Mixture Of Picloram Research Articles

Matching herbicide application rates with the environmental conditions and growth stages of nodding thistle (Carduus nutans) and hairy buttercup (Ranunculus sardous) in pastures

Glasshouse experiments were conducted to evaluate whether herbicide application rates could be reliably reduced without compromising the efficacy of the herbicide. The seedling, and vegetative and preflowering plants of nodding thistle (Carduus nutans) and hairy buttercup (Ranunculus sardous) were treated with different rates of glyphosate or a mixture of picloram and triclopyr. Half of the plants were well-watered at all times while the other half was moisture-stressed for 1 week before the herbicide treatments were applied. Hairy buttercup was more susceptible to glyphosate than nodding thistle, while both were equally susceptible to the picloram/triclopyr mixture. Moisture stress significantly reduced the efficacy of both herbicide treatments, regardless of the plant development stage or the herbicide rate applied.

The Control of a Highly Invasive Tree Cinchona pubescens in Galapagos1

Red quinine tree has been recognized as a serious weed in the Galapagos National Park for three decades. During this time, a variety of control methods have been implemented, initially with poor results. In this article, we reviewed past efforts to control red quinine tree and tested a variety of herbicides and selective application methods. A mixture of picloram and metsulfuron (240 and 15 g ai/L, respectively) killed 73 to 100% of trees when applied to connecting machete cuts around the circumference of tree trunks (hack and squirt [HS]) at concentrations of 5, 10, and 20% in water, with larger trees requiring higher concentrations for best results. Although this herbicide mixture also was effective when applied using other methods, HS was the least labor intensive and costly. The control methods developed could be used to combat this weed in other locations including Hawaii and Tahiti.Nomenclature: Metsulfuron; picloram; red quinine tree, Cinchona pubescens Vahl.Additional index words: Cinchona succirubra, Galapagos National Park, Hawaii.Abbreviations: BB, basal bark; CDRS, Charles Darwin Research Station; CS, cut stump; DBH, diameter at breast height; GNP, Galapagos National Park; GS, girdle and squirt; HS, hack and squirt; H, hack only; MASL, meters above sea level; WS, wide-band hack and squirt.

Effect of Tillage Timing on Herbicide Toxicity to Field Bindweed

When can tillage be resumed after herbicide treatment of field bindweed (Convolvulus arvensis L.) without reducing control ? This question was answered with experiments on a clay loam soil in the semi-arid southern Great Plains in mid-summers of 1979, 1985, and 1986 when field bindweed vigor was visually rated as good, fair, or poor, respectively. Plant vigor was controlled by availability of soil water. Highest control, about 95%, of field bindweed 9 mo after application of 2,4-D, glyphosate, and dicamba was aehieved when vigor was good. Control with picloram + 2,4-D was not affected by plant vigor. When field bindweed growth was rated as good, control with dicamba, glyphosate, and a mixture of 2,4-D and picloram was not reduced when sweep tillage was delayed for 1 day after treatment (DAT). To achieve maximum control with 2,4-D, tillage had to be delayed 7 DAT. When plant vigor was fair, control was not reduced with picloram + 2,4-D when tillage was delayed 2 DAT. Glyphosate and dicamba gave maximum control after 3 DAT delay, and 2,4-D required a 7 DAT delay for maximum effectiveness. With poor plant vigor, picloram + 2,4-D, a herbicide combination that persisted in the soil, gave best control when tillage was delayed 2 DAT. Dicamba, a less persistent herbicide, required a 7 DAT delay for maximum controL Control was not better than zero 9 mo after treatment with glyphosate or 2,4-D when plants had poor vigor.

Economic evaluation of field bindweed (Convolvulus arvensis) control

This research compared seven field bindweed control treatments to a check in a 3-yr winter wheat-sorghum-fallow rotation. Treatments included 3 wk intervals of sweep tillage combined with one or two annual applications of 2,4-D (tillage and 2,4-D). Two other treatments were the same as tillage and 2,4-D, except dicamba or a mixture of picloram and 2,4-D were applied once in October after wheat harvest. A fourth treatment was identical to tillage and 2,4-D, except imazapyr was sprayed immediately after harvest of wheat. Also, three no-tillage systems using glyphosate and 2,4-D at monthly intervals were supplemented with either dicamba, picloram and 2,4-D, or imazapyr the same as in treatments involving tillage and 2,4-D. The check was sweep tilled every 6 wk. All treatments controlled field bindweed in one rotation of two fallow periods and two crops. After control was accomplished, wheat and sorghum yields were about twice the check. Using 1995 costs and returns, profit for an owner-operator for the two fallow periods and two crops was $123 ha−1for tillage and 2,4-D, compared to $19 ha−1for the check. Tillage and 2,4-D supplemented with picloram or imazapyr were almost as profitable as tillage and 2,4-D. Because of high herbicide cost and low yields, no-tillage treatments lost money. Profits with a 33:67 owner-tenant rental agreement were $105 and $21 ha−1, respectively, for owner and tenant using tillage and 2,4-D. With no field bindweed control practice, the tenant lost $33 ha−1and the owner made $51 ha−1.

Economic Evaluation of Field Bindweed (Convolvulus arvensis) Control in a Winter Wheat-Fallow Rotation

Field bindweed infests millions of hectares in the Great Plains greatly reducing productivity and value of land. The standard practice for field bindweed control is sweep tillage at 3 wk intervals combined with one or two annual 2,4-D) applications during the 14 mo fallow period in a winter wheat-fallow crop rotation. This was compared to tillage and 2,4-D in conjunction with dicamba or a mixture of picloram+2,4-D applied once during the first October of the first 14 mo fallow period. Also, three no-tillage systems were included using glyphosate+2,4-D at monthly intervals. Two of the treatments were supplemented with dicamba, or picloram+2,4-D as in the sweep tillage system. All treatments controlled field bindweed in two fallow periods and two winter wheat crops, and increased winter wheat yields to about twice the control. Sweep tillage at 3 wk intervals combined with 2,4-D resulted in $36 ha−1profit for an owner-operator compared to $15 ha−1loss with no herbicide or tillage treatment. On average no-tillage lost $35 ha−1. Other treatments, although controlling field bindweed, lost from 35 to $186 ha−1. To determine if long-term benefit after control was achieved, average yields for the area were used to calculate profits using normal farming practices. Profits were 136, 78, and $-50 ha−1, respectively, for sweep tillage and 2,4-D, no-tillage, and the untreated check. In a standard 33:67 owner-tenant rental, profits to the owner for the control period were 90, −33, and $43 ha−1, respectively for tillage and 2,4-D, no-tillage, and untreated check. The tenant lost from $24 to 69 ha−1for the three systems indicating owners must modify rental agreements during a field bindweed control program.

Control of Woody Plants in Grazing Lands on the Pacific Coast of Mexico

Greenhouse and field experiments were conducted to evaluate herbicides for control of Palma de llano (Sabal rosei Mart.), jarretaders (Acacia hindsii Benth), huinol (Acacia cymbispina Sprague & Riley), and guazima (Guazuma ulmifolia Lam.), woody species encroaching in grazing lands on the Pacific Coast of Mexico. In the greenhouse, picloram at 0.14 and 0.28 kg ae/ha killed all jarretadera, huinol, and guazima plants. Mixtures of picloram + clopyralid, dicamba, or triclopyr at 0.07 + 0.07 and 0.14 + 0.14 kg/ha also killed most plants. Trielopyr killed all huinol at 0.14 and 0.28 kg/ha but not all jarretadera or guazima. Clopyralid was effective on jarretadera and huinol but not as effective as picloram. Dicamba was ineffective on jurretadera and killed 88 to 100% of the huinol and gunzima plants at 0.28 kg/ha. The palm could not be grown in the greenhouse. In the field, foliar sprays of triclopyr or picloram st 0.4 and 0.3 g ae/L water, respectively, killed 70% or more of the jarretadera, huinol and gunzima but 77% or less of the palm. No herbicide successfully controlled jarretadera in 1988. Hexazinone applied to the soil killed 82% or more of the palm plants at 0.5 g ai/2.5 cm of stem diameter. Soil-applied tebuthiuron pellets were not effective on jarretaders or palm, but the briquettes (Brush Bullets) at 2 and 4 g/ 2.5 cm of stem diameter killed 50, 60, and 83% or more of the huinol, palm, and guazima plants, respectively.

The application of various chemicals to cuts made in the stem bases of Brachystegia spiciformis Benth., Julbernardia globiflora (Benth.) Troupin and Terminalia sericea Burch. ex DC.

Picloram‐potassium and various mixtures of picloram with 2,4‐D amine, 2,4,5‐T ester or amine, or 2,4,5‐T ester alone were injected into incisions made in the cambium of standing Brachystegia spiciformis and Julbernardia globiflora trees. Each arboricide was tested at a range of application rates, at different times of the year and at three different sites for each species. Picloram‐potassium and 2,4,5‐T ester were also tested on Terminalia sericea trees. Glyphosate, MCPA, mixtures of mecoprop and 2,4,5‐T amine and different mixtures of 2,4‐D ester with 2,4,5‐T ester, cacodylic acid and Tandex were tested on B. spiciformis and J. globiflora trees at one site and only in January. Aboricides containing picloram, with or without the addition of 2,4‐D or 2,4,5‐T, were the most effective chemicals for the control of trees. Higher application rates were required to kill B. spiciformis and J. globiflora between May and October when they were not actively growing. T. sericea trees were susceptible to arboricide tr...

The application of various picloram formulations to cut stumps of Brachystegia spiciformis Benth., Julbernardia globiflora (Benth.) Troupin, Terminalia sericea Burch. ex DC. and Acacia karroo Hayne trees

Trees were felled 150 mm above ground level and various mixtures of picloram with 2,4‐D araine, 2,4,5‐T amine in water solution or 2,4,5‐T ester in diesel oil were applied to the freshly‐cut surfaces. Mixtures of picloram/2,4‐D amine and picloram/2,4,5‐T amine, both water soluble, gave the highest kill rates when applied to trees in the growing season (October and May). The oil emulsifiable picloram/2,4,5‐T ester formulation tended to be effective throughout the year and high kill rates were frequently obtained with applications made in June or July. Application rates of picloram/2,4‐D amine or picloram/2,4,5‐T amine (expressed as g a.e. picloram per mm girth) required to kill 80% of the trees were 0,012–0,016 for A. karroo; 0,016–0,037 for T. sericea and 0,037 for J. globiflora. Few of the treatments applied to B. spiciformis trees resulted in kill rates of more than 65%.

Control of Huisache and Honey Mesquite with a Carpeted Roller Herbicide Applicator

Several herbicides were evaluated for control of honey mesquite (Prosopis glandulosa Torr.) and huisache [Acacia farnesiana (L.) Willd.] using a tractor-mounted carpeted roller. Foliar sprays of picloram + 2,4,5-T at 0.28 + 0.28 and 0.56 + 0.56 kg/ha were included for comparison. When applied by carpeted roller, picloram at 60 g/L killed about 40% of the honey mesquite plants whereas 120 g/L killed 63 to 83% of the plants after 2 years. Clopyralid at 60 or 120 g/L killed 65% or more of the plants. Mixtures of picloram + clopyralid (1:1) at 30 + 30 g/L killed 53 to 73%, whereas 60 + 60 g/L killed 93 to 98% of the honey mesquite. Clopralid + triclopyr (1:1) 30 + 30 g/L killed 48 to 58% of the plants, while 60 + 60 g/L killed 80 to 95%. Picloram + 2,4,5-T (1:1) applied by the carpeted roller was usually more effective than foliar sprays of picloram + 2,4,5-T. For huisache, picloram, clopyralid, or picloram + clopyalid at a total of 60 or 120 g/L killed 60% or more of the plants after 1 year. Picloram + clopyralid at 60 + 60 g/ L applied in 1983 and 1984 killed 92% or more of the huisache. Picloram + 2,4,5-T at 60 + 60 g/L killed 73 to 83%, but foliar sprays of picloram + 2,4,5-T were sometimes ineffective. Glyphosate, dicamba, triclopyr and 2,4,5-T applied alone reduced the canopy of honey mesquite and huisache but usually killed few plants. Honey mesquite was controlled from spring applications, whereas, summer and fall treatments controlled huisacbe.

Response of Huisache (Acacia farnesiana) Seedlings to Herbicides Applied with a Model Carpeted Roller

Mortality of potted huisache seedlings averaged 87 to 100% 18 weeks after picloram or clopyralid was applied with a model carpeted roller at concentrations as low as 7.5 g ae/L. A 1:1 mixture of picloram and clopyralid was equally effective. Triclopyr was effective only when applied to small seedlings in the spring, and an ester was more effective than an amine formulation. A 1:1 mixture of clopyralid and triclopyr ester was intermediate in effectiveness between the two herbicides applied alone. Adding surfactant increased canopy reduction and plant mortality (P = 0.1 to 0.01), especially at lower herbicide concentrations.

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.

Gas Chromatographic Determination of N-Nitrosodialkanolamines in Herbicide Di- or Trialkanolamine Formulations

A modified method is presented to determine trace quantities of N-nitrosodiethanolamine (NDElA) and N-nitrosodiisopropanolamine (NDiPlA) in the triisopropanolamine (TiPlA) formulation of a mixture of picloram and 2,4-D. Aqueous sample is extracted with dichloromethane to remove organic interferences, and then the aqueous layer is passed sequentially through chloride anion exchange column, hydrogen cation exchange column, and Clin-Elut extraction tube. The final eluate, 10% acetone in ethyl acetate, is concentrated. The isolated nitrosamines are converted to the corresponding trimethylsilyl (TMS) derivatives and determined by gas chromatography (GC) on a DB1 column coupled with a thermal energy analyzer (GC-TEA). Eight samples of commercial TiPlA formulations are analyzed. Maximum detected levels of NDElA and NDiPlA were 0.6 and 0.9 ppm, respectively, expressed relative to total weight of active ingredients. Analysis of 13 samples of herbicide DElA formulation using a previously established method and a DB225 column gave NDElA results of 0.7-6.0 ppm. NDiPlA was not detected in those samples. Results are confirmed by GC-mass spectrometry (GC/MS) with oxygen negative chemical ionization (ONCI) detection. Detection limits for both nitrosamines are 0.05 or 0.07 ng (0.1 or 0.17 ppm) for GC-TEA detection, depending on the analytical columns used, and 20 pg (0.04 ppm) for GC/MS detection. Recoveries of NDElA are 87-109% for DElA formulation spiked at 2.6 and 3.9 ppm and 90-115% for TiPlA formulation spiked at 0.2-0.3 ppm. Similarly, recoveries of NDiPlA are 95.7-100% for the DElA formulation spiked at 0.24 and 0.48 ppm, and 82-118% for the TiPlA formulation spiked at 0.2-0.3 ppm.

Herbicide Mixtures for Control of Honey Mesquite (Prosopis glandulosa)

Clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) was superior to 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid], dicamba (3,6-dichloro-o-anisic acid), picloram (4-amino-3,5,6-trichloropicolinic acid), and triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} for control of honey mesquite (Prosopis glandulosaTorr. ♯ PRCJG) in the field. However, equal ratio mixtures of clopyralid + picloram or triclopyr (0.28 + 0.28 or 0.56 + 0.56 kg ae/ha) were as effective for honey mesquite control as clopyralid at rates of 0.56 and 1.12 kg/ha. Equal mixtures of picloram + 2,4,5-T, picloram + triclopyr, picloram + dicamba, triclopyr + 2,4,5-T, or triclopyr + dicamba were less effective in controlling honey mesquite than clopyralid alone or clopyralid + picloram or triclopyr in 1:1 mixtures. In the greenhouse, mixtures of clopyralid + 2,4,5-T, picloram, or triclopyr were highly effective for the control of honey mesquite. Mixtures of 2,4,5-T + picloram, 2,4,5-T + triclopyr, or triclopyr + picloram were also effective when applied at 0.28 + 0.28 kg/ha.

Dynamique de la végétation d'emprises de lignes de transport d'énergie

We made a preliminary study of the impact of phytocides on plant dynamics in the corridors of Hydro-Québec power lines. Three hypotheses were tested: the first assumed that the phytocides changed vegetation composition and structure in the corridors; the second assumed that the corridor under the power line favored the development of an ecotone at its border with the forest; the third assumed that the method used for initial cutting of the corridors (bulldozer or chain saw) affected the forthcoming vegetation for over 15 years. Vegetation was sampled on one control power line and four power lines maintained with mixtures of picloram, 2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, and sodium trichloroacetate. Multidimensional statistical analysis was used to show the underlying structure of the raw data and to test the hypotheses. We found out that phytocides are very efficient on woody species to the advantage of herbs, mostly grass, which invaded the corridors and created rather stable artificial communities. No significant ecotone was found at the border line of the corridors and the forest. The influence of the method for initial cutting of the corridors, although severe the first few years, disappeared after about 10 years under the action of the phytocides.

Influence of Picloram Alone or Plus 2,4-D on Control of Wild Oats (Avena fatua) with Four Postemergence Herbicides

Field experiments were conducted for 2 yr to determine the influence of picloram (4-amino-3,5,6-trichloropicolinic acid) and a commercial mixture of picloram plus 2,4-D [(2,4-dichlorophenoxy)acetic acid] (1:16, w/w) on control of wild oats (Avena fatua L. # AVEFA) with four postemergence herbicides. The phytotoxicity to wild oats of barban (4-chloro-2-butynyl m-chlorocarbanilate) or difenzoquat (1,2-dimethyl-3,5-diphenyl-1H-pyrazolium) in 1981 and diclofop {2-[4-(2,4-dichlorophenoxy)-phenoxy] propanoic acid} or flamprop [N-benzoyl-N-(3-chloro-4-fluorophenyl)-DL-alanine] in 1981 and 1982 was reduced when these herbicides were applied in a mixture with picloram plus 2,4-D. Consequently, the use of these mixtures for broad-spectrum weed control in one spray operation is not recommended. Picloram applied at a rate equivalent to the amount present in the picloram plus 2,4-D mixture did not influence the control of wild oats obtained with any herbicide, indicating that the antagonism was due to the 2,4-D component of the picloram plus 2,4-D mixture.

Triclopyr for Control of Honey Mesquite (Prosopis julifloravar.glandulosa)

Triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} was aerially applied at four locations in Texas to determine effectiveness of the amine and ester formulations for the control of honey mesquite [Prosopis juliflora(Swartz) DC. var.glandulosa(Torr.) Cockerell # PRCJG]. The ester formulation was superior to the amine in most trials. Honey mesquite control with triclopyr amine was comparable to that with 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] while control with triclopyr ester was similar to that attained with a 1:1 mixture of 2,4, 5-T and picloram (4-amino-3,5,6-trichloropicolinic acid). Honey mesquite control obtained with a 1:1 mixture of 2,4,5-T and dicamba (3,6-dichloro-o-anisic acid) was intermediate between that with the 2,4,5-T and picloram mixture and that with 2,4,5-T alone. Efficacy of triclopyr increased as rates were increased from 0.3 to 0.6 kg ae/ha and from 0.6 to 1.1 kg/ha. Triclopyr formulations were effective when applied in either water or diesel oil/water emulsions. Honey mesquite control from triclopyr in combination with picloram was generally comparable to that from the mixture of picloram and 2,4,5-T.

Picloram in Water and Soil from a Semiarid Pinyon‐Juniper Watershed

AbstractA mixture of picloram (4‐amino‐3,5,6‐trichloropicolinic acid) at 2.8 kg acid equivalent (ae)/ha and 2,4‐D [(2,4‐dichlorophenoxy) acetic acid] at 5.6 kg acid equivalent/ha was aerially applied onto 113 ha of a 146‐ha pinyon‐juniper watershed [Juniperus osteosperma (Torr.) Little and Pinus edulis Engelm., respectively] in north‐central Arizona. Picloram residues in runoff water and soil were monitored. Picloram was detected in runoff water leaving the treated area for 30.5 months after application. The highest concentration, 320 ppbw, was in the initial runoff after treatment. A total of 1.1% of the picloram applied left the treated area in runoff water. Picloram was not detected farther than 5.6 km downstream. The picloram concentration was relatively constant during runoff events unless water from snow melt or from an untreated area mixed with the runoff from the treated area. Less picloram came from an area with individually treated trees than from an area with broadcast application. Dip (grab), single‐stage flood, or splitter‐box water samples all gave comparable picloram contents from the same location with the same runoff event. Picloram was detected in the soils for 44 months, mainly below the 45‐cm depth down to bedrock at 122 cm.

Soil temperatures and regrowth of gorse burnt after treatment with herbicides

Abstract Herbicide treatments were applied to established gorse ( Ulex europaeus L.) 7,4, and 2 months before burning. Time of spraying had no significant effect on the measured parameters. Ten months after burning 46% of the untreated gorse was regrowing compared with 11% of plants treated with 6 kg/ha 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) and 5% of those treated with a mixture of picloram (4-amino-3, 5, 6-trichloropicolinic acid) and 2,4,5-T (1.2 + 4.8 kg/ha). During the burn the temperature profile with time and depth was recorded using thermocouples and a data logger. Soil temperature in the top 2 mm increased by up to 237°C during the fire, but at a depth of 4 cm an increase of only 6°C was recorded at the hottest site. Before the burn there were 2600 seeds/m2 in the top 10 cm of soil compared with 1000 seeds/m2 5 weeks after the burn.

The effect of Tordon 101 herbicide on soil organic matter balance

Forest clearance followed by brush control using Tordon 101 (a mixture of picloram and 2,4-dichlorophenoxyacetic acid), caused a decreased thickness of surface organic matter on power line rights-of-way in northern Ontario. The resultant exposure of mineral soil encourages recolonization by tree seedlings. Surface organic matter loss must therefore be controlled to avoid brush-control problems from seeded-in tree species. Erosion is unimportant in removing litter, but decreased net aerial primary production and hastened organic matter decay following spraying are crucial. Organic matter decomposition is increased because soil temperatures rise when the shading plant canopy is killed by the herbicide. The rise in soil temperature is insufficient, however, to entirely account for the hastened decomposition observed. A low-growing, herbicide-resistant, shade-producing, decay-resistant plant canopy is the ideal as a natural or artificial cover crop for transmission corridors. We conclude that Tordon's capacity to push succession back to an early stage is not related solely to its selective toxicity but also to changes in community metabolism.

Bush control : The control ofbrachystegia boehmiiandcolophospermum mopanein Rhodesia using a picloram/2,4‐d mixture

Abstract Mature Brachystegia boehmii and Colophospermum mopane trees were treated with Tordon 101 (a 1 : 4 mixture of picloram and 2,4‐D) at five rates and at three different times of the year. The arboricide was applied with a syringe to freshly cut stem tissues, either to cuts in the bark, or to the lower lip of ringbarked trees or (in various ways) to cut stumps. Some treatments were repeated at several sites. Responses to arboricide were not markedly influenced by the method of application. Overall, prising the bark from the wood of cut stumps and placing arboricide in the gap so formed, resulted in the highest percentage kills. Applications were most effective in the growing season (November to March). Medium sized trees were more readily killed than smaller or larger ones. Response to arboricide varied between sites.