Unfortunately, over time pesticide resistance also increased in weed populations so seed traits continue to change to add more active ingredients tolerances. To maintain herbicide effectiveness for the current seed traits, many spray tank mixes now contain multiple active ingredients such as glufosinate and 2,4-D. Adjuvants are a valuable tool to optimize these increasingly complicated tank mixes and help them succeed across a wide range of application conditions.
Glufosinate and 2,4-D work with a broad range of seed traits in most commodity crops, so they are often used together in tank mixes or combined with other active ingredients. These complex tank mixes can benefit from the addition of surfactants, water conditioners, and multifunctional adjuvants to enhance weed control and keep applications on target.
Glufosinate is a herbicide that has both contact and systemic mode of actions. It works with a broad range of seed traits over many commodity crops. Like many herbicide active ingredients, environmental conditions and tank mix interactions can create challenges for glufosinate.
Application environment, time of day applied, antagonism, and foaming are a few common hurdles that glufosinate applicators face. Glufosinate uptake is optimized under sunny, warm conditions, but also does better in humid environments and struggles in arid conditions. Also, the differences among in-can surfactants in the various glufosinate formulations on the market can make it challenging to optimize each tank mix for maximum effectiveness.
Glufosinate requires a high carrier volume (15-20 gallons per acre) to achieve the best spray coverage possible and good wetting. Glufosinate labels typically recommend the use of ammonium sulfate (AMS). As dry AMS is bulky and therefore not always practical, the functionality of dry AMS can be replaced or enhanced with liquid alternatives or adjuvants that help tank mixes provide similar effectiveness with lower rates of AMS. The dry AMS or the alternatives, together with humectants, can help mitigate the reduced effectiveness in arid conditions.
An optimized, high-quality surfactant is needed to balance good leaf coverage with herbicide uptake. If droplet spreading is excessive, the droplets have a greater surface area and evaporate more quickly, potentially reducing herbicide uptake. If droplets are not spread enough, there won’t be sufficient coverage to provide good weed control. An optimized surfactant will balance these two goals and provide good coverage without reducing herbicide uptake. To assure that the spray droplets remain wet long enough on the leaf surface, adding a humectant can also prolong droplet drying time, giving the herbicide more time to get into the target weed.
Glufosinate can react with calcium ions and lose its functionality. Therefore, water conditioners are essential to prevent the interaction of glufosinate with hard water ions.
Glufosinate foams easily, so use a defoamer to optimize the mixing and application process.
Tank mixing glufosinate with other actives like clethodim or 2, 4-D is very common to provide better control over a range of weed species. If an oil-based active ingredient is added as a tank mix partner, a COC or MSO can enhance the effectiveness of the pesticide.
The systemic herbicide 2,4-D is available in multiple formulation types, including amine, ester, and choline versions. The amine and ester versions have been used for broadleaf control historically, but new 2,4-D choline formulations have gained popularity with the Enlist seed trait platform and have lower drift and volatility potential than older formulations.
In tank mixes with 2,4-D, ACC-ase inhibitor herbicides are typically used for volunteer corn and grass control. Grass control herbicides can antagonize phenoxy herbicides like 2,4-D. 2,4-D also has been reported to have diminished control of Kochia in regions like the western corn belt, and inconsistent control of other broadleaf weeds in other regions of the USA.
As pesticide resistance continues to increase, more active ingredients are being combined into complex tank mixes. In turn, new seed traits are being developed to prepare crops to handle the broader mix of active ingredients. Looking ahead, XtendFlex will be the next soybean seed trait to take center stage showcasing its glufosinate, dicamba, and glyphosate tolerance capabilities. As seed traits and herbicide tank mixes continue to evolve into the future, adjuvants will be an important tool to optimize applications and reduce the onset of herbicide resistance.
Surfactants are widely used across the world – in fact, you probably use surfactants every day in soaps, detergents, toothpaste, cosmetics, and countless other applications. Surfactants are just as important in agriculture and turf and understanding how and when to use the right surfactant can make or break a successful application.
Pre-emergence herbicide applications offer a valuable tool to prevent or reduce weed infestations early in the season. While these applications are helpful, it can be a challenge to achieve optimum results. Adjuvant use is increasing and studies continue to prove their effectiveness.
Leaders from Exacto and other companies recently took part in advocacy activities in Washington, DC, engaging in twenty-four meetings with congressional leadership, senators, and the Environmental Protection Agency (EPA). They addressed a major challenge related to the Endangered Species Act (ESA).
Failed weed control may resemble herbicide resistance, but it’s not always the culprit. Recent cases of HPPD-inhibitor (group 27) herbicide failures have shown that certain application errors are more common culprits than resistance. This research shows ways to overcome these application challenges.
Cutting-edge discussions on golf course maintenance, including adjuvants and wetting agents, took place at the 2024 GCSAA Conference. The Exacto team was in full swing, bringing spray adjuvants, wetting agents, and innovative formulations to the table.
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