Amine Endothall Considerations

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 Amine Endothall

Target Plant Scientific Name Use Pattern Compatible Herbicides
Hydrilla Hydrilla verticillata Occasional/Spot Low rates in combination with potassium endothall
Hygrophila Hygrophila polysperma Occasional Low rates in combination with potassium endothall
Crested floating heart Nymphoides cristata Occasional Low rates in combination with potassium endothall 

Table B:  Water Uses and Functions

Water Use Parameters Management Considerations
Downstream Uses and Needs
  • Do not apply within 600 feet of functioning potable water intake
  • No irrigation restrictions listed for liquid formulation of this compound
Fish and Wildlife Mgmt.  
Vegetation planting No issues related to this tool
Forage and prey No issues related to this tool
Fisheries
  • Highly toxic – blue gill, rainbow trout, channel catfish, daphnia EC50 >1.00 ppm
  • Fish may be killed by doses in excess of 0.3 ppm
Non-game wildlife No issues related to this tool
Endangered species No issues related to this tool at operational rates (0.05 – 0.3 ppm) and strategies
Waterfowl Non-toxic to waterfowl – mallard duck LD50 > 5,000 ppm
Flood Control No issues related to this tool
Navigation and Access No issues related to this tool
Irrigation
  • No issue related to this tool for established plants
  • Consult label for possible irrigation restrictions for newly seeded or transplanted plants
Livestock Consumption No issues related to this tool for applications in Florida public waters
Potable Water
  • Apply 600 feet or greater from a functioning potable water intake
  • Coordinate applications with water facility operator
    • Public consumption of water only when the MCL is below 0.1 ppm
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 Generally applied at 0.05 – 0.3 ppm in combination with potassium endothall for hydrilla control
Breakdown / Inactivation Half  life in water about one week or less
Microbial Microbial metabolism is  primary degradation pathway
Adsorption

Does not adsorb to suspended solids or sediments

Photodegradation

Does not degrade by photolysis

Dissipation Break down fairly rapidly in water so dissipation is minimal
Formulation  
Liquid
  • Available in liquid formulation
    • 53% active ingredient – contains 2 lb. endothall acid / gallon
Solid
  • Available in granular formulation
    • 11.2% active ingredient – rates are based on endothall acid
Mode of Action
 
Contact
  • Interferes with protein and lipid synthesis – disrupts cell membrane and respiration
  • Somewhat mobile in plant tissues
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
  • Used occasionally with potassium endothall as a resistance management strategy
Waterbody Parameters  Management Considerations
Hydrology  
Water depth Important to know water depth to calculate appropriate dose
Water volume Generally used for hydrilla control in small areas in combination with potassium endothall – volume of treated area is essential to calculate appropriate dose
Water movement Need at least 24 hours of exposure for hydrilla control
Water chemistry  
Dissolved oxygen (DO) Usually no issues related to this parameter since control areas are fairly small
pH, alkalinity, hardness No issues related to this tool
Nutrient content
No issues related to this tool – primarily used for small-scale hydrilla control
Water transparency Need actively growing plants for herbicide uptake
Sediment characteristics  
Composition  
  • Sand/Clay – no issues related to this tool
  • Organic – no issues related to this tool
Potential for resuspension Does not adsorb to suspended material
Plant Physiology Parameters  Management Considerations
Plant origin/ growth potential  
Native Amine endothall is an algaecide, but is infrequently permitted or used by FWC for this purpose alone in Florida waters
Non-native Little to no use with this compound
Invasive   Occasionally  used at low rates in conjunction with potassium endothall to spot control new hydrilla infestations for example at boat ramps, or used with potassium endothall to control small areas of hydrilla as part of resistance management efforts
Plant growth stage (target/non-target) Need actively growing plants for herbicide uptake
Plant susceptibility (target/non-target)
  • Apply to actively growing target plants
  • May control vallisneria when used at higher rates in combination with potassium endothall
Potential for regrowth (target/non-target)
  • Hydrilla regrowth depends on extent of control, water clarity and depth
    • Regrowth is slower if root crowns killed – limited to tuber/turion sprouting
  • Native plants southern naiad and Illinois pondweed are controlled by endothall, but usually recover during the same or next growing season
Climate Parameters  Management Considerations
Weather
  • Daily
    • Need at least 24 hours of contact for hydrilla control
    • Dependant on dose and water temperature
    • Windy conditions may increase dissipation in spot or band applications
  • Seasonally
    • Less herbicide may be required in cooler months
    • Microbial breakdown is slower so herbicide active for longer period
    • Actively growing plants in late winter / early spring increases uptake
Light intensity No issues related to this tool – not broken down by photolysis
Water temperature Endothall degradation can occur more rapidly in warmer water (>80°) which could result in reduced efficacy

Table D: Other Parameters

Parameter Management Considerations
Cost No generics available
Anticipated Control Amount  
Spatial Area of control is generally confined to the area to which endothall is directly applied – some dissipation and control may result outside of application zone
Duration
  • Control duration depends on dose, extent of control, water clarity, and depth
    • If hydrilla root crowns killed then regrowth is slower – from tubers/turions only
Time to Achieve Control Symptoms in 5-7 days and control in 1-3 weeks
Contractor/Equipment
  • Usually applied via boat-mounted drop hoses as a tank mix with potassium endothall
  • Aerial applications are not conducted in Florida with this compound for aquatic plant control
  • Granular formulation applied with blower
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