Propylene Glycol Butyl Ether Esters Research Articles

Sand Sagebrush (Artemisia filifolia) and Brittle Pricklypear (Opuntia fragilis) Control

Experiments were conducted at Bridgeport, NE, during 1983 through 1987 to select alternatives for silvex and 2,4,5-T for sand sagebrush and brittle pricklypear control. Of the six herbicides examined, the butoxyethyl ester of 2,4-D at 2.2 kg ae/ha was equivalent to the propylene glycol butyl ether ester of silvex or 2,4,5-T for sand sagebrush control. The potassium salt of picloram at 0.3 kg ae/ha was equal to silvex for brittle pricklypear control.

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.

Reproductive Biology and Control ofSolanum dimidiatumandSolanum carolinense

Studies were conducted to investigate the reproductive biology and herbicide response of horsenettle (Solanum carolinenseL. # SOLCA) and robust horsenettle (Solanum dimidiatumRaf. # SOLDM) that are common in peanut (Arachis hypogaeaL.) production. Of these two species, horsenettle had a higher rate of seed germination, greater ability for seedling establishment in a competitive situation (pasture), greater ability to regenerate from smaller root fragments, and greater ability to regenerate from progressively greater depths in soil. Horsenettle was relatively more sensitive to glyphosate [N-(phosphonomethyl)glycine] (1.1 and 2.2 ai kg/ha), propylene glycol butyl ether esters of 2,4-D [(2,4-dichlorophenoxy)acetic acid] (0.8 and 1.7 ae kg/ha), and the ethanolamine salt of 2,4-D (1.7 ae kg/ha) than robust horsenettle. Conversely, robust horsenettle was more sensitive to dicamba [3,6-dichloro-2-methoxybenzoic acid)] (0.3 and 0.6 ae kg/ha). In a field study, dicamba applied annually in July or August for 2 yr at a rate of at least 1.1 kg/ha controlled 92% or more.

Toxicities of butoxyethanol ester and propylene glycol butyl ether ester formulations of 2,4-dichlorophenoxy acetic acid (2,4-D) to juvenile salmonids.

Continuous-flow toxicity tests were conducted to determine acute toxic effects of butoxy-ethanol ester (BOEE) and propylene glycol butyl ether ester (PGBEE) formulations of 2,4-D on juvenile chinook salmon (Oncorhynchus tshawytscha) and steelhead-rainbow trout (Salmo gairdneri). A chronic toxicity test with chinook salmon egg-to-fry was conducted to determine effects of BOEE on survival and growth. The hydrolysis in water of 2,4-D esters to 2,4-D acid was influenced by the presence of fish. Median lethal concentrations (96-hr LC50 values) indicated that PGBEE (170 to 355 μg/L) was slightly more toxic (37 to 57%) than BOEE (303 to 525 μg/L). The LC50 values also indicated that chinook salmon were generally more sensitive than steelhead-rainbow trout and that fry and smolts were equally sensitive to the 2,4-D esters. Static tests substantially underestimated BOEE toxicity when compared to dynamic tests. Based on reduced survival and growth of chinook salmon alevins and fry, the estimated maximum safe chronic exposure concentration under these test conditions is 40 μg/L BOEE.

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.

Amino Acid Conjugates in 2,4-D Treated Soybean (Glycine max) and Red Oak (Quercus rubra)

A modified analytical procedure involving gas-liquid chromatography was used to investigate the relative amounts of 2,4-D [(2,4-dichlorophenoxy)acetic acid] and two of its amino acid conjugate metabolites, 2,4-D-Asp [(2,4-dichlorophenoxy)acetylaspartic acid] and 2,4-D-Glu [(2,4-dichlorophenoxy)acetylglutamic acid], in soybean [Glycine max (L.) Merr. var. Amsoy] plants, soybean callus tissue and red oak (Quercus rubra L.) plants at 2, 4, and 10 days after application of either 2,4-D, its ester, or its salts. 2,4-D-Asp and 2,4-D-Glu were found as major metabolites in all soybean tissues analyzed and their amounts varied depending upon the days following treatment, the formulation of treatment, and the plant substrate (0.03 to 57 ppm for 2,4-D-Asp and 0.05 to 75 ppm for 2,4-D-Glu). The amount of amino acid conjugates peaked at 2 days after treatment of callus tissue and 4 days after treatment of soybean plants. Much higher amounts of these amino acid conjugates were obtained from soybean plants treated with the propylene glycol butyl ether ester of 2,4-D than plants treated with amine salts of 2,4-D. No amino acid conjugates were observed with red oak plants.

Biology and Control of Tall Ironweed (Vernonia altissima)

Tall ironweed (Vernonia altissimaNutt.) is a perennial with underground, axillary vegetative buds from which new shoots are produced. In a 2-yr study, tall ironweed plants averaged 6115 seeds/plant. Germination of buried seeds increased with increased time of burial. Foliar herbicide applications were evaluated for control of tall ironweed plants in the pre- to early-bud stages of growth. The triethylamine salt or ethylene glycol butyl ether ester of triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} was the most effective, providing 93 to 90% control of top growth and regrowth of tall ironweed. The butoxyethanol and propylene glycol butyl ether esters of 2,4-D [(2,4-dichlorophenoxy) acetic acid] alone and in combination with the amine salt of triclopyr also provided excellent control.

Pharmacokinetics of 2,4,5-T PGBE ester applied dermally to rats.

The pharmacokinetic profile of the herbicide 2,4,5-T PGBE ester (propylene glycol butyl ether esters of 2,4,5-trichlorophenoxyacetic acid) 14C-labeled in the ring was examined in rats given a single dermal application of 5 mg/kg. The rate of absorption of the ester through the skin was lower than the rate of hydrolysis to 2,4,5-T acid and the rate of excretion of 2,4,5-T in the urine. Urinary excretion of radioactivity was apparently first order with a half-life of approximately 24 h. Clearance of radioactivity from blood plasma, liver kidneys, and the remaining carcass was also apparently first order with half-life values ranging from 25 to 37 h. Six days (144 h) after application of the dose, an average of 98.7 +/- 5.1% of the applied radioactivity was recovered in he urine, and approximately 97% of the urinary radioactivity was identified as 2,4,5-T acid. The tissue-to-plasma ratios of 14C activity in liver and kidney were similar to those observed previously in rats given a single iv dose of 5 mg/kg 2,4,5-T acid. The results of this study indicate that the pharmacokinetic model for 2,4,5-T PGBE ester in rats is similar to that for 2,4,5-T acid. This similarity suggests the chronic exposures to 2,4,5-T acid and its PGBE ester would be toxicologically comparable. The low rate of absorption of the ester through the skin suggests that removal of the ester from the skin by washing after exposure might substantially reduce the dose of 2,4,5-T received by this route. Since the urinary excretion rate of 2,4,5-T in humans is known, a similar pharmacokinetic model for humans may be developed to calculate the absorbed dose of 2,4,5-T based on urinary excretion data.

Fringed Sagebrush (Artemisia frigida) Control in Western Nebraska

Two experiments were conducted to determine the most effective herbicide treatments for fringed sagebrush (Artemisia frigida Willd.) control in rangelands. In the first study the potassium salt of picloram (4-amino-3,5,6-trichloropicolinic acid) at 0.1, 0.6, and 0.8 kg/ha; picloram + the propylene glycol butyl ether ester of 2,4-D [(2,4-dichlorophenoxy)acetic acid] at 0.1 + 1.1 kg/ha; the monoethanolamine salt of 3,6-dichloropicolinic acid at 1.1 kg/ha; 3,6-dichloropicolinic acid + 2,4-D at 0.6 + 1.1 kg/ha; and the dimethylamine salt of dicamba (3,6-dichloro-o-anisic acid) + 2,4-D at 0.6 + 1.1 kg/ha applied in late summer at flowering, showed the greatest potential for fringed sagebrush control. In the second experiment, the potassium salt of picloram at 0.3 kg/ha applied either in the spring or late summer gave 94 to 100% fringed sagebrush control, respectively, 1 yr after application. Control of fringed sagebrush had declined to 50% 3 yr after application. Production of perennial grasses from plots receiving picloram at 0.3 kg/ha in 1976 was increased by 410 kg/ha in 1977, 450 kg/ha in 1978, and 430 kg/ha in 1979 over that of the untreated plots.

Concentration and determination of the propylene glycol butyl ether esters of 2,4-dichlorophenoxyacetic acid (PGBE 2,4-D) in air.

A method has been developed and validated for the determination of airborne propylene glycol butyl ether ester and the dipropylene glycol butyl ether ester of 2,4-dichlorophenoxyacetic acid. The method is designed to collect samples in the breathing zone of workers for 4 hours at 150 mL/min. using a tube containing 750 mg of Amberlite XAD-2 resin and a portable pump. Recoveries of 85.2% and 81.4% were obtained for the two esters over a range of 0.67 and 13.3 mg/m3 by desorption wih hexane. The extracts were analyzed by electron capture gas chromatography using a highly efficient and inert bonded Carbowax 20-M column packing. The recovery was not affected by 80% relative humidity or refrigerated storage for two weeks. Some loss in recovery was observed for the 0.67 mg/m3 level when samples were stored at room temperature for two weeks. The overall precision of the method for the two esters is +/- 17% and +/- 16% at the 95% confidence level.

Effectiveness and Distribution of 2,4,5-T, Triclopyr, Picloram, and 3,6-Dichloropicolinic Acid in Honey Mesquite (Prosopis julifloravar.glandulosa)

Greenhouse-grown honey mesquite [Prosopis juliflora(Swartz) DC. var.glandulosa(Torr.) Cockerell] plants were treated with the propylene glycol butyl ether esters of 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid], the triethylamine salt or the ethylene glycol butyl ether esters of triclopyr {[(3,5,6-trichloro-2-pyridinyl) oxy]acetic acicd}, the potassium salt of picloram (4-amino-3,5,6-trichloropicolinic acid), or the monoethanol amine salt of 3,6-dichloropicolinic acid applied at the rate of 1.1 kg/ha to soil, foliage, or soil plus foliage. All herbicides were effective as foliar sprays in killing the stems of honey mesquite. When applied to the soil, picloram and 3,6-dichloropicolinic acid killed all above ground stems, and the ester and amine formulation of triclopyr killed 70 and 91% of the stem tissue, respectively, but 2,4,5-T was ineffective. Accumulation of herbicides in leaves 10 days after foliar spray was 28, 167, and 266 μg/g fresh wt for triclopyr, 3,6-dichloropicolinic acid, and picloram, respectively. Upward transport of picloram and 3,6-dichloropicolinic acid (2.7 to 5.9 μg/g) was also more extensive than that of 2,4,5-T or triclopyr after soil treatment. Higher concentrations of 3,6-dichloropicolinic acid than 2,4,5-T, triclopyr, or picloram usually was found in honey mesquite stems and roots 3, 10, or 30 days after application to soil or foliage. This may be one reason that 3,6-dichloropicolinic acid is highly effective in controlling honey mesquite.

Solid absorbent collection and gas chromatographic determination of the propylene glycol butyl ether esters of 2,4,5-T in air.

A method has been developed and validated for the collection of the propylene glycol butyl ether esters of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in air and their determination by gas chromatography with electron capture detection. The samples are collected on XAD-2 resin, desorbed in diethyl ether prior to analysis. The procedure is designed for industrial hygiene monitoring to provide an accurate 4 hour time-weighted average of the exposure level. Recoveries were found to be 97 +/- 8% (2 sigma) for the propylene glycol butyl ether esters of 2,4, 5-T in the concentration range of 0.70 ppb (v/v) to 5.00 ppm (v/v). Breakthrough concentrations, storage effects and humidity effects were also investigated.

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.

Control of Spring Parsley on Rangeland

Several herbicides were evaluated for control of spring parsley [Cymopterus watsonii(Coult. & Rose) Jones]. The propylene glycol butyl ether esters and dimethylamine salt of (2,4-dichlorophenoxy)acetic acid (2,4-D) applied at 2 lb/A were 99% effective. Ninety-nine percent control was achieved also with 0.5 lb/A of 4-amino-3,5,6-trichloropicolinic acid (picloram) and 2,4-D amine + picloram at 0.4 + 0.1 lb/A, 2,4-D amine + picloram at 0.33 + 0.17 lb/A, and (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) + picloram at 0.25 + 0.25 lb/A.

Chemical Control of Western False Hellebore

Several herbicides were evaluated for control of western false hellebore (Veratrum californicumDurand). The dimethylamine salt and propylene glycol butyl ether esters of (2,4-dichlorophenoxy)acetic acid (2,4-D), potassium salt of 2-[(4-chloro-o-tolyl)oxy]propionic acid (mecoprop), and the butoxy ethanol ester of 2-(2,4,5-trichlorophenoxy)propionic acid (silvex) controlled 95 to 99% of the plants when applied at 2 lb/A followed by 2 lb/A of the dimethylamine salt of 2,4-D the second year. Optimum control was achieved when plants were treated after the last leaf had expanded and before flower bud initiation.

The Degradation Kinetics of an Ester of Silvex and the Persistence of Silvex in Water and Sediment

The degradation kinetics of propylene glycol butyl ether (hereafter referred to as PGBE) ester of 2-(2,4,5-trichlorophenoxy) propionic acid (silvex) and the persistence of silvex in water and sediment were studied under impounded conditions. PGBE ester of silvex was applied to the surface of three ponds at the rate of 9 kg/ha/A. Water and sediment samples were collected at 4, 12, 24, and 48 hr after treatment and were extracted for PGBE ester of silvex immediately after collection. The concentrations of PGBE ester of silvex and silvex present in the water and sediment samples were determined by gas chromatography. Physico-chemical and mineralogical characteristics of the sediment samples collected prior to treatment were determined. The hydrolysis of PGBE ester of silvex to silvex obeyed first order reaction kinetics, the specific reaction rate constants for the three ponds being 0.09 hr−1, 0.10 hr−1, and 0.14 hr−1. Fifty percent hydrolysis of PGBE ester of silvex occurred in 5 to 8 hr, 90% hydrolysis occurred in 16 to 24 hr, and 99% hydrolysis occurred in 33 to 49 hr. The concentration of silvex in water initially increased, but decreased to zero by the end of 3 weeks. Adsorption of both the PGBE ester of silvex and silvex appeared to occur on the sediment; essentially complete disappearance of both occurred by the fifth week following treatment. Under laboratory conditions, silvex adsorption by the sediments conformed to the Freundlich adsorption equation.

Some Chronic Effects of 2,4-D on the Bluegill (Lepomis macrochirus)

Bluegills (Lepomis macrochirus) were exposed to the propylene glycol butyl ether ester of 2,4-D in six ponds at Tishomingo, Oklahoma, one concentration per pond in five ponds, and a control pond. The fish and the pond environment were studied for five months to measure chronic effects on the fish and persistence of the herbicide in pond water, bottom sediments, and aquatic vegetation. Small quantities of 2,4-D were found in pond waters for six weeks after application. Residues of 2,4-D were found in vegetation and in bottom sediments in the highest-treated pond for six weeks. No 2,4-D was detected in fish after four days. One-fifth of the fish treated at 10 ppm died within 8 days; mortality was almost negligible among bluegills exposed to 5 ppm or less. Spawning among bluegills treated at 10 and 5 ppm was delayed about two weeks. Growth was faster among bluegills in these high-treatment ponds than in the low-treatment ponds which received 1.0, 0.5, and 0.1 ppm 2,4-D. Pathologic lesions were seen in the fish; high-treatment fish had earlier and more severe effects than did low-treatment fish. The pathology involved liver, vascular system, and brain, with depletion of liver glycogen, globular deposits in the blood vessels, and stasis and engorgement of the circulatory system of the brain. Little pathology was seen after 84 days.

Determination of 2,4,5-trichlorophenoxyacetic acid and its propylene glycol butyl ether esters in animal tissue, blood, and urine

Determination of 2,4,5-trichlorophenoxyacetic acid and its propylene glycol butyl ether esters in animal tissue, blood, and urine

Extraction, Separation, and GLC Detection of Silvex and Its Propylene Glycol Butyl Ether Ester in Fish Tissue

Abstract A method is described for the quantitative analysis of silvex and its propylene glycol butyl ether ester in fish tissue. A methanolic extraction and gas chromatographic detection yielded recoveries from fortified fish tissue of 80 to 96% at levels of 0.005 to 1 ppm for the ester and 84 to 98% at 0.002 to 1 ppm for the acid. In an additional recovery study, the extraction procedure was monitored with the PGBE ester labeled at the carboxylic carbon (14C). Live fish were exposed to an aqueous environment containing the labeled PGBE ester and were extracted by the procedure. It was found that 95% of the PGBE ester and its degradation products can be extracted from the tissue with methanol.

Control of Green Rabbitbrush and Big Sagebrush with 2,4-D and Picloram

A mixed stand of green rabbitbrush (Chrysothamnus viscidiflorus (Hook.) Nutt. var. puberulus Jepson) and big sagebrush (Artemisia tridentata Nutt.) was sprayed at different dates for 3 years with potassium salt of 4-amino-3,5,6-trichloropicolinic acid (picloram) at ¼, ½, and 1 1b/A, propylene glycol butyl ether esters of 2,4-dichlorophenoxyacetic acid (2,4-D) at 1, 2, and 3 1b/A, and a mixture of triisopropanolamine salts of picloram plus 2,4-D at ¼ plus 1 and ½ plus 2 1b/A. Picloram at ½ and 1 1b/A controlled rabbitbrush but not sagebrush. Poor rabbitbrush control and fair to good sagebrush control resulted from 2,4-D. The mixture of picloram and 2,4-D controlled rabbitbrush well but only partially controlled sagebrush. Forage release from brush control was negligible the first 2 years after spraying. During the third and subsequent years, production of crested wheatgrass (Agropyron desertorum (Fisch.) Schult.) was greatly increased.