@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{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{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{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} }
 @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} }