Oxiteno: SURFOM®8963 — An Innovative Solution for High Load Glufosinate Formulation
May. 4, 2021
There is an expectation of significant growth in the world population in the years to come and, to be able to produce food for a massive population, new technologies and improved weed management schemes are pivotal to ensure maximized yields. Oxiteno solution not only enables new technologies in the field but also contributes to sustainable practices.
The most used herbicide for weed management has been the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) inhibitor, glyphosate. However, after the increase in the number of existing glyphosate-resistant weeds, glufosinate has become a key tool in the weed control. Besides being effective in the management of glyphosate-resistant weeds, glufosinate can also control acetolactate synthase (ALS) and triazine-resistant weeds. Glufosinate is, then, a broad-spectrum contact herbicide with some systemic action used to control grass and broad-leaf weeds.
Currently, glufosinate formulations are sold under various brand names by several companies. The herbicide usage has been growing fast in the past years and today its usage represents more than 32M ha. It’s estimated to reach $992 m. in market value in 2023 and its growth is due to a number of reasons, such as the above-mentioned resistant weeds, but also due to the existing seed technologies developed to be resistant to glufosinate, the emerging resistance to other herbicides such as auxins (dicamba and 2,4-D, for example) and protoporphyrinogen oxidase (PPO) inhibitors. These reasons, along with ban on paraquat also support the estimated continuous increase in use of glufosinate in the next years.
Usually, formulations comprising glufosinate-ammonium are marketed at up to 280 g/L of active ingredient as soluble liquids (SL) and contain anionic alkyl ether surfactants. Increasing the active ingredient load is a strategy to improve efficiency of packaging and transport while minimizing exposure to the pesticide, as the end user must handle lower amounts of formulation to achieve a specified coverage area.
To help in the improvement of herbicides market, Oxiteno has developed a novel solution, SURFOM®8963 for high load glufosinate formulations at 420 g/L. This innovative solution is based on a synergistic combination of an amphoteric surfactant that acts as an uptake enhancer and a hydrotrope that compatibilizes the high electrolyte content ensuring the formulation’s stability.
In the past decade Oxiteno has presented a surfactant composition for high load glyphosate formulations and, following from that surfactant we developed the solution for glufosinate.
One challenge for increased loads, considering current marketed formulations, is the high amount of surfactant, limiting the space to increase glufosinate amount. SURFOM®8963 could not only increase the active ingredient concentration but also lower surfactant load in the formulation.
Table 1 presents the loads for a 420g/L glufosinate formulation using the innovative SURFOM®8963 in which is visible that the amount of surfactant is rather low.
Table 1. Suggestive glufosinate formulation using SURFOM®8963
SURFOM®8963 is a very low viscosity liquid that presents good stability following CIPAC’s guidelines and even further considering longer periods at elevated temperature, as presented in Table 2. The solution is still liquid at negative temperatures and presents excellent antifoaming properties.
Table 2. Physicochemical and stability data for SURFOM®8963
Glufosinate formulation using SURFOM®8963 can be mixed with other herbicides and micronutrients even in hard water without precipitation.
This formulation was used for numerous bioefficacy tests in both greenhouse and field trials. Among weed species that jeopardize the main crops in high producing countries like Brazil and the USA, we selected Digitaria insularis, Conyza canadensis, Amaranthus tuberculatus, Acalypha ostryifolia and Ambrosia artemisiifolia.
The greenhouse tests were performed using Oxiteno’s capabilities, which includes a growth chamber and a single nozzle track sprayer, shown in Figure 1.
Figure 1. Generation III research sprayer used for bioefficacy tests at Oxiteno
These greenhouse tests were performed with five replicates against two weed species spraying the high load formulation prepared with SURFOM®8963 (420 g/L) and a Brazilian, standard load, benchmark formulation (200 g/L), both at half label AI equivalent dose in order to compare the results, presented in Figure 2.
Figure 2. Results obtained from greenhouse trials for a benchmark formulation and Oxiteno's solution for high load glufosinate formulation (SURFOM®8963) at half recommended dose.
From greenhouse study it is evident that SURFOM®8963 delivers same control as the currently marketed formulations (standard load) since the results were not significantly different by the Tukey test at 95% confidence.
Field trial was performed at Mississippi State University using a backpack sprayer and each tested plot measuring 3 by 12 m, presenting uniform population of weeds. We tested Oxiteno’s formulation using SURFOM®8963 (420 g/L) and a benchmark commonly found in the US market (280 g/L), all at full recommended dose (AI equivalent). The plots were rated at five different times and the reading at 21 days after application is shown in Figure 3.
Figure 3. Results obtained from field trials for a benchmark formulation and Oxiteno's solution for high load glufosinate formulation (SURFOM®8963) at full recommended dose.
Field trial results were analyzed using a Fischer’s projected LSD at α=0.05 and confirmed that Oxiteno’s high load glufosinate formulation delivers same level of control as the benchmarks when used at equivalent AI concentration.
The amphoteric surfactant present in SURFOM®8963 is patented by Oxiteno (US10779530B2) and the synergistic combination with a hydrotrope, that makes SURFOM®8963 capable of compatibilizing the high electrolyte load is published in a continuation in part patent (US20200404923A1).
In conclusion, SURFOM®8963 is a very low viscosity and low foaming product, delivers effective control of glyphosate, ALS and triazine-resistant weeds and is compatible with other herbicides and micronutrients in the tank mix. The considerable increase in glufosinate load allows the end user to handle lower volumes of formulation to control the weeds, reduces the amount of plastic spent in packages and also optimizes the transportation because less volume of formulation is required to be transported meaning less fuel is spent and lower carbon is emitted, supporting sustainability, a very important pillar for Oxiteno.
This article will be published in AgroPages '2021 Formulation & Adjuvant Technology' magazine to be published this May.
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