantly (P < 0.05) decreased water column total P levels and shifted mobile sediment P fractions (i.e., labile, reductant-soluble, organic) to the residual fraction. Total N/P ratios (by mass) significantly increased and were sustained at over 30:1 in the Hickory Meadows irrigation pond and 100:1 in the Chockyotte irrigation pond throughout the study. Consequent changes in the algal assemblage included decreases in dominance and overall density of cyanobacteria as well as a shift away from scum-forming genera (e.g., Microcystis spp. and Anabaena [Dolichospermum] sp.) to planktonic forms (e.g., Pseudanabaena sp. and Planktolyngbya sp.). This research provides information regarding mitigation of in situ water and sediment P toward shifting nutrient ratios and altering algal assemblage composition.}, number={5}, journal={Environmental Science and Pollution Research}, author={Bishop, W. M. and Richardson, Robert}, year={2018}, pages={4544–4557} }
 @article{nawrocki_richardson_hoyle_2016, title={Monoecious hydrilla tuber dynamics following various management regimes on four North Carolina reservoirs}, volume={54}, journal={Journal of Aquatic Plant Management}, author={Nawrocki, J. J. and Richardson, R. J. and Hoyle, S. T.}, year={2016}, pages={12–19} }
 @misc{true-meadows_haug_richardson_2016, title={Monoecious hydrilla-A review of the literature}, volume={54}, journal={Journal of Aquatic Plant Management}, author={True-Meadows, S. and Haug, E. J. and Richardson, R. J.}, year={2016}, pages={1–11} }
 @article{richardson_haug_netherland_2016, title={Response of seven aquatic plants to a new arylpicolinate herbicide}, volume={54}, journal={Journal of Aquatic Plant Management}, author={Richardson, R. J. and Haug, E. J. and Netherland, M. D.}, year={2016}, pages={26–31} }
 @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{stallings_seth-carley_richardson_2015, title={Management of Aquatic Vegetation in the Southeastern United States}, volume={6}, ISSN={2155-7470}, url={http://dx.doi.org/10.1093/jipm/pmv002}, DOI={10.1093/jipm/pmv002}, abstractNote={Aquatic vegetation is managed throughout the southeastern United States with the guidance of state and federal aquatic plant management plans. These plans often suggest ways to promote the growth of beneficial aquatic plants while attempting to guide the reduction and elimination of unwanted “weedy species.” Aquatic species are divided into the categories of algae, submersed, emergent, and floating species and this classification is based on the morphology and growth habit of the identified species. These species are surveyed using multiple research techniques designed to identify and manage the resource based on the needs of the stakeholder. Management practices can be subdivided into physical, mechanical, biological, and chemical control to reduce or eliminate an undesirable weed species. This document reviews current literature related to management of aquatic plants and provides an overview of problematic aquatic weeds in the southeastern United States.}, number={1}, journal={Journal of Integrated Pest Management}, publisher={Oxford University Press (OUP)}, author={Stallings, K. D. and Seth-Carley, D. and Richardson, R. J.}, year={2015}, month={Mar}, pages={3–3} }
 @article{hall_spooner_richardson_hoyle_frederick_2014, title={POSTEMERGENCE CONTROL OF MICROSTEGIUM VIMINEUM ON RIPARIAN RESTORATION SITES WITH AQUATIC-USE REGISTERED HERBICIDES}, volume={50}, ISSN={["1752-1688"]}, DOI={10.1111/jawr.12210}, abstractNote={AbstractMicrostegium vimineum is an invasive grass introduced from Asia that has spread throughout riparian areas of the eastern United States threatening native riparian vegetation. Postemergence (POST) herbicides registered for aquatic use were evaluated for control of M. vimineum on two riparian restoration sites in the Piedmont and Upper Coastal Plain of North Carolina. This study found that standard and lower than standard rates of diquat, fluridone, flumioxazin, glyphosate, imazamox, and imazapyr reduced weed stem density and biomass at 6 and 30 weeks after treatment (WAT). Both rates of bispyribac and penoxsulam provided less control of M. vimineum. Visual ratings showed both rates of diquat, flumioxazin, imazamox, and imazapyr controlled 63‐100% of M. vimineum at 6 WAT and 84‐100% at 30 WAT. Fluridone and glyphosate provided slightly less control. Bispyribac and penoxsulam treatments provided less control at 6 and 30 WAT compared to the other treatments. Plots treated with both rates of diquat, flumioxazin, imazamox, and imazapyr were nearly devoid of all vegetation at 30 WAT. Recommendations include POST application of lower than standard rates of diquat, flumioxazin, fluridone, glyphosate, imazamox, and imazapyr on riparian restoration sites infested with M. vimineum. Immediate vegetation management measures including temporary and permanent plant cover should be employed on treated sites where weeds are completely eradicated to prevent erosion.}, number={3}, journal={JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION}, author={Hall, Karen R. and Spooner, Jean and Richardson, Robert J. and Hoyle, Steve T. and Frederick, Douglas J.}, year={2014}, month={Jun}, pages={533–542} }
 @article{lewis_jeffries_gannon_richardson_yelverton_2014, title={Persistence and Bioavailability of Aminocyclopyrachlor and Clopyralid in Turfgrass Clippings: Recycling Clippings for Additional Weed Control}, volume={62}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-13-00119.1}, abstractNote={The synthetic auxin herbicides, aminocyclopyrachlor and clopyralid, control dicotyledonous weeds in turf. Clippings of turfgrass treated with synthetic auxin herbicides have injured off-target plants exposed to herbicide-laden clippings. Labels of aminocyclopyrachlor and clopyralid recommend that clippings of treated turfgrass remain on the turf following a mowing event. Alternative uses for synthetic auxin-treated turfgrass clippings are needed because large quantities of clippings on the turf surface interfere with the functionality and aesthetics of golf courses, athletic fields, and residential turf. A white clover bioassay was conducted to determine the persistence and bioavailability of aminocyclopyrachlor and clopyralid in turfgrass clippings. Aminocyclopyrachlor and clopyralid were each applied at 79 g ae ha−1 to mature tall fescue at 56, 28, 14, 7, 3.5, and 1.75 d before clipping collection (DBCC). Clippings were collected, and the treated clippings were recycled onto adjacent white clover plots to determine herbicidal persistence and potential for additional weed control. Clippings of tall fescue treated with aminocyclopyrachlor produced a nonlinear regression pattern of response on white clover. Calculated values for 50% response (GR50) for visual control, for normalized difference vegetative index (NDVI), and for reduction in harvested biomass were 20.5, 17.3, and 18.7 DBCC, respectively, 8 wk after clippings were applied. Clippings of tall fescue treated with clopyralid did not demonstrate a significant pattern for white clover control, presumably because clopyralid was applied at a less-than-label rate. The persistence and bioavailability of synthetic auxin herbicides in clippings harvested from previously treated turfgrass creates the opportunity to recycle clippings for additional weed control.}, number={3}, journal={WEED SCIENCE}, author={Lewis, Dustin F. and Jeffries, Matthew D. and Gannon, Travis W. and Richardson, Robert J. and Yelverton, Fred H.}, year={2014}, pages={493–500} }
 @article{archambault_bergeron_cope_richardson_heilman_corey_netherland_heise_2015, title={Sensitivity of freshwater molluscs to hydrilla-targeting herbicides: providing context for invasive aquatic weed control in diverse ecosystems}, volume={30}, ISSN={["2156-6941"]}, DOI={10.1080/02705060.2014.945104}, abstractNote={Hydrilla (Hydrilla verticillata) is an invasive aquatic weed that has spread rapidly throughout the USA, especially in the southeast. A common control method is the application of aquatic herbicides, such as fluridone and endothall. However, there is limited documentation on the effects of herbicides commonly used to control hydrilla and other aquatic weeds on many non-target freshwater species and no published information exists on the toxicity of these herbicides to freshwater molluscs. We exposed juveniles (96 h) and glochidia (48 h) of the unionid mussel Lampsilis siliquoidea and adults (28 d) of Lampsilis fullerkati to a formulation of fluridone (Sonar – PR®) in laboratory toxicity tests. The early life stages of L. siliquoidea were also exposed to a formulation of the dipotassium salt of endothall (Aquathol – K®) in separate tests. Juveniles of the freshwater gastropod snail, Somatogyrus viriginicus (Lithoglyphidae), were exposed (96 h) to the Sonar – Genesis® fluridone formulation. Endpoints were survival (all species and life stages) as well as siphoning behavior and foot protrusion (adult mussels). Median lethal fluridone concentrations (LC50s) were 865 μg/L (95% CI, 729–1,026 μg/L) for glochidia (24 h), 511 μg/L (309–843 μg/L) for juvenile L. siliquoidea (96 h), and 500 μg/L (452–553 μg/L) for juvenile S. viriginicus (96 h). No mortality occurred in the 28-d exposure of adult L. fullerkati and we found no statistically significant effect of fluridone concentration on foot protrusion (p = 0.06) or siphoning behavior (p = 0.08). The 24-h LC50 for glochidia exposed to the dipotassium salt of endothall was 31.2 mg/L (30.3–32.2 mg/L) and the 96-h LC50 for juvenile mussels was 34.4 mg/L (29.3–40.5 mg/L). Freshwater molluscs were more sensitive to fluridone and endothall than most other species previously tested. Fluridone and endothall concentrations typically recommended for hydrilla treatment (5–15 μg/L and 1–5 mg/L, respectively) were not acutely toxic to the molluscs we tested and a 28-d exposure to fluridone was not lethal to adult mussels even at the highest concentration (300 μg/L), indicating minimal risk of short-term exposure effects.}, number={3}, journal={JOURNAL OF FRESHWATER ECOLOGY}, author={Archambault, Jennifer M. and Bergeron, Christine M. and Cope, W. Gregory and Richardson, Robert J. and Heilman, Mark A. and Corey, J. Edward, III and Netherland, Michael D. and Heise, Ryan J.}, year={2015}, pages={335–348} }
 @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{lewis_richardson_yelverton_wentworth_2013, title={Bioavailability of Aminocyclopyrachlor and Triclopyr plus Clopyralid from Turfgrass Clippings in Aquatic and Riparian Plants}, volume={61}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-13-00013.1}, abstractNote={Synthetic auxin herbicides are widely utilized in golf course settings for selective broadleaf weed control. Aminocyclopyrachlor (AMCP) is a newly registered pyrimidine carboxylic acid with similar chemical mode-of-action and structure to triclopyr (TRIC) and clopyralid (CLPY). Off-target injury on terrestrial plants has been documented following exposure to turfgrass clippings previously treated with TRIC and CLPY. Management practices on golf courses can distribute turfgrass clippings into water bodies; however, research has not evaluated the bioavailability of synthetic auxin residues from turfgrass clippings to aquatic and riparian plants within these environments. A bioassay study was conducted to determine the response of alligatorweed and parrotfeather to tall fescue clippings previously treated with synthetic auxin herbicides. Previously treated AMCP and TRIC + CLPY clippings were placed into growth containers mimicking a lentic system containing both alligatorweed and parrotfeather. Results indicated all herbicide treated clippings induced significant growth responses to alligatorweed and parrotfeather growth compared to a nontreated mulch and nontreated control. Alligatorweed control was greater from AMCP clippings treated 14, 7, 3, and 1 DBCC (49, 60, 90, and 80%, respectively) than comparative TRIC + CLPY clippings (33, 25, 37, and 64%, respectively) at 10 weeks after treatment (WAT). Parrotfeather control was greater from AMCP clippings (57 to 87%) than TRIC + CLPY clippings (9 to 63%) collected from all days before clipping collection (DBCC) timings when evaluated 6 WAT. At 10 WAT, greater parrotfeather control and shoot reduction was observed from AMCP than TRIC + CLPY clippings when treated 14, 7, and 3 DBCC. Based on these data, synthetic auxin residues can become bioavailable to aquatic and riparian plants within aqueous environments.}, number={4}, journal={WEED SCIENCE}, author={Lewis, Dustin F. and Richardson, Robert J. and Yelverton, Fred H. and Wentworth, Thomas R.}, year={2013}, pages={594–600} }
 @article{lewis_jeffries_strek_richardson_yelverton_2013, title={Effect of Ambient Moisture on Aminocyclopyrachlor Efficacy}, volume={27}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-12-00131.1}, abstractNote={Aminocyclopyrachlor (AMCP) is a newly developed synthetic auxin herbicide for broadleaf weed control in turfgrass systems. AMCP has been observed to undergo rapid photodecomposition in shallow water when exposed to sunlight. Most herbicide applications on golf courses occur during the morning when dew is still present on the turfgrass canopy. These conditions could result in efficacy loss if photolysis occurred while AMCP is suspended in dew droplets. Research was conducted to determine the effect of ambient moisture on AMCP efficacy. AMCP (79 and 105 g ae ha−1), aminopyralid (280 g ae ha−1), and two AMCP granular formulations (84 g ha−1) were applied to dew-covered (WET) and dew-excluded (DRY) ‘Tifway' bermudagrass plots. Herbicide treatments applied to WET plots had greater visually rated bermudagrass injury than respective treatments applied to DRY plots at 7 and 21 d after treatment (DAT), with the exception of aminopyralid at 21 DAT. Normalized difference vegetative index on turfgrass quality complemented visual ratings, indicating greater turfgrass quality reductions when applied to WET vs. DRY plots. These results indicate that AMCP applications made to dew-covered turfgrass can increase herbicidal efficacy, and no significant losses due to photodegradation were observed.}, number={2}, journal={WEED TECHNOLOGY}, author={Lewis, Dustin F. and Jeffries, Matthew D. and Strek, Harry J. and Richardson, Robert J. and Yelverton, Fred H.}, year={2013}, pages={317–322} }
 @article{emerine_richardson_arellano_2013, title={Porcelain Berry (Ampelopsis brevipedunculata), Bushkiller (Cayratia japonica), and Virginia-Creeper,(Parthenocissus quinquefolia) in Interspecific Competition.}, volume={6}, ISSN={["1939-747X"]}, DOI={10.1614/ipsm-d-12-00008.1}, abstractNote={AbstractPorcelain berry and bushkiller are confamilial, exotic, perennial vines in the Vitaceae family that are considered nuisance/invasive weeds of natural and riparian areas in the eastern United States. To better understand the competitive abilities of these aggressive weeds, greenhouse competition experiments were conducted on cuttings of porcelain berry, bushkiller, and Virginia-creeper, a native member of the Vitaceae family. Plants grown singly or in combination were monitored for stem growth and biomass production. In this research, porcelain berry and Virginia-creeper exhibited similar rates of stem growth, whereas bushkiller grew taller and faster than either of the other species. Porcelain berry stem growth was reduced in competition with bushkiller. All three species exhibited reduced stem biomass when grown with both other species. Root biomass of porcelain berry and Virginia-creeper were not affected by competition, but bushkiller, which produced the heaviest roots, exhibited reduced root biomass when grown with both other species. Porcelain berry root length was reduced by competition with both other species, but neither Virginia-creeper nor bushkiller root lengths were affected by competition. These results indicate that bushkiller is likely the strongest competitor of the three species studied. In these experiments, porcelain berry was less aggressive and vigorous than bushkiller but was similar to Virginia-creeper.}, number={1}, journal={INVASIVE PLANT SCIENCE AND MANAGEMENT}, author={Emerine, Sherrie E. and Richardson, Robert J. and Arellano, Consuelo}, year={2013}, pages={99–104} }
 @article{west_lewis_richardson_2012, title={Fragment Size and Planting Depth Affect the Regenerative Capacity of Bushkiller (Cayratia japonica)}, volume={5}, ISSN={["1939-747X"]}, DOI={10.1614/ipsm-d-12-00007.1}, abstractNote={AbstractBushkiller (Cayratia japonica) is a herbaceous, perennial vine that reproduces from seed and vegetative root structures within its native range. However, this species is considered invasive in the United States due to prolific shoot production, which can overtop surrounding vegetation. Cultural control practices, such as mulching, have been observed to further the spread of this species through regeneration of root fragments. Research was conducted to determine the regenerative capacity of bushkiller root fragments (1 to 7 cm; 2.5 to 18 inches) buried at various depths (0 to 40 cm). Root length and planting depth affected leaf number, shoot number, plant height, and shoot biomass. Bushkiller leaf density, shoot density, plant height, and dry weight increased as root fragment length increased from 1 to 7 cm; conversely, these variables decreased as planting depth increased from 0 to 40 cm. Results indicate bushkiller regeneration capacity from root fragments is extremely high and control practices that fragment roots should be avoided to reduce further spread.}, number={4}, journal={INVASIVE PLANT SCIENCE AND MANAGEMENT}, author={West, Amanda M. and Lewis, Dustin F. and Richardson, Robert J.}, year={2012}, pages={397–401} }
 @article{west_richardson_gardner_hoyle_2011, title={Bushkiller (Cayratia japonica) Response to Selected Herbicides}, volume={4}, ISSN={["1939-747X"]}, DOI={10.1614/ipsm-d-10-00038.1}, abstractNote={AbstractBushkiller, an aggressive perennial vine native to Southeast Asia, has invaded several sites in Alabama, North Carolina, Texas, Louisiana, and Mississippi. Bushkiller has only recently been discovered in North Carolina. The potential economic and environmental consequences associated with established exotic invasive perennial vines and the lack of published control measures for bushkiller prompted research to be conducted at North Carolina State University that may be used in an early-detection rapid-response program. Field and greenhouse studies were conducted to determine bushkiller response to selected foliar-applied herbicides. Field study 1 evaluated efficacy of glyphosate, triclopyr, triclopyr plus 2,4-D, triclopyr plus aminopyralid, and triclopyr plus glyphosate applied postemergence to bushkiller. No control was evident from any treatment at 10 mo after application. In a separate experiment, aminocyclopyrachlor, imazapyr, metsulfuron, sulfometuron, and sulfometuron plus metsulfuron were applied postemergence to bushkiller. Control with aminocyclopyrachlor, imazapyr, sulfometuron, and sulfometuron plus metsulfuron was 88 to 99% at 10 mo after application. Each treatment was also applied to bushkiller in a greenhouse trial. Aminocyclopyrachlor and triclopyr-containing treatments generally resulted in the greatest control, lowest dry weights, and shortest vine lengths among the treatments. These results indicate that several herbicides may be employed initially in an early-detection, rapid-response program for bushkiller. Additional research is needed to determine how effective these herbicides would be in multiple-season treatments that may be required at well established bushkiller infestation sites.}, number={1}, journal={INVASIVE PLANT SCIENCE AND MANAGEMENT}, author={West, Amanda M. and Richardson, Robert J. and Gardner, Andrew P. and Hoyle, Steve T.}, year={2011}, pages={73–77} }
 @article{lewis_hoyle_fisher_yelverton_richardson_2011, title={Effect of Simulated Aminocyclopyrachlor Drift on Flue-Cured Tobacco}, volume={25}, ISSN={["0890-037X"]}, DOI={10.1614/wt-d-11-00037.1}, abstractNote={Flue-cured tobacco is sensitive to foliar and soil residues of off-target synthetic auxin drift. Aminocyclopyrachlor is a newly developed synthetic auxin herbicide that may be used in right-of-way applications for broadleaf weed and brush control. Aminocyclopyrachlor is considered a reduced-risk alternative in rights-of-way compared with similar compounds because of its low application rate and volatility risk. However, no research is available on the response of field-grown, flue-cured tobacco to aminocyclopyrachlor drift exposure. Research was conducted in 2009 and 2010 at the Border Belt Tobacco Research Station in Whiteville, NC, to determine the response of ‘NC 71’ flue-cured tobacco to five simulated drift rates of aminocyclopyrachlor (0.31, 1.6, 3.1, 15.7, and 31.4 g ae ha−1) and one aminopyralid (6.1 g ae ha−1) simulated drift rates applied pretransplant incorporated, pretransplant unincorporated, 3 wk after transplant, and 6 wk after transplant. All herbicide rates and application timings caused significant visual tobacco injury, ranging from slight to severe with increasing herbicide drift rates. Tobacco plant heights and fresh weights were reduced at all application timings receiving ≥ 15.7 g ha−1aminocyclopyrachlor and the comparative aminopyralid rate.}, number={4}, journal={WEED TECHNOLOGY}, author={Lewis, D. F. and Hoyle, S. T. and Fisher, L. R. and Yelverton, F. H. and Richardson, R. J.}, year={2011}, pages={609–615} }
 @article{west_richardson_arellano_burton_2010, title={Bushkiller (Cayratia japonica) Growth in Interspecific and Intraspecific Competition}, volume={58}, ISSN={["1550-2759"]}, DOI={10.1614/ws-09-051.1}, abstractNote={Bushkiller was evaluated under inter- and intraspecific competition. In experiment 1, bushkiller, trumpetcreeper, and wild grape were greenhouse-grown alone and in two or three species mixtures in pots. Of the three species, bushkiller grew the tallest and had the greatest final biomass when grown alone. When all three species were grown together, bushkiller grew over twice the height of trumpetcreeper, over three times the height of wild grape, and over four times the biomass of either competing species. Plots of height over time showed that competition did not affect bushkiller or wild grape growth rate, but trumpetcreeper growth was reduced when grown with bushkiller. In experiment 2, bushkiller was grown in cultures of one, two, and three plants per pot to determine intraspecific competition effects on growth. Final height of bushkiller was not affected by intraspecific competition; however, bushkiller biomass decreased with increasing competition.}, number={3}, journal={WEED SCIENCE}, author={West, Amanda M. and Richardson, Robert J. and Arellano, Consuelo and Burton, Michael G.}, year={2010}, pages={195–198} }
 @article{true_richardson_hipkins_gardner_2010, title={Efficacy of selected aquatic herbicides on common reed}, volume={48}, journal={Journal of Aquatic Plant Management}, author={True, S. L. and Richardson, R. and Hipkins, P. L. and Gardner, A. P.}, year={2010}, pages={121–123} }
 @article{emerine_richardson_true_west_roten_2010, title={Greenhouse response of six aquatic invasive weeds to imazamox}, volume={48}, journal={Journal of Aquatic Plant Management}, author={Emerine, S. E. and Richardson, R. J. and True, S. L. and West, A. M. and Roten, R. L.}, year={2010}, pages={105–111} }
 @article{richardson_marshall_uhlig_zandstra_2009, title={Virginia Creeper (Parthenocissus quinquefolia) and Wild Grape (Vitis spp.) Control in Fraser Fir}, volume={23}, ISSN={["0890-037X"]}, DOI={10.1614/WT-08-028.1}, abstractNote={Virginia creeper and wild grape are troublesome perennial vines that often infest Christmas tree plantations. Field studies were conducted to evaluate Fraser fir injury and Virginia creeper and wild grape control with directed applications of triclopyr (1,680 g ai/ha) alone and in combination with 2,4-D (1,120 g ai/ha), clopyralid (280 g ai/ha), and halosulfuron (36 g ai/ha). Additional treatments included 2,4-D, clopyralid, glyphosate (1,120 g ai/ha), halosulfuron, hexazinone (560 g ai/ha), mesotrione (105 g ai/ha), and sulfometuron (71 g ai/ha) applied alone; and a mixture of hexazinone plus mesotrione. In the triclopyr-containing treatments, Fraser fir injury ranged from 6 to 13% at 1 mo after treatment (MAT) and was 4 to 8% at 11 MAT. Leader growth was not impacted by the herbicide treatments. At 11 MAT, all triclopyr-containing treatments controlled Virginia creeper 93 to 98% and wild grape 98 to 100%, which was greater than the control observed with glyphosate at 63 and 59%, respectively. Virginia creeper and wild grape control with 2,4-D was 88 to 90%. Clopyralid, halosulfuron, hexazinone, hexazinone plus mesotrione, mesotrione, and sulfometuron provided less than 66% control of both perennial vines. Directed applications of triclopyr-containing treatments or 2,4-D were effective management tools for selective removal of wild grape and Virginia creeper from Fraser fir Christmas tree plantations. Additional research is needed on the potential sensitivity of other commonly grown Christmas tree species to triclopyr-containing treatments.}, number={1}, journal={WEED TECHNOLOGY}, author={Richardson, Robert J. and Marshall, Michael W. and Uhlig, Robert E. and Zandstra, Bernard H.}, year={2009}, pages={184–187} }
 @article{richardson_2008, title={Aquatic plant management and the impact of emerging herbicide resistance issues}, volume={22}, ISSN={["1550-2740"]}, DOI={10.1614/wt-07-034.1}, abstractNote={Aquatic plants provide many benefits to the environment, but must be managed when growth reaches nuisance levels or when invasive plant species are released. Management tactics include biological, chemical, cultural, mechanical, and physical tools. Each specific management technique has advantages and disadvantages. In addition, the implementation of these techniques can become complicated because of the multiple users, managers, and stakeholders that may be present on large bodies of water. As an example, hydrilla is the most economically damaging aquatic weed in the United States. It reproduces through fragmentation, turions, and occasionally seed and can colonize a wide variety of aquatic environments. The most common management tactics for hydrilla include biological, chemical, and mechanical tools. Triploid grass carp have been the primary biological control agent, whereas fluridone has been the only systemic herbicide used. Because of heavy utilization of fluridone, biotypes have developed resistance to this herbicide in Florida. Although several acetolactate synthase-inhibiting herbicides are in development, herbicides with additional modes of action are needed for resistance management. Other aquatic plant management needs include additional control tactics for algae and additional extension resources for public education. Nomenclature: Fluridone, hydrilla, Hydrilla verticillata (L.f.) Royle, triploid grass carp, Ctenopharyngodon idella Val}, number={1}, journal={WEED TECHNOLOGY}, author={Richardson, Robert J.}, year={2008}, pages={8–15} }
 @article{cain_martinez_kokkinos_turner_richardson_abud_huelsken_robinson_de iongh_2008, title={Differential requirement for β-catenin in epithelial and fiber cells during lens development}, volume={321}, ISSN={0012-1606}, url={http://dx.doi.org/10.1016/j.ydbio.2008.07.002}, DOI={10.1016/j.ydbio.2008.07.002}, abstractNote={Recent studies implicate Wnt/β-catenin signaling in lens differentiation (Stump, R. J., et al., 2003. A role for Wnt/beta-catenin signaling in lens epithelial differentiation. Dev Biol;259:48–61). β-catenin is a component of adherens junctions and functions as a transcriptional activator in canonical Wnt signaling. We investigated the effects of Cre/LoxP-mediated deletion of β-catenin during lens development using two Cre lines that specifically deleted β-catenin in whole lens or only in differentiated fibers, from E13.5. We found that β-catenin was required in lens epithelium and during early fiber differentiation but appeared to be redundant in differentiated fiber cells. Complete loss of β-catenin resulted in an abnormal and deficient epithelial layer with loss of E-cadherin and Pax6 expression as well as abnormal expression of c-Maf and p57kip2 but not Prox1. There was also disrupted fiber cell differentiation, characterized by poor cell elongation, decreased β-crystallin expression, epithelial cell cycle arrest at G1–S transition and premature cell cycle exit. Despite cell cycle arrest there was no induction of apoptosis. Mutant fiber cells displayed altered apical–basal polarity as evidenced by altered distribution of the tight junction protein, ZO1, disruption of apical actin filaments and abnormal deposition of extracellular matrix, resulting in a deficient lens capsule. Loss of β-catenin also affected the formation of adhesion junctions as evidenced by dissociation of N-cadherin and F-actin localization in differentiating fiber cells. However, loss of β-catenin from terminally differentiating fibers had no apparent effects on adhesion junctions between adjacent embryonic fibers. These data indicate that β-catenin plays distinct functions during lens fiber differentiation and is involved in both Wnt signaling and adhesion-related mechanisms that regulate lens epithelium and early fiber differentiation.}, number={2}, journal={Developmental Biology}, publisher={Elsevier BV}, author={Cain, Sarah and Martinez, Gemma and Kokkinos, Maria I. and Turner, Kirsty and Richardson, Robert J. and Abud, Helen E. and Huelsken, Joerg and Robinson, Michael L. and de Iongh, Robb U.}, year={2008}, month={Sep}, pages={420–433} }
 @article{richardson_roten_west_true_gardner_2008, title={Response of selected aquatic invasive weeds to Flumioxazin and Carfentrazone-ethyl}, volume={46}, journal={Journal of Aquatic Plant Management}, author={Richardson, R. J. and Roten, R. L. and West, A. M. and True, S. L. and Gardner, A. P.}, year={2008}, pages={154–158} }
 @article{uhlig_bird_richardson_zandstra_2007, title={Soil fumigants to replace methyl bromide for weed control in ornamentals}, volume={17}, number={1}, journal={HortTechnology}, author={Uhlig, R. E. and Bird, G. and Richardson, R. J. and Zandstra, B. H.}, year={2007}, pages={111–114} }
 @article{richardson_whaley_wilson_hines_2004, title={Weed control and potato (Solanum tuberosum) tolerance with dimethenamid isomers and other herbicides}, volume={81}, ISSN={1099-209X 1874-9380}, url={http://dx.doi.org/10.1007/bf02870175}, DOI={10.1007/bf02870175}, number={5}, journal={American Journal of Potato Research}, publisher={Springer Science and Business Media LLC}, author={Richardson, Robert J. and Whaley, Cory M. and Wilson, Henry P. and Hines, Thomas E.}, year={2004}, month={Sep}, pages={299–304} }