Reeves Petroff MSU Extension Pesticide Education Specialist

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Reeves PetroffMSU ExtensionPesticide Education
Specialist

• http//mtpesticides.org

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Water Quality Pesticide Performance
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How water quality affects certain pesticides
Goal

• Minerals
• pH
• Dirty Water

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How water quality affects certain pesticides
Goal

• Weak acid herbicides
• Insecticides
• Organophosphates
• Carbamates

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Water
- Covalent Bonds shared electrons
pH of 7 neutral

• Universal Solvent Dissolves attracts many
  substances

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Hydrological Cycle
Adds minerals and pH to water
CO2 H20 carbonic acid
Carbonate CO3Alkaline
Bicarbonate HCO3Alkaline
Minerals
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What Causes pH in water?
CarbonicAcidH2CO3
CO2 H20
Acid
BicarbonateHCO3
CarbonateCO3
Alkaline
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Water
Primary diluent
New Term

• Why water quality is important!
• 1 pint or 1 quart per acre
• 30 GPA application volume
• 99 and 93 of spray solution

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Minerals
Hard Water
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Total Dissolved Solids
ppm
grains 17 ppm per grain
TDS
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Common mineral elements in Montana water
Ions -
Charged atoms
nitrate (NO3-)
potassium (K)
iron (Fe, Fe),
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What is hard water?
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How is TDS measured?

• Weight
• EC
• Chemical reaction (Test Strips)

Calcium 666 ppm Sulphate 2434
ppm Magnesium 234 ppm Chloride 32 ppm
Sodium 130 ppm Bicarbonate 346 ppm
3842 ppm.
TDS gt 500 mg/L (ppm) is salty to taste
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Types Of Water
? Drinking water lt500 TDS (EPA) ? Fresh Water
lt1,000 TDS ? Brackish 1,000-5,000 TDS ?
Highly Brackish 5,000-15,000 TDS ? Saline
15,000-30,000 TDS ? Sea Water 30,000-40,000
TDS ? Brine 40,000-300,000 TDS
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Understanding Water HardnessWater Softening
Ion Exchange

• Resin Beads
• anionic (-)
• hold cations()

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Mg
Ca
Na
Na
Ca
Mg
Mg
Na
Mg
Na
Na
Mg
Flow
Ca
Na
Mg
Ca
Mg
Na
Na
Na
Ca
Na
Ca
Na
Ca
Na
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Water Quality Effects on Herbicides
Hard Water
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Weak Acid Herbicides

• Most affected by hard water and pH

• Acids release H ions in water
• Weak acids release H slightly

Glyphosate Roundup Paraquat
Gramoxone Clethodim Select Sethoxydim
Poast Many 2,4-D products
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Weak Acid Herbicides
CH3 NH2 CH3
Dissociation splitting of the molecule
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Weak Acid Herbicides
CH3 NH2 CH3
Ca
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- Herbicide molecule -

• Penetrate the target weed intact
• Travel to the site of action
• Kill the plant.

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CH3 NH2 CH3
Intact molecule more plant penetration
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Water pH Herbicides
What is pH?

• Measures H ions
• potential Hydrogen
• More H lower pH more acid

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Logarithmic
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pH

• 0 to 14
• 7 is neutral
• Logarithmic - 102 100
• pH of 3 has 100 times H as pH of 5

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pH and Herbicides

• Acidic conditions for most herbicides
• pH 3 to 6
• Lower pH avoids dissociation
• The exceptions
• Ally
• Escort
• Read the label

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pH
Hard Water
High pH dissociation Molecule is vulnerable
CH3 NH2 CH3
Ca
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Bicarbonate Waters

• Associated with sodium
• gt 500 ppm high pH
• Affects 2,4-D
• Affects dim herbicides
• Poast - sethoxydim
• Select clethodim
• Achieve -tralkoxydim

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Bicarbonate Waters- Solution -

• Use maximum allowed rate
• Apply during optimal growth stage
• Adjuvants
• - Non-ionic Surfactant (NIS)
• - Acidifiers/buffers

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Water Quality Effects on Herbicides
Turbidity

• diquat (Reglone, Reward)
• paraquat (Gramoxone)
• glyphosate (Roundup, Touchdown, etc.

Dirt
Organic MatterOM
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Water Quality Effects on Herbicides

• Binds the herbicide

Roundup
- - OM --
Herbicide not absorbed

• Clogs screens
• Pumps?

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TSS Solutions

• Clean water supply
• Filtering

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pH Insecticides

• Organophosphates
• Malathion
• Parathion
• Carbamates
• Sevin

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Solutions?
1. Test the water

• Test strips
• Meters
• Labs

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Test strips

• Easy to use
• Cheap - 8 to 20
• Some combine ph hardness
• Improved accuracy

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Meters
pH, EC, TDS 179.00

• Accurate
• Calibrated
• 100

www.gemplers.com
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Labs

• Collection guidance
• Tests performed
• How to interpret results
• 50 100

http//mtpesticides.org ? Links ? Labs
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• Less ions present
• Example
• 25 to 15 GPA
• Only if practical
• pH still a problem
• Label?

1. Test the water
2. Reduce Water Volume
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• More pesticide ions present
• More costly
• Non-target damage?

1. Test the water
2. Reduce Water Volume
3. Use maximum allowed rate
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• Mix what you need
• Smaller areas
• Planning
• Scouting
• Good notes

1. Test the water
2. Reduce Water Volume
3. Use maximum allowed rate
4. Spray ASAP after mixing
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1. Test the water
2. Reduce Water Volume
3. Use maximum allowed rate
4. Spray ASAP after mixing
5. Adjuvants
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Adjuvants

• Additives to improve performance

• Acidifiers
• Buffers

• Conditioners
• Ammonium Sulfate (AS)
• Non-ionic surfactants (NIS)

www.herbicide-adjuvants.com
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