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Crop Protection Chemistry: Adjuvants
Doug Linscott, Research Chemist
Melissa Olds, Sr. Formulation Chemist
Pacific Northwest Vegetable Pest Management Conference
November 16, 2017
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Tank Mixing Basics
Definition:
Tank mix: process of mixing several crop protection
products into one mixture to be used for application
Why are tank mixtures used?
─Convenience
─Control of broader spectrum of pests (insects,
weeds, or fungus)
─Enhancement of active ingredient
• Adjuvant
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Adjuvant: Definition
Any substance that enhances, or is intended
to enhance, the effectiveness of a crop
protection product, improving the biological
activity or handling characteristics.
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Adjuvants are classified into two categories:
1. Activator adjuvants
2. Spray modifier adjuvants
Adjuvant Types
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Adjuvants: Activator
• Non-Ionic Adjuvants are most
common type used, often referred to as
NIS.
• Neutral charge, thus no exchange with
other ions in tank mixture such soluble
liquids (SL).
• Applications to waxy leaf surface would
be ideal use for this adjuvant class.
• Ionic Adjuvants are not as
commonly used as NIS.
• Charge of ionic adjuvants is
either positive or negative
which can impact biological
efficacy of active ingredient
and/or tank mix compatibility.
• Crop Oil Concentrate (COC)
Adjuvants are mixture of oil
or petroleum with non-ionic
adjuvant.
• May apply when seeking to
enhance penetration of leaf
surface.
• Reduce water evaporation
during dry and hot conditions.
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Adjuvants: Spray Modifier
• Compatibility Agents are
used to aid distribution of the
charge of tank mixture.
• Examples include phosphate
ester containing adjuvants.
• Wetters/Spreaders
reduce surface tension
of spray droplet, thus
increasing coverage.
• Ideal use for contact
herbicides
• Buffering Agents adjust pH of tank mixture, either basic or acidic.
• Always read label for recommended pH range.
• Measure pH of water source using for tank mix application.
Drift Control Agents are added to tank mixture to alter physical properties of spray droplets by increasing average droplet size.
• Hard Water Conditioners reduce
interaction with ions (i.e. dissolved salts) in
water with crop protection products.
• Example includes ammonium sulfate (AMS)
interacting with hard water ions so as to
improve biological efficacy of glyphosate.
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Tank Mixture Example: Adjuvant Selection
Product Name Use Rate
1. Initial Water (50%) 10 gal/acre
2. AMS solution 2 % v/v
3. Oil Dispersion (OD) 1 pt./acre
4. Soluble Liquid (SL) 6 oz./acre
5. Emulsifiable Concentrate (EC) 3 oz./ acre
6. Adjuvant #1 0.25 % v/v
7. Remaining water
**Always follow product label/use guides/other materials for all registered
uses, use rates, and product recommendations.
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Tank Mixture Example #1
1. 50% of total water
volume
2. AMS solution
(2% v/v)
4. SL (6 oz/acre) +
EC (3 oz/acre)
5. Adjuvant #1 (0.25% v/v) 6. Final Tank Mix
Solution after addition of
remaining water
3. OD (1 pt/acre)
Residue on beaker after pouring out Tank Mix
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Tank Mixture Example #1
Product Name Use Rate
1. Initial Water (50%) 10 gal/acre
2. AMS solution 2 % v/v
3. Oil Dispersion (OD) 1 pt./acre
4. Soluble Liquid (SL) 6 oz./acre
5. Emulsifiable Concentrate (EC) 3 oz./ acre
6. Adjuvant #2 0.25 % v/v
7. Remaining water
**Always follow product label/use guides/other materials for all registered
uses, use rates, and product recommendations.
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Tank Mixture Example #1
1. 50% of total water
volume
2. AMS solution
(2% v/v)
4. SL(6 oz/acre) +
EC (3 oz/acre)
5. Adjuvant #2 (0.25% v/v) 6. Final Tank Mix Solution after
addition of remaining water
3. OD (1 pt/acre)
Container after pouring out Tank Mix with Adjuvant #2
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Tank Mixture Example #2
Product Name Use Rate
1. Initial Water (50%) 10 gal/acre
2. Suspension Concentrate (SC) 4.5 pt/acre
3. Remaining water
Product Name Use Rate
1. Initial Water (50%) 20 gal/acre
2. Suspension Concentrate (SC) 4.5 pt/acre
3. Remaining water
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Tank Mix Example #2
10 gal/acre 20 gal/acre
10 gal/acre20 gal /
acre
Above: Undisturbed for 24 hrs.
Above: After 2 inversions of jar
10 gal/acre
20 gal /
acre
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Tank Mix Example #2
10 gal/acre 20 gal/acre
10 gal/acre20 gal /
acre
Above: Undisturbed for 24 hrs.
Above: After 2 inversions of jar
10 gal/acre
20 gal /
acreAddition of 0.4% v/v of flow aid
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Adjuvant: Summary
• Adjuvants are either activator or spray modifier.
• Activator adjuvants include non-ionic, ionic and ammonium fertilizers.
• Spray modifier adjuvants include compatibility agents, hard water
conditioners, buffering agents, antifoam, drift control agents,
stickers/deposition agents, dyes, wetter/spreader agents, UV
absorbents.
• Consider both tank mix compatibility and biological efficacy when
selecting adjuvant.
• Perform a jar test for all tank mixtures, especially when in doubt!
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