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Center For Aquatic And Invasive Plants

Center For Aquatic And Invasive Plants

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*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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