Garlon 3A Research Articles

Forty years of spruce–fir stand development following herbicide application and precommercial thinning in central Maine, USA

We examined the development of a 33-year experiment in spruce–fir stands that received nine herbicide treatments (applied aerially in 1977), with and without precommercial thinning (PCT) (applied in 1986). We tested two commonly held assumptions about the long-term effects of herbicide and PCT in mixedwood stands managed for softwoods: (i) herbicide release produces stands dominated by softwoods and (ii) PCT promotes both softwood dominance and merchantable volume. All herbicides were effective at releasing balsam fir ( Abies balsamea (L.) Mill.) and spruce ( Picea spp.) from overtopping shrubs and hardwoods that had naturally regenerated following clearcut harvesting in 1970. Glyphosate (Roundup), triclopyr amine (Garlon 3A), 2,4,5-T, and a mixture of 2,4,5-T and 2,4-D herbicide treatments were all effective at shifting long-term species composition to softwood dominance after 30 years, irrespective of the rates applied. Herbicide-treated stands that did not receive PCT were overstocked with softwoods for at least 24 years and produced less than half of the merchantable softwood volume by 40 years than herbicide-treated stands that received PCT. Intolerant hardwoods dominated untreated stands for all 33 years of the experiment. When unsprayed plots received PCT, however, they produced stands at 40 years that were compositionally and structurally indistinguishable from those that had received both herbicide and PCT treatments. Results from this experiment clearly demonstrated that early herbicide application, regardless of type and rate of herbicide, created softwood-dominated mixedwood stands over the long term and that PCT more than doubled merchantable softwood volume within 25 years of application.

Evaluating Tolerance of Herbicide and Transplantation by Cane (a Native Bamboo) for Canebrake Restoration

Canebrakes (bamboo grasslands dominated by Arundinaria spp.) were once a widespread ecosystem across the Southeastern United States, and many species of wildlife depended upon them. Early settlers replaced this system with subsistence agriculture and today few canebrakes remain. The restoration of canebrakes is critical to the recovery of several wildlife species; however, restoration is complicated because (1) seed is uncommon and often predated, (2) competition from hardwood species, including the exotic Chinese privet (Ligustrum sinesnse), often prevent cane establishment, and (3) cane depends on disturbance regimes that have been disrupted in the Southeast. We investigated the tolerance of Switch cane (Arundinaria tecta) to four commonly used herbicides that are effective at controlling privet and other hardwoods: hexazinone (Velpar-L), glyphosate (Razor Pro), triclopyr (Garlon 3A), and imazapyr (Chopper). We also investigated the possibility of transplanting cane culms, and the factors affecting successful transplant. Cane tolerated hexazinone and triclopyr but was damaged or killed by glyphosate and imazapyr. Although many measures of weather and cane condition were not predictors of transplant success, the Keetch–Byram drought index was a strong predictor, and is available through most state forestry offices. Selective herbicides and deliberately timed transplantation may be important canebrake restoration tools.

Effect of Chemical and Manual Release on Live Oak Sprouts and Other Vegetation in a Ponderosa Pine Plantation on a Poor Site

Abstract In their quest to increase vegetation management alternatives, managers continue to test new treatments and to apply old ones to different species. In this northern California study, the new treatment was undiluted Velpar applied with a spot-gun; the old treatments were Garlon 3A, Garlon 4, and manual release; and the different species was canyon live oak (Quercus chrysolepis). Principal categories of vegetation in the new plantation were hardwoods (mostly live oak root-crown sprouts), shrubs, forbs, and grasses. Planted 2-yr-old ponderosa pine (Pinus ponderosa var. ponderosa) seedlings were part of the plant community. Eleven growing seasons after treatment (1988–1998), hardwood sprouts in the untreated control averaged 1,850/ac, combined shrubs over 3,600/ac, forbs 5,900/ac, and grasses more than 19,500/ac. Mean hardwood height in 1998 was significantly shorter when treated with Velpar and Garlon 4 than in the control. Significantly longer needles for pines in the Velpar and manual release treatments in 1989 forecast a significant difference among treatments that was realized in 1994, when mean stem diameter of pines at 12 in. above ground was significantly larger in all treatments than in the control. Stem height and diameter of pine did not differ significantly among treatments in 1998, but needle length again indicated that it would in the near future. Ten years may not be enough time to fully evaluate release treatments on poor sites with hard-to-control species. West. J. Appl, For. 18(1):22–28.

Herbicide Hardwood Crop Tree Release in Central West Virginia

Abstract Chemical crop tree release treatments were applied to young hardwood stands at three sites in central West Virginia to evaluate the effectiveness of glyphosate as Accord (41.5% SL), imazapyr as Arsenal AC (53.1% SL) and Chopper (27.6% EC), and triclopyr as Garlon 3A (44.4% triethylamine salt SL), and Garlon 4 (61.6% butoxyethyl ester EC) using hack-and-squirt injection and low volume stem bark band application methods. American beech (Fagus grandifolia Ehrh.) was a major competitor to black cherry (Prunus serotina Ehrh.) crop trees at each site. The treatments were applied in June and evaluated 12 months after treatment. A numerical rating system ranging from 1 to 7 (0–100% crown affected), which utilized visual symptoms, was used to evaluate the efficacy of each treatment. Trees receiving a rating of 5 (75% crown control) or greater were considered controlled.After 12 months, almost complete control (99+%) was achieved with the Accord, Garlon 3A, and Arsenal AC injection treatments across all study sites. The low volume stem bark band treatments used in this study were not effective. The imazapyr treatments adversely affected several crop trees and are not recommended for hardwood crop tree release. Some crop tree damage was inflicted by the Accord treatments, but when suggested guidelines are followed, Accord is recommended for crop tree release treatments. No crop tree damage was observed in the Garlon 3A treatments. The costs of the injection treatments expressed in dollars/ft2 of basal area controlled were as follows: Accord ($0.91), Garlon 3A ($1.04), and Arsenal AC ($0.84). The Northeast Decision Model Stand Inventory Processor using the NE-TWIGS growth simulator was used to predict the future composition and value of projected stands. The stem injection treatments more than doubled projected growth of black cherry basal area. Real rates of return for investment in weed tree control averaged 8.77% for stem injection treatments. This study indicates that chemical crop tree release treatments using stem injection with label recommended solutions of Accord or Garlon 3A are an effective way to increase the future value of Appalachian hardwood stands. North. J. Appl. For. 18(2):46–54.

Vegetation Management along Transmission Utility Lines in the United States and Canada

A survey investigating vegetation control methods along transmission rights-of-way was sent to 220 Utility Arborist Association companies. The survey contained questions regarding right-of-way characteristics, control methods used, total dollars spent on vegetation management, and priorities of the vegetation management program. The ROW area reported represented over 48% of all the investor-owned ROWs over 39 Kv in service throughout the United States. More than 75% of the respondents reported using herbicides on their rights-of-way. However, acres treated mechanically outnumbered those treated chemically by a margin of 2.7:1. Garlon 3A and Garlon 4 topped all herbicides, with a combined 220,574 projected gal (834,961 L) of the estimated 549,869 gal (2,081,474 L) of herbicide applied to transmission rightsof- way in 1995. It appears that quite low levels of active ingredients are being applied per acre. Basal, high-volume foliar, and low-volume foliar with a backpack or handgun applications accounted for approximately 75% of the acres of transmission ROWs treated with herbicides.

Use of ELISA immunoassay kits as a complement to HPLC analysis of imazapyr and triclopyr in water samples from forest watersheds.

The herbicide triclopyr (3,5,6-trichloro-2-pyridinyl)-oxyacetic acid has been marketed by the Dow Chemical Co. since the mid 1970’s as the triethylammonium salt (Garlon 3A) and as the ethylene glycol butyl ether ester (Garlon 4). Shortly after its introduction, McKellar (1977) published a method for the extraction, isolation, and electron capture gas chroinatographic analysis of triclopyr and two of its major metabolites in soil and water samples. A number of environmental fate studies of triclopyr have been published since then, each of which has used the McKellar method or a minor modification of it (Oloffs et al. 1986; Deubert et al. 1986; Norris et al. 1987; Whisenant et al. 1989). Glas (1978) developed a method along similar lines for the analysis of triclopyr in plant tissues as did Bovey et al. (1983). While state-of-the-art for their day, these methods are laborintensive and time-consuming. They use large volumes of dichloromethane which has been designated a hazardous material by the EPA, making its disposal difficult and expensive. These methods also involve derivitization with diazomethane, which is an explosion hazard and requires handling of highly carcinogenic precursors. We have developed a rugged high-performance liquid chromatographic (HPLC) method for analysis of the free-acid form of triclopyr in environmental water samples. This method features solid-phase extraction (SPE) and a lead diacetate cleanup to remove interfering humic substances. We have applied this method to the analysis of over two thousand water samples from a major environmental fate study we conducted on the Ouachita National Forest, Arkansas, but only 10 samples could be processed in one technician-day. Samples from environmental fate studies collected in one day frequently exceed 200-300 so there is a great need for a method which will accelerate the analysis of these samples.

Spatial analysis of herbicide decay rates in louisiana

This analysis presents results based on a five-yearstudy recently supported by the Louisiana Departmentof Transportation and Development (DOTD) in which theacute toxicity, fate and effect of herbicide mixtureson human health and the environment were assessed. Three sites were routinely sprayed by DOTD to killweeds along the roadsides. Two herbicide mixtures wereused, 2,4-D and Roundup, and Garlon 3A and Roundup.Water, vegetation, soil and sediment samples werecollected quarterly for three years and were analyzedfor pesticide content to study the fate and impact ofherbicides in the environment. Results indicate acorrelation between soil type, herbicide type, andpersistence of the herbicide in the environment. Usingthe correlations found in these data, spatial analysisidentified areas where herbicide use may potentiallycause surface water and sediment contamination, basedon soil composition/properties, type of herbicideapplied, and proximity of water bodies to sprayed areas.

English Ivy (Hedera helix) Response to Postemergence Herbicides

Abstract One application of Roundup at 2.2 or 4.5 kg ai/ha (2.0 or 4.0 lb/A) with or without surfactant, Weedar 64 (2.4-D amine) at 1.1 kg ae/ha (1.0 lb/A), Banvel at 0.6 kg ae/ha (0.5 lb/A), or Garlon 3A at 0.6 kg ae/ha (0.5 lb/A) reduced new shoot growth of English ivy 10 weeks after treatment by 46 to 80%. Roundup at 4.5 kg/ha plus non-ionic surfactant was the only single application treatment that reduced older shoot growth of English ivy (41% reduction) 19 weeks after treatment. English ivy outgrew injury from all other single application treatments. Two applications of Weedar 64 completely controlled English ivy. Two applications of Roundup at 4.5 kg/ha (4.0 lb/A), with or without surfactant, eliminated new shoot growth 11 weeks after treatment, and reduced total shoot weight by approximately 60% 15 weeks after treatment. English ivy shoot weight decreased when the rate of Roundup was increased from 2.2. to 4.5 kg/ha (74 versus 92% reduction) 7 weeks after treatment, but adding a non-ionic surfactant did not further reduce shoot weight. Two applications of Banvel or Garlon (52 and 67% reduction, respectively, 7 weeks after treatment) were less effective than two applications of Roundup at 4.5 kg/ha (4.0 lb/A) in reducing English ivy shoot growth.

Young Spruce-Fir Forests Released by Herbicides I. Response of Hardwoods and Shrubs

Abstract Responses of shrubs and hardwoods to 9 aerial herbicide treatments were evaluated in a replicated conifer-release experiment in a 7-year-old spruce-fir clearcut in west-central Maine. All herbicides and rates of application reduced hardwood and shrub cover by 50% or more in year 9, 2 years after treatment. Cover more than 1.5 m tall was nearly eliminated by treatments with triclopyr amine (Garlon 3A®), glyphosate (Roundup®), or a high rate of 2,4,5-T. Phenoxy herbicides (2,4-D and 2,4,5-T) led to short-term reductions in birches, maples, aspen, and raspberry, and little change in willows. Pin cherry was also controlled by these treatments but died out before year 16, regardless of whether it was sprayed. Untreated controls increased in total cover by about 50% between years 7 and 9 and also in abundance of cover >1.5 m tall. Much cover less than 1.5 m tall was left by all treatments other than triclopyr at a high rate. By the 16th year, major differences in height and cover still existed between all treatments and the controls. North. J. Appl. For. 9(4):126-130.

Seed Germination, Physical and Chemical Control of Catclaw Mimosa (Mimosa pigravar.pigra)

Catclaw mimosa, an exotic member of the Leguminosae, occurs in three areas of Florida. Propagation is by seed only. Seeds collected from Florida were used for germination, growth, and herbicide evaluation studies. Seeds germinated at 75 to 94% but were not influenced by different environmental conditions under which they were stored. Greenhouse-grown plants cut or burned off at ground level failed to regrow. However, plants cut at 2 cm or more above ground level regrew from lateral shoots. Sixteen herbicides were evaluated to determine their effects on 6- to 8-wk-old plants grown in the greenhouse. Catclaw mimosa was killed by picloram, tebuthiuron, hexazinone and sulfometuron at 0.4, 0.07, 0.14, and 0.56 kg ha-1, respectively. Dicamba at 1.12, triclopyr at 1.12 (Garlon 3A and 4), linuron at 4.48, and glyphosate at 8.96 kg ha-1were also effective. Chlorsulfuron and metsulfuron killed 9 out of 10 plants at the highest rates tested. Four herbicides, imazapyr, thifensulfuron, DPX-L5300, and atrazine killed 50% or less of the plants at the highest rates of each compound tested. Fosamine did not kill catclaw mimosa at the rates tested.

Acute physiological stress responses of juvenile coho salmon (Oncorhynchus kisutch) to sublethal concentrations of garlon 4®, garlon 3a® and vision® herbicides

AbstractJuvenile coho salmon (Oncorhynchus kisutch) were exposed for 4 h to sublethal concentrations of the herbicides Garlon 4®, Garlon 3A®, and Vision®. Trials were performed in a closed‐system respirometer that measured oxygen consumption of fish prior to and during a 4‐h exposure. At the end of the exposure period, plasma glucose and lactate concentrations, hematocrit, and leucocrit were measured as indicators of acute physiological stress. There were no biologically significant indications of acute physiological stress in fish exposed to Garlon 4, Garlon 3A, or Vision at 5 to 80% of the 96‐h LC50 concentrations. The results suggest that threshold herbicide concentrations causing physiological stress in short‐term exposure (4 h) in juvenile coho salmon may be higher than the 96‐h LC50 value for those herbicides. It was concluded that sublethal concentrations of Garlon and Vision herbicides do not induce significant physiological stress responses in juvenile coho salmon during a 4‐h exposure period.

Acute avoidance reactions and behavioral responses of juvenile rainbow trout (Oncorhynchus mykiss) to garlon 4®, garlon 3A® and vision® herbicides

AbstractLaboratory bioassay experiments were conducted with juvenile rainbow trout (Oncorhynchus mykiss) to determine the acute lethal (96‐h LC50) values of the forest‐use herbicides Garlon 3A®, Garlon 4®, and Vision® with 15% and 10% surfactant formulations, and the threshold concentrations of these herbicides that would cause behavioral effects. A Y‐maze apparatus was used to determine the threshold concentration of each herbicide that elicited either an avoidance or a preference reaction from rainbow trout fry after a one‐hour exposure period. Rainbow trout fry were observed for qualitative behavioral changes (e.g., increased coughing and ventilatory rates, loss of equilibrium, etc.) over a four‐day period of exposure to a wide range of chemical strengths. Nominal concentrations of the herbicides eliciting threshold avoidance reactions in test fish were 150 ppm Vision‐10% surfactant, 54 ppm Vision‐15% surfactant, 19.2 ppm Garlon 4, and 800 ppm Garlon 3A, which were, respectively, 2, 2, 8, and 2 times the 96‐h LC50 values determined for each herbicide. Preferential reactions to the herbicide solutions were not observed. Qualitative behavioral changes were observed in rainbow trout fry at levels from 25% (Garlon 4) to 50% (Garlon 3A, Vision‐10% and ‐15% surfactants) of the 96‐h LC50 values. Nominal concentrations of the herbicides causing threshold changes in fish behavior were 37.5 ppm Vision‐10% surfactant, 13.5 ppm Vision‐15% surfactant, 0.60 ppm Garlon 4, and 200 ppm Garlon 3A.

Directed Foliar Sprays of Forestry Herbicides for Loblolly Pine Release

Abstract Six herbicides were compared as directed foliar sprays applied in May, July, and September on seven hardwood species and on loblolly pine. Equal-cost mixtures that met or exceeded minimum labeled rates were tested for Weedone 2,4- DP, Gadon 4, Garlon 3A, Arsenal Applicator Concentrate, Roundup, Escort, and Roundup + Escort. Test hardwoods were sweetgum, southern red oak, water oak, red maple, pignut hickory, dogwood, and yellow poplar. Crown volume reduction and rootstock reduction after one growing season were the main indicators of efficacy. Using directed sprays, yellow poplar was the easiest species to control, and pignut hickory was the most difficult. Control of sweetgum was most effective with Weedone, Arsenal, and Roundup. For control of oaks, the most effective applications were in July with Arsenal, Garlon 4 and 3A, and Roundup; but these and other hardwood species tended to refoliate 2 years after Arsenal treatment. Herbicide safety to loblolly pine was best with Arsenal and Escort, while injury was greatest with Roundup and Garlon 3A, which might have potential use in precommercial thinnings. South. J. Appl. For 14(4):199-206.

Control of Young Mediterranean Saltwort (Salsola vermiculata) with Postemergence Herbicides

Mediterranean saltwort has become an established weed in the upper San Joaquin Valley and the Temblor Range areas of California. Fifteen herbicides were evaluated to determine their effects on 6- to 8-week-old plants grown in the greenhouse. Mediterranean saltwort was killed by chlorsulfuron3, hexazinone, and metribuzin at low rates. Triclopyr4(Garlon 3A and Garlon 4), atrazine, imazapyr, glyphosate, dicamba, bromacil, karbutilate, and simazine were effective at higher rates. Four herbicides, asulam, pendimethalin, amitrole, and fosamine, did not kill Mediterranean saltwort at the rates tested.

Toxicity of nine benchmark chemicals to Skeletonema Costatum, a marine diatom

AbstractThe purpose of this study was to determine the sensitivity of a marine diatom to eigm common chemicals and one herbicide. The 50% reduction in the number of cells per milliliter and that of total cell volume × 104 μm3/ml was estimated in relation to each of the nine chemicals. Nominal concentrations of triclopyr triethylamine salt (Garlon 3A), K2Cr2O7, 4—chlorophenol and phenol were slightly toxic (>10 mg/L) according to the U.S. Environmental Protection Agency classificatory scheme, while diethanolamine, chlorobenzene, chloroform, acetone and ethanol were classified as practically nontoxic (>100 mg/L). No observed effect levels were found for each of the two cell measurements in relation to each of the chemicals tested for the 5—d period of the test. The range was found to be from 1 to 6,000 mg/L for total cell count and from 0.65 to 6,000 mg/L for total cell volume. Data on the sensitivities of other organisms to the group of common chemicals are also included. The marine diatom proved to be less sensitive to K2Cr2O7 and diethanolamine than the green alga Selenastrum capricornutum.

Acute toxicity to juvenile Pacific salmonids of Garlon 3A, Garlon 4, triclopyr, triclopyr ester, and their transformation products: 3,5,6-trichloro-2-pyridinol and 2-methoxy-3,5,6-trichloropyridine.

Acute toxicity to juvenile Pacific salmonids of Garlon 3A, Garlon 4, triclopyr, triclopyr ester, and their transformation products: 3,5,6-trichloro-2-pyridinol and 2-methoxy-3,5,6-trichloropyridine.

Impact of Season of Harvest and Site Quality on Cut-Stump Treatment of Piedmont Hardwoods

Abstract Herbicide treatments were made to the cambial area of Piedmont hardwoods immediately after chainsaw clear-felling using Roundup® Velpar L ®, Tordon 101R®, Garlon 3A®, and Banvel CST®. Evaluations of the materials used were based on both percent kill of treated stumps and percent control of sprouting. Efficacy was determined for stumps treated during the dormant and growing season and for those growing on good versus poor sites. The interaction between herbicide and season of harvest was significant, with Tordon 101R, Velpar L, and Banvel CST all performing better on the dormant season-harvested areas. Garlon 3A and Roundup gave slightly better control of sprouting on the growing season-harvested areas. Based on percent kill, the Roundup, Garlon 3A, and Tordon 101R treatments were significantly more effective in controlling resprouting than the Velpar L and Banvel CST treatments. Two years after treatment, plots receiving the herbicide treatments had significantly less hardwood competition present. The hardwood basal area averaged 16.1 ft²/ac on untreated areas as opposed to 7.0 ft²/ac on the stump treated areas. South.J. AppL For. 11(1):46-49.

Silvicultural Management of Beech and the Beech Bark Disease

Abstract Herbicides were used to control dense, advance reproduction of American beech and sprouting from roots and stumps of harvested beech in a northern hardwood stand in eastern Maine. Beech comprised 51% of the overstory basal area and was highly defective as a result of the beech bark disease. Beech saplings accounted for 80% of the advance reproduction. The herbicides glyphosate (Roundup®) or triclopyr (Garlon 3A®), applied using a backpack mist blower, were effective in reducing advance reproduction of beech by 100% and 93%, respectively. When applied in frills on larger beech six weeks prior to harvesting, glyphosate reduced the number of sprouts, two growing seasons after treatment, by 85%; triclopyr by 87%. Beech individuals believed to be resistant to infestation by the beech scale were left as a component of the residual overstory, along with sugar maple, red maple, yellow birch, and paper birch. The two-stage application of herbicides followed by shelter-wood harvesting is a strategy for managing stands dominated by defective beech. North. J. Appl. For. 3:89-91, Sept. 1986.

Hardwood Topkill by Four Herbicides Injected at Wide Spacings

Abstract Mixed southern hardwood species ranging from 1 to 12 inches dbh were injected with 2,4-D at 2-inch spacings and with Tordon 101®, Garlon 3A®, and Roundup® at 5-inch spacings. Tordon and Garlon killed 92 and 93% of all stems and were rated as satisfactory. Roundup and 2,4-D killed 82 and 80% of injected stems; although neither was significantly less effective than Tordon and Garlon, both were rated as only marginally satisfactory.