Mitigating Insecticide Runoff from RIFA Treatments

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Mitigating Insecticide Runoff from RIFA
Treatments

• Kean S. Goh and Dave Kim
• Environmental Monitoring Pest Management
• Department of Pesticide Regulation
• 830 K Street, Sacramento, CA 95814
• kgoh_at_cdpr.ca.gov
• [phone]

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Environmental Hazards

• This pesticide is extremely toxic to fish and
  aquatic invertebrates."

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Outline

• Introduction
• Insecticide Characteristics
• Environmental Conditions
• Pesticide Management Practices
• Prevention and Mitigation Measures
• Summary

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Introduction

• RIFA treatments - large geographic area
• Surface water runoff potential
• Historical monitoring data
• Aquatic toxicity
• Runoff prevention and mitigation

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Sampling Plan

• Insecticide Concentration
• Offsite movement
• Dissipation study
• Turf, Soil, Water
• Assessing Mitigations

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Arroyo Trabuco
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Offsite Movements (Definitions)

• Spray drift
• primary, secondary
• Runoff
• dissolved in water
• adsorbed to soil particles and organic materials

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The Insecticides

• Bifenthrin (Talstar)
• Chlorpyrifos (Dursban, Lorsban)
• Diazinon
• Fenoxycarb (Award)
• Hydramethylnon (Amdro)
• Pyriproxyfen (Distance)

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Insecticide Characteristics

• Vapor Pressure (mm Hg)
• Water Solubility (ppm, mg/L)
• Soil Adsorption Coefficient (Koc)
• Field Dissipation (t1/2, days)

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Physico-Chemical Properties
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Water Solubility (ppm)
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Soil Adsorption Coefficient (x 1000)
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Field Dissipation Half-Life (Days)
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Aquatic Toxicity (LC50)
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Aquatic Toxicity
1.8
1.6
1.4
1.2
R. Trout
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D. magna
0.8
0.6
0.4
0.2
0
Diazinon
Bifenthrin
Fenoxycarb
Chlorpyrifos
Pyriproxyfen
Hydramethylnon
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Climatic Conditions

• Rainfall
• duration, amount, and intensity
• timing of rainfall after application
• time to runoff after inception of rainfall

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Soil Characteristics

• Texture
• Organic matter content
• Moisture content
• Surface compaction and crusting
• Slope
• Aggregation

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Pesticide Management Practices

• Pesticide placement
• soil, foliar applied, potting mix
• Erosion/runoff control
• Cropping patterns
• Irrigation management
• duration, amount, intensity, and timing

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Runoff Prevention Mitigation

• Runoff survey
• Insecticide selection
• Application
• Containment
• Water recovery
• Buffer strip

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Runoff Site Survey

• Terrain, water flow,
• proximity to water bodies
• Storage area
• Mixing loading area
• Wash area
• Application site

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Insecticide Selection

• Efficacy
• Formulation
• Physico-chemical properties
• Dose (use rate)
• Aquatic toxicity

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Application

• Label
• Environmental Hazards
• Use Directions
• Rate
• Timing
• rain irrigation
• Precision application
• Calibration

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Label Environmental Hazards

• This pesticide is extremely toxic to fish and
  aquatic invertebrates.
• Do not apply directly to water.
• Drift and run-off from treated areas may be
  hazardous to aquatic organisms in neighboring
  areas.
• Do not contaminate water when disposing of
  equipment washwaters.

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Label Recommendation

• Do not apply if rain is expected within 12 hours

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Containment

• Rain shelter
• Containment of spills
• storage area, mixing loading, wash pad
• Containment of runoff water
• Rinsate reuse, treatment
• Tailwater pond/bioswale

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Water Recovery

• Re-circulating system
• Tailwater recovery
• phytotoxicity (herbicide residues)
• microbial degradation, photodegradation
• hydrolysis

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Buffer Strip

• Water soluble vs. adsorped
• Buffer area
• Vegetation strip
• grass, cover crop
• Organic material strip

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Summary

• Do Precision Application
• Timing of application to prevent rain washoff
• Control timing and amount of watering to prevent
  runoff
• Containment of runoff water
• Recapture tailwater and reuse of water
• Use buffer strips

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Acknowledgment

• Calif. Dept. of Food Agric.
• Center for Analytical Chemistry
• Pest Detection/Emergency Projects
• State Water Resource Control Board
• Dept. of Health Services
• Calif. Department of Fish Game
• Co. Agric. Commissioners