Whether lawn care operators (LCOs) need a refresher or are using a new formulation, learning to properly tank mix products for sprayers and spreader-sprayers will help ensure success with the property and equipment.
How to mix
Before adding a product to the tank, it’s important operators understand the proper mixing order, according to the PBI-Gordon team — including Eric Reasor, Ph.D., Southeast research scientist; Brian Aynardi, Ph.D., Northeast research scientist; Chrissie Segars, Ph.D., West research scientist; and Jeff Marvin, Ph.D., director of field research.
The order LCOs should follow is:
- Water-soluble packets
- Dry formulations
- Ammonium sulfate
- Compatibility agents and anti-foamers
- Dispersed liquid formulations
- Liquid drift retardants
- Other liquid formulations
- Adjuvants and micronutrients
- Liquid fertilizers
If LCOs mix products in the wrong order or combine them with incompatible products, the product may not dissolve or may cause excessive foaming, says Ben Pease, Ph.D., turfgrass agronomist for The Andersons Plant Nutrient Group. Users should add products one at a time in the tank and think about the application of each.
“If there’s a product that needs to stay on the leaf, for example, you don’t want to mix it with a product that needs to get to the soil,” Pease says. “You’re going to lose the efficacy of one.”
What to avoid
One of the most common mistakes with tank mixing is adding materials before adding enough water, which can cause separation, Pease says.
“If you’re mixing right into the sprayer, you want to make sure the tank is at least 50 percent full of water and then add the products,” he says.
LCOs should also check if products are compatible, as some products are not intended to be mixed together. For example, tank-mixing bensumec and carfentrazone can lead to turfgrass injury. Tank-mixing phenoxy herbicides and ACCase inhibitors can antagonize and decrease herbicide control. Mixing liquid iron products with low pH and 2,4-D amine with large pH differences can lead to sludging.
To test products for compatibility, operators can use the jar test to simulate what will happen when mixing multiple products together. To perform a jar test, LCOs need a quart jar with a sealable lid. Add a pint of water to the jar if used as a carrier. Add each product and shake between additions. LCOs should check for settling and solubility issues after about 30 minutes (or 60 minutes at most), Pease says.
Not all incompatibilities can be resolved by adding more water or a compatibility agent. The PBI-Gordon team explains there are cases where adding more water, detergent soap, nonionic surfactant, compatibility agent or pH adjuster might help.
Keeping records of specific tank mixtures helps operators stay organized and track problem tank mixes. Take note of carrier source, water source/quality, water temperature, water volume, any fertilizer source, product names, formulations types, application rates and mixing order, the PBI-Gordon team says.
Proper cleanout
Another important component of tank mixing is how to clean out the equipment between uses or before storing. Performing a double-rinse when going from one application to the next helps ensure the operator isn’t combining an old chemical with the new one, says George Kinkead, president of Turfco.
“Drain the tank, rinse it out and check the manual to make sure you’re using the appropriate drain with each tank to ensure it’s being flushed,” he says. “Check the filter at the same time to see what condition it’s in and if there are foreign objects in the tank.”
Once the system is completely flushed, LCOs can spray water through it to ensure the spray pattern and nozzle are working up to spec.
“Make sure your employees know you value cleaning and maintaining the machine,” Kinkead says.
