: The purpose of this work was to evaluate the efficacy of mechanical cutting and herbicide applications to control invasive phragmites at Times Beach, a 56-acre nature preserve located in Buffalo, New York. The overall objective of this five-year project is to replace the dense monotypic stands of phragmites with a diverse native plant community that will repair ecosystem function.

Early-season recommendations to improve herbicide efficacy and selectivity when targeting Eurasian watermilfoil (Myriophyllum spicatum L.) have been adopted by many aquatic plant managers in the upper Midwest. To address the role of treatment timing and exposure, two mesocosm studies were conducted on plants established the prior fall to evaluate short- and long-term exposure scenarios when the auxin mimic herbicide triclopyr ([3,5,6-trichloro-2-pyridinyl)oxy]acetic acid) is used for selective control of Eurasian watermilfoil (EWM). The first study included liquid and granular triclopyr applied at 1.5 mg L-1 in late February and late April 2009 under high-water-exchange conditions (12-h half-life). The second trial included static liquid exposures for early March and late April 2011 treatments at use rates of 0.25, 0.5, and 1.5 mg L-1 and liquid and granular treatments at 1.5 mg L-1 under high-waterexchange conditions (5-h half-life). The second study also included the native species American pondweed (Potamogeton nodosus Poir.), Illinois pondweed (P. illinoensis Morong), and vallisneria (Vallisneria americana Michx.). In the first study, February triclopyr treatments with liquid and granular formulations did not reduce biomass compared to the untreated plants during a May harvest, whereas both April treatments resulted in complete control of EWM. Results of the second trial indicated that treatment timing (March vs. April) was not a significant factor for static treatments (0.25 to 1.5 mg L-1) and near 100% EWM control was achieved. In contrast, under high flow conditions, the March liquid treatment did not differ from the untreated reference plants. The granular treatment reduced EWM by 55% compared to the untreated reference, yet it still increased in biomass by 4-fold compared to the initial biomass. The April treatments were more effective than the March applications under conditions of high water exchange. The native plants evaluated were not impacted by treatment timing, rate, formulation, or exposure scenario. Results demonstrate early-season treatments were effective regardless of treatment timing under extended triclopyr exposure periods; however, in areas of high-water-exchange early treatments of EWM resulted in reduced plant control. Managers can use this information to determine if early- or later-season treatments are warranted based on the likely exposure scenario.

Bispyribac-sodium [2,6-bis(4,6-dimethoxypyrimidin-2yloxy)benzoic acid] recently received a USEPA Section 3 aquatic registration for control of hydrilla and other nuisance aquatic plants. Similar to the herbicides penoxsulam [2(2,2-difluoroethoxy)-N-(5,8-dimethoxy [1,2,4] triazolo[1,5c]pyrimidin-2-yl)-6 (trifluoromethyl) benzenesulfonamide] and imazamox [2-[4,5-dihydro-4-methyl-4-(1-methylethyl)5-oxo-1H-imidazol-2-yl]-5-(methoxymethyl)-3-pyridinecarboxylic acid], bispyribac-sodium inhibits the production of branched-chain amino acids by binding to the acetolactate synthase (ALS) enzyme (Tranel and Wright 2002). Without these essential amino acids, protein synthesis and growth are inhibited, ultimately resulting in plant death (WSSA 2007). While the ALS inhibitors target the same plant enzyme, the large number of ALS inhibitors registered for terrestrial use attests to significant differences in plant selectivity between these compounds; therefore, evaluation of two or three different ALS inhibitors on a suite of plant species may yield very different outcomes. For example, Koschnick et al. (2007) reported EC50 values for penoxsulam, bispyribacsodium and imazamox on duck potato shoot biomass (Sagittaria lancifolia L.) to be 9, 105, 96 lg (9, 105, and 96 ppb) active ingredient (ai) L , respectively. If the management goal was to control hydrilla without damaging stands of duck potato, then the use of penoxsulam may not be the product of choice since herbicide concentrations of 5 to 20 lg L 1 are required. Systematic efficacy evaluations on both nontarget and target weeds are important for determining use patterns of the ALS herbicides. Previous work on water hyacinth (Eichhornia crassipes (Mart.) Solms) has shown that penoxsulam is effective as either a subsurface or foliar application (Richardson and Gardner 2007, Wersal and Madsen 2010). Also, imazamox is efficacious against water hyacinth and water lettuce (Pistia stratiotes L.) at higher subsurface application rates, but this product is ineffective against giant salvinia (Salvinia molesta D.S. Mitchell) (Emerine et al. 2010). Little to no information is available on the efficacy of bispyribac-sodium on water hyacinth, water lettuce or giant salvinia. Although other herbicides such as 2,4-D, carfentrazone-ethyl, chelated copper, diquat and glyphosate are effective on water hyacinth, water lettuce and/or giant salvinia (Westerdahl and Getsinger 1988, Lopez 1993, Nelson et al. 2001, Langeland et al. 2002, Glomski et al. 2003, Glomski and Getsinger 2006), the ALS inhibitors represent a new mode of action for controlling floating aquatic plants. With the discovery of fluridone resistance in hydrilla (Michel et al. 2004, Arias et al. 2005) and diquat resistant dotted duckweed (Koschnick et al. 2006) it has become important to not rely on any one mode of action to control any invasive plant. While many aquatic herbicides including 2,4-D, diquat, and glyphosate have become cost effective mainstays of maintenance control programs, there are still issues with injury and selectivity when applied to native/ non-native mixed communities containing bulrush (Scirpus spp.), spatter-dock (Nuphar lutea L.), cattail (Typha spp.), and other species (White 1965, Langeland et al. 2009, University of Florida 2011). New products need to be utilized in management programs that will not only minimize damage to nontarget species, but also provide acceptable control of target plants. Because of the limited amount of efficacy data available for bispyribac-sodium, studies were conducted to evaluate the activity of subsurface and foliar applications of bispyribac-sodium on the floating weeds water hyacinth, water lettuce and giant salvinia.

: The purpose of this work was to develop and utilize a rapid, small-scale primary screening method to evaluate the activity of a recently registered aquatic herbicide, flumioxazin, against 23 native emergent plant species and five invasive emergent species. In evaluating potential use patterns of new aquatic herbicides, it is important to determine concentrations that impact target as well as non-target vegetation. The recently registered aquatic herbicide flumioxazin is efficacious against the floating weeds water lettuce (Pistia stratiotes L.) and giant salvinia (Salvinia molesta Mitchell) (Richardson et al. 2008) as well as the submersed species hydrilla (Hydrilla verticillata (L.f.) Royle) (Mudge and Haller 2006) and Eurasian watermilfoil (Myriophyllum spicatum L.) (Getsinger et al. 2011). These species are often found in close proximity to or intermixed with native emergent vegetation and information on the impact of flumioxazin to most emergent plant species is limited. Information regarding the selectivity of flumioxazin (and other aquatic herbicides) will help resource managers decide which herbicides, use rates, and timing of application are most appropriate to reduce injury to the native emergent species present. This work has become increasingly relevant as research conducted last year demonstrated a potential selective use pattern for flumioxazin in areas where water lettuce is intermixed with emergent species (Netherland 2011). The endangered snail kite (Rosthramus sociabilis) is utilizing habitats in areas of large-scale floating plant control operations. Current operational use of the broad-spectrum herbicide diquat, while highly effective at controlling water lettuce, generally results in significant visual injury symptoms on numerous emergent plant species.

: The purpose of this work was to evaluate flumioxazin and imazamox alone and in combination with glyphosate as potential alternatives for controlling Japanese knotweed at Times Beach, a 56-acre nature preserve located in Buffalo, New York. Times Beach is a 56-acre nature preserve located in Buffalo, New York. The site was initially constructed by the USACE Buffalo District as a confined disposal facility (CDF) in 1971. The CDF was partially filled and closed in 1976 at the request of the Ornithological Society of Buffalo (Simmers and Lee 1997). The site consists of three distinct ecological zones (aquatic, wetland and upland) and is utilized by more than 200 species of resident and migratory birds (Andrle 1986, Simmers and Lee 1997). Approximately 46 acres of Times Beach has been designated as a state wetland by the New York State Department of Environmental Conservation. Times Beach is located adjacent to the Buffalo River Area of Concern (AOC) and within the Niagara River Bi-national AOC. The site is dominated by invasive species such as phragmites (Phragmites australis (Cav.) Trin. Ex Steud.), Japanese knotweed (Polygonum cuspidatum Siebold & Zucc.), common buckthorn (Rhamnus cathartica L.) and mugwort (Artemisia vulgaris L.). The U.S. Army Engineer Research and Development Center in collaboration with the U.S. Army Corps of Engineers (USACE) Buffalo District developed an invasive species management and restoration plan for Times Beach. Removal of invasive species combined with enhancement of native plant communities will ultimately result in repaired ecosystem function. The Times Beach management and restoration plan was initiated in October 2012 with funding from the U.S. Environmental Protection Agency s (EPA) Great Lakes Restoration Initiative (GLRI). Because the majority of the site is classified as a state wetland, only aquatic herbicide formulations registered by the U.S. EPA and the state of New York can be applied.

When evaluating potential use patterns of new aquatic herbicides, it is important to determine effects on target as well as nontarget vegetation. Small-scale primary screens that provide data on the relative sensitivity of a species to a given herbicide or herbicide use rate can be used to enhance the design of more-costly and time-consuming, large-scale, growth-chamber and mesocosm studies. Flumioxazin (2-[7-fluoro-3,4-dihydro-3-oxo-4-(2-propynyl)-2H1,4-benzoxazin-6-yl]-4,5,6,7-tetrahydro-1H-isoindole1,3(2H)-dione) and carfentrazone-ethyl (ethyl a,2-dichloro5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4triazol-1-yl]-4-fluorobenzenepropanoate) are protoporphyrinogen oxidase (protox)–inhibiting herbicides recently registered by the U.S. Environmental Protection Agency (USEPA) for use in aquatic sites. These protox inhibitors disrupt chlorophyll synthesis and result in formation of oxygen radicals that damage cell membranes, causing them to leak cell contents. This leakage of electrolytes was measured and used to determine herbicide injury following exposure to protox inhibitors. Electrolyte leakage was measured at 5 d posttreatment for 15 submersed aquatic plant species exposed to flumioxazin at 0, 200, and 400 l ga i L 1 (0, 0.0000265, and 0.000053 ppb) and to carfentrazoneethyl at 0 and 200 l ga i L 1 in small-scale laboratory assays. In these assays, flumioxazin significantly increased electrolyte leakage for coontail (Ceratophyllum demersum L.) and curlyleaf pondweed (Potamogeton crispus L.). Eurasian watermilfoil (Myriophyllum spicatum L.), fanwort (Cabomba caroliniana Gray), hydrilla [Hydrilla verticillata (L. f.) Royle], longbeak buttercup (Ranunculus longirostris Godr.), springtape (Sagittaria kurziana Gluck), variable watermilfoil (Myriophyllum heterophyllum Michx.), and waterstargrass [Heteranthera dubia (Jacq.) MacM.]. Species that were not significantly affected by flumioxazin included American pondweed (Potamogeton nodosus Poir.), common elodea (Elodea canadensis Michx.), Illinois pondweed (Potamogeton illinoensis Morong), sago pondweed [Stuckenia pectinatus (L.) Boerner], southern naiad [Najas guadalupensis (Spreng.) Magnus], and American eelgrass (Vallisneria americana Michx.). Of the species tested, carfentrazone-ethyl only increased electrolyte leakage of coontail, Eurasian watermilfoil, and variable watermilfoil.

In situ hyperspectral reflectance data were studied at 50 wavebands (10 nm bandwidth) in the 400 to 900 nm spectral range to determine their potential for discriminating among 6 aquatic weed species: curly-leaf pondweed (Potamogeton crispus L.), hydrilla (Hydrilla verticillata [L.F.] Royle), Eurasian watermilfoil (Myriophyllum spicatum L.), northern milfoil (Myriophyllum sibiricum Kom.), hybrid milfoil (Myriophyllum spicatum * Myriophyllum sibiricum), and parrotfeather (Myriophyllum aquaticum [J.M. da Conceicao] Vellozo). The species were studied on 3 dates: May 11, May 30, and July 1, 2009. All 6 species were studied on the 2 May dates, while only 4 species (hydrilla, Eurasian watermilfoil, hybrid milfoil, and parrotfeather) were studied on the July date. To determine the optimum bands for discriminating among the species, 2 procedures were used: multiple comparison range test and step-wise discriminant analysis. Multiple comparison range test results for both May dates showed that most separations among species occurred at bands in the green-red edge, red, and red near-infrared (NIR) edge spectral regions. For the July date, the largest number of separations among species occurred at all green and most red bands, as well as some red-NIR edge and NIR bands. Using stepwise discriminant analysis, 9 bands for May 11 and 10 bands for May 30 in the blue to NIR spectral regions had the highest power of discrimination among the 6 species. For the July date, 7 bands in the red-NIR edge and NIR regions were useful for discriminating among the 4 species.

In situ hyperspectral reflectance data were studied at 50 bands (10 nm bandwidth) over the 400-900 nm spectral range to determine their potential for distinguishing among nine aquatic plant species: American lotus [Nelumbo lutea (Willd.) Pers.], American pondweed (Potamogeton nodusus Poir.), giant duckweed [Spirodela polyrrhiza (L.) Schleid.], Mexican waterlily (Nymphaea mexicana Zucc.), white waterlily (Nymphaea odorata Aiton), spatterdock [Nuphar lutea (L.) Sm.], giant salvinia (Salvinia molesta Mitchell), waterhyacinth [Eichhornia crassipes (Mart.) Solms] and waterlettuce (Pistia stratiotes L.). The species were studied on three dates: 30 May, 1 July and 3 August 2009. All nine species were studied in July and August, while only eight species were studied in May; giant duckweed was not studied in May due to insufficient availability. Two procedures were used to determine the optimum bands for discriminating among species: multiple comparison range tests and stepwise discriminant analysis. Multiple comparison range tests results for May showed that most separations among species occurred at bands 795-865 nm in the near-infrared (NIR) spectral region where up to six species could be distinguished. For July, few species could be distinguished among the 50 bands; most separations occurred at the 715 nm red-NIR edge band where four species could be differentiated. The optimum bands in August occurred in the green (525-595 nm), red (605-635 nm) and red-NIR edge (695-705 nm) spectral regions where up to six species could be distinguished. Stepwise discriminant analysis identified 11 bands in the blue, green, red-NIR edge and NIR spectral regions to be significant to discriminate among the eight species in May. For July and August, stepwise discriminant analysis identified 15 bands and 13 bands, respectively, from the blue to NIR regions to be significant for discriminating among the nine species.

Abstract : Lake Gaston is a large, multiple purpose impoundment on the Roanoke River between eastern North Carolina and Virginia. Invasive plants have been increasing on the lake since 1982. By 2002, over 1,200 ha of the lake were infested with several invasive plants, and an integrated management program (herbicides and grass carp) was underway. To improve herbicide performance on the lake, this study focused on three phases for controlling the lake's invasive submersed vegetation (the plants targeted were monoecious and dioecious hydrilla; Eurasian watermilfoil; egeria; and the bluegreen alga, lyngbya; non-target plants evaluated were vallisneria and southern naiad.) Phase one summarizes herbicide dose-response interactions (concentration and exposure time (CET) relationships) for controlling these plants using older aquatic herbicides; phase two evaluates CET relationships for new aquatic herbicides; and phase three provides interim management guidance for Lake Gaston. Product-specific CET information is best utilized when combined with site-specific water exchange patterns found in plant stands targeted for chemical applications. Prescriptive treatments can then be developed to selectively remove invasive plants. Results from evaluations showed that control of target plants was dependent upon product specific herbicide CET relationships, with efficacy ranging from poor to excellent. Information provided in this report can be used for developing prescriptive treatment strategies for selectively controlling invasive plants on Lake Gaston. Recommendations for specific herbicides should be viewed as a "best fit" based on current information. This interim chemical control guidance should be refined once site-specific water exchange processes are determined for treatment sites on Lake Gaston.

Eurasian watermilfoil (Myriophyllum spicatum L.) and hybrid watermilfoil (Myriophyllum spicatum x M. sibiricum) are invasive submersed plants that coexist in the Great Lakes and Pacific Northwest regions. The auxin-mimic herbicides triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) and 2,4-D (2,4-dichlorophenoxy acetic acid) are commonly used to control these species at recommended use rates of 1.5 to 2.5 mg L-1 and 2.0 to 4.0 mg L-1, respectively. Recent field data suggest that following some early season applications, control of watermilfoil may be related to extended exposures to low concentrations of these herbicides. Two greenhouse studies were conducted to determine the efficacy of lower concentrations and extended exposures of 2,4-D and triclopyr on both Eurasian and hybrid watermilfoil. Concentrations evaluated included 0, 25, 70, 100 and 250 mu g L-1 2,4-D amine or triclopyr. At 7 weeks after treatment, Eurasian watermilfoil biomass was significantly reduced with all rates of 2,4-D and triclopyr in both studies. Triclopyr at rates of 70 to 250 mu g L-1 controlled hybrid watermilfoil by 88 to 100% in study 1, while all rates of triclopyr resulted in 100% control of hybrid watermilfoil in study 2. The 2,4-D treatments of 25 to 100 mu g L were not different from the untreated control, whereas the 250 mu g L-1 treatment resulted in a 95% biomass reduction for hybrid milfoil in study 1. In study 2, 2,4-D at 70 mu g L-1 and higher controlled hybrid watermilfoil by 93 to 100%. Results from these studies indicate that low rates and extended exposures of both triclopyr and 2,4-D can be effective at controlling both Eurasian and hybrid watermilfoil; however, different hybrid watermilfoil accessions may respond differently to low concentrations of the auxin-mimic herbicides. The ability to utilize low concentrations of these compounds in areas with limited water exchange may represent a cost-effective, selective, and large-scale treatment strategy not fully utilized today.

Eurasian watermilfoil ( Myriophyllum spicatum L.) and hybrid watermilfoil ( Myriophyllum spicatum × M. sibiricum ) are invasive submersed plants that coexist in the Great Lakes and Pacific Northwest regions. The auxin-mimic herbicides triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) and 2,4-D (2,4-dichlorophenoxy acetic acid) are commonly used to control these species at recommended use rates of 1.5 to 2.5 mg L -1 and 2.0 to 4.0 mg L -1 , respectively. Recent field data suggest that following some early season applications, control of watermilfoil may be related to extended exposures to low concentrations of these herbicides. Two greenhouse studies were conducted to determine the efficacy of lower concentrations and extended exposures of 2,4-D and triclopyr on both Eurasian and hybrid watermilfoil. Concentrations evaluated included 0, 25, 70, 100 and 250 μg L -1 2,4-D amine or triclopyr. At 7 weeks after treatment, Eurasian watermilfoil biomass was significantly reduced with all rates of 2,4-D and triclopyr in both studies. Triclopyr at rates of 70 to 250 μg L -1 controlled hybrid watermilfoil by 88 to 100% in study 1, while all rates of triclopyr resulted in 100% control of hybrid watermilfoil in study 2. The 2,4-D treatments of 25 to 100 μg L -1 were not different from the untreated control, whereas the 250 μg L -1 treatment resulted in a 95% biomass reduction for hybrid milfoil in study 1. In study 2, 2,4-D at 70 μg L -1 and higher controlled hybrid watermilfoil by 93 to 100%. Results from these studies indicate that low rates and extended exposures of both triclopyr and 2,4-D can be effective at controlling both Eurasian and hybrid watermilfoil; however, different hybrid watermilfoil accessions may respond differently to low concentrations of the auxin-mimic herbicides. The ability to utilize low concentrations of these compounds in areas with limited water exchange may represent a cost-effective, selective, and large-scale treatment strategy not fully utilized today.

Bowmer, K. H., G. McCorkelle and G. R. Sainty. 1992. Potential use of bensulfuron methyl for sediment application in irrigation systems in Australia. J. Aquat. Plant Manage. 30:44-47. Chapman, R. L., D. E. Bayer and N. J. Lang. 1972. Observations on the dominant algae in experimental California rice fields. J. Phycol. Suppl . 8:17. Chen, Z., P. Juneau and B. Qiu. 2007. Effects of three pesticides on the growth, photosynthesis and photoinhibition of the edible cyanobacterium GeXian-Mi ( Nostoc ). Aquat. Toxic. 81:256-265. Desikachary, T. V. 1959. Cyanophyta . Indian Council of Agricultural Research, New Delhi. 686 pp. Getsinger, K. D., G. O. Dick, R. M. Crouch and L. S. Nelson. 1994. Mesocosm evaluation of bensulfuron methyl activity on Eurasian watermilfoil, Vallisneria, and American pondweed. J. Aquat. Plant Manage. 32:1-6. Glomski, L. M. and K. D. Getsinger. 2006. Carfentrazone-ethyl for control of giant salvinia. J. Aquat. Plant Manage. 44: 36-138. Glomski, L. M. and M. D. Netherland. 2007. Efficacy of diquat and carfentrazone-ethyl on variable-leaf milfoil. J. Aquat. Plant Manage. 45:136-138. Glomski, L. M. and M. D. Netherland. 2008. Effect of water temperature on 2,4-D ester and carfentrazone-ethyl applications for control of variable-leaf milfoil. J. Aquat. Plant Manage. 46:119-121. Glomski, L. M., A. G. Poovey, and K. D. Getsinger. 2006. Effect of carfentrazone-ethyl on three aquatic macrophytes. J. Aquat. Plant Manage. 44:67-69. Gray, C. J., J. D. Madsen, R. M. Wersal and K. D. Getsinger. 2007. Eurasian watermilfoil and parrotfeather control using carfentrazone-ethyl. J. Aquat. Plant Manage. 45:43-46. Haller, W. T., A. M. Fox and C. A. Hanlon. 1992. Inhibition of hydrilla tuber formation by bensulfuron methyl. J. Aquat. Plant Manage. 30:48-49. Hill, J. E. and A. J. Fisher. 1999. The framework for weed control programs in California rice. UC Cooperative Extension Rice Meetings, Feb. 1999. University of California, Davis. http://www.plantsciences.ucdavis.edu/ ucceRice/news/weedtalk.htm. Accessed 3 March 2009. Kim, J. and C. Lee. 2006. Differential responses of two freshwater cyanobacteria, Anabaena variabillis and Nostoc commune , to sulfonylurea herbicide bensulfuron-methyl. J. Microbiol. Biotechnol. 16:52-56. Koschnick, T. J., W. T. Haller and A. W. Chen. 2004. Carfentrazone-ethyl pond dissipation and efficacy on floating plants. J. Aquat. Plant Manage. 42:103108. Langeland, K. A. and F. B. Laroche. 1992. Hydrilla growth and tuber production in response to bensulfuron methyl concentration and exposure time. J. Aquat. Plant Manage. 30:53-58. Ma, J, L. Xu, S. Wand, R. Zheng, S. Jin, S. Huang and Y. Huang. 2002. Toxicity of 40 herbicides to the green alga Chlorella vulgaris . Ecotox. Environ. Safety 51:128-132. Nelson, L. S., M. D. Netherland and K. D. Getsinger. 1993. Bensulfuron methyl activity on Eurasian watermilfoil. J. Aquat. Plant Manage. 31:179-185. SAS Institute, Inc. 2004. SAS OnlineDoc® 9.1.3. SAS Institute, Inc., Cary, NC. Spencer, D. and G. Ksander. 1987. Comparison of three methods for extracting chlorophyll from aquatic macrophytes. J. Freshw. Ecol . 4:201-208. Spencer, D., C. Lembi and R. Blank. 2006. Spatial and temporal variation in the composition and biomass of algae present in selected California rice fields. J. Freshw. Ecol. 21:649-656. Van, T. K. and V. V. Vandiver, Jr. 1992. Response of monoecious and dioecious hydrilla to bensulfuron methyl. J. Aquat. Plant Manage. 30:41-44. Van, T. K. and V. V. Vandiver, Jr. 1994. Response of hydrilla to various concentrations and exposures of bensulfuron methyl. J. Aquat. Plant Manage. 32:7-11.