Center For Aquatic And Invasive Plants

Triclopyr Considerations

*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.

These considerations are not meant to replace or contradict the EPA approved label.
Always read and follow the pesticide label for each product used.

Table A: Herbicide Use Patterns for Triclopyr

Target Plant	Scientific Name	Use Pattern	Compatible 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 Parameters	Management 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 Parameters	Management 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 Parameters	Management 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 Parameters	Management 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 Parameters	Management 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

Parameter	Management 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