Premix Active Ingredients Offer Greater Efficacy Together

Premix formulations help fight resistance and benefit sustainable crop production.
Premix Active Ingredients Offer Greater Efficacy Together
In 2018, soybean and cotton farmers were contending with glyphosate-, ALS- and PPO-resistant weeds, especially Palmer amaranth and waterhemp. Residual herbicides and multiple post-emergence applications followed by additional expenditures of time and money on mechanical removal of weeds were often necessary. Commodity prices were low; margins were tight; and growers had little room for error on input decisions.

Although commodity prices have taken a turn and are at historic highs in 2021, weed resistance continues to persist and grow throughout the US.

One notable difference is the availability of premix formulations. “The need to apply multiple herbicide sites of action simultaneously to manage our most troublesome weedy pests is extremely important — premixes can help ensure that a grower achieves this goal,” says Stanley Culpepper, Ph.D., extension weed scientist at the University of Georgia. “For example, if dicamba and Dual Magnum (S-metolachlor) are applied as a premix, then that ensures both a post-emergence and residual product with activity against our most troublesome pest, Palmer amaranth, is used, making for a more sustainable program.”

We like having the curative in combination with the preventive. You’re knocking out some of the disease that started but also extending the length of control.

James Hadden
Fungicide Technical Product Lead
Syngenta US
Pete Eure, herbicide technical product lead with Syngenta, lists some of the fundamental benefits premixes bring to farmers. The packaging is more convenient, as farmers don’t have to store multiple jugs. Premixes also reduce the margin for error because applicators aren’t measuring and tank-mixing various products in the field or at the shop. The active ingredient (AI) components are formulated so farmers don’t have to worry about compatibility issues. In addition to all these advantages, premixes can target the same weed at multiple sites of action, so if the weed exhibits resistance at one site, the product may still be effective at another site.

Older AIs Are Sometimes “New”

New AIs don’t come around very often. Common wisdom is that the golden age of herbicide AI discovery has passed. More often manufacturers reformulate tried-and-true chemistries into new products, as with Tavium® Plus VaporGrip® Technology herbicide. New premixes offer the ability to optimize the product formulation. An optimized formulation can improve weed control and crop safety, and reduce drift and off-target movement. In many cases inert ingredients and surfactants play such a critical role in a product’s performance. Dicamba received its first registration in 1967, and metolachlor came along nine years later in 1976.

At its best, reformulation takes two or more chemistries that target weeds, diseases or pests along different pathways and creates a new product that is strong enough to meet today’s resistance challenges.

Culpepper explains that it’s more important for a chemistry to be new to the targeted weeds than new to the market. “Even with older sites of action,” Culpepper says, “that doesn’t mean that in my fields I’ve used all of the available chemistries. In essence, it’s a new site of action if I’ve never used it on a respective field, which makes that product potentially very valuable.”

As Culpepper points out, it’s not the registration date of an AI that matters. An older AI that is effective can be just as important as any other tool in the toolbox. Diversity in management options gets more important every day when it comes to weed control.

Premixes Fight Fungicide Resistance

James Hadden, Syngenta fungicide technical product lead, says a good premix fungicide should provide an enhanced spectrum of activity to control diseases that a single chemistry may miss. “You want to use two different sites of action, typically, and hit the fungus from two different flanks,” he says, “so you get better potency against the diseases.”

Pest resistance is a matter of natural selection, and premixes use that to their advantage.

“The resistant mutants are already out there in nature,” says Tyler Harp, technical product lead with Syngenta. “The fungicide is just selecting for them.”

When a fungicide is applied and kills all the spores of a targeted pathogen except for that one existing mutant, that mutant no longer has any competition. Now it is going to flourish and reproduce to create a new generation that has the resistance mutation.

“But if you have a premixture with three sites of action, it spreads the selection pressure across all three fungicides, and finding a mutant out there that will be resistant to three different sites of action is extremely rare,” Harp explains.

The best fungicide premixes will give growers both a curative and a preventive function, managing pathogens before and after they germinate.

“A lot of the formulations Syngenta is putting out now have longer durations of control, and they’re preventive in nature,” Hadden says. “We like having the curative in combination with the preventive. You’re knocking out some of the disease that started but also extending the length of control.”

According to Harp, it’s always important to have good resistance management, but especially so in crops like corn and soybeans where only one or two fungicide applications may be made in a season.

“A premix in those markets is like having it all and maximizing stewardship in one application,” Harp says.

Fighting Herbicide Resistance With Premixes

As with fungicide premixes, the challenge for developing new weed management premix products is producing formulations that target multiple effective sites of action and spread out selection pressure. Premixes don’t just deliver weed control results in the short term.

“When we develop a new premix at Syngenta,” says Eure, “we come with multiple effective sites of action and AIs. What this allows us to do is deliver broader-spectrum, more consistent control of problem weeds like Palmer amaranth and waterhemp.”

Tavium Plus VaporGrip Technology herbicide is an example of putting that theory to work in the field. The first premix of dicamba and S-metolachlor, Tavium delivers two sites of action, for both contact and residual control of tough weeds.

This multipronged approach protects farmers’ yield potential not only in the year the herbicide application is made, but also in the following year because it reduces weed seed production. That’s very important because that reduction means a smaller weed seed bank in that field and easier weed management decisions in the coming years.

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Weed control with premix formulations helps fight resistance and benefits sustainable #cropproduction.

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