alligatorweed biology ecology and management
DESCRIPTION
Presentation on the invasive plant Alligatorweed.TRANSCRIPT
Ryan M. Wersal, Ph.D.Mississippi State University
Geosystems Research Institute
Missouri Department of Conservation Invasive Plant Workshop
Powder Valley Nature Center, Kirkwood, MO May 16th and 17th
Benefits of Aquatic PlantsStabilize 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
Non-native vs. Native Community
Myriophyllum spicatumEurasian watermilfoil
Vallisneria americanaWater celery
Canopy Structure
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)
Alligatorweed distribution in the United States by Hydrologic Units
Alligatorweed distribution in the MidSouth Region
Alligatorweed HabitatNuisance in subtropical
aquatic and wetland areas, can be rooted in submersed to moist soil, especially ditch and stream habitats, forms floating matsMajor problem in the
Ross Barnett Reservoir and MS Delta
Potentially has two biotypes
Ross Barnett Reservoir, MS
Alligatorweed IDNon-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)
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
Alligatorweed IDKey identifying characteristic:
Stems almost always hollow
Can Be Confused With:Sessile joyweed (Alternanthera sessilis)
Not widespread
Ludwigia spp.StarrImages
Kim Starr
Ecological ImpactsDegradation of water quality
Reduction in species diversity
Suppresses native plant species
Potential impacts on endangered species
Alters animal communities
Lake Jackson, MS Blue Lake, MS
Little Eagle Lake, MS Blue Lake, MS
Lake Jackson, MSAlligatorweed
Human Use ImpactsReduces access to
water
Reduces property values
Limits recreation
Impedes navigation
Increases flood duration & intensity
Human health
Management Options
Biological
Chemical
Mechanical
Physical
Institutional
Alligatorweed ManagementBiological
Alligatorweed flea beetleStem borer moth
Chemical2,4-D, triclopyr, imazapyr, glyphosate
Mechanical - None
Physical - None
Biological ControlAlligatorweed flea
beetle (Agasicles hygrophila)
Works well south of Vicksburg-Jackson-Montgomery (I-20 corridor)
Biological ControlStem borer moth (Vogtia
malloi)
Active throughout MS
May be more of an option for Missouri than flea beetle due to climate
Typically not present near agricultural areas where insecticides are used
(Photograph courtesy USDA, ARS by Willey C. Durden.)
(Photograph courtesy USDA, ARS)
Small Scale TrialsImazapyr, 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
Field ControlImazapyr, 1 to 4 pints/acreTriclopyr, 3 to 8 quarts/acre2,4-D, 2 quarts/acreGlyphosate, 2 quarts/acreNon-ionic surfactant, 1 pint/acreIn Mississippi, 2,4-D and glyphosate are
being used alone or as a tank mix
Always read the herbicide label
Hobbs and Humphries 1995. Conserv. Biol. 9:761-770.
Other ResourcesUNIVERSITYCenter for Aquatic and Invasive Plants
aquat1.ifas.ufl.eduMississippi State University GRI
www.gri.msstate.eduMSU Extension Service
msucares.com/pubs/publications/p1532aquatic.pdf
FOUNDATIONAquatic Ecosystem Restoration Foundation
www.aquatics.org
PROFESSIONAL SOCIETYAquatic Plant Management Society
www.apms.org North American Lake Management Society
www.nalms.org
GOVERNMENTAquatic Plant Control Research Program
www.wes.army.mil/el/aqua/aqua.htmlUSGS Aquatic Nonindigenous Species Site
nas.er.usgs.gov
Ryan Wersal, Ph.D.
Geosystems Research Institute
Box 9652
Mississippi State, MS 39762
Ph (662) 325-4595
Fax (662) 325-7692