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

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 irrigation restrictions listed for liquid formulation of this compound Do not use treated water for irrigation: Up to 0.3 ppm - 7 days after application 0.3-3.0 ppm - 14 days after application
Livestock Consumption	Do not use treated water for animal consumption or domestic purposes: Up to 0.3 ppm - 7 days after application 0.3-3.0 ppm - 14 days after application
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 23.36% active ingredient rates are based on 2 lb. endothall acid / gallon
Solid	Available in granular formulation 5% 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

Last updated: 13 September 2011

Plant Management in Florida Waters : An Integrated Approach