Water Hyacinth
Lori Moshman Department of Entomology, LSU AgCenter
ASWM Invasive Species Webinar November 30, 2017
Agriculture Victoria
Overview
• Water hyacinth biology and identification • History and spread • Current impacts • Effective control methods • Biological control • Case studies • Future outlook and recommendations
ELAW
Water hyacinth may be confused with natives
Center et al. 2002. In Van Driesche, R., et al., 2002. Biological Control of Invasive Plants in the Eastern United States
Frogbit, Limnobium spongia
S.L. Winterton
Pickerelweed, Pontederia cordata
K. Yatskievych
Heteranthera reniformis
Identification
Look for: • Bulbous base • Fleshy stems • Dark roots • Leaf shape
• Mat-forming • History of known infestation
P. Chadwick/DK Images
Landcare SJ
Management strategies: Mechanical
Pros: • Immediate gratification
Cons: • Hard to dispose of material • Increases plant fragmentation • Heavy use of labor and fuel • Can’t keep up with growth rate • Can’t reach areas with limited
access
May be appropriate for small infestations
Management strategies: Chemical
Pros: • Immediate gratification • Easier than mechanical removal
Cons: • Negative environmental effects • Can’t reach areas with limited
access • Expensive
California State Parks
Appropriate where immediate results are needed or as an integrated approach
Management strategies: Biological Pros: • Works passively • Host-specific • Suppresses plant vigor
Cons: • Control can take years • Monitoring and re-releases
required • Success limited in temperate
climates Katherine Parys
Appropriate for large and recurrent infestations
Biological control agents in the U.S.
G. Strickland
Neochetina eichorniae Neochetina bruchi
S. Marcus
Niphograpta albiguttalis Megamelus scutellaris
Waterhyacinth weevils (Neochetina spp.)
• First released in Florida in 1972
• N. bruchi prefer older leaves and N. eichhorniae prefer younger leaves
• Feeding activity is complementary: better with both species present
• Control possible in 3-5 years
Coetzee et al. 2009. In Muniappan, R., et al., 2009. Biological Control of Tropical Weeds using Arthropods.
Waterhyacinth moth (Niphograpta albiguttalis)
• First released in Florida in 1976
• Established throughout gulf coast states
• Feeding does not directly kill plants, but slows growth and encourages secondary pathogens
• Larvae prefer smaller, bulbous plants
Coetzee et al. 2009. In Muniappan, R., et al., 2009. Biological Control of Tropical Weeds using Arthropods.
Waterhyacinth planthopper (Megamelus scutellaris)
• First released in Florida in 2010
• Nymphs and adults feed on all leaf surfaces
• Winged and wingless forms exist
• Impact on infestations is still being studied
UF/IFAS Featured Creatures http://entnemdept.ufl.edu/creatures/beneficial/bugs/Megamelus_scutellaris.htm
P. Tipping
P. Tipping
Case study: LSU Crest Lake, Baton Rouge
Outcome: • Several mechanical and chemical
control efforts were made to reduce the spread of water hyacinth in the lake
• Regular monitoring and early action are the best ways to prevent excessive growth
Control programs are best tailored to fit specific needs
Factors to consider: • Prevention and early action • Climate/ecoregion • Severity of the infestation • Available personnel • Land use restrictions
Despite invasiveness, water hyacinth is still valued…
Aquatic plant product trade
Aquaria, ponds, koi gardens
Water hyacinth is part of a complex of invasive floating aquatic plants
Water lettuce, Pistia stratiotes Giant salvinia, Salvinia molesta Water hyacinth, Eichornia crassipes