Crop Protection Chemistry: Adjuvants

Transcription

1 Crop Protection Chemistry: Adjuvants Doug Linscott, Research Chemist Melissa Olds, Sr. Formulation Chemist Pacific Northwest Vegetable Pest Management Conference November 16, 2017

2 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 2

3 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. 3

4 Adjuvant Types Adjuvants are classified into two categories: 1. Activator adjuvants 2. Spray modifier adjuvants 4

5 Adjuvants: Activator 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. 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. 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. 5

6 Adjuvants: Spray Modifier Compatibility Agents are used to aid distribution of the charge of tank mixture. Examples include phosphate ester containing adjuvants. 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. 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. Wetters/Spreaders reduce surface tension of spray droplet, thus increasing coverage. Ideal use for contact herbicides 6

7 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 # % v/v 7. Remaining water **Always follow product label/use guides/other materials for all registered uses, use rates, and product recommendations. 7

8 Tank Mixture Example # % of total water volume 2. AMS solution (2% v/v) 3. OD (1 pt/acre) 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 Residue on beaker after pouring out Tank Mix 8

9 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 # % v/v 7. Remaining water **Always follow product label/use guides/other materials for all registered uses, use rates, and product recommendations. 9

10 Tank Mixture Example # % of total water volume 2. AMS solution (2% v/v) 3. OD (1 pt/acre) 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 Container after pouring out Tank Mix with Adjuvant #2 10

11 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 11

12 Tank Mix Example #2 10 gal/acre 20 gal / acre Above: Undisturbed for 24 hrs. 10 gal/acre 20 gal/acre 10 gal/acre 20 gal / acre Above: After 2 inversions of jar 12

13 Tank Mix Example #2 10 gal/acre 20 gal / acre Above: Undisturbed for 24 hrs. 10 gal/acre 20 gal/acre Addition of 0.4% v/v of flow aid 10 gal/acre 20 gal / acre Above: After 2 inversions of jar 13

14 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! 14

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