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Center For Aquatic And Invasive Plants

Center For Aquatic And Invasive Plants

Center for Aquatic and Invasive Plants Logo    Plant Management in Florida Waters

Center for Aquatic and Invasive Plants Logo    Plant Management in Florida Waters

NDPES Logo

*Important: See Reference Guide Beforehand

No single herbicide is appropriate for controlling all invasive aquatic plants (or nuisance growths of native aquatic plants), in all situations. A herbicide may perform differently depending on the waterbody, its use, the time of year—or even the time of day. Therefore, aquatic plant managers must have a thorough understanding of how each herbicide acts in Florida aquatic systems. The following parameters are evaluated when considering this herbicide to manage aquatic plants in a specific waterbody. Each parameter is linked to an explanation and examples are provided to demonstrate their relevance to developing comprehensive aquatic plant management strategies.


Table A: Herbicide Use Patterns for Triclopyr

Target PlantScientific NameUse PatternCompatible Herbicides
Tussocks Floating and emergent herbaceous and woody species Occasional Used alone
Primrose willow Ludwigia octovalvis/peruviana Occasional Used alone

Table B: Water Uses and Functions

Water Use ParametersManagement Considerations
Downstream Uses and Needs
  • No issues related to this tool
Fish and Wildlife Mgmt.  
Vegetation planting
  • Avoid drift and potential damage to adjacent susceptible plants
Forage and prey
  • No issues related to this tool
Fisheries
  • Formulated triclopyr practically non-toxic to fish
    • Rainbow trout LC50 – 96-hour ~552 mg/L
    • Bluegill sunfish LC50 – 96-hour ~891 mg/L
Non-game wildlife
  • No issues related to this tool
Endangered species
  • Avoid drift and potential damage to susceptible plants in endangered species habitat
Waterfowl
  • Non-toxic to waterfowl
    • Mallard duck LC50 > 5,000 ppm
Flood Control
  • No issues related to this tool
Navigation and Access
  • No issues related to this tool
Irrigation
  • Do not use treated water for 120 days following application, or
  • Triclopyr level at the water intake is determined by laboratory analysis to be < 1.0 ppb or less
Livestock Consumption
  • There are no restrictions on livestock consumption of treated water
  • Do not allow lactating dairy animals to graze treated areas until the next growing season
Potable Water
  • Variable setback distances from functioning potable water intake
    • Depend on size and rate of application – consult label for specifics
  • To apply within setback distances, the intake must be shut off until the triclopyr level at the water intake is determined to be < 0.4 ppm
Recreation  
Boating
  • No issues related to this tool
Fishing
  • No fish consumption restrictions
Hunting
  • No issues related to this tool
Swimming
  • No swimming restrictions

Table C: Herbicide, Waterbody, Plant, and Climate Parameters

Herbicide ParametersManagement Considerations
Herbicide Rate
  • Foliar applications generally at 3-8 quarts / acre with non-ionic surfactant
  • Basal bark applications generally at 10% solution with methylated seed oil
Breakdown / Inactivation
  • Short half-life in water depending on season and water depth – see photolysis
Microbial
  • Microbial metabolism is primary degradation pathway in soil – half-life ~45 days
Adsorption
  • Does not bind strongly or adsorb to soil particles
Photolysis
  • Primary degradation pathway in water
    • Half-life of 2.5 days (shallow water/summer) to 14 days (deep/winter)
Hydrolysis
  • Not sensitive to hydrolysis
Dissipation
  • Not used to control submersed plants in Florida – not applied directly to water
    • Does not adsorb to soils – may be more persistent and more mobile in soils
Formulation  
Liquid
  • Available in liquid formulation
Solid
  • Available in solid formulation combined with 2,4-D amine salt
Mechanism of Action
  • Classified in WSSA Resistance Grouping #4
    • Auxin mimic
Mode of Action  
Systemic
  • Absorbed by foliage and translocates throughout plant tissues
  • Moves to areas of new growth and causes a disruption in hormone levels
  • Interferes with normal expansion and division of plant cells
    • Acts like a growth stimulant in some plant tissues and a growth retardant in others
    • Symptoms include cupped leaves and twisted stems
    • Vascular tissue becomes crushed, stops movement of essential nutrients and sugars
    • Plant essentially grows itself to death
Plant Growth Regulator
  • Not used as a plant growth regulator in Florida aquatic plant control applications
Stewardship  
Herbicide resistance
  • No tolerance or resistance issues reported in Florida
  • Rotate or use with 2,4-D, imazapyr, or glyphosate where appropriate
Waterbody ParametersManagement Considerations
Hydrology  
Water depth
  • No issues related to this tool
    • Not used for in-water applications at this time in FWC-funded programs
Water volume
  • No issues related to this tool
    • Not used for in-water applications at this time in FWC-funded programs
Water movement
  • No issues related to this tool
    • Not used for in-water applications at this time in FWC-funded programs
Water chemistry  
Dissolved oxygen (DO)
  • Slow acting herbicide used for shoreline applications and spot control within secluded marshes
    • DO is less concern
pH, alkalinity, hardness
  • No issues related to this tool
Nutrient content
  • Slow acting herbicide used for shoreline applications and spot control within secluded marshes
Water transparency
  • No issues related to this tool
    • Not used for in-water applications at this time in FWC-funded programs
Sediment characteristics  
Composition
  • Sand/Clay – no issues related to this tool
  • Organic – no issues related to this tool
Potential for re-suspension
  • No issues related to this tool
  • Does not readily adsorb to suspended material in tank mix water
Plant Physiology ParametersManagement Considerations
Plant origin / growth potential  
Native
  • Evaluated for spatter-dock (Nuphar advena) control
    • Ineffective even at high rates and applied with 2,4-D
  • Tussocks – mixed floating masses of woody and herbaceous plants
    • Foliar applications at 3-8 qt / ac
    • Usually applied with glyphosate, 2,4-D, or imazapyr
Non-native
  • Primrose willow
    • Foliar application at ~1.0 gpa
    • In-water application at 1-2 ppm with 2,4-D
Invasive

  • Not applied to control invasive plants in FWC-funded program at this time
Plant growth stage (target/non-target)
  • Need actively growing plants for herbicide uptake
  • May need higher rates for mature plants
Plant susceptibility (target/non-target)
  • Auxin-like activity
  • Controls woody and broadleaf plants
  • Most grasses and other monocots are tolerant
  • Apply to actively growing target plants
  • Apply when potential for drift is minimal to avoid damage to non-target plants
Potential for regrowth (target/non-target)
  • Kills roots of susceptible plants allowing longer control than herbicides that only kill standing crop
Climate ParametersManagement Considerations
Weather Daily

  • Rainfast in about two hours after application
  • May damage adjacent woody or susceptible broadleaf plants due to drift
    • Subject to FL DACS organo-auxin rule – 5E-2.033 F.A.C.
    • Applications prohibited in winds above 10 mph

Seasonally

  • Selectivity increases in winter when non-target plants like buttonbush are dormant
Light intensity
  • May break down faster in clearer water or in more direct summer light
Water temperature
  • No issues related to this tool

Table D: Other Parameters

ParameterManagement Considerations
Cost
  • Generics are available
  • Other herbicides with similar target plant control and use patterns are available
Anticipated Control Amount  
Spatial
  • Area of control is generally confined to the area to which triclopyr is directly applied
Duration
  • Kills roots of susceptible plants allowing longer control than herbicides that only kill standing crop
Time to Achieve Control
  • Symptoms in as little as 24 hours
  • Complete kill in several weeks after application
Contractor/Equipment
  • Foliar applications by backpack for spot control
  • Airboat or ATV for small-scale applications
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