Reeves Petroff MSU Extension Pesticide Education Specialist http

Reeves Petroff MSU Extension Pesticide Education Specialist http: //mtpesticides. org Knowledge, Information & Links

How water quality affects certain pesticides • Minerals • p. H • Dirty Water Goal

How water quality affects certain pesticides Goal • Weak acid herbicides • Insecticides – Organophosphates – Carbamates

+ H O + H -+ O - H - Covalent Bonds – shared electrons p. H of 7 = neutral -Universal Solvent – Dissolves & attracts many substances

Hydrological Cycle Adds minerals and p. H to water CO 2 + H 20 = carbonic acid Carbonate CO 3 Alkaline Bicarbonate HCO 3 Alkaline Minerals

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

Minerals Hard Water

Total Dissolved Solids ppm grains * 17 ppm per grain TDS

Common mineral elements in Montana water Ions - Charged atoms Positive Charge (cations) Negative Charge (anions) Calcium (Ca++) Sulphate (SO 4 -) Magnesium (Mg++) Chloride (Cl -) Sodium (Na+) Bicarbonate (HCO 3 -) nitrate (NO 3 -) potassium (K+) iron (Fe++, Fe+++),

What is hard water? ppm/Gal Grains/Gal Soft 0 - 60 0 – 3. 5 Mod. Hard 60 - 120 3. 5 – 7. 0 Hard 120 - 180 7. 0 – 10. 5 Very Hard Over 180 Over 10. 5 Reference: Montana Environmental Health Association – Sanitarian’s Field Guide

How is TDS measured? Calcium = 666 ppm Sulphate = 2434 ppm Magnesium = 234 ppm Chloride = 32 ppm Sodium = 130 ppm Bicarbonate = 346 ppm 3842 ppm. • Weight • EC • Chemical reaction (Test Strips) TDS > 500 mg/L (ppm) is salty to taste

Types Of Water Drinking water <500 TDS (EPA) Fresh Water : <1, 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

Understanding Water Hardness Water Softening – Ion Exchange Na+ Na+ Na+ • Resin Beads • anionic (-) • hold cations(+)

Mg++ Ca++ Ca++ Na+ Mg++ Na+ Na+ Flow Na+ Mg++ Ca++ Na+ Mg++ Na+ Ca++ Na+ Na+ Na+

Water Quality Effects on Herbicides Hard Water Maximum Water Hardness Glyphosate (Roundup) use rate Grains/US gal. ppm Ca. C 03 equivalent Low Rates for Annual Grass Weeds 20 350 Higher rates for Perennial Weeds 40 700

Weak Acid Herbicides • Most affected by hard water and p. H • Acids release H+ ions in water • Weak acids release H+ slightly Glyphosate – Roundup Paraquat – Gramoxone Clethodim – Select Sethoxydim – Poast Many 2, 4 -D products

Weak Acid Herbicides C C-O - C-CH 3 C CH 3 | +NH 2 | CH 3 Dissociation – splitting of the molecule

Weak Acid Herbicides C CH 3 | - 3 O CH CC- +Ca + C C C-O - C-CH 3 C +NH 2 | CH 3

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

CH 3 | C C-O -+NH 2 | C-CH 3 C Intact molecule = more plant penetration

Water p. H & Herbicides What is p. H? • Measures H+ ions • potential Hydrogen • More H+ = lower p. H = more acid

Logarithmic

p. H and Herbicides • Acidic conditions for most herbicides – p. H 3 to 6 • Lower p. H avoids dissociation • The exceptions • Ally • Escort • Read the label

p. H Hard Water High p. H = dissociation Molecule is vulnerable C C-O - +Ca+ C-CH 3 C CH 3 | +NH 2 | CH 3

Bicarbonate Waters • Associated with sodium • > 500 ppm & high p. H • Affects 2, 4 -D • Affects “dim” herbicides • Poast - sethoxydim • Select – clethodim • Achieve -tralkoxydim

…dim herbicides

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

Water Quality Effects on Herbicides • diquat (Reglone, Reward) • paraquat (Gramoxone) • glyphosate (Roundup, Touchdown, etc. Organic Matter OM Turbidity Dirt Total Suspended Solids TSS

Water Quality Effects on Herbicides • Binds the herbicide + Herbicide not + Roundup + - OM absorbed + - • Clogs screens • Pumps?

TSS – Solutions • Clean water supply • Filtering Settle basin Filters

p. H & Insecticides • Organophosphates – Malathion – Parathion • Carbamates – Sevin

Solutions? 1. Test the water • Test strips • Meters • Labs

Test strips • Easy to use • Cheap - $8 to $20 • Some combine ph & hardness • Improved accuracy

Meters • Accurate p. H, EC, TDS $179. 00 • Calibrated • $100 + www. gemplers. com

Labs • Collection guidance • Tests performed • How to interpret results • $50 – $100+ http: //mtpesticides. org Links Labs

1. Test the water 2. Reduce Water Volume • Less ions present • Example: 25 to 15 GPA • Only if practical • p. H still a problem • Label?

1. Test the water 2. Reduce Water Volume 3. Use maximum allowed rate • More pesticide ions present • More costly • Non-target damage?

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

Adjuvants • Additives to improve performance • Acidifiers • Buffers p. H • Conditioners • Ammonium Sulfate (AS) • Non-ionic surfactants (NIS) Hard Water www. herbicide-adjuvants. com