Isooctyl Ester Research Articles

Permeation of a 2,4-D isooctyl ester formulation through neoprene, nitrile, and Tyvek protection materials.

Tyvek (laminated saranax) and unsupported nitrile gloves gave protection from permeation against formulation concentrates and aqueous emulsions of Esteron 99 [isooctyl ester of (2,4-dichlorophenoxy)acetic acid] under conditions simulating extremes of field conditions. Neoprene gloves, whether unsupported or supported, lined or unlined, were permeated much more than unsupported nitrile gloves. An initial penetration was observed for all the materials. A cosolvent effect involving the "inert components" was observed, as implied by the appearance of inert components in the hexane collection medium of the ASTM cell before and with the 2,4-D ester. Degradation occurred in the neoprene and supported glove materials since nonformulation components also were detected on the collection side. The glove selection procedure involved the characteristics of single surrogate compounds in the brochure of a glove manufacturer, in addition to the characteristics of the carrier and inert ingredients. This procedure was sufficient to predict correctly that nitrile would protect better than neoprene; however, direct experimental confirmation was necessary to select the type of nitrile material which provided optimum protection.

Conditions Influencing Turbinella Oak (Quercus turbinella) Mortality from Picloram or Picloram and 2,4-D

Turbinella oak was sprayed with picloram-containing herbicides on 90 dates throughout 81 months. A mixture of triisopropanolamine salts of picloram and 2,4-D was compared to the potassium salt of picloram on 44 dates, and to a mixture of isooctyl ester of picloram and propylene glycol butyl ether esters of 2,4-D on 42 dates. Low rates of herbicide treatments were used to increase the sensitivity to environmental factors and plant growth stages. Turbinella oak mortality was greater with the mixture of picloram and 2,4-D amines than with picloram alone or the mixture of picloram and 2,4-D esters. The mixture of picloram and 2,4-D esters did not kill any plants. The combination of available soil moisture at the 60-cm depth, no senescent or falling leaves, and full-sized leaves was the best indicator of when to apply picloram or the mixture of picloram and 2,4-D amines. No turbinella oak were killed when soil at the 60-cm depth was dry or leaves were falling at the time of treatment.

Wild-oat herbicide studies: barban herbicidal activity for wild-oat ( Avena fatua L.) control as influenced by adjuvants

The effect of barban at 0·35 kg a.i./ha alone or in mixture with eight surfactants at 0·5% (v/v), and two organic salts at 0·5% (v/w) on wild oat ( Avena fatua L.) fresh weight was investigated in the glasshouse. Barban with Atplus 411F and with Renex-36 reduced wild-oat fresh weight by 68–77% and 69–86%, respectively, compared with the untreated control, whereas barban alone reduced fresh weight by 36–48%. Barban with added ammonium sulphate also reduced fresh weight by 71%. The three-way mixture (barban+surfactant+ammonium sulphate) did not further reduce fresh weight. Mixtures of Atplus 411F and Renex-36 added in different proportions to barban reduced fresh weight by amounts similar to individual combinations of each surfactant and barban. The increased activity of barban when applied with Renex-36 counteracted the antagonistic effect of 2,4-D isopropyl ester or MCPA iso-octyl ester on wild-oat fresh-weight reduction, compared with barban plus 2,4-D or MCPA without surfactant. Simulated rainfall did not decrease wild-oat fresh-weight reduction with the barban/Renex-36 mixture. Under field conditions, barban plus Atplus 411F and ammonium sulphate gave better wild-oat control than barban alone and increased wheat-grain yield. This treatment also did not reduce wheat tolerance. More [ 14C]-barban was absorbed by wild oat when [ 14C]-barban was mixed with Atplus 411F or Renex-36 than when applied alone. The increased adsorption may provide some explanations for the improved wild-oat control with barban/adjuvant mixture.

The toxicity of 2,4-dichlorophenoxyacetic acid to the adult crested newt

The toxicity of the herbicide Agroxone 5, a commercial formulation of the iso-octyl ester of 2,4-dichlorophenoxyacetic acid (2,4-D), in the adult crested newt (Triturus cristatus carnifex) was tested after percutaneous exposure. The compound was lethal to all the animals within 72 hr at concentrations of 100, 125, and 150 ppm. Males appeared to be more susceptible than females to the toxic effects of 2,4-D, since the LT50 values at 75 ppm were 102 and 132 hr for male and female newts, respectively. At 50 ppm, all the males died within 31 days of exposure, whereas the females were still alive at the end of the 3-month experiment. Only one male died at 25 ppm after 21 days. Vacuolar degeneration of liver parenchyma and necrosis of kidney tubules were found at lethal concentrations of 2,4-D. The severity of the lesions was related to the duration of exposure more than to the concentration of the herbicide.

Carcinogenicity and toxicity of 2,4-dichlorophenoxyacetic acid

2,4-Dichlorophenoxyacetic acid (2,4-D) is carcinogenic in male and female rats and probably also in mice. Male and female rats ingesting 2,4-D developed increased incidences of malignant neoplasms. Lymphosarcomas were increased in rats of both sexes, and neoplasms of the mammary gland in female rats. Male rats also had carcinomass of the endocrine organs. 2,4-D isooctyl ester was carcinogenic for the lymphoreticular system in female mice. 2,4-D and 2,4-dichlorophenol also were promoters of neoplasms of the skin in mice. Male mice given 2,4-D isopropyl ester developed an increased incidence of neoplasms of the lung. 2,4-D also is mutagenic and teratogenic in animals and causes poisoning in animals and human beings.

Relative airborne losses of commercial 2,4-D formulations from a simulated wheat field

The relative airborne losses of seven commercial 2,4-D (2,4-dichlorophenoxyacetic acid) formulations were evaluated in a simulated wheat field. The formulations tested were butyl ester, isooctyl ester, two propylene glycol butyl ether esters, ethanol/isopropyl amine, and two dimethyl amines. The butyl and isooctyl esters exhibited the greatest airborne losses, followed by the propylene glycol butyl ether esters. The amines were nearly nonvolatile. Two to 4 days after application, the 2,5-dichloro-4-hydroxyphenoxyacetic acid metabolite of 2,4-D predominated in all air samples. This material as well as the 2,4-D acid predominated in all plant samples with only traces of the parent esters observed. No extractable 2,4-D related residues were detected in the soil.

Residues of 4‐(2,4‐Dichlorophenoxy)butyric Acid in Winter Wheat

AbstractResidue data were collected during a 1‐year field investigation to support a label amendment for the use of 2,4‐DB (4‐[2,4‐dichlorophenoxy]butyric acid) in small grains. The 2,4‐DB was applied to ‘blue boy’ winter wheat (Triticum aestivum L.) at the “recommended” and “twice the recommended” rates as the dimethylamine salt (1.68 and 3.36 kg ai [active ingredient]/ha) and the isooctyl ester (1.12 and 2.24 kg ai/ha). Low levels of 2,4‐DB residues (4.9–7.4 ppmw) were found in wheat straw harvested 70 d after spraying with the isooctyl ester formulation, but no 2,4‐DB residues were found in wheat straw treated with the dimethylamine form. The grain did not contain detectable levels of 2,4‐DB or 2,4‐D [(2,4‐dichlorophenoxy] acetic acid) residues from any 2,4‐DB treatment. No difference in yield between the control and 2,4‐DB‐treated plots was obtained. Rainfall that occurred 4 h after application may have resulted in some loss of the herbicide and the data presented should be considered preliminary.

Changes in the Yield of Forage following the Use of Herbicides to Control Aspen Poplar

Changes in the Yield of Forage following the Use of Herbicides to Control Aspen Poplar

The Antagonistic Action of 2,4-D and Bromoxynil on Glyphosate Phytotoxicity to Barley (Hordeum vulgare)

The absorption, translocation, metabolism, and retention of an isopropylamine formulation of glyphosate [N-(phosphonomethyl)glycine] in the presence and absence of the commercial dimethylamine salt and isooctyl ester formulations of 2,4-D [(2,4-dichlorophenoxy)acetic acid], or the commercial isooctyl ester formulation of bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) was investigated in barley (Hordeum vulgare L. 'Summit′). In all treatments, absorption of 14C-glyphosate continued for up to 24 h, but no further absorption occurred with a further 48 h of treatment. A considerable reduction in absorption and translocation of 14C-glyphosate occurred when it was applied to the leaf surface in a mixture with the commercial formulation of either 2,4-D amine, 2,4-D ester, or bromoxynil. When a 14C-glyphosate solution was spotted on the leaf adjacent to drops of the commercial formulation of either 2,4-D amine, 2,4-D ester, or bromoxynil, no reduction in absorption or translocation of 14C-glyphosate occurred. The herbicide components of the 2,4-D amine and bromoxynil formulations were solely responsible for reduced absorption and translocation of 14C-glyphosate. No 14C-glyphosate metabolites were detected in barley following treatment with 14C-glyphosate either alone or mixed with the commercial formulations of 2,4-D amine or bromoxynil. No 14C-glyphosate complexes were detected in mixtures of the commercial formulations of 2,4-D amine, 2,4-D ester, or bromoxynil with 14C-glyphosate. Barley leaves retained less glyphosate when it was spray-applied together with the commercial formulation or the solvent system of 2,4-D amine.

Herbicide Dispersal Patterns: HI. as a Function of Formulation

The distribution patterns of several herbicide formulations sprayed on adaxial leaf surfaces were determined using scanning electron microscopy coupled with cathodoluminescence and x-ray microanalysis. The sodium and amine salts of MCPA {[(4-chloro-o-tolyl) oxy] acetic acid} sprayed on sugar beet (Beta vulgarisL.) leaves appeared as discrete deposits above the anticlinal cell walls that represented the location of spray drops that adhered to the leaf. When the sodium salt was applied to bermudagrass [Cynodon dactylon(L.) Pers.], the pattern of distribution was the same; however, each deposit was significantly smaller. The iso-octyl ester of MCPA coalesced into numerous, small, thick deposits on the cuticle of sugar beet leaves. The distribution of a wettable powder formulation of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino-s-triazine] appeared as uniform deposits over the anticlinal and periclinal cell walls that represented the location of aqueous spray drops after application. When a flowable formulation of atrazine was applied, there was a significant preferential accumulation of the herbicide at the edges of the separate deposits. One commercial formulation of propanil (3′,4′-dichloropropionanilide) yielded deposits that were crystalline, one that was partially crystalline, and one that was noncrystalline.

Gas chromatographic measurement of volatility of herbicide esters

The vapour pressures of eleven herbicide esters were calculated from gas chromatographic measurement of relative retention volumes (dibutyl phthalate = 1) on a non-polar SE-30 column. Measurements were made at temperatures from 72 to 182°C, but by assuming that the ratio of the latent heat of vaporization of the ester to that of dibutyl phthalate was independent of temperature, values for vapour pressure could be extrapolated to 25°C. Vapour pressures at 25°C ranged from 2.5·10 −4 mmHg for 2,4-D ethyl ester to 1.9·10 −7 mmHg for picloram isooctyl ester.

Fate of 2,4‐D in a Naff Silt Loam Soil

AbstractLaboratory studies were conducted to determine the adsorption, desorption, hydrolysis, and breakdown of commercially formulated isooctyl ester and dimethylamine salt of 2,4‐D [(2,4‐dichlorophenoxy) acetic acid] in a Naff silt loam soil. More 2,4‐D was adsorbed to the surface soil than to soil at lower depths, and the percentage of 2,4‐D adsorbed decreased as the total amount of 2,4‐D present increased. Adsorbed 2,4‐D was gradually desorbed from soil by successively exchanging the solution in equilibrium with soil with distilled water. Formulated 2,4‐D isooctyl ester applied to moist soil underwent hydrolysis to the anionic form at a rapid rate, with >80% of the ester hydrolyzed in 72 hours. High amounts of 2,4‐D in runoff (sediment and water) retarded the active degradation of carboxyl‐14C 2,4‐D when 2,4‐D was incubated in runoff from a wheat field treated with various formulations and rates of 2,4‐D. The presence of the ester formulation at the high rate of application increased the lag period before degradation of carboxyl‐14C and ring‐14C 2,4‐D occurred in soil. However, once the active breakdown of carboxyl‐14C and ring‐14C 2,4‐D was initiated, little difference could be detected in the degradation patterns. At the end of the 10 weeks of incubation in runoff or in soil, only 1% of the 14C‐2,4‐D originally applied to the soil could be identified as 2,4‐D.

Breakdown and Movement of 2,4-D in the Soil Under Field Conditions

The fate of 2,4-D [(2,4-dichlorophenoxy)acetic acid] in the soil under winter wheat (Triticum aestivumL. ‘Nugaines’) and fallow cropping schemes was studied under the field conditions of eastern Washington in 1973 and 1974 using formulated dimethylamine salt and isooctyl ester of 2,4-D. Soil samples taken 1 hour after herbicide application showed that amine-treated plots retained considerably more applied 2,4-D than ester-treated plots. The rapidity of 2,4-D breakdown decreased gradually with time, and at the end of 6 months, an average of 0.04 ppm of 2,4-D remained in the sampled soil profile regardless of formulation, application rate, or cropping scheme. Loss of 2,4-D from the soil surface in runoff occurred when the plots were irrigated heavily one day after the herbicide application. The herbicide was also leached into the soil profile by both irrigation and natural precipitation. Herbicide concentrations in the sampled portion of the upper soil profile decreased during the summer and then increased slightly in the fall.

Residues of 2, 4-D in air samples from Saskatchewan: 1966-1975.

Residues of 2,4-D (2,4-dichlorophenoxyacetic acid) in air samples from several sampling sites in central and southern Saskatchewan during the spraying seasons in the 1966-68 and 1970-75 periods were determined by gas-liquid chromatographic techniques. Initially, individual esters of 2,4-D were characterized by retention times and confirmed further by co-injection and dual column procedures. Since 1973, however, only total 2,4-D acid levels in air samples have been determined after esterification to the methyl ester and confirmed by gc/ms techniques whenever possible. Up to 50% of the daily samples collected during the spraying season at any of the locations and during any given year contained 2,4-D, with butyl esters being found most frequently. The daily 24-hr mean atmospheric concentrations of 2,4-D ranged from 0.01 to 1.22 mug/m3, 0.01 to 13.50 mug/m3, and 0.05 to 0.59 mug/m3 for the iso-propyl, mixed butyl and iso-octyl esters, respectively. Even when the samples were analysed for the total 2,4-D content, i.e. from 1973 onwards, the maximum level of the total acid reached only 23.14 mug/m3. In any given year and at any of the sampling sites, about 30% of the samples contained less than 0.01 mug/m3 of 2,4-D. In another 40% of the samples, the levels of 2,4-D ranged from 0.01 to 0.099 mug/m3. Only about 30% of the samples contained 2,4-D concentrations higher than 0.1 mug/m3, with only 10% or less exceeding 1 mug/m3. None of the samples, obtained with the high volume particulate sampler, showed any detectable levels of 2,4-D, indicating little or no transport of 2,4-D adsorbed on dust particles or as crystals of amine salts.

Mechanical Control of Eurasian Watermilfoil in Maryland with and without 2,4-D Application

Eurasian watermilfoil (Myriophyllum spicatum L.) increased from a minor annoyance of a few thousand acres in the late 1950’s, to a major nuisance covering over 200,000 acres in waters of the upper portion of the Chesapeake Bay in 1964. From 1961 through 1964, the effectiveness of underwater mowing of milfoil using a mechanical mower with and without subsequent application of 2,4-dichlorophenoxyacetic acid was investigated in medium and near maximum salinity ranges for milfoil in tributaries of Maryland’s western shore. Milfoil normally reaches the surface by early May, and begins to sink in high salinity waters about September 15, and in lower salinities about October 15. Depending on the type of activity for which milfoil control is instituted, mowing must be repeated at least monthly during the usual mid-May to mid-September growing season. In this study it was effective only for the season in which it was made. New nodal growth to 18 inches or more per month from cut milfoil stems or fragments made cutting impractical for large areas. Cutting followed by herbicide application when new growth offered sufficient vegetative containment of applied 2,4-D impregnated attaclay granules extended milfoil’s vulnerable period to 2,4-D beyond anthesis. The butoxyethanol ester of 2,4-D was more effective than the iso-octyl ester. In study plots no adverse affects were noted to endemic fauna. Prime submersed waterfowl food plants, previously retarded by the dense milfoil over-story, made rapid growth once the milfoil was thinned or removed. These preferred waterfowl foods evidenced no undesirable responses to either cutting or to 2,4-D.

Toxicity of Various Formulations of 2,4-D to Salmonids in Southeast Alaska

To determine acute toxicity to juvenile (1) pink, chum, coho, and sockeye salmon, (2) Dolly Varden char, and (3) rainbow trout, 2,4-D acid, butyl and isooctyl esters were tested in southeast Alaska. A comparable test was made in Oregon using coho salmon fingerlings. The mean percent mortality after 96 h and the highest concentration of herbicide that did not produce any mortality were determined for each formulation tested.At less than 50 ppm 2,4-D acid produced no mortality except in pink salmon fry. The butyl ester was most toxic causing nearly complete mortality in all species at concentrations > 1.0 ppm and the isooctyl ester least toxic of the ester formulations. Alaskan and Oregon coho fingerlings were similar in their responses to 2,4-D acid, butyl and isooctyl esters. The toxicities of three different formulations of isooctyl ester, a PGBE ester, and butyl ester to Alaskan coho fingerlings were also determined. There were few or no differences in toxicity among isooctyl ester formulations. The butyl and PGBE esters were similar in toxicity.

Limitations of Surfactant and pH Effects on Herbicide Behavior in Woody Plants

Additions of surfactants to the isooctyl ester of (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) and the dimethylamine of 3,6-dichloro-o-anisic acid (dicamba) generally did not increase absorption or translocation of the herbicides when they were applied to foliage of five hardwood species and loblolly pine (Pinus taedaL.). Adjusting pH of the formulations to 3, 6, or 9 with a buffering solution had small and inconsistent effects upon absorption and translocation.

Effect of 2,4-DB on White Clover Seed Production

Seed fields of white clover (Trifolium repens L. ‘New Zealand’ and ‘Louisiana S-1′) were treated with the dimethylamine salt and the isooctyl ester of 4-(2,4-dichlorophenoxy)-butyric acid (2,4-DB). Rates of application were 0.56, 1.12, and 1.68 kg/ha. Applications were made at the vegetative, bud, and flowering stages of growth. All treatments applied at the vegetative and bud stages of growth significantly reduced white clover seed production. Reductions in clover seed production usually became more severe as the rate of 2,4-DB increased.

Pre- and postnatal studies on 2,4,5-trichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid and their derivatives in rats

The herbicides 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) (containing less than 0.5 mg/kg of 2,3,7,8-tetrachlorodibenzo-p-dioxin) and 2,4-dichlorophenoxyacetic acid (2,4-D) induced fetopathy and an increased incidence of skeletal anomalies following single daily po doses of 100–150 mg/kg on days 6–15 of gestation. Increased frequency of skeletal defects was also observed in single trials with butyl, isooctyl, butoxyethanol and dimethylamine derivatives of 2,4-D. The observed skeletal defects did not appear to be incompatible with postnatal survival. Following treatment of dams with 2,4,5-T, 2,4-D and their butyl esters and the isooctyl ester of 2,4-D, weight gain and viability of the offspring were within control limits. The findings suggest that postnatal parameters were unrelated to the teratologic potential of the chemicals.

The effect of 2.4-dichlorophenoxyacetic acid (2.4-D) and esters of 2.4-D on rat embryonal, foetal and neonatal growth and development

This study evaluated the effects of 2.4-D, of the propylene glycol butyl ether ester of 2.4-D (PGBE) and of the isooctyl ester of 2.4-D (IO) on foetal development and neonatal growth and survival. Dose levels of 2.4-D up to a maximum tolerated dose of 87·.5 mg/kg4day or molar equivalents of PGBE or IO were administered to pregnant Sprague-Dawley rats on days 6–15 of gestation. Foetuses were delivered by Caesarean section on day 20 of gestation and were examined grossly, measured and weighed. Following routine preparations, the soft tissues and skeletons were examined. Signs of embryotoxicity and foetotoxicity, such as decreased foetal body weight, subcutaneous oedema, delayed ossification of bone, lumbar ribs and wavy ribs were observed at high dose levels; considered overall, the responses were dose-related. Teratogenic effects, however, were not seen at any dose level. 2.4-D did not affect fertility, gestation, viability or lactation. PGBE and IO had no effect on fertility and gestation indices, but the highest dose levels decreased viability and lactation indices. Neonatal growth and development were not altered by treatment during pregnancy.