Progress 09/01/10 to 08/19/15
Outputs
Progress Report Objectives (from AD-416): Objective 1: Improve understanding of weed life history and population dynamics (including effects of habitat alteration and assessment in canals and managed wetlands), biosystematics, and molecular biology to develop tools to undermine the success of weeds such as water primrose- willow species, perennial pepperweed, purple loosestrife, cordgrass, giant reed, and Eurasian milfoil, and to restore invaded riparian, marsh, and aquatic ecosystems. Objective 2: Determine the effectiveness of integrated weed management, including potential new herbicides on weeds such as hydrilla (Hydrilla verticillata), pondweeds (Potamogeton, nodosus, P. crispus, Stuckenia pectinata), Eurasian watermilfoil (Myriophyllum spicatum) and exposed sediments during seasonal drawdown (dewatering) for weeds such as M. spicatum, Western milfoil (M. hippuroides) in irrigation systems. Objective 3: Determine the applicability of biological control agents for water primrose-willows, Mexican mosquito fern, Brazilian waterweed, giant reed (including tricin host production effects on natural enemies), M. spicatum, and water hyacinth (Eichhornia crassipes), including plant ecology in relation to biological control for L. hexapetala and E. crassipes. Objective 4: Develop effective rapid response methods for new introductions of aquatic invasive weeds such as E. densa, P. crispus, and Undaria, or Japanese kelp (Undaria pinnatifida), and adapt these technologies to control invasive freshwater plant species, marine macroalgae and invasive marine plants. Approach (from AD-416): 1) A demographic study will determine how temporal and spatial variation in factors affecting Uruguayan water primrose contribute to overall population dynamics and improved management and restoration at Lagun de Santa Rosa. 2) Egeria Carbon Hydrogen Nitrogen (CHN) and associated insect communities will be determined monthly at invaded/ non-invaded sites at in the Sacramento/San Joaquin Delta using presence/absence and hydroacoustical and videographic methods. 3) Eurasian watermilfoil will be sampled (weekly to monthly) in the Truckee and Fall Rivers along streamflow gradients. 4) Effects of simulated herbivory on Giant reed and effects on root growth (abundance, life span) will be quantified from images recorded with a video camera system within the minirhizotrons at weekly intervals. Success of active (planting desirable species) versus passive (recruitment from resident propagules) re-vegetation will be assessed in giant reed managed sites. 5) Effects of native and non- native submersed plants on rhizosphere microflora will be assessed in replicated mesocosms and natural populations. 6) Replicated applications of fluridone, copper will be made in water and with penoxsulam, or acetic acid to canals and canal sediment. 7) Methods to eradicate Curlyleaf pondweed will be evaluated in indoor and outdoor tanks using diquat, endothall, and penoxsulam under short and long-day conditions. This is a final report for this project which has reached its five year term maximum. This work continues under the new project 2030-22000-028- 00D with the same title, Aquatic and Riparian Weed Management to Protect U.S. Water Resources in the Far West United States." Please see the report for the new project for additional information. Progress was made in addressing all four objectives over the five years of the project despite significant changes in personnel over the five year period. In particular, significant progress has been made in elucidating the biology, taxonomy, and genetics of invasive Ludwigia species, and addressing issues relating to their management and restoration of invaded sites. Significant progress has also been made regarding the biology, ecology, and management of invasive giant reed. For objective 1, ARS scientists in Davis, California, reviewed the life history characteristics of curlyleaf pondweed (Potamogeton crispus), and determined that the key life history stage for management is the asexually-produced axillary turion. While turion production can be reduced through the use of traditional herbicides used at less conventional times of the year, no research has been done on the use of nonchemical methods to target turion production or survival. Cooperators at the University of California-Davis completed studies on the non- chemical management of P. crispus. Control techniques examined included benthic barriers, treatment with acetic acid, and combining hot water with a benthic mat to kill curlyleaf pondweed turions. ARS scientists also completed studies on the temperature and photosynthetic response of giant reed (Arundo donax). These studies detailed the effect of shading on subsequent growth of giant reed, indicating that riparian shade may be one avenue for control of this species. Additional analysis also indicated that giant reed is a serious threat to flood control, increasing the risk of flooding by filling the riparian channels, increasing the roughness coefficient, and reducing flow rates. In support of Objective 1, analyses of experiments to evaluate physiological integration of resources in invasive Ludwigia hexapetala (Uruguayan primrose-willow) as a strategy for colonization and spread were completed. Ramet growth, biomass allocation and leaf morphology responded strongly to sun vs. shade regardless of integration status. Fitness of daughter ramets increases through physiological conditions in sun, suggesting restoration of shaded riverine habitat may reduce fitness of the invasive clonal plants. Three additional mesocosm experiments were completed, evaluating the response of invasive Ludwigia cytotypes (L. peploides (water primrose), diploid; L. hexapetala, decaploid) to sediment nutrient and above- canopy light gradients. Rapid relative growth and transition to reproduction stage in L. peploides may explain establishment success of the diploid during the initial establishment of invasive asexual ramets, though the longer life stages of the polyploidy ultimately support greater invasive spread. In 2015, ARS scientists completed analyses of data from two additional experiments to evaluate differences in growth from asexual shoot fragments and perennial rhizomes of the two cytotypes to light (shade vs. sun) and nutrient availability (high vs. low). In support of Objective 2, ARS scientists in Davis, California, completed experimental tests of an integrated management strategy utilizing grazing by sheep and tillage to reduce biomass and control invasive Ludwigia hexapetala in seasonal wetlands at a national wildlife refuge in California�s Sacramento Valley. Alternative treatment effects on biomass reduction of the target weed were evaluated. Plant community succession was also evaluated for two years following treatments. In 2015, the efficacy of biocontrol (sheep grazing) and tillage treatment combinations were evaluated, treatment effects on magnitude and duration of reduction of biomass of the target weed, and plant community succession over time. Results suggest reduction of weed biomass by sheep prior to disking is effective for management of Ludwigia hexapetala. This method of biological control reduces fossil fuel use, the amount of mechanical tillage required and overall management cost. The effectiveness of the method also eliminates the need for chemical control alternatives in sensitive wildlife habitat. Integrated management using sheep grazing and tillage for weed suppression has resulted in improvement in habitat quality with post-treatment succession to important waterfowl food plants and other vegetation desired by wetland refuge managers. Addressing Objective 2, ARS scientists and cooperators have completed initial research on the use of drawdown combined with bare-ground applications of selected herbicides to control flowering rush (Butomus umbellatus), a recent invader to shallow waters and irrigation canals of the Pacific West. Working with the U.S. Army Engineer Research and Development Center, U.S. Army Corps of Engineers � Seattle District, Idaho State Department of Agriculture, and Bonner County (Idaho) Weed Management on field sites in Idaho, ARS scientists at Davis, California, have completed the first year of a control demonstration project. Selected combinations of imazapyr, imazamox, 2,4-D and a surfactant were applied to test plots of bare ground invaded by flowering rush. Treatments were made just after the sprouting of flowering rush from rhizomes, on lake areas dewatered for reservoir winter pool levels. Preliminary testing indicates more than 80% reduction in plant cover and 90% reduction in rhizome bud density, the key propagule for plant survival. This approach can be used on numerous reservoirs and irrigation canals in the western U.S. that are drawn-down over the winter and early spring, reducing the input of herbicides into surface water and avoiding potential issues with aquatic endangered species. In support of Objective 3, ARS scientists evaluated the effect of mechanical defoliation on the photosynthesis of giant reed, to simulate the effect of a leaf herbivory from potential biological control agents. Studies indicated the necessary amount of defoliation that would be needed to reduce the growth and viability of giant reed stands from grazing insects or vertebrate grazers. In other research, the suitability of the milfoil weevil (Euhrychiopsis lecontei) for control of Eurasian watermilfoil (Myriophyllum spicatum) utilized continuous temperature data collected over two years. Sufficient control of Eurasian watermilfoil by the weevil can only be achieved if at least three weevil generations per year can be produced. Temperature-based modeling found that the goal of three generations could not be reached in the cold-water river, Fall River, until well below the area that is a significant habitat for salmonids. The weevil therefore is unlikely to be a suitable control for Eurasian watermilfoil in this river, or in other rivers infested with Eurasian watermilfoil that serve as habitat for cold-water species, such as the Truckee River, which drains Lake Tahoe and supports a population of the endangered Lahontan Trout. In support of Objective 4, ARS scientists, working with the California State Parks, Division of Boating and Waterways, are seeking to improve the environmental compatibility of management with herbicides. One major concern for managing invasive aquatic plants is the impact of management activities on rare, threatened, and endangered species; particularly federally-listed endangered species. Toxicity testing of adjuvants and herbicides on Delta smelt has indicated that the surfactant is far more toxic than the herbicide formulation itself. Other surfactants are available, but their efficacy has not yet been tested to determine if they are just as effective as the current standard. Working with California Division of Boating and Waterways and University of California- Davis Plant Sciences, ARS scientists at Davis, California, have designed and implemented a field plot test of three new surfactants and the standard surfactant, with a constant rate of glyphosate herbicide. All three new surfactants are much less toxic to fish, based on the California label data. Based on this trial, scientists will replace the standard surfactant with a much less toxic alternative that is equally as effective. ARS scientists are also evaluating the environmental drivers to the sprouting of tubers and growth of monoecious and dioecious hydrilla. Working with the U.S. Army Engineer Research and Development Center, ARS scientists have designed and implemented experiment to evaluate the effects of cool season temperatures (14, 16, 18, and 20 C) and photoperiod on the sprouting and growth of monoecious and dioecious hydrilla in greenhouse and environmental chambers. This study will fine- tune the effect of early spring water temperatures on the early growth of these two hydrilla biotypes. Accomplishments 01 Naturalized weevil a poor fit for managing Eurasian watermilfoil. Eurasian watermilfoil (Myriophyllum spicatum) invades a wide variety of water resources, including cold and cool water streams used by trout and salmon as critical habitat. Seeking an alternative to the use of herbicides in endangered species habitats, some have suggested the use of a native insect herbivore, which is sold commercially. ARS scientists at Albany and Davis, California, used a two-year data set of water temperatures from several sites in the Fall River (California) as input for a model on the growth and development of the native milfoil weevil, Euhrychiopsis lecontei. Models of generation time interval indicated that the weevil populations would not be able to produce three generations per growing season in this and other Western rivers, which are considered essential habitat for trout and salmon fisheries. Therefore, the native milfoil weevil would not likely provide control of Eurasian watermilfoil in western rivers because of the short growing season and cool water temperatures. These results indicate that other methods of control are needed to manage the exotic plant in these systems.
Impacts
(N/A)
Publications
- Spencer, D.F., Liow, P., Pitcairn, M.J., Villegas, B. 2014. Seed size and nutrient content variation for twenty-one invasive and native California and Oregon taxa of the tribe Cynareae (Asteraceae). Madrono. 61(4):339-349.
- Glover, R., Drenovsky, R., Futrell, C.J., Grewell, B.J. 2015. Clonal integration in Ludwigia hexapetala under different light regimes. Aquatic Botany. 122:40-46.
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Progress 10/01/13 to 09/30/14
Outputs
Progress Report Objectives (from AD-416): Objective 1: Improve understanding of weed life history and population dynamics (including effects of habitat alteration and assessment in canals and managed wetlands), biosystematics, and molecular biology to develop tools to undermine the success of weeds such as water primrose- willow species, perennial pepperweed, purple loosestrife, cordgrass, giant reed, and Eurasian milfoil, and to restore invaded riparian, marsh, and aquatic ecosystems. Objective 2: Determine the effectiveness of integrated weed management, including potential new herbicides on weeds such as hydrilla (Hydrilla verticillata), pondweeds (Potamogeton, nodosus, P. crispus, Stuckenia pectinata), Eurasian watermilfoil (Myriophyllum spicatum) and exposed sediments during seasonal drawdown (dewatering) for weeds such as M. spicatum, Western milfoil (M. hippuroides) in irrigation systems. Objective 3: Determine the applicability of biological control agents for water primrose-willows, Mexican mosquito fern, Brazilian waterweed, giant reed (including tricin host production effects on natural enemies), M. spicatum, and water hyacinth (Eichhornia crassipes), including plant ecology in relation to biological control for L. hexapetala and E. crassipes. Objective 4: Develop effective rapid response methods for new introductions of aquatic invasive weeds such as E. densa, P. crispus, and Undaria, or Japanese kelp (Undaria pinnatifida), and adapt these technologies to control invasive freshwater plant species, marine macroalgae and invasive marine plants. Approach (from AD-416): 1) A demographic study will determine how temporal and spatial variation in factors affecting Uruguayan water primrose contribute to overall population dynamics and improved management and restoration at Lagun de Santa Rosa. 2) Egeria Carbon Hydrogen Nitrogen (CHN) and associated insect communities will be determined monthly at invaded/ non-invaded sites at in the Sacramento/San Joaquin Delta using presence/absence and hydroacoustical and videographic methods. 3) Eurasian watermilfoil will be sampled (weekly to monthly) in the Truckee and Fall Rivers along streamflow gradients. 4) Effects of simulated herbivory on Giant reed and effects on root growth (abundance, life span) will be quantified from images recorded with a video camera system within the minirhizotrons at weekly intervals. Success of active (planting desirable species) versus passive (recruitment from resident propagules) re-vegetation will be assessed in giant reed managed sites. 5) Effects of native and non- native submersed plants on rhizosphere microflora will be assessed in replicated mesocosms and natural populations. 6) Replicated applications of fluridone, copper will be made in water and with penoxsulam, or acetic acid to canals and canal sediment. 7) Methods to eradicate Curlyleaf pondweed will be evaluated in indoor and outdoor tanks using diquat, endothall, and penoxsulam under short and long-day conditions. In support of Objective 1, we completed analyses of experiments to evaluate physiological integration in invasive Ludwigia hexapetala (Uruguayan primrose-willow) clones in response to light as a strategy for colonization and spread. Ramet growth, biomass allocation and leaf morphology responded strongly to sun vs. shade regardless of integration status. Fitness of daughter ramets increases through physiological conditions in sun, suggesting restoration of shaded riverine habitat may reduce fitness of the invasive clonal plants. A manuscript reporting this effort will be submitted this year. In another mesocosm experiment, we evaluated the response invasive Ludwigia cytotypes (L. peploides (water primrose), diploid; L. hexapetala, decaploid) to sediment nutrient and above- canopy light gradients. Under high nutrient availability L. peploides produced 1.8-fold more biomass and 1.7-fold more leaves than L. hexapetala, though the polyploid produced longer shots than the diploid. The two plant taxa varied greatly in their architecture, due to differences in branching. Rapid relative growth and transition to reproduction stage in L. peploides may explain establishment success of the diploid during the initial establishment of invasive asexual ramets, though the longer life stages of the polyploidy ultimately support greater invasive spread. Additional experiments to test the response of asexual shoot fragments and perennial rhizomes of the two cytotypes to light (shade vs. sun) and nutrient availability (high vs. low) are underway. Also for Objective 1, we evaluated the capacity of the riparian invader, Arundo donax (giant reed) to recover from removal of its above ground biomass in natural sites. This aquatic weed is being used a source of biomass for energy production in parts of its exotic range. We monitored giant reed plants, which had been cut either once in a year or twice in two years, at four Northern California locations. Results indicate that giant reed can regrow and restore the plant to the height, stem density, leaf chlorophyll content, and biomass that it possessed prior to removal of all of the aboveground biomass during the same growing season as the cutting occurred. Detailed stand measurements indicated that leaves and leaf area were not evenly distributed across stem height, but were greatest at heights between 1 m above the ground and 1 m below the shoot tip. At one site, specific leaf area and leaf chlorophyll content were inversely related to the height of the leaf on the stem. At a second site, specific leaf area was not related to the height of the leaf on the stem, but leaf chlorophyll content was inversely related as observed for the first site. In this study, giant reed regrowth occurred under different climatic conditions than previously reported. The species� ability to recover from cutting highlights the need for management techniques, which target the belowground rhizome and root system. This information provides a baseline against which to judge the effects of management techniques. Also for Objective 1, progress on scientific research to trigger adaptive management actions for control of invasive Lepidium latifolium (perennial pepperweed) supported by a cooperative agreement with California Department of Parks and Recreation included completion of efficacy trials to evaluate spatially explicit, weed phenology-based herbicide treatment of the target weed in endangered species occupied tidal wetlands of the Suisun Marsh in the Sacramento-San Joaquin Delta and San Francisco Estuary ecosystem. A book chapter and written reports were prepared and technology was transferred through outreach presentations to interdisciplinary weed management teams and to wetland and aquatic habitat managers. In support of Objective 2, we conducted two field experiments in California to evaluate efficacy of registered herbicides for control of giant reed, an invasive weed in riparian habitats. Foliar applications of these herbicides may be restricted in some areas, such as those, which are within the range of threatened or endangered species. The first experiment evaluated the effects of three herbicides (glyphosate, imazapyr, and triclopyr) injected into all of the stems within a giant reed (5 mL stem-1). In this experiment, leaf chlorophyll content, the proportion of living stems, and the number of new stems produced during the year after treatment declined (> 80%) following injection of either full strength glyphosate or imazapyr. The effects of injecting full strength triclopyr were considerably less. In a second experiment, different proportions (0, 10%, 25%, or 100%) of the stems within a plant were injected with full strength glyphosate. Results indicated that it was necessary to inject all of the stems within a clump to achieve the greatest reduction in the plant growth characteristics measured. These results imply that giant reed may be successfully controlled by injecting full strength glyphosate (5 mL stem-1) into all of the stems within a clump. While labor intensive and thus potentially more costly this method, offers a new method for managing giant reed in sensitive sites where foliar spray applications of herbicides may be restricted. Also in support of Objective 2, we continued to test an integrated strategy using tillage and grazing by sheep to reduce biomass and control invasive Ludwigia hexapetala in a seasonal wetland. In 2014, two years following integrated treatments, we collected response data on succession on plant species composition and abundance in the wetland plant community, and we are analyzing results. To date, the results of this integrated weed management trial are very promising. Preliminary analyses suggest control of the primary invader has been outstanding, and weed suppression has been followed by succession to desirable vegetation within the managed wetlands. For Objective 3, ARS scientists in Albany, California, have conducted choice and no-choice tests with Hydrellia spp. flies from Argentina as potential biological control agents for Egeria densa. The flies actively locate Egeria densa and oviposit on leaf material exposed to the air at the surface of the water. Eggs hatch and larvae infest leaf tissue causing necrosis and soft-rot of vegetative plant material. Extensive leaf destruction occurs with moderate amounts of feeding damage. Unfortunately, no-choice experimental tests revealed that these insects also actively oviposit on the native aquatic plant Elodea canadensis. There were no significant differences found in trials where the flies were exposed to one species or another individually. In choice tests, where the adult flies were simultaneously exposed to both Egeria densa and Elodea canadensis, the flies favored Egeria densa but still significantly oviposited on and damaged Elodea canadensis. Studies are still underway to test differential developmental and fecundity rates of F2+ generation off-spring and subsequent levels of fecundity and survival, however, we believe that this agent will be unsuitable for introduction into North America, and thus plan to stop testing this species further in the United States. Colonies of these flies are being provided to South African Entomologists for further testing in that country as they do not have a similar conflict with any native Elodea species in Africa.
Impacts
(N/A)
Publications
- Spencer, D.F., Linquist, B.A. 2014. Reducing rice field algae and cyanobacteria abundance by altering phosphorus fertilizer applications. Paddy and Water Environment. 12:147-154.
- Spencer, D.F., Enloe, S.F., Pitcairn, M.J., Di Tomaso, J.M. 2014. Impacts of mowing and bud destruction on Centaurea solstitialis growth, flowering, root dynamics and soil moisture. Weed Research. 54:140-150.
- Spencer, D.F., Ksander, G.G., Tan, W., Liow, P., Whitehand, L.C. 2012. Influence of application timing on the impact of glyphosate on giant reed (Arundo donax L.). Journal of Aquatic Plant Management. 49:106-110.
- Spencer, D.F. 2012. Response of Arundo donax L. (giant reed) to leaf damage and partial defoliation. Journal of Freshwater Ecology. 27:77-87. DOI: 10.1080/02705060.2011.615523.
- Grewell, B.J., Baye, P.R., Fiedler, P.L. 2014. Shifting mosaics: vegetation of Suisun Marsh. In: Moyle, P.B., Manfree, A., Fiedler, P.L, editors. Suisun Marsh: Ecological history and possible futures. Berkeley, California:University of California Press. p.65-101.
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Progress 10/01/12 to 09/30/13
Outputs
Progress Report Objectives (from AD-416): Objective 1: Improve understanding of weed life history and population dynamics (including effects of habitat alteration and assessment in canals and managed wetlands), biosystematics, and molecular biology to develop tools to undermine the success of weeds such as water primrose- willow species, perennial pepperweed, purple loosestrife, cordgrass, giant reed, and Eurasian milfoil, and to restore invaded riparian, marsh, and aquatic ecosystems. Objective 2: Determine the effectiveness of integrated weed management, including potential new herbicides on weeds such as hydrilla (Hydrilla verticillata), pondweeds (Potamogeton, nodosus, P. crispus, Stuckenia pectinata), Eurasian watermilfoil (Myriophyllum spicatum) and exposed sediments during seasonal drawdown (dewatering) for weeds such as M. spicatum, Western milfoil (M. hippuroides) in irrigation systems. Objective 3: Determine the applicability of biological control agents for water primrose-willows, Mexican mosquito fern, Brazilian waterweed, giant reed (including tricin host production effects on natural enemies), M. spicatum, and water hyacinth (Eichhornia crassipes), including plant ecology in relation to biological control for L. hexapetala and E. crassipes. Objective 4: Develop effective rapid response methods for new introductions of aquatic invasive weeds such as E. densa, P. crispus, and Undaria, or Japanese kelp (Undaria pinnatifida), and adapt these technologies to control invasive freshwater plant species, marine macroalgae and invasive marine plants. Approach (from AD-416): 1) A demographic study will determine how temporal and spatial variation in factors affecting Uruguayan water primrose contribute to overall population dynamics and improved management and restoration at Lagun de Santa Rosa. 2) Egeria Carbon Hydrogen Nitrogen (CHN) and associated insect communities will be determined monthly at invaded/ non-invaded sites at in the Sacramento/San Joaquin Delta using presence/absence and hydroacoustical and videographic methods. 3) Eurasian watermilfoil will be sampled (weekly to monthly) in the Truckee and Fall Rivers along streamflow gradients. 4) Effects of simulated herbivory on Giant reed and effects on root growth (abundance, life span) will be quantified from images recorded with a video camera system within the minirhizotrons at weekly intervals. Success of active (planting desirable species) versus passive (recruitment from resident propagules) re-vegetation will be assessed in giant reed managed sites. 5) Effects of native and non- native submersed plants on rhizosphere microflora will be assessed in replicated mesocosms and natural populations. 6) Replicated applications of fluridone, copper will be made in water and with penoxsulam, or acetic acid to canals and canal sediment. 7) Methods to eradicate Curlyleaf pondweed will be evaluated in indoor and outdoor tanks using diquat, endothall, and penoxsulam under short and long-day conditions. In support of Objective 1, we tested clonal integration of resources under light regimes for Ludwigia hexapetala that may promote colonization and spread. Light strongly impacted the growth, morphology and biomass allocation in ramets regardless of integration status. Phenology shifted in shade: Ramets flowered early suggesting shade prompts a shift to sexual reproduction and dispersal via seeds. Parent ramets produced less biomass with integration, while daughters were more fit with higher biomass when integrated with a parent in sun. We tested the use of floating aquatic weeds in constructed wetlands for wastewater treatment, and added invasive L. hexapetala to anaerobic digesters for biogas production. Harvesting, sedimentation and gasification were responsible for nitrate removal, respectively. Repeat harvesting decreased nitrate removal compared to no harvesting. Biogas production offset management costs. Integrating constructed wetlands into treatment systems can enhance wastewater/organic waste treatment. We tested an integrated strategy using sheep to reduce biomass of L. hexapetala and 2 levels of tillage in a seasonal wetland, and are collecting response data. In support of Objective 2, we measured photosynthetic rates of Arundo in cultures and field sites for 3 years. We found strong linear relationships between net carbon fixation and electron transport rates. Molar ratio increased with increasing irradiance, but was negatively related to leaf temperature and intercellular CO2 concentration. Results help validate the use of fluorometry to assess photosynthetic attributes of A. donax. To evaluate A. donax contribution to flood risk, we determined Manning�s coefficient and later used it to estimate the impact of A. donax at 3 California river sites. Model simulations show that A. donax within a stream channel has a direct effect on flooded areas, causing increases up to 10% above baseline conditions. Values for Manning�s coefficient for A. donax can be used in conjunction with environmental conditions to prioritize areas for management. For objective 3, biological control studies were conducted on Hydrillia spp. flies that attack Egeria densa were located and tested in cooperation with Fundaci�n para el Estudio de Especies Invasivas (FuEDEI) in Argentina. These agents were imported to our quarantine facility for study of their safety and impact. With FuEDEI we are also studying control agents for Ludwigia spp. Our focus is on determining which natural enemies warrant further investigation for biological control prior to requesting USDA-APHIS permits for entry into our quarantine facility. The Arundo wasp was released at one site for control of giant reed. Releases and establishment of Megamelus scutellaris for control of water hyacinth were made at 3 Delta sites, but populations are too low to measure impact. Following assessment of the lack of effectiveness of the milfoil weevil, this project has been terminated due to inadequate efficacy of the insect in coldwater rivers.
Impacts
(N/A)
Publications
- Curado, G., Rubio-Casai, A., Figueroa, E., Grewell, B.J., Castillo, J.M. 2013. Native plant restoration combats environmental change: development of carbon and nitrogen sequestration capacity using small cordgrass in European salt marshes. Environmental Monitoring and Assessment. 185:8439- 8449. DOI 10.1007/s10661-013-3185-4.
- Spencer, D.F., Colby, L., Norris, G.G. 2103. An evaluation of flooding risks associated with giant reed (Arundo donax). Journal of Freshwater Ecology. 28:397-409. DOI: www.tandfonline.com/doi/abs/10.1080/02705060. 2013.769467.
- Whitcraft, C., Grewell, B.J., Baye, P.R. 2012. Tidal wetland vegetation and ecotone profiles: The Rush Ranch Open Space Preserve. In: Palaima, A., editor. Ecology, Conservation, and Restoration of Tidal Marshes. Berkeley, California: University of California Press. p. 113-114.
- Cohen, M.J., Hare, C., Kozlowski, J., Mccormick, R.S., Chen, L., Parish, M. , Schneider, L., Knight, Z., Nelson, T.A., Grewell, B.J. 2012. Wastewater polishing by a channelized macrophyte-dominated wetland and anaerobic digestion of the harvested phytomass. Journal of Environmental Science and Health. 48(3):319-330.
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Progress 10/01/11 to 09/30/12
Outputs
Progress Report Objectives (from AD-416): Objective 1: Improve understanding of weed life history and population dynamics (including effects of habitat alteration and assessment in canals and managed wetlands), biosystematics, and molecular biology to develop tools to undermine the success of weeds such as water primrose- willow species, perennial pepperweed, purple loosestrife, cordgrass, giant reed, and Eurasian milfoil, and to restore invaded riparian, marsh, and aquatic ecosystems. Objective 2: Determine the effectiveness of integrated weed management, including potential new herbicides on weeds such as hydrilla (Hydrilla verticillata), pondweeds (Potamogeton, nodosus, P. crispus, Stuckenia pectinata), Eurasian watermilfoil (Myriophyllum spicatum) and exposed sediments during seasonal drawdown (dewatering) for weeds such as M. spicatum, Western milfoil (M. hippuroides) in irrigation systems. Objective 3: Determine the applicability of biological control agents for water primrose-willows, Mexican mosquito fern, Brazilian waterweed, giant reed (including tricin host production effects on natural enemies), M. spicatum, and water hyacinth (Eichhornia crassipes), including plant ecology in relation to biological control for L. hexapetala and E. crassipes. Objective 4: Develop effective rapid response methods for new introductions of aquatic invasive weeds such as E. densa, P. crispus, and Undaria, or Japanese kelp (Undaria pinnatifida), and adapt these technologies to control invasive freshwater plant species, marine macroalgae and invasive marine plants. Approach (from AD-416): 1) A demographic study will determine how temporal and spatial variation in factors affecting Uruguayan water primrose contribute to overall population dynamics and improved management and restoration at Lagun de Santa Rosa. 2) Egeria Carbon Hydrogen Nitrogen (CHN) and associated insect communities will be determined monthly at invaded/ non-invaded sites at in the Sacramento/San Joaquin Delta using presence/absence and hydroacoustical and videographic methods. 3) Eurasian watermilfoil will be sampled (weekly to monthly) in the Truckee and Fall Rivers along streamflow gradients. 4) Effects of simulated herbivory on Giant reed and effects on root growth (abundance, life span) will be quantified from images recorded with a video camera system within the minirhizotrons at weekly intervals. Success of active (planting desirable species) versus passive (recruitment from resident propagules) re-vegetation will be assessed in giant reed managed sites. 5) Effects of native and non-native submersed plants on rhizosphere microflora will be assessed in replicated mesocosms and natural populations. 6) Replicated applications of fluridone, copper will be made in water and with penoxsulam, or acetic acid to canals and canal sediment. 7) Methods to eradicate Curlyleaf pondweed will be evaluated in indoor and outdoor tanks using diquat, endothall, and penoxsulam under short and long-day conditions. Substantial progress was made to improve knowledge and control of aquatic and riparian weeds. Arundo donax (giant reed): Experiments evaluated whether defoliation or leaf damage affect stem growth, leaf production, or photosynthetic rates. Defoliation did not affect stem height or leaves per stem, leaf damage did not affect electron transport rates (ETR), and defoliated stems maintained ETRs similar to rates of undamaged leaves suggesting low to moderate leaf damage or defoliation alone may not significantly reduce growth or the persistence of A. donax. Cyanobacteria: In water-seeded rice systems, Nostoc spongiaeforme hinders crop growth by dislodging and reducing light to seedlings. We investigated the timing of P fertilizer application to reduce cyanobacteria while maintaining rice yields and water quality. Early- season water P concentration and Nostoc occurrence were highest when fertilizer was applied pre-plant. In fields with delayed P application, water P increased immediately following application but subsequently declined. Further trials confirm that delayed fertilizer applications can maximize rice yield while reducing early-season interference from cyanobacteria. Ludwigia (water primroses): Field experiments tested integrated management methods for L. hexapetala control. Hydrologic control with mechanical removal and glyphosate use improved efficacy in canals. Timing and frequency of disking were evaluated for control in seasonal wetlands. Disking at flowering stage improved control and reduced emergence of L. hexapetala from soil seed banks. Sheep grazing trials to reduce biomass prior to disking and reduce management cost are underway. In mesocosms, we are evaluating functional traits and physiological integration by L. hexapetala for control across resource gradients. Lepidium latifolium (pepperweed): Field experiments suggest 2, 4-D has minimal non-target effects but does not provide effective control in estuarine wetlands, while Imazapyr reduced cover by 90% but had persistent non-target effects to native vegetation. Biological Control: Field assessments of herbivores feeding on Egeria densa did not reveal effective natural enemies in the Sacramento/ San Joaquin Delta, reinforcing the need to test newly identified fly species (Hydrillia spp.) in South America that are now permitted for entry. Colonies of Euhrychiopsis lecontei are being maintained for assessment of their efficacy for control of Eurasian watermilfoil in cold water habitats. Field and modeling studies indicate weevils from midwestern US will not be effective in California. Locally-collected colonies are being assessed. Natural enemies of Ludwigia spp. are under study, including resident flea beetle Altica litigata, for defoliation potential. Studies to identify and use insect pheromones as aggregation agents have been assessed. Molecular studies separating A. litigata from closely related species indicate California specimens are unique relative to similar insects elsewhere in USA. A South American insect, Megamelus scutellaris, has been released in the Delta where survival and efficacy assessments for waterhyacinth control are underway. Accomplishments 01 Improving biological control of Eurasian watermilfoil. A combined field assessment and modeling study documented that the native North American insect Euhrychiopsis lecontei was not predicted to be an effective natur enemy of Eurasian watermilfoil in the Fall River of California. This spring-fed river has very cold water that allows Eurasian watermilfoil t grow, yet is too cold for this insect to substantially impact this plant under these conditions. Water temperatures typically remain below the ovipositional threshold of 15 degree C in this waterway. ARS scientists from Davis, and Albany, CA, assessed environmental conditions at 71 monitoring stations along this 35 km long waterway to determine that Eurasian watermilfoil growth and development can occur along the entire waterway, however, the biological control insect would only be able to live and reproduce in a limited fashion and thus not significantly suppress this aquatic invasive weed. This work is important as local lan and waterway managers saved spending $100,000s on weevil augmentation programs that would be expected to fail. Now, ARS scientists are working to assess other means of controlling this pest plant. 02 Rapid response to winged primrose-willow. In late summer 2011, a newly introduced species of Ludwigia invaded rice fields in Butte County, California. ARS scientists from Davis, California, used morphological an cytological methods to confirm the identification of winged primrose- willow (Ludwigia decurrens) from South America, and then worked with loc land managers to eliminate this new weed and to block future introductio pathways. California rice production on 500,000 acres in the Sacramento Valley contributes over $1.3 billion dollars annually to the California economy. In recent years, weed control costs have skyrocketed reducing profitability of production, and rice producers have seen dramatic increases in the resistance of weeds to conventional herbicides. The mos effective, economical, and ecologically sound approach to managing invasive plants is to prevent their invasion in the first place, and proactive response to new weeds with rapid detection, response and eradication is imperative. ARS delivered educational presentations on identification and rapid response management techniques at four winter rice grower workshops throughout the Sacramento Valley, and assisted University of California Cooperative Extension farm advisors and agricultural commissioners with outreach education for prevention of the spread of winged primrose-willow in rice fields and adjacent, natural wetlands.
Impacts
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Publications
- Grewell, B.J., Whitcraft, C., Baye, P. 2011. Estuarine Vegetation at Rush Ranch Open Space Preserve, San Francisco Bay National Estuarine Research Reserve, California. San Francisco Estuary and Watershed Science. 9(3):1- 29 and Appendix, 21pp.
- Whitcraft, C.R., Grewell, B.J. 2011. Evaulation of perennial pepperweed (Lepidium latifolium) management in a seasonal wetland in San Francisco Estuary prior to restoration of tidal hydrology. Wetlands Ecology and Management. 20:35-45.
- Spencer, D.F. 2012. Response of Arundo Donax to Intermittent Shading. Journal of Invasive Plant Science and Management. 5:317-322.
- Lundy, M.E., Spencer, D.F., Van Kessel, C., Hill, J.E., Linquist, B.A. 2012. Managing phosphorus fertilizer to reduce algae, maintain water quality, and sustain yields in water-seeded rice. Agriculture, Ecosystems and Environment. 131(2012):81-87 doi:10.1016/j.fcr.2012.03.005.
- Drenovsky, R.E., Grewell, B.J., D'Antonio, C.M., Funk, J.L., James, J.J., Molinari, N., Parker, I.M., Richards, C.L. 2012. A functional trait perspective on plant invasion. Annals Of Botany. 110:141-153.
- Spencer, D.F., Liow, P., Lembe, C.A. 2013. Influence of a non-copper algicide on the cyanobacterium, Nostoc spongiaeforme, and the green alga, Hydrodictyon reticulatum, in field and laboratory experiments. Paddy and Water Environment. 11(1):611-617.
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) Objective 1: Improve understanding of weed life history and population dynamics (including effects of habitat alteration and assessment in canals and managed wetlands), biosystematics, and molecular biology to develop tools to undermine the success of weeds such as water primrose- willow species, perennial pepperweed, purple loosestrife, cordgrass, giant reed, and Eurasian milfoil, and to restore invaded riparian, marsh, and aquatic ecosystems. Objective 2: Determine the effectiveness of integrated weed management, including potential new herbicides on weeds such as hydrilla (Hydrilla verticillata), pondweeds (Potamogeton, nodosus, P. crispus, Stuckenia pectinata), Eurasian watermilfoil (Myriophyllum spicatum) and exposed sediments during seasonal drawdown (dewatering) for weeds such as M. spicatum, Western milfoil (M. hippuroides) in irrigation systems. Objective 3: Determine the applicability of biological control agents for water primrose-willows, Mexican mosquito fern, Brazilian waterweed, giant reed (including tricin host production effects on natural enemies), M. spicatum, and water hyacinth (Eichhornia crassipes), including plant ecology in relation to biological control for L. hexapetala and E. crassipes. Objective 4: Develop effective rapid response methods for new introductions of aquatic invasive weeds such as E. densa, P. crispus, and Undaria, or Japanese kelp (Undaria pinnatifida), and adapt these technologies to control invasive freshwater plant species, marine macroalgae and invasive marine plants. Approach (from AD-416) 1) A demographic study will determine how temporal and spatial variation in factors affecting Uruguayan water primrose contribute to overall population dynamics and improved management and restoration at Lagun de Santa Rosa. 2) Egeria Carbon Hydrogen Nitrogen (CHN) and associated insect communities will be determined monthly at invaded/ non-invaded sites at in the Sacramento/San Joaquin Delta using presence/absence and hydroacoustical and videographic methods. 3) Eurasian watermilfoil will be sampled (weekly to monthly) in the Truckee and Fall Rivers along streamflow gradients. 4) Effects of simulated herbivory on Giant reed and effects on root growth (abundance, life span) will be quantified from images recorded with a video camera system within the minirhizotrons at weekly intervals. Success of active (planting desirable species) versus passive (recruitment from resident propagules) re-vegetation will be assessed in giant reed managed sites. 5) Effects of native and non- native submersed plants on rhizosphere microflora will be assessed in replicated mesocosms and natural populations. 6) Replicated applications of fluridone, copper will be made in water and with penoxsulam, or acetic acid to canals and canal sediment. 7) Methods to eradicate Curlyleaf pondweed will be evaluated in indoor and outdoor tanks using diquat, endothall, and penoxsulam under short and long-day conditions. Formerly 5325-22000-019-00D (02/1/2011) Research on six non-native and invasive aquatic plants was conducted. Giant Reed: Over 1,700 Giant Reed (Arundo) buds, were tracked, their locations on stems noted, and their contribution to expansion of clones (clumps) was determined. Data showed that the leading edge of bud advance on stem about 17 cm/year and that clones can persist in a wide range of moisture and temperature. Growth models showed that optimal control and prevention of expansion may be achieved by either complete stem removal and by blocking growth of rhizome. Experiments were conducted near Davis and Fresno, California detailing the response of Giant Reed (Arundo) to the herbicide glyphosate applied in spring, summer and fall. Leaf greenness, number of living and dead stems, and the number of newly emerging stems were measured monthly. Results indicates that best control is achieved with fall treatment with 1.5% glyphosate. Primrose Willows (Ludwigia): Genetic characteristic such as chromosome numbers were determined in California and Oregon populations of Primrose willows (Ludwigia species) to determine how these characteristics may be associated with plant structure. Studies on relationships between Ludwigia and a Primrose-eating native flee beetle showed that volatile chemicals were produced in response to feeding by this insect, which may be a protective response. Follow up study sites and their nutrient characteristics were identified for field research in the Russian River watershed. South American Spongeplant: Growth of South American spongeplant, a non-native invasive floating-type weed newly established in the Sacramento-San Joaquin River Delta, was compare in controlled condition under late winter, early spring and in outdoor mid-summer conditions in natural Delta water and in Delta water diluted to produced 25% of natural nutrients. Results and field observations suggest that South American spongeplant will easily survive typical winters in the Delta and may be protected from hard frost since the growing tissues are partially in the water, which provides insulation. Eurasian watermilfoil Biological Control: Cultures of Eurasian watermilfoil were established under controlled conditions and inoculated with a native insect herbivore, the �Milfoil weevil�. Feeding activity was quantified, and studies on the reproduction and other life-cycle traits were begun. Field sites for potential augmentative release were evaluated including the Fall River in Northern California. Curlyleaf pondweed Control: Baseline studies were completed in several sites at Lake Tahoe that are infested with Eurasian watermilfoil and curlyleaf pondweed. The distribution and abundance of these invasive plants were determined. Sites will be used in assessing various non-chemical control actions including use of natural (jute) and synthetic materials (�bottom barriers�) to cover the plants, and mechanical harvesting. Sampling stations were established in the Sacramento-San Joaquin Delta and Lake Tahoe to compare the dispersal, growth and reproductive characteristics of curlyleaf pondweed. Accomplishments 01 Rapid response to South American sponge plant. The highly diverse natur aquatic habitats in California, including the Sacramento-San Joaquin Del (Delta) are threatened by an increased spread of South American sponge plant, a newly introduced floating aquatic plant native to South and Central America. To understand the environmental limits to its dispersal ARS scientists from Davis, California, examined its growth rate under three temperature and day-length conditions that represent late winter, early summer and mid-summer in the Delta. Winter conditions did not kill the plant, but rather increased its surface cover at 10 to 12 C. Levels nitrogen in the leaves varied with external levels and suggest that increased nutrient inputs will greatly increase growth rates. These results along with the persistence of plants throughout winter months, have prompted state agencies to initiate regulatory actions and rapid responses in an attempt to prevent further impacts. 02 Improving control of giant reed (Arundo). Arundo donax, is a tall perennial invasive grass that in the U.S., spreads exclusively by vegetative (especially clonal) means and can invade and alter many riparian ecosystems in the western U.S. Improved management strategies c result from better understanding the dynamics of its vegetative growth a the mechanisms by which annual growth expands its cover. Results of extensive analysis of growth patterns, the role of new �buds� on shoots, coupled with understanding herbicide efficacy showed that optimal contro can be achieved by complete removal of shoots and by methods that can affect the rhizomes. These studies by ARS scientists at Davis, CA also showed that Giant Reed is capable of establishing in a wide range of temperature and moisture conditions. These results provide a basis for development of models that may predict the types of sites that are likel to become invaded by Arundo, and sites that should be monitored for new incursions. 03 Management of water primrose willows (Ludwigia). Several species common known as �water primrose� or �primrose willows� have spread dramatically over the past 10 years in the western US waters; yet, little is known about their genetic make-up, growth characteristics and habitat requirements. Studies were completed by ARS scientists in Davis, CA that better characterize the genetic differences among Ludwigia species, and their nutrient requirements. In addition, the interaction between some Ludwigia species and insect herbivores suggest that chemical substances released or found in these plants may serve as cues, or deterrents to potential biological control agents. This information will be helpful i searches for effective biocontrol agents in South America where the Ludwigia species are native. 04 Management of aquatic weeds at Lake Tahoe. Lake Tahoe, the second deepe lake in the US, is an Outstanding National Resource Water, and has been impacted by two non-native aquatic weeds which are the Eurasian watermilfoil and Curlyleaf pondweed. Multi-year surveys and assessment o infested sites have been made over the past 16 years showing an increase spread of these aquatic weeds in several marinas and along several areas of the lake shoreline. The long-term assessment by ARS scientists in Dav CA showed the continued spread of invasive plants, and this, coupled wi new threats from quagga and zebra mussels prompted new management action and regulatory changes that form the basis of an integrated aquatic invasive species program for the Tahoe Basin (Lake Tahoe Basin Aquatic Invasive Species Plan). The Plan helps protect Lake Tahoe from further infestations and insures that the full benefit of public uses for commer and recreation will be sustained, while improving ecological functions i the lake. Thus, the benefit accrues to millions of annual tourists and local residents who value this alpine lake. 05 Expanded control of Brazilian waterweed. The non-native submersed plant �Egeria� or Brazilian waterweed has impacted commercial navigation, recreation and water delivery from the Sacramento-San Joaquin Delta for many years. Successful control in over 3,000 acres was achieved in past years through collaborative efforts of ARS, state and other federal agencies. In 2011, methods were refined and expanded to encompass anothe 700 acres of highly infested areas. Control of Brazilian waterweed is no expected to encompass over 5,000 acres with reductions of over 75% of biomass.
Impacts
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Publications
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