Presented by Garrett Noles Hydrilla verticillata (L.f.) Royle

Common Names + Synonyms Common- Hydrilla, water thyme, Florida elodea Latin binomials- Hottonia serrata, Hydrilla angustifolia, Hydrilla ovalifolia, Leptanthes verticillata, Serpicula verticillata, Elodea verticillata Photo by USDA/ARS

Taxonomy Family- Hydrocharitaceae (Tape-grass family) Reproduction- Mainly vegetative propagation Dioecious (mostly in US) & rarely monoecious Morphology- Stems: long and slender, white in color Leaves- dark green, strap shaped, saw-toothed margins Grow in dense clusters, branching towards surface of water

Turions Turions- “dark green buds on some leaf axils” Subterranean turions- yellow tuber like buds attached to root folicles plants.ifas.ufl.edu

Current distribution of Hydrilla verticillata USDA Plants 2010

Ecological Impacts Can outcompete other desirable aquatic plants Can slow water flow thus increase water temperature Can use the oxygen resources in a water body Some evidence of allelopathy discouraging plant biodiversity (if interested view starred paper) Can alter important freshwater fish habitat

Economic Impacts Can reduce water recreation Turions and fragments can clog irrigation canals Can reduce hydropower productivity Mechanical and chemical treatments can add up over a period of time to be costly

Biological Control Hydrilla leaf-mining fly and hydrilla tuber weevil Both found in India mid 80’s Are major species specific predators for Hydrilla plants.ifas.ufl.edu

Insect Herbivory Effects 14,000 L tanks Each divided into 32 sections Competition tests and herbivory tests in different tanks Concluded that combo of bio controls are most effective Doyle et.al. 2007

Bio Control Cont. Another biological enemy to hydrilla from Asia Grow fast, and consume tubers/turions! However, grass carp are not species specific foragers Ctenopharyngodon idella (Grass Carp)

Effectiveness of Grass Carp Consume large amounts until they reach maximum size Smaller fish consume more vegetation Once size limit is reached, no longer a great control agent Osborne 1981

Chemical Controls Endothall (Aquathol K) Can be used selectively Kills vegetation, not tubers Diquat (Reward) Is effected by water solids(silt) Usually used for one season Reward prices vary, check local provider ($ /gallon) Aquathol powder form prices also vary ( $ /10 lbs) Aquathol liquid form ($ / 2.5 gallons)

Work Cited California Invasive Plant Council (2010) Cal-IPC Resources on Hydrilla verticillata. April 18, Doyle R, Grodowitz M, Smart M, Owens C (2007) Separate and interactive effects of competition and herbivory on the growth, expansion, and tuber formation of Hydrilla verticillata. Biological Control 41: Kulshreshtha M, Gopal B (1983) Allelopathic influence of Hydrilla verticillata on the distribution of Ceratophyllum species. Aquatic Botany 16: * Osborne JA, Sassic NM (1981) The size of grass carp as a factor in the control of Hydrilla. Aquatic Botany 11: University of Florida IFAS (2009) Center for Aquatic and Invasive Plants. April 17, 2010 USDA, ARS The Agriculture Research Service Database ( 21 April 2010). ARS Headquarters, Washington DC,

Work Cited Cont. USDA, NRCS The PLANTS Database ( 21 April 2010). National Plant Data Center, Baton Rouge, LA USA. Washington State Department of Ecology (2010) Aquatic Plant Management- Aquatic Herbicides. April 16, Washington State Department of Ecology (2010) Aquatic Plant Management- Triploid Grass Carp. April 17, 2010.