BMP’s for Atrazine and Ametryn

Curtis RainboltCurtis Rainbolt

University of FloridaUniversity of Florida

Why be concerned?Why be concerned?

– Important herbicides for Important herbicides for weed control in FL weed control in FL sugarcane and sod sugarcane and sod productionproduction

– Commonly found in low Commonly found in low concentrations in concentrations in surface water samplingsurface water sampling

– Usage of atrazine has Usage of atrazine has been limited in other been limited in other areas due to high levels areas due to high levels in waterin water

Atrazine (Aatrex, others)Atrazine (Aatrex, others)

• Widely used in FL sugarcane productionWidely used in FL sugarcane production– Both preemergence and postemergence Both preemergence and postemergence

applicationsapplications– Up to 10 lb/A of atrazine applied per growing Up to 10 lb/A of atrazine applied per growing

season for sugarcaneseason for sugarcane– Up to 6 lb/A of atrazine applied per growing season Up to 6 lb/A of atrazine applied per growing season

for sod on muck (3lb/A on sand)for sod on muck (3lb/A on sand)– Applied to a large percentage of sugarcane acreage Applied to a large percentage of sugarcane acreage

in Floridain Florida

Ametryn (Evik)Ametryn (Evik)

• Commonly used in FL sugarcane Commonly used in FL sugarcane productionproduction– Postemergence applicationPostemergence application– Up to 1.5 lb per application (2 applications)Up to 1.5 lb per application (2 applications)

• Usually used at much lower ratesUsually used at much lower rates• Not as heavily used as atrazineNot as heavily used as atrazine

Atrazine Chemical Atrazine Chemical CharacteristicsCharacteristics

– Water solubility not Water solubility not particularly high (33 particularly high (33 mg/L)mg/L)

– Binding to soil organic Binding to soil organic matter not extremely matter not extremely strong (Koc=128 ml/g)strong (Koc=128 ml/g)

– Atrazine is less bound, Atrazine is less bound, but less water soluble but less water soluble than ametrynthan ametryn

– Average field half-life Average field half-life of 60 daysof 60 days

Ametryn Chemical Ametryn Chemical CharacteristicsCharacteristics

– Water solubility higher Water solubility higher than atrazine (194 than atrazine (194 mg/L)mg/L)

– Binding to soil organic Binding to soil organic matter strong relative matter strong relative to atrazine (Koc=362 to atrazine (Koc=362 ml/g)ml/g)

– In field half-life of 60 In field half-life of 60 daysdays

– Ametryn is more Ametryn is more bound, but more water bound, but more water solublesoluble

Detection in water samplingDetection in water sampling

Sampling at stations Sampling at stations throughout EAAthroughout EAA

• 18+ years data available18+ years data available• Atrazine and ametryn Atrazine and ametryn

both commonly detected both commonly detected at stations in EAAat stations in EAA

• Levels are generally Levels are generally very lowvery low– But they are often found!!!But they are often found!!!

How do they get in the water?How do they get in the water?

– Spray drift from fieldSpray drift from field

– Spills during mixing Spills during mixing

– Back-siphoning into water body when Back-siphoning into water body when filling spray tanks filling spray tanks

– Water soluble portion moves with runoff Water soluble portion moves with runoff waterwater

– Portion bound to organic matter moves Portion bound to organic matter moves with sediment erosionwith sediment erosion

How can we minimize atrazine How can we minimize atrazine and ametryn in water?and ametryn in water?

• Minimize physical Minimize physical spray drift into bodies spray drift into bodies of waterof water

• Use care when mixing Use care when mixing and loading herbicidesand loading herbicides– Spills near water Spills near water

bodies can result in bodies can result in large amounts of large amounts of concentrated product concentrated product entering waterentering water

Setback RequirementsSetback Requirements• Always follow label Always follow label

requirement regarding requirement regarding setbacks (Found on all setbacks (Found on all atrazine labels)atrazine labels)– DO NOT mix/load within DO NOT mix/load within

50 ft of any well, sinkhole, 50 ft of any well, sinkhole, stream, river, or lakestream, river, or lake

– DO NOT apply within 66 ft DO NOT apply within 66 ft of where field runoff of where field runoff enters a stream or riverenters a stream or river

– DO NOT apply within 200 DO NOT apply within 200 ft of any lake or reservoirft of any lake or reservoir

Anti-Back-Siphoning Anti-Back-Siphoning

• Make sure all equipment Make sure all equipment used to supply water is used to supply water is equipped with devices to equipped with devices to prevent back-siphoning prevent back-siphoning from the spray/mix tank if from the spray/mix tank if the motor shuts offthe motor shuts off

• Do not apply to saturated soils Do not apply to saturated soils – More runoff of both water soluble herbicide, More runoff of both water soluble herbicide,

and soil particles with herbicide attachedand soil particles with herbicide attached

• Holding waterHolding water– Allows the herbicide to be absorbed by soil Allows the herbicide to be absorbed by soil

particles and settle out, or degradeparticles and settle out, or degrade

How can we minimize atrazine How can we minimize atrazine and ametryn in water?and ametryn in water?

Nutrient BMP’s Impact Herbicide Nutrient BMP’s Impact Herbicide MovementMovement

• Practices that Practices that minimize sediment minimize sediment transporttransport– Herbicides often Herbicides often

bound to sedimentbound to sediment

• Vegetative buffers on Vegetative buffers on field edgesfield edges– Can reduce movement Can reduce movement

of herbicides attached of herbicides attached to soil particlesto soil particles

Take Home MessageTake Home Message

• Atrazine and ametryn are importantAtrazine and ametryn are important– Good stewardship can minimize the amount Good stewardship can minimize the amount

found in surface watersfound in surface waters• Use common senseUse common sense• Follow label directionsFollow label directions• Phosphorus BMP’s also help reduce occurrence Phosphorus BMP’s also help reduce occurrence

UF/IFAS Pesticide InfoUF/IFAS Pesticide Info

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