Center For Aquatic And Invasive Plants

Carfentrazone 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 Carfentrazone

Target Plant	Scientific Name	Use Pattern	Compatible Herbicides
Uruguayan primrose willow complex	Ludwigia grandiflora/hexapetala	Occasional	Combined with imazamox

Table B: Water Uses and Functions

Water Use Parameters	Management Considerations
Downstream Uses and Needs	Do not apply within ¼ mile upstream of functioning potable intake in rivers
Fish and Wildlife Mgmt.
Vegetation planting	No issues related to this tool
Forage and prey	No issues related to this tool – potential for bioaccumulation is low
Fisheries	Moderately toxic to fish 96-hour LC₅₀ = 1.6 mg/L in rainbow trout and 2.0 mg/L in bluegill sunfish Daphnia magna 48-hour LC₅₀ > 10 mg/L
Non-game wildlife	No issues related to this tool
Endangered species	No issues related to this tool at operational rates (~4.0 oz/ac) and strategies
Waterfowl	Non-toxic to waterfowl Mallard duck and bobwhite quail oral LD₅₀ > 2,250 mg/kg
Flood Control	No issues related to this tool
Navigation and Access	No issues related to this tool
Irrigation	Do not use treated water for 1 day after application to < 20% of waterbody Do not use treated water for 14 days after application to > 20% of waterbody
Livestock Consumption	Do not use water for livestock consumption for I day after applying to 20-50% of waterbody
Potable Water	Do not apply within 1/4 mile of functioning potable water intake in lakes Do not apply within 1/4 mile upstream of functioning potable intake in rivers
Recreation
Boating	No issues related to this tool
Fishing	No fish consumption restriction – does not bioaccumulate in fish
Hunting	No issues related to this tool
Swimming	No swimming restriction

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

Herbicide Parameters	Management Considerations
Herbicide Rate	Apply at 4.0 oz/ac with 32 oz/ac imazamox to control Ludwigia grandiflora/hexapetala
Breakdown / Inactivation	Short half-life in water depending on season and water depth – see hydrolysis
Microbial	Microbial metabolism is primary degradation pathway in soil – half-life < 1.5 days
Adsorption	Does not bind in sediments or adsorb to soil particles
Photolysis	Susceptible to photolytic degradation
Hydrolysis	Primary degradation pathway in water Half-life of 3-5 days in water
Dissipation	Minimal with the very short half-life and use pattern of foliar applications
Formulation
Liquid	Available as a liquid formulation which is emusifiable in water
Solid	Not available in solid formulations
Mechanism of Action	Classified in WSSA Resistance Grouping #14 Protoporphyrinogen Oxidase (PPO) enzyme inhibitor
Mode of Action
Contact	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
Stewardship
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 Parameters	Management Considerations
Hydrology
Water depth	Not an issue with FL use pattern – foliar applications to emergent plants
Water volume	Not an issue with FL use pattern – foliar applications to emergent plants
Water movement	Not an issue with FL use pattern – foliar applications to emergent plants
Water chemistry
Dissolved oxygen (DO)	Not an issue with FL use pattern – foliar applications to small areas of emergent plants
pH, alkalinity, hardness	Not an issue with FL use pattern – foliar applications to emergent plants Does not bind with organic or clay particles in tank mix
Nutrient content	Not an issue with FL use pattern – small-scale emergent plant management
Water transparency	Not an issue with FL use pattern – foliar applications to emergent plants
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 adsorb to suspended material in water body or in tank mix water
Plant Physiology Parameters	Management Considerations
Plant origin / growth potential
Native	Not used to target native plants in FWC Programs
Non-native	Not used to target non-native plants in FWC Programs
Invasive	Ludwigia grandiflora/hexapetala Applied directly to leaves at 4.0 oz/ac + 32 oz/ac imazamox Not confirmed if carfentrazone adds long-term efficacy above imazamox alone May provide faster control Rapid shoot burndown may reduce translocation, reducing long-term control Addition of carfentrazone may reduce selectivity somewhat to comingled plants
Plant growth stage (target/non-target)	Need actively growing plants for herbicide uptake L. grandiflora/hexapetala has high submersed rhizome vs above water leaf / shoot mass Early spring foliar applications may be ineffective – not enough above-water mass Floating / submersed leaves not effectively controlled with foliar treatment Follow-up applications may be necessary for late summer, dense, woody growth
Plant susceptibility (target/non-target)	Does not control adjacent knotgrass, torpedograss, pickerelweed, turfgrass
Potential for regrowth (target/non-target)	Injury to comingled non-target plants is usual minimal with eventual regrowth
Climate Parameters	Management Considerations
Weather	Daily Needs 1-2 hours of contact for good herbicidal activity Seasonally Need actively growing target plants for herbicide uptake
Light intensity	Not an issue with FL use pattern – foliar applications to emergent plants
Water temperature	Not an issue with FL use pattern – foliar applications to emergent plants

Table D: Other Parameters

Parameter	Management Considerations
Cost	No generics available Similar chemistry available with flumioxazin Generally more expensive than 2,4-D or diquat
Anticipated Control Amount
Spatial	Control is confined to the area to which carfentrazone is directly applied to target plants
Duration	Efficacy improves when applying to actively growing plants with high emergent leaf/shoot biomass
Time to Achieve Control	Symptoms in 2-5 days – control in 3-4 weeks
Contractor/Equipment	Foliar applications by backpack, airboat for small-scale applications to Ludwigia spp.