Herbicide Compatibility and Mixing
Overview
The student will be able to define and describe herbicide formulation types. Students will understand basics and importance of a jar test. Students will be able to follow tank mixing order instructions
Weed Science: Herbicide Compatibility and Mixing Order Lab
Approximate class time: 60-90 min
Overview:
Students will review the types of herbicide formulations and proper tank mixing order
Objectives:
The student will be able to define and describe herbicide formulation types. Students will understand basics and importance of a jar test. Students will be able to follow tank mixing order instructions
Teacher Materials Needed:
National Pesticide Applicator Certification Core Manual (pdf version available online)
Herbicide tank mixing with household products lab materials
YouTube (optional)
Student Materials Needed:
Herbicide compatibility and mixing order observation worksheet
Activity:
- Teacher defines herbicide formulation types from CH4 in National Pesticide Applicator Certification Core Manual
- Teacher discusses mixing compatibility
- Teacher reviews jar test
- Watch YouTube video “The Jar Test” https://www.youtube.com/watch?v=Hz-5X2XFc4s
- Teacher reviews APPLES mixing order
- Place students into groups of 2 or 3
- Students conduct Jar Test
- Students conduct APPLES tank mixing order
Teacher Resources:
- Active ingredient- the actual chemical in the product mixture that kills the plant
- Solution- active ingredient truly dissolves in water, usually transparent, does not require agitation in the herbicide tank
- Suspension- active ingredient is impregnated on solid carrier. Solid carrier is then suspended in the solution, not fully dissolved, requires agitation in the herbicide tank
- Emulsion- active ingredient is a liquid dispersed within another liquid. Usually milky appearance. Some agitation required in the herbicide tank
- Formulation types
- Emulsifiable concentrate (EC): Liquid active ingredient, one or more petroleum-based solvents. Mixed with water or other light oil as a carrier; agitation required
- Solution (SL): Active ingredient is dissolved in a liquid carrier as a true solution. Requires further dilution; no agitation required
- Flowable (F): Active ingredient impregnated on a very fine powder that is suspended into a liquid. Result is a very thick liquid requires further dilution. agitation required
- Wettable powder (WP): Dry, finely ground dust; mixed with water; do not dissolve in water; form a suspension most widely used formulations. agitation required
- Soluble powder (SP): Looks like wettable powders but completely dissolve to form a true solution. no agitation required
- Water-dispersible granule (WDG): Dry, finely ground dust formed into a granule particle; mixed with water; do not dissolve in water; form a suspension
- Mixing compatibility
- Mixing multiple herbicides together is legal unless prohibited by the label
- Mixing multiple types of formulations may cause incompatibilities
- Clumping, precipitates
- Cause active ingredients to become inactive
- May increase activity of active ingredients and cause plant injury
- Conduct a jar test to test out compatibility prior to mixing in a tank
- Jar Test- Better to have gel, precipitate, sludge, or concrete in a jar rather than in your sprayer
- Always wear PPE when pouring or mixing pesticides.
- Perform this test in a safe area away from food and sources of ignition.
- Pesticide used in this test should be put into the spray tank when completed and applied to a labeled site.
- Rinse all utensils and jars and pour rinse water into spray tank.
- Mixing Order- A.P.P.L.E.S a specific mixing sequence to ensure compatible formulations mix well
- A. Agitate
- P. Powders soluble
- P. Powder dry (WDG, WP)
- L. Liquid flowable
- E. Emulsifable concentrate
- S. Solutions
- Each ingredient must be uniformly mixed (agitated) before adding the next component
Herbicide Tank Mixing with Household Products
Lab Materials
- Text resources: National Pesticide Applicator Certification Core Manual (pdf version available online) Chapter 4
- Household materials:
- Emulsifiable concentrate: Pine -sol floor cleaner
- Solution: bottled liquid dark tea
- Flowables/Liquids: Pepto-Bismol
- Wettable powder: hot chocolate powder mix
- Soluble powder: powder sugar
- Water-dispersable granule (WDG) or dry flowable (DF): powder milk
- Pint jars with lids for each student group
- Magnetic stir plate for agitation or use jar lid to secure and shake
- Milk (liquid coffee creamer packets)
- Lemon juice
- Baking powder
- vinegar
- Lab Prep:
- Label each household material item with its formulation name and suffix
- Print one Herbicide mixing order observation worksheet per student group
- Gather jars, mixing spoons or magnetic stir plate
Herbicide Compatibility and Mixing Order Observation Worksheet
*The compatibility jar test conducted in this lab activity has been scaled down to serve as a demonstration. The steps required to conduct a jar test using real pesticides will be included on the label or can be found on the web
Compatibly Jar Test #1-
Fill 2 jars half full of bottled liquid black tea
Add 3 teaspoons of milk to both jars.
Add 1 teaspoon of lemon juice to one jar.
Shake both jars and observe after a few minutes.
Observation notes:
Would you spray either of the mixtures? Why or Why not?
Compatibly Jar test #2 –
Fill 2 jars half full of water.
Add 1 tablespoon of baking powder to each jar
Add a ¼ to ½ cup of vinegar to one jar
Shake both jars and observe after a few minutes.
Observation notes:
Would you spray either of the mixtures? Why or Why not?
A.P.P.L.E.S. mixing order: Practice following APPLES by making your own herbicide tank mix using the household formulation samples provided