Recipient Organization
NORTH CAROLINA STATE UNIV
(N/A)
RALEIGH,NC 27695
Performing Department
Crop & Soil Sciences
Non Technical Summary
Invasive aquatic plants cause significant environmental and economic impacts. Invasive species have been identified as the second leading cause of species extinctions. Invasive plants disrupt ecosystems, reduce biodiversity, and also cause impacts to humans including reducing property values, impairing recreation, restricting drinking water, blocking irrigation, increasing habitat for disease vectors, etc. Understanding the biology of these species and evaluting appropriate management practices is essential in order to mitigate the damage caused by invasion. The proposed research will improve the current understanding of the biology of important invasive aquatic weeds. This research will improve the efficiency of management programs and reduce environmental impacts. This project will also improve survey methods allowing invasive plants to be detected earlier and more efficiently, which will also reduce potential environmental impacts.
Animal Health Component
50%
Research Effort Categories
Basic
30%
Applied
50%
Developmental
20%
Goals / Objectives
Goal: Improve our understanding of the biology of major invasive aquatic weeds and improve control methods for those plants.Objectives:1. Evaluate the biology of Hydrilla verticillata in flowing systems and determine appropriate control strategies.2. Investigate the parameters of foliar herbicide application to aquatic weeds and determine methods to improve herbicide delivery.3. Improve methodology for survey and monitoring of invasive aquatic weeds.
Project Methods
1. Evaluate the biology of Hydrilla verticillata in flowing systems and determine appropriate control strategies.Evaluate the effectiveness of intermittent (pulse) herbicide applications on invasive hydrilla and desirable Vallisneria americana and Potamogeton illinoensis. Geographically separated populations have been shown to have differential responses to herbicide treatment (Beets 2019; Gosselin 2017). As such, these trials will include dioecious hydrilla from FL and VA (Philpott Lake, USACE reservoir), monoecious hydrilla from NC and PA, Vallisneria americana from several geographically distinct locations including NC and NY, Potamogeton illinoensis from FL and a location TBD, and Nuphar advena from FL and NC. We will also include the newly described hydrilla biotype from CT river (Tippery et al. 2020; Greg Bugbee CT Agricultural Experiment Station will collaborate by providing plants).Standard intermittentMonoecious hydrilla and CT river hydrilla will be established in mesocosms at NCSU, while dioecious hydrilla (fluridone and endothall-sensitive) will be established in mesocosms at the Center for Aquatic Invasive Plants, FL. NCSU trials will be split between mesocosms near Raleigh, NC (315 ft elevation) and Laurel Springs, NC (3,800 ft elevation) in order to utilize two distinct climates. Methodology will build on that of Netherland (2015). Herbicide will be applied as intermittent doses with plants rinsed and moved to non-treated water for select intervals and then exposed to treatment again. Treatments will be applied with exposure intervals of 3, 6, or 12 days alternating between treated (3 day intervals) and non-treated water similar to previously successful intermittent fluridone and endothall treatments conducted on monoecious hydrilla alone (Netherland, 2015; pers com Dr. Justin Nawrocki, 2020). The proposed study will expand on previous work with the inclusion of additional biotypes, populations and species, as well as a broader range of herbicide active ingredients and rates. Monoecious and dioecious experimental units will be established 3 to 4 weeks prior to treatment. Harvests will be performed 90 days after treatment. Dioecious hydrilla has slower initial accumulation of biomass than monoecious hydrilla, however this 90 period should encompass a large enough growth period to achieve maximal biomass in small mesocosms. Potential differences in growth between monoecious and dioecious hydrilla can be accounted for using relative growth calculations. Plant matter will be dried to obtain dry biomass. Potential treatments include endothall (2, 3, and 4 ppm), florpyrauxifen-benzyl (10, 30, 50 ppb), and fluridone (2, 4, 6 ppb), with rates as total active ingredient applied across applications. [Specific rates, timings, etc. for each objective/trial will be finalized during the project kickoff video conference between the research team and the APCRP technical team.]B. Endothall Pulse Followed by Diquat PulseThis trial will evaluate the efficacy of endothall treatment followed by diquat and vice versa. Planned treatments are as follows. Rates and exposures are subject to change with additional information.Endothall applied at 2 ppm with an exposure time of 12 hours. After water exchange and a 12 hour recovery period diquat (0.375 ppm) will be applied for 12 hoursDiquat (0.375 ppm) for 12 hours. After water exchange and a 12 hour recovery period, endothall (2 ppm) will be applied with an exposure time of 12 hoursDiquat (0.375 ppm) for 12 hours, followed by endothall (2 ppm) for 12 hoursEndothall (2 ppm) for 12 hours, followed by diquat (.375 ppm) for 12 hoursEndothall (2ppm) plus diquat (0.375 ppm) for a 6 hour exposureEndothall (2 ppm) plus diquat (0.375 ppm) for a 12 hour exposureEndothall (2ppm) plus diquat (0.375 ppm) for a 24 hour exposureEndothall (2 ppm) for a 12 hour exposureEndothall (2 ppm) for a 24 hour exposureDiquat (0.375 ppm) for a 12 hour exposureDiquat (0.375 ppm) for a 24 hour exposureEndothall (2 ppm) static exposureDiquat (0.375 ppm) static exposurea non-treated controlMethods regarding study locations, plant species, flow rates, and data collection will be mirrored to those of the standard intermittent studies described above in section A.2. Investigate the parameters of foliar herbicide application to aquatic weeds and determine methods to improve herbicide delivery.NCSU research will focus on creeping floating habit (CFH) plants. Initial mesocosm-scale experiments will use small containers (trash cans or shallow totes (dependent on results from initial pilot studies)). Stem fragments of alligatorweed and creeping water primrose will be placed in potting media (topsoil amended with Osmocote™ @ 3 g/L and capped with sand) in pots (6" round) which will then be placed into the mesocosms and positioned in shallow water atop a stand of pre-determined volume, if necessary. Plants will be allowed to root and acclimate for at least 14 days to achieve active growth. Each mesocosm will have 3 - 30 gallons of water (dependent on chosen mesocosm type). Plants of uniform size and appearance will be selected for trials. Water level will be maintained by adding water twice a week as necessary. Prior to treatment, pots will be capped with a solid agar layer to avoid loss of product in soil. During treatment, the mesocosms (EU's) will be set-up such that they hold the maximum amount of water and pots remain completely submerged as to not interfere with overspray volume calculations. Concentrations of RWT in the water column will be measured with an in-situ probe.3. Improve methodology for survey and monitoring of invasive aquatic weeds.