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

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


*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 Flumioxazin

Target PlantScientific NameUse PatternCompatible Herbicides
Water lettuce Pistia stratiotes Frequent Alone for water lettuce – with 2,4-D or penoxsulam when mixed with water hyacinth
Cuban club-rush Cyperus blepharoleptos Frequent Combine with glyphosate
Ludwigia uraguayensis complex Ludwigia grandiflora & L. hexapetala Frequent Combine with glyphosate
Occasionally 2,4-D or imazamox
Hydrilla Hydrilla verticillata Occasional Alone or combine with diquat or potassium endothall
Ambulia Limnophila sessiliflora Occasional Alone or with diquat
Fanwort Cabomba caroliniana Occasional Alone or with diquat

Table B: Water Uses and Functions

Water Use ParametersManagement Considerations
Downstream Uses and Needs
  • For use in slow moving or quiescent waters
  • Do not apply in intertidal areas or estuaries
  • Downstream uses minor concern
    • Contact type herbicide with short half- life
Fish and Wildlife Mgmt.  
Vegetation planting
  • Avoid contact and potential damage to adjacent susceptible plants
    • Especially water lilies within application zone
Forage and prey
  • No issues related to this tool
  • Moderately toxic to fish
    • LC50 (96-hour) = 2.3 mg/L in rainbow trout and 21 mg/L in bluegill sunfish
    • Daphnia magna LC50 = 6 mg/L
Non-game wildlife
  • No issues related to this tool
Endangered species
  • No issues related to this tool
  • Non-toxic to waterfowl – mallard duck LC50 > 2,250 mg/kg
Flood Control
  • No issues related to this tool
Navigation and Access
  • No issues related to this tool
  • Irrigation restrictions from 0-5 days may apply for turf and ornamental plants
    • See label for application method, rate and depth for possible restriction
Livestock Consumption
  • There are no restrictions on livestock consumption of treated water
Potable Water
  • No potable water use restrictions
  • No issues related to this tool
  • No fish consumption restriction
  • No issues related to this tool
  • No swimming restriction

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

Herbicide ParametersManagement Considerations
Herbicide Rate
  • See plant physiology parameter considerations below for current rates by plant species
    • 50-200 ppb for submersed applications
    • 2-8 oz/ac for foliar applications
Breakdown / Inactivation
  • Short half-life in water depending on season, water depth and especially pH
  • Microbial metabolism is the primary degradation pathway in soil – half-life ~45 days
  • Does not bind in sediments or adsorb to soil particles
  • Susceptible to photodegradation with a half-life of ~3 days
  • Primary degradation pathway in water – especially sensitive in low pH waters
    • Half-life of four days at pH = 5 and minutes at pH = 9.0 in laboratory tests
  • Dissipation is minimal with the very short half-life
  • Not available in aqueous formulation
  • Water dispersible granular herbicide
    • Mix with water and apply as liquid solution
Mechanism of Action
  • Classified in WSSA Resistance Grouping #14
    • Protoporphyrinogen oxidase (PPO) enzyme inhibitor
Mode of Action  
  • Inhibits protoporphyrinogen oxidase enzyme important in chlorophyll synthesis
  • Absorbed through the leaves – does not move in the plant
  • Causes formation of a light-absorbing chlorophyll precursor outside of the chloroplast
    • This compound absorbs energy from sunlight, but cannot pass through the Z-scheme
    • Energy is passed on to oxygen, creating radical oxygen and cell membrane disruption
Plant Growth Regulator
  • Not used as a plant growth regulator in Florida aquatic plant control applications
Herbicide resistance
  • No tolerance or resistance issues reported in Florida
  • Resistance has been reported for PPO inhibitors in terrestrial applications
    • Rotate or combine with other active ingredient where appropriate
Waterbody ParametersManagement Considerations
Water depth
  • Important to know water depth to calculate appropriate concentration for submersed applications
Water volume
  • Important to have accurate bathymetry to calculate appropriate concentration for submersed applications
Water movement
  • Do not apply to flowing water
  • Can be used in slow moving, quiescent waters
Water chemistry  
Dissolved oxygen (DO)
  • Relatively fast-acting contact type herbicide
  • Controlling large area may reduce dissolved oxygen level
    • Wait 10-14 days if treating as much as half of the waterbody
pH, alkalinity, hardness
  • Half-life is pH dependent in field tests
    • Low pH (6.0-6.2) = 39 hours
    • Medium pH (7.0-7.2) = 18.6 hours
    • High pH (>8.5) = 1.7 hours
  • Use buffer if tank mix water exceeds pH 7
  • Apply submersed applications early in morning when pH is generally at lower values
Nutrient content
  • No issues related to this tool
Water transparency
  • Higher light intensity usually equates to more robust growth of submersed target plants
Sediment characteristics  
  • 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 adsorb to suspended material in water body or in tank mix water
Plant Physiology ParametersManagement Considerations
Plant origin / growth potential  
  • Fanwort
    • Use to control cabomba at about 200 ppb
    • Cabomba usually present in lower pH waters
  • Ambulia (Limnophila sessiliflora)
    • Alone at 200 ppb
    • Combination of flumioxazin at 100 ppb + diquat at 370 ppb
      • Very active on water lilies at this rate

  • Water lettuce
    • 2-4 oz / ac applied foliarly
    • 50 ppb for submersed application to control water lettuce
      • Need an area >15 ac to compensate for dissipation
  • Hydrilla (and Hygrophila (Hygrophila polysperma))
    • Alone at 200 ppb
    • Combination of flumioxazin at 100 ppb + diquat at 370 ppb
      • Ludwigia grandiflora and torpedograss control at 4 oz / ac + 7.5 pt / ac glyphosate
      • Increasing use for selective water lettuce control
      • ~50 ppb for submersed applications and 2-8 oz / ac foliar application
      • 4 oz / ac + 4 oz / ac penoxsulam for water lettuce / water hyacinth mix
  • Ludwigia uraguayensis complex and Cuban club-rush
    • 4 oz flumioxazin + 96-120 oz glyphosate / ac
    • Adding flumioxazin accelerates knockdown – unclear if it increases efficacy
Plant growth stage (target/non-target)
  • Need actively growing plants for herbicide uptake
  • Mature plants are more difficult to control due to higher carbohydrate reserve
Plant susceptibility (target/non-target)
  • Good alternative to diquat for controlling water lettuce mixed with bulrush
    • Does not cause bulrush stem spotting or browning associated with diquat applications
  • Foliar applications when wind speed < 10 mph to reduce damage from drift
  • Apply in early fall (Oct/Nov) or late winter (Feb/Mar) for best hydrilla control
    • Lower biomass and pH likely lower
  • Water lilies in application zone may be impacted
    • Especially when applied with diquat for hydrilla control
Potential for regrowth (target/non-target)
  • Thorough water lettuce control
    • Regrowth from seed or new plants flushed into control zone
  • Regrowth is rapid when applied to mature or slowly growing hydrilla
    • Must kill root crowns to slow regrowth from tubers
Climate ParametersManagement Considerations
Weather Daily

  • Needs 4-8 hours of contact for good herbicidal activity


  • Need actively growing target plants for herbicide uptake
Light intensity
  • Higher light intensity usually equates to stronger growth and therefore better control of young submersed plants (hydrilla / cabomba)
Water temperature
  • No issues related to this tool

Table D: Other Parameters

ParameterManagement Considerations
  • No generics available
  • Similar chemistry available in carfentrazone
    • Not as much operational monitoring or use of carfentrazone
Anticipated Control Amount
  • Area of submersed plant control (hydrilla, cabomba, limnophila, hygrophila) is generally confined to the area to which flumioxazin is directly applied
  • Low-dose submersed applications with expectations of dispersal to control water lettuce
  • Hydrilla efficacy improves when applying to young actively growing plants
  • Better efficacy during cooler weather – October/November – February/March
  • Longer control duration when root crowns killed
Time to Achieve Control
  • Floating plants
    • Needs 1-2 hours of foliar contact for control activity
    • Symptoms in 3-5 days – control in 7-14 days
  • Submersed plants
    • Needs 4-6 hours for good control activity
    • Symptoms in 7-14 days – control in 14-28 days
  • Foliar applications by backpack, airboat for small-scale applications to water lettuce
  • Shallow hose for submersed application to control water lettuce
  • Apply with deep water trailing hoses for larger scale submersed plant control
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