Glyphosate is one of the most widely used herbicides in agriculture, and many formulations are available since the patent for Roundup® herbicide expired in 2000. The addition of generic products to the marketplace gives you more options but may make product selection more confusing.
It’s important to consider product formulations, including active and inactive ingredients, when making comparisons.
Every product that contains glyphosate uses the acid form of the active ingredient to provide herbicidal activity. However, acids can be unstable in chemical formulations, so glyphosate acid is formulated as a salt to improve product stability and enhance plant absorption.
Several salts are commonly used in glyphosate formulations, including potassium, isopropylamine, ammonium, and trimesium.
To accurately determine the herbicidal power of a product, it’s important to refer to its acid equivalent (a.e.) amount, not its active ingredient (a.i.) amount. The a.e. refers to the concentration of the glyphosate acid, expressed as pounds acid equivalent per gallon (lbs a.e./gal).
For example, imagine Product A has 5.5 lbs. of glyphosate potassium salt per gallon, with an a.e. of 4.5 lbs. per gallon. Product B has 4 lbs. of glyphosate isopropylamine salt per gallon, with an a.e. of 3 lbs. per gallon.
When comparing these products based on their a.e. ratios, Product A is 50% more concentrated than Product B (4.5 lbs. a.e. vs. 3 lbs. a.e.). To achieve a comparable application rate, growers should apply 50% less of Product A to get the same amount of glyphosate acid (and herbicidal activity) per acre as Product B.
Willowood Glyphosate 5 is an isopropylamine salt formulation similar to the original Roundup. It has 5.4 pounds lbs. active ingredient per gallon of glyphosate isopropylamine salt, which has an a.e. of 4 lbs. per gallon. Isopropylamine salt glyphosate formulations are proven, dependable formulations with good mixing and handling characteristics.
Willowood Glyphosate 6 is a potassium salt formulation herbicide. It has 5.5 pounds lbs. of active ingredient per gallon, with an a.e. of 4.5 lbs. per gallon. Potassium salt glyphosate formulations may provide better rainfastness and improved performance when applied during adverse conditions compared to isopropylamine salts.
The answer really depends on your situation. Both products provide strong broad-spectrum weed control and are labeled for use on the same crops. The main difference between the two products is their salt formulation, which impacts application rates.
Glyphosate 5, with an a.e. of 4 lbs. per gallon, has higher labeled application rates. You can expect to achieve similar herbicide performance with a lower rate of Glyphosate 6.
In most cases, a glyphosate herbicide’s salt formulation alone doesn’t significantly affect its performance. Research has shown some weed-species-specific responses to different glyphosate salts, but overall there isn’t sufficient research to support a superior formulation.
What can affect performance is the addition of inert ingredients, including surfactants, that may enhance spray characteristics and product uptake. Be sure to compare the a.e. of specific products, but also each product’s inert ingredients to make apples-to-apples comparisons.
For a complete weed control solution, you can buy also common glyphosate tank mix partners, including residual herbicides, AMS water conditioners, and surfactants, through FBN for even more cost savings. With a convenient online platform, transparent pricing and direct-to-farm delivery available on your schedule, FBN puts Farmers First®.
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