The Dos and Don’ts of Safe and Effective Herbicide Application: Part 3

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​Disclaimer: This series is informational only and does not act as a substitute for the Indianan herbicide Applicators Certification. For more information on obtaining an Indianan herbicide Applicator License please see the Office of the Indiana State Chemist. This is the third article in the series, to read Part 2 click here.
Herbicides are vital tools for maintaining healthy gardens and farms, but their potency demands careful handling to ensure safety and effectiveness. This article explores the safety considerations when handling, transporting, storing, and mixing herbicides as well as how to properly clean your equipment after use. All herbicides and additives mentioned below can be purchased at your local farm supply store or online. 

​Mixing Herbicides Safely

• Read the Label: Always read the herbicide label thoroughly before mixing. The label contains critical information about the correct dosage, safety precautions, and compatible equipment. REMEMBER: The herbicide label is the law. For specific information regarding chemical hazards, first aid, handling, etc. consult the Chemical Safety Data Sheet (SDS).
• Wear Protective Gear: Different herbicides may require different protection from exposure to chemicals. Consult the herbicide label to determine what protective equipment is needed for your application. General protective gear required includes close toed shoes/boots, long pants, long sleeve shirt, chemical resistant gloves, and safety glasses. Other less common equipment may include protective face masks with respirators or protective face shields.
• Use a Dedicated Area: Mix herbicides in a well-ventilated, designated area away from pets, children, and susceptible plant life. A clean, stable surface is essential to avoid spills. In the event of a spill, clean-up equipment should be nearby and accessible. More information on this can be found below.​

The herbicide label provides important information about the safety considerations and uses of an herbicide. The label is the law!

• Measure Accurately: Use precise measuring tools to ensure you’re mixing the correct amounts. Over-concentration can damage plants and increase toxicity, while under-concentration may reduce effectiveness. A designated, appropriately sized mixing cup is essential for accurate measurements. Depending on the quantity of herbicides being mixed, you may find that a small measuring cup with milliliter markings works best or that a larger cup with ounces, cups, or gallons marked out makes the most sense.
• Add Water First: When mixing, add roughly half of the total water to your sprayer or mixing container before adding the herbicide. This helps to prevent foaming and ensures a more even mixture.
  • Water used to mix herbicide should be ideally clean well water. If using city water it may be necessary to add chemicals to mitigate far “hard water” or water with higher or lower pH. Continue reading to learn more about additives.
• Mix Thoroughly: Agitate the mixture well to ensure even distribution of the herbicide. An uneven mixture can lead to inconsistent application and ineffective weed control.

Herbicide Mixing Order
Safe and effective herbicide application depends on applying a chemical that works as it is intended in the proper concentration throughout the entire mixture. When mixing or diluting herbicides from concentrates, follow these steps to achieve best results. Directions listed are for filling the tank to capacity, adjust amounts if not filling to capacity.

1. Ensure your spraying and application equipment is clean and maintained (more information below under Cleaning Equipment Safely)
2. Fill your clean tank between ½ and ¾ full with clean water. If adding a compatibility agent, anti-foaming agent, ammonium sulfates, or other water conditioning agents add at this time. Do not add surfactants at this point.
   1. The most common additive, ammonium sulfate, can help condition hard water for glyphosate (Round Up, etc.) mixtures, increasing the effectiveness of the herbicide. To learn more about ammonium sulfate, read this article from Purdue Extension.
3. Agitate contents to ensure an even mixture.
4. Add herbicide required for the desired concentration.
   1. Necessary concentrations are usually listed on the herbicide label for the most common plants that can be treated using the herbicide. Percentages of herbicide are measured using the concentrated form directly from the bottle. I.e. a  1 gallon mixture mixed to 5% concentration would use 6.4 oz. of herbicide concentrate and 121.6 oz. of water/dye/other additives.
5. Add final additives such as surfactant, marking dye, drift control agents, etc.
   1. Surfactants help reduce surface tension of a liquid, allowing it to more easily spread over the surface of leaves.
   2. Marking Dyes are concentrated dyes used to change the color of your herbicide. Use these to help visualize where herbicides have been sprayed. This is particularly useful in areas with high foot traffic or larger areas that may be difficult to see your progress.
   3. Drift Control Agents are adjuvants that help reduce the proportion of small droplets which are prone to being carried off-target by the wind or air currents.
6. Agitate contents to ensure an even mixture.
7. Add the rest of your water and seal tank.
8. Final agitation to ensure an even mixture. Larger tanks will require more thorough agitation.
9. Periodically check mixture to ensure there is no separation of chemicals or undissolved solids. 

Storing Herbicides Properly
Using the proper storage methods, herbicides in their concentrated form can retain their potency and effectiveness for 2-5 years. Use the methods below to get the best life out of your herbicides. 

• Original Containers: Always store herbicides in their original containers with labels intact. This prevents confusion and ensures that you have access to all necessary safety information.
• Secure Location: Store herbicides in a locked, dry, and cool place, away from food, feed, and water sources. Ensure that the storage area is out of reach of children and animals and not exposed to direct sunlight.
• Check for Leaks: Regularly inspect containers for leaks or damage. If you find any compromised containers, transfer the contents to a new container, ensuring you also transfer the label.
• Follow Local Regulations: Adhere to local regulations for storing chemicals. Some areas may have specific guidelines for herbicide storage to prevent environmental contamination.
• Secondary Storage: Storing herbicides inside a secondary container is an easy way to contain any accidental spills if a container leaks. Cheap plastic totes work amazingly for storage in your garage or for transport to the worksite.
• Store More Hazardous Chemicals on Lower Shelves: Storing higher risk or hazardous chemicals on lower, easier to reach shelves reduces the risk from dropping containers and the likelihood of a spill.

Cleaning Equipment Safely

• Triple Rinse Method: Clean your equipment using the triple rinse method. Rinse the sprayer three times, each time filling it with water, shaking it well, and spraying out the rinse water.
• Use Cleaning Agents: For more thorough cleaning, use recommended cleaning agents or detergents. Follow the manufacturer’s instructions for the best results.
• Dispose of Rinse Water Properly: Never dispose of rinse water near water sources or drainage systems. Apply it to an area where the herbicide was used or follow local disposal guidelines. Water used to clean herbicide can also be stored along with your other chemicals for future mixing and application.
• Regular Maintenance: Regularly inspect and maintain your equipment. Clean nozzles, filters, and hoses to ensure they are free from residue and clogs.
• Personal Hygiene: After cleaning, thoroughly wash your hands, face, and any other exposed skin with soap and water. Wash your protective clothing separately from other laundry.​

• Maintenance – Equipment maintenance is incredibly important for both your personal safety and environmental safety. Follow the below tips to help maintain your equipment.
  1. Read the Owner’s Manual – Some manuals will contain maintenance suggestions, schedules, etc. They will also contain the specifics for what parts work for your sprayer. Start by reading the manual to understand your specific piece of equipment.
  2. Inspect your Equipment – Before, during, and after your application it is important to ensure your spray equipment is functioning properly. It is good practice to routinely check O-rings, rubber seals, valves, etc. to ensure high quality equipment.
  3. Thoroughly Clean your Equipment – Many herbicides are considered corrosive and can quickly degrade rubber seals. To minimize this, do not allow herbicide to sit in the spray tank for extended periods of time and triple rinse your equipment. Note: After mixing herbicides with water, the effective period is drastically reduced. Lower concentration herbicides lose their effectiveness faster than higher concentration herbicides. For further guidance, consult with the Office of the Indiana State Chemist.
  4. Replace Parts – Replace and repair parts using only manufacturer approved parts. Depending on the brand of your sprayer, there may be many options of cheap knock-off equipment or spare parts. For best results only use parts recommended by the manufacturer.

• Spills: Despite all of our best efforts to store and mix herbicides safely sometimes accidents happen. Having cleaning tools nearby helps us to stay prepared for when accidents occur. Spills over certain thresholds may be required to be reported to the Environmental Protection Agency. Read your herbicide label to understand what this threshold is or, when in doubt call the National Response Center (1-800-424-8802). To learn more about herbicide reporting requirements visit the EPA website here.
  1. Wear protective equipment: Before attempting to clean an herbicide spill, put on the necessary protective equipment as listed on the label first such as boots, nitrile gloves, and face masks as necessary.
  2. Soak up herbicide: Soak up any excess standing herbicides. Scott shop towels, universal absorbent mat pads and kitty litter are all great tools to soak up and remove herbicide.
  3. Remove contaminated dirt: If the spill occurred over dirt remove and double bag any dirt contaminated with herbicide. 

Please send any questions you may have to either Hamilton County Soil and Water or directly to the Office of the Indiana State Chemist.
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