Filling your spray tank with multiple crop protection products requires the same precision as applying herbicides in the field.
It's necessary to follow a specific loading order to achieve harmony among the products. If you mix the ingredients out of order or don't start with enough water and agitation, you can clump or gel an entire tank that forces costly, time-consuming cleanup of clogged pumps, hoses and nozzles.
“Like a food recipe, you can’t expect a good outcome if you just throw all ingredients together. It’s the same with a tank-mix to overcome physical incompatibility,” says Joe Ikley, North Dakota State University weed scientist. “By not following herbicide label recommendations, you can end up with salts out of solution or a tank of sludge.”
“Like a food recipe, you can’t expect a good outcome if you just throw all ingredients together. It’s the same with a tank-mix to overcome physical incompatibility.”
While several acronyms are used to help remember the essential roadmap of chemical additions to a tank-mix, Ikley likes A.P.P.L.E.S., detailed in the 2021 North Dakota Weed Control Guide.
First, always check herbicide labels for a specific mixing sequence. If you can't find a list, add pesticide and adjuvant formulations to a half or three-quarter-full tank of water using the A.P.P.L.E.S. method:
As you follow this list, add the pesticide then the adjuvant for each category. For example, add a soluble-powder pesticide, then ammonium sulfate (AMS) adjuvant because it's a soluble powder.
Ikley says it’s critical to start with a lot of water in the tank — at minimum half-full, three-quarters full is even better – and make sure agitation is running. “Another good tip is to wait a couple of minutes between adding products, so each one goes into solution. And don’t forget that products take longer to go into solution in cold water, especially dry herbicides.”
“Another good tip is to wait a couple of minutes between adding products, so each one goes into solution. And don’t forget that products take longer to go into solution in cold water, especially dry herbicides.”
Formulated products should not touch each other. If you’re adding products through an induction cone, don’t just pour in product after product. “Be sure to flush the cone with a couple gallons of water before moving on to the next product,” Ikley says.
In addition, be sure to pay attention to product shelf life. “Given challenges with the supply chain this year, be cautious of products that are three to five years old,” he adds. “I’d recommend a jar test of your tank-mix to check compatibility before filling a whole sprayer.”
Ikley also reminds growers of the differences among generic formulations and compatibility issues. “For example, a generic glyphosate could be a potassium salt, a DMA-salt or an IPA-salt formulation, and some don’t mix as well as others. Generic herbicide formulations usually are not as good as the branded product from the company, which spent years developing the formulation.”
Parking a sprayer with a tank-mix of products to wait out a storm can cause separation issues. “It’s best to run the agitation pump at least twice a day. Some newer sprayers have a low-voltage pump that agitates the mix automatically,” he adds.
“Occasionally, we see some product degradation over time as they sit in water for days. We see that most often with Group 1 herbicides (ACCase Inhibitors) used for controlling grass or volunteer corn in soybeans.”
There are three good resources that Ikley recommends for tank-mix information. “Consult the herbicide labels first. Second, most of your annual state university weed control guides should have a section on herbicide mixing. And I like to recommend Precision Labs’ Mix Tank app (also on their website) that allows you to pop in all your products, and it should give you a mixing order,” he says.
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