Tank-mix Adjuvants Research Articles

Effect of Tank-Mix Adjuvants on the Efficiency of Chlorpyrifos and Cyhalothrin Formulations against Cotton Bollworms

Reduction infestation percentages of spiny bollworm (SBW), Earias insulana (Boisd.),and pink bollworm (PBW), Pectinophora gossypiella (Saund.),on cotton treated with some chlorpyrifos and cyhalothrin formulations alone or/and mixed with Top Film or Tritone K adjuvants were investigated under field conditions. Adjuvants/insecticides mixtures enhanced the reduction percentages of E. insulana infestation, compared with individually applied insecticides. Mixtures of Top Film with chlorpyrifos or cyhalothrin formulations gave the highest reduction percentages of infestation, where general reduction average ranged between 81% and 89.7%, and between 86.5% and 93.2%, respectively. Moreover, Tritone K mixed with cyhalothrin formulations displayed adequate infestation reduction, as general reduction averages ranged between 80.6% and 88.1%. In general, tank mixing of both adjuvants with cyhalothrin formulations enhanced the efficiency of formulation greater than mixing adjuvants with chlorpyrifos formulations against E. insulana. On the other hand, the infestation percent of P. gossypiella was lower than that of E. insulana in untreated cotton plants. The formulations alone or their mixtures with adjuvants gave good reduction of infestation, where the general reduction averages ranged between 88% and 93.5%, and between 70.6% and 87.1% for formulations/adjuvants mixtures and formulations alone, respectively.

Round-Robin Evaluation of ASTM Standard Test Method E2798 for Spray Drift Reduction Adjuvants

Abstract Drift Reduction Agent has been defined in ASTM Standard E1519 Terminology Relating to Agricultural Tank Mix Adjuvants as “a material used in liquid spray mixtures to reduce spray drift.” ASTM Standard E609 Terminology Relating to Pesticides defines drift as “the physical movement of an agrochemical through the air at the time of application or soon thereafter to any non- or off-target site. Drift shall not include movement to non- or off-target sites caused by erosion, migration, volatility or wind blown soil particles that occur after application unless specifically advertised on the label.” Because there are many commercial tank mix adjuvants designed to reduce spray drift, there is a need to establish an ASTM Standard Test Method to evaluate their effectiveness. ASTM Standard E2798 is the new test method developed for the Characterization of Performance of Pesticide Spray Drift Reduction Adjuvants for Ground Application. This paper presents the data generated from the round-robin testing of this method. The method provides guidelines for the measurement of parameters pertaining to the performance of drift reduction adjuvants under simulated field application conditions. The measurements can be made in a wind tunnel or a spray chamber. The method describes the preparation, composition, and test/application conditions for droplet size, spray pattern measurements, and fines reduction. The exact selection of application conditions such as nozzle type and tank mix partner may vary according to the intended use conditions.

Rain-induced removal of copper from apple leaves: Influence of rain properties and tank-mix adjuvants on deposit characteristics at the micro scale

Application of copper fungicides is an integrative component in the control of apple scab. As shown in the past, tank-mix adjuvants might reduce the rain-induced removal of active ingredients. The aims of this study were a) to characterize the impact of defined rain amount on the removal of Cu-oxychloride (Cu-Ox) and Cu-hydroxide (Cu-Hyd) from apple seedling leaves, b) to examine the influence of ethoxylated seed oil adjuvants on deposit properties at the micro scale and their possible influence in reducing the fungicide erosion from the leaves, and finally c) to evaluate the influence of previous adjuvant application on the rainfastness of copper ions. Losses of Cu-Hyd and Cu-Ox from seedling leaves exposed to 5 mm heavy rain reached almost 80% of the original Cu load. Wash-off extent of Cu-Ox could be reduced by using the rapeseed oil ethoxylate RSO 5 (47%), the linseed oil ethoxylate LSO 10 (47%), or the soybean oil ethoxylate SBO 10 (40%). However, in case of Cu-Hyd, none of the adjuvants was able to increase the tenacity of the copper on the leaves. Rainfall removed the bulky deposits and induced changes in the typical shape of the crystals. Furthermore, a reorganization of the spatial distribution of the remaining active ingredient (a.i.) was induced, which was very often embedded in a thin layer of adjuvants. In general, the adjuvants had a significant impact on droplet spread, whereas the area effectively covered with the a.i. was affected to a lesser extent. For both Cu-Hyd and Cu-Ox rewetting of the original deposit under controlled conditions resulted in an increased spread area but reduced the area effectively covered with Cu. Our results showed no clear relationship between the area covered by Cu ions and their adhesion to the surface, i.e. rainfastness. Finally, our studies indicated that previous spray treatments might influence the rain-induced removal of copper.

Spray Droplet Size, Drift Potential, and Risks to Nontarget Organisms from Aerially Applied Glyphosate for Coca Control in Colombia

A wind tunnel atomization study was conducted to measure the emission droplet size spectra for water and Glyphos (a glyphosate formulation sold in Colombia) + Cosmo-flux sprays for aerial application to control coca and poppy crops in Colombia. The droplet size spectra were measured in a wind tunnel for an Accu-Flo nozzle (with 16 size 0.085 [2.16 mm] orifices), under appropriate simulated aircraft speeds (up to 333 km/h), using a laser diffraction instrument covering a dynamic size range for droplets of 0.5 to 3,500 μm. The spray drift potential of the glyphosate was modeled using the AGDISP spray application and drift model, using input parameters representative of those occurring in Colombia for typical aerial application operations. The droplet size spectra for tank mixes containing glyphosate and Cosmo-Flux were considerably finer than water and became finer with higher aircraft speeds. The tank mix with 44% glyphosate had a D v0.5 of 128 μm, while the value at the 4.9% glyphosate rate was 140 μm. These are classified as very fine to fine sprays. Despite being relatively fine, modeling showed that the droplets would not evaporate as rapidly as most similarly sized agricultural sprays because the nonvolatile proportion of the tank mix (active and inert adjuvant ingredients) was large. Thus, longer range drift is small and most drift that does occur will deposit relatively close to the application area. Drift will only occur downwind and, with winds of velocity less than the modeled maximum of 9 km/h, the drift distance would be substantially reduced. Spray drift potential might be additionally reduced through various practices such as the selection of nozzles, tank mix adjuvants, aircraft speeds, and spray pressures that would produce coarser sprays. Species sensitivity distributions to glyphosate were constructed for plants and amphibians. Based on modeled drift and 5th centile concentrations, appropriate no-spray buffer zones (distance from the end of the spray boom as recorded electronically ±5%) for protection of sensitive plants were 50–120 m for coca spray scenarios and considerably lower for poppy spray scenarios. The equivalent buffer zone for amphibia was 5 m. The low toxicity of glyphosate to humans suggests that these aerial applications are not a concern for human health.

Impact of adjuvants on bentazon efficacy on selected broadleaf weeds

Tank-mix adjuvants can increase the efficacy of herbicides. Therefore, the effects of different rates of bentazon alone or tank-mixed with ammonium sulfate, non-ionic (0.25% Induce) or organosilicone (0.1% Kinetic) adjuvants were investigated on cocklebur ( Xanthium strumarium), black nightshade ( Solanium nigrum), velvetleaf ( Abutilon theophrasti), and stranglervine ( Morrenia odorata) under greenhouse condition. There were variations in susceptibility of the four weed species to bentazon-adjuvants tank-mixture treatments. Black nightshade control never exceeded 55% with all bentazan treatments rates from 0.84 to 2.24 kg ha −1 with or without the adjuvants. While cocklebur was completely controlled with the application of bentazon at 1.12 kg ha −1, or with bentazon at 0.84 kg ha −1 plus one of the three adjuvants, with insignificant differences between adjuvants. The limited factor of controlling velvetleaf and stranglervine is the bentazon rate. Complete foliar death (98–100%) of velvetleaf and stranglervine was with bentazon at 1.68 kg ha −1 alone or with Induce or Kinetic adjuvant. The results suggested that black nightshade was difficult-to-control weed, while cocklebur was susceptibility to bentazon at lowest rate (0.84 kg ha −1) plus adjuvant. Mixing adjuvant with bentazon generally enhanced common cocklebur and black nightshade control, while addition of adjuvant to bentazon at all rates for controlling stranglervine did not cause any significant difference.

Imazapyr Absorption and Translocation in Northern Red Oak and Red Maple as Affected by Herbicide Formulation and the Adjuvant Methylated Seed Oil

Abstract Imazapyr-based herbicides are important in removing deciduous hardwood species from conifer plantations. Imazapyr can be applied as a site preparation (pre-establishment) application or as a postestablishment herbaceous or release application. Herbicide efficacy is dependent, in part, on how much herbicide is absorbed and translocated throughout the target weed species. Herbicide absorption can be strongly influenced by herbicide formulation or tank-mix adjuvants. Little data are available on imazapyr absorption and translocation by woody species. The objective of this research was to compare the absorption and translocation of six experimental formulations of imazapyr to a commercial formulation, Chopper®, with and without methylated seed oil (MSO), in northern red oak (Quercus rubra L.) and red maple (Acer rubrum L.). Saplings of both species were grown in the greenhouse until they reached a height of approximately 1 m. Trees were blocked according to size, and treatments were randomly assigned within blocks. For the absorption study, five leaves were selected per plant and received two 1-μL drops of 14C-imazapyr-labeled solution. Leaves were rinsed at 2, 8, 24, 72, and 144 h after treatment (HAT). Absorption was quantified as 14C imazapyr that was not collected in the rinse solution. All experimental formulations that were tank-mixed with MSO increased absorption on oak compared to Chopper+MSO. Not all experimental formulations increased absorption in maple, and absorption data were highly variable. Absorption continued for at least 72 HAT in both species for most formulations. For the translocation study, one leaf was treated with two 1-μL drops of 14C-imazapyr-labeled solution. The leaf was rinsed at 144 HAT, and the plant was harvested and divided into sections: above treated leaf, treated leaf, below treated leaf, and roots. The majority (52–91 %) of the applied imazapyr remained in the treated leaf. More imazapyr was translocated from the leaf of red oak than red maple. Translocated 14C accumulated in the tissue above the treated leaf (3–13 % of absorbed) and in the roots (3–34 %). Including the adjuvant MSO and optimizing the herbicide formulation increased the absorption of imazapyr in red maple and northern red oak.

Effects of diquat and fomesafen applied alone and in combination with a nonylphenol polyethoxylate adjuvant on Lemna minor in aquatic indoor microcosms

The influence of tank-mix adjuvants on pesticide toxicity remains largely unknown. Agral ® 90, a nonylphenol polyethoxylated tank-mix adjuvant, has been used with diquat (bipyridylium herbicide) and fomesafen (diphenyl-ether herbicide) in aquatic indoor microcosms in order to compare the toxicity of the single compounds and of binary herbicide–adjuvant mixtures to Lemna minor. Twenty-four microcosms were used and treatments were performed with substances alone or with herbicide–adjuvant binary mixtures, at two concentrations levels (44.4 and 222.2 μg/L for the herbicides, and 100 and 500 μg/L for Agral 90). Toxicity was assessed weekly for 1 month through growth measurements, as inferred from the relative frond number (RFN) and relative frond area (RFA). Concentrations of diquat and fomesafen in water and sediments were measured weekly. The herbicides showed very different behaviour in microcosms, with a rapid disappearance of diquat from the aqueous phase whereas fomesafen levels remained almost constant over time. Diquat strongly inhibited the growth of L. minor whereas fomesafen had no effect on plant growth. Presence of the adjuvant only slightly reduced the effect of the lowest concentration of diquat, probably as a result of dispersion of the herbicide at the water surface. It is concluded that tank-mix adjuvant designed to improve herbicide efficiency in the terrestrial environment did not have any effect on aquatic plants when applied to the aquatic environment.

Possibilities To Use Tank-Mix Adjuvants for Better Fungicide Spreading on Triticale Ears

Tank-mix adjuvants can increase the overall performance of plant protection products. Their most important ways of action are the improved retention, spreading, wetting, and penetration of the pesticide on the target and the reduction of fine droplets. In this paper, deposition and spreading of the systemic fungicide propiconazole on triticale ears were quantified. A better deposition and spreading of fungicide on the ear may be a possible help for the Fusarium problem in triticale, wheat, and other cereals. Triticale ears were applied with propiconazole in combination with 11 different tank-mix adjuvants. Vegetable oil, alcohol ethoxylates, lactate ester, trisiloxanes, and an amphoteric molecule were included in this experiment. When no tank-mix adjuvant was used, the lower part of the ear was reached five times less by the propiconazole spray than the upper part of the ear. When the tank-mix adjuvant was combined with the propiconazole formulation, an increase in residue on both the upper and the lower part of the ear was observed. A higher residue on the upper half of the ear means a better deposition, while a higher residue on the lower part of the ear is related to a better downward spreading over the grains and the needles of the ear. The combination of those two observations makes it interesting to use tank-mix adjuvants for the prevention of mycotoxin-producing Fusarium species. The advantages are emphasized even more when cost effectiveness was calculated. The use of a proper tank-mix adjuvant can result in 40% lower cost per application per hectare.

Quantitative determination of the influence of adjuvants on foliar fungicide residues

The correct use of adjuvants can increase the overall performance of plant protection products significantly. Their most important ways of action are the improved retention, spreading, wetting and penetration of the pesticide on the target and the reduction of fine droplets which counters the problem of spray drift. The increase in efficiency of the pesticide application may cause an increased impact on the environment. This is possible in two ways: firstly, because of the presence of the adjuvant molecule in the environment and secondly because of the influence of the adjuvant on the plant permeability and consequently the pesticide residue. In the present work, the latter problem is studied on Triticale and lettuce. Propiconazole was applied on Triticale at its maximum approved rate. On lettuce tolylfluanid was applied. The applications on Triticale and lettuce were combined with four and six different types of adjuvants, respectively. Two of them, Trend90 and Actirob B, are authorized tank-mix adjuvants in Belgium. The other tested adjuvants are in experimental stage: two polymers, one organosilicone, an amphoteric molecule and two mono-branched alcohol ethoxylates. The influence of these different adjuvants on the residue of the applied pesticides was monitored several weeks. For both Triticale and lettuce, the use of the different kinds of adjuvants showed a trend towards higher detected residues on the leafs. Nevertheless, the degradation rates of the applications with adjuvants were comparable to that of the control.

Cationic-based Crop Oil Concentrates

Abstract For most of six decades, crop oil concentrates (COCs) have been used as important tank mix adjuvants for increased pesticidal penetration. For the past 30 years, cationic surfactants have been known to enhance the bio-efficacy of numerous acid-based herbicides, especially glyphosate. With the advent of glyphosate-tolerant crops, glyphosate has become almost universal in its use. This has led to some issues with weeds hard to control with glyphosate alone. Recently a practice has developed where other herbicides and COC formulations are mixed with glyphosate to address problems with glyphosate-tolerant plants. A field study was conducted to develop a COC containing cationic surfactants that would deliver excellent, stable emulsification of the oil phase and boost the herbicidal activity of both glyphosate and the admixed herbicide. This COC worked very efficiently in a broad range of waters as well as ultra-high electrolyte environments such as ammonium sulfate solutions common to glyphosate applications.

Leaf surface characteristics of apple seedlings, bean seedlings and kohlrabi plants and their impact on the retention and rainfastness of mancozeb

A study was made of the influence of the upper leaf surface characteristics on the retention and rainfastness of the contact fungicide mancozeb with and without tank-mix adjuvants (RSO 5 and RSO 60) on apple seedlings, bean seedlings and kohlrabi plants. Large differences in roughness, in the amount and composition of surface waxes and in the retention and rainfastness of mancozeb were found among species. Strong correlations between roughness and total amount of surface waxes and mass of C29 alkane in the wax mass were also found. Fungicide retention was strongly, negatively correlated with surface roughness, total epicuticular wax, amount of C29 alkane and the total mass of alkanes. Rainfastness correlated strongly or very strongly with the amount of C28 alcohol and C33 alkane. The addition of a more hydrophobic (RSO 5) or a more hydrophilic (RSO 60) adjuvant to the spray solution influenced retention and rainfastness, and also altered the correlation coefficients. The present results support earlier observations which show that the success of adjuvants in enhancing the retention and rainfastness of agrochemicals depends on the characteristics of the leaf surface.

Fatty Amine Alkoxylates as Effective Adjuvants for Strobilurin Fungicide Applications on Field and Orchard Crops

Abstract Agrochemical adjuvants are widely used to improve the efficacy of pesticide applications. Improvement can be interpreted as “better weed control,” “better disease control,” or “reducing the amount of active ingredient required” for control. Claims related to the adjuvant function vary from “wetter,” “spreader,” and “sticker” to “penetrant” and “synergist.” While most activator adjuvants are applied as ‘tank mix’ additives, the fatty amine alkoxylates are also suitable as formulation-adjuvants for in-can product developments. During the past decade, Akzo Nobel Surface Chemistry has synthesized complex alkoxylates of selected fatty amines for application with relatively hydrophobic pesticides and directed their evaluation as adjuvants for application enhancement of many pesticides in trials conducted around the world. Among those adjuvant trials were applications with systemic and contact fungicides. The application of fatty amine alkoxylates as efficacy-enhancing tank mix adjuvants for triazole fungicides was previously presented [1]. However, there are very little data published regarding the use of this class of surfactants as activator adjuvants with the newer strobilurin fungicides. This paper presents an introduction to a new application for fatty amine alkoxylates as efficacy enhancers for strobilurin fungicides. Results are presented from field applications in 2004 as conducted with several strobilurin fungicides in multiple crop types.

Improvement of the Residual Activity of a Cucurbitacin-based Adult Corn Rootworm (Coleoptera: Chrysomelidae) Insecticide

Areawide management of the corn rootworm, Diabrotica spp., focuses on managing adult beetles to decrease egg deposition. The primary management tool for this approach is a commercial bait composed of a feeding stimulant (cucurbitacin), inert ingredients, and a small quantity of insecticide. Cucurbitacin-based baits have had poor residual insecticidal activity that decreases efficacy and economic practicality. These studies were designed to extend the residual activity of 2 commercial bait formulations, Slam Prader® and Slam SD® (MicroFlo Co., Lakeland, FL), by adding materials as a tank-mixed adjuvant or as a part of the formulation to prevent wash-off by rain. Initial assays with Slam Prader identified low pH gluten and sodium lignate to have the greatest potential to provide rainfastness with a trend for less residual activity with higher concentrations (>2% of spray volume) of adjuvant. An additional assay demonstrated that low pH gluten was effective for resisting wash-off by natural rain when added to the Slam SD as a formulation ingredient. Large-plot experiments conducted over 2 yrs in growers' fields in northwestern Illinois failed to show a statistically significant advantage of gluten and lignin additives. For both years, all bait treatments provided adequate management of the adult corn rootworm for 3 wks after application. Based on sticky trap counts, insecticide treated plots maintained beetle populations below the economic threshold of 5 corn rootworms/trap/day and significantly below the corn rootworm density in the untreated plots.

Evaluation of tank mix adjuvants and nozzles for agricultural sprays

Evaluation of tank mix adjuvants and nozzles for agricultural sprays

Effects of some agricultural tank-mix adjuvants on the deposition efficiency of aqueous sprays on foliage

The effects of 10 commercially available tank-mix adjuvants on the retention and coverage of aqueous sprays on foliage were examined quantitatively under track sprayer conditions, following application at their maximum recommended rates. Substantial enhancement of fluorescein retention was observed only on water-repellent barley and peas, but the differences in performance between the additives were considerable. Addition of the water-soluble tallow amine and nonylphenol surfactants gave the largest increases in retention, whereas there was little improvement in efficiency compared with water alone after inclusion of either the latex- or pinolene-based products or ammonium sulphate. Retention enhancement was also achieved using the mineral oil, vegetable oil, methylated vegetable oil and phospholipid ECs and the organosilicone surfactant, but this was often much less than that obtained for the water-soluble surfactants; the best EC was the methylated vegetable oil which also had the highest emulsifier content. Although spray quality was altered significantly in the presence of many of the adjuvants, modifications to this parameter alone could not account for changes observed in deposition efficiency, because retention enhancement was recorded in sprays with volume median diameters both smaller and larger than water. There was a better correlation between retention efficiency and the dynamic surface tension of the corresponding spray liquids, with the exception of the organosilicone, which, as expected from its high surface activity, gave essentially complete spray coverage on leaves. Nevertheless, good coverage could still be achieved by adding the two water-soluble surfactants, as well as the methylated vegetable oil and phospholipid ECs. Coverage performance of the other adjuvants tested was poor in comparison, reflecting, in part, their inferior retention enhancing properties.