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Alligatorweed Biology Ecology and Management


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Presentation on the invasive plant Alligatorweed.

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Alligatorweed Biology Ecology and Management

  1. 1. Ryan M. Wersal, Ph.D. Mississippi State University Geosystems Research InstituteMissouri Department of Conservation Invasive Plant WorkshopPowder Valley Nature Center, Kirkwood, MO May 16th and 17th
  2. 2. Benefits of Aquatic Plants Stabilize lake sediments, reduce resuspension Increase sedimentation, reduce turbidity Provide habitat for insects, forage fish, fish spawning and YOY fish Provide food for waterfowl, other animals
  3. 3. Non-native vs. Native Community Myriophyllum spicatum Vallisneria americana Eurasian watermilfoil Water celery
  4. 4. Canopy Structure
  5. 5. Alligatorweed (Alternanthera philoxeroides) Emergent perennial native to South America (Vogt et al. 1979) Nuisance aquatic species in over 32 countries worldwide (Gunasekera and Bonila 2001) Major problem in Southern U.S. aquatic and riparian areas (Kay and Haller 1982) Hollow stems form extensive, dense mats on water surface (Kay and Haller 1982) Impedes boat traffic, increases flood risk, clogs irrigation canals, harbors pathogen-carrying insects, reduces overall water quality and property value (Madsen 2004)
  6. 6. Alligatorweed distribution in theUnited States by Hydrologic Units
  7. 7. Alligatorweed distribution in the MidSouth Region
  8. 8. Alligatorweed Habitat Nuisance in subtropical aquatic and wetland areas, can be rooted in submersed to moist soil, especially ditch and stream habitats, forms floating mats  Major problem in the Ross Barnett Reservoir and MS Delta  Potentially has two biotypes Ross Barnett Reservoir, MS
  9. 9. Alligatorweed ID Non-native emergent perennial plant Emergent or submersed Stems form a tangled mass Leaves simple and opposite on stems Leaves elliptical Typically glabrous (very little if any hair)
  10. 10. Alligatorweed ID Several-flowered whitish head Flowers borne in leaf axils Flowers always on stalks up to 2 inches in length Mature seeds not known to occur Spread via vegetative growth and fragmentation
  11. 11. Alligatorweed ID Key identifying characteristic:  Stems almost always hollow
  12. 12. Can Be Confused With: Sessile joyweed (Alternanthera sessilis)  Not widespread Ludwigia spp. StarrImages Kim Starr
  13. 13. Ecological Impacts Degradation of water quality Reduction in species diversity Suppresses native plant species Potential impacts on endangered species Alters animal communities
  14. 14. Lake Jackson, MS Blue Lake, MSLittle Eagle Lake, MS Blue Lake, MS
  15. 15. Human Use Impacts Reduces access to water Reduces property values Limits recreation Impedes navigation Increases flood duration & intensity Lake Jackson, MS Human health Alligatorweed
  16. 16. Management Options Biological Chemical Mechanical Physical Institutional
  17. 17. Alligatorweed ManagementBiological Alligatorweed flea beetle Stem borer mothChemical 2,4-D, triclopyr, imazapyr, glyphosateMechanical - NonePhysical - None
  18. 18. Biological Control Alligatorweed flea beetle (Agasicles hygrophila) Works well south of Vicksburg-Jackson- Montgomery (I-20 corridor)
  19. 19. Biological Control Stem borer moth (Vogtia malloi) Active throughout MS May be more of an option for Missouri than flea beetle due to (Photograph courtesy USDA, ARS by Willey C. Durden.) climate Typically not present near agricultural areas where insecticides are used (Photograph courtesy USDA, ARS)
  20. 20. Small Scale Trials Imazapyr, triclopyr, glyphosate (DIA salt and IPA salt), imazamox, 2,4-D, diquat (maximum label rate), and penoxsulam (maximum label rate) offered similar effective control for 12 weeks Carfentrazone and diquat provided rapid biomass reduction but regrowth began within days after application
  21. 21. Field Control Imazapyr, 1 to 4 pints/acre Triclopyr, 3 to 8 quarts/acre 2,4-D, 2 quarts/acre Glyphosate, 2 quarts/acre Non-ionic surfactant, 1 pint/acre In Mississippi, 2,4-D and glyphosate are being used alone or as a tank mixAlways read the herbicide label
  22. 22. Hobbs and Humphries 1995. Conserv. Biol. 9:761-770.
  23. 23. Other ResourcesUNIVERSITY PROFESSIONAL SOCIETYCenter for Aquatic and Invasive Plants Aquatic Plant Management Society www.apms.orgMississippi State University GRI North American Lake Management Society www.nalms.orgMSU Extension Service GOVERNMENT Aquatic Plant Control Research Program ic.pdf USGS Aquatic Nonindigenous Species SiteFOUNDATION Ecosystem Restoration Foundation
  24. 24. Ryan Wersal, Ph.D.Geosystems Research InstituteBox 9652Mississippi State, MS 39762Ph (662) 325-4595Fax (662)