Determination of 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid in tomato plants and other commercial crops by microcoulometric gas chromatography

A residue method based on microcoulometric gas chromatography is described for 2,4-D and 2,4,5-T in tomato plants and other commercial crops. Intensive cleanup includes extractions with two different buffers and, after conversion of the free acids to the methyl esters, final cleanup is achieved with a Kontes Sweep Co-distillation Apparatus. With a sample weight of 100 g of tomato plant, 0.5 μg can be determined with a recovery of 72 to 96% for 2,4-D and 94 to 100% for 2,4,5-T.     

Persistence of 2,4,5-T in a heavy clay soil

The persistence of the herbicide 2,4,5-T was studied at different controlled temperatures and moisture levels in Regina heavy clay. Degradation approximated to first-order kinetics and the half-life varied from about 4 days at 35°C and 34% soil moisture to about 60 days at 10°C and 20% soil moisture. The laboratory data were used in conjunction with the appropriate measurements of surface soil temperature and moisture content in the field to simulate the degradation pattern for the herbicide in five separate micro-plot experiments. Satisfactory agreement with the observed patterns of loss was obtained in two of the experiments but in the other three, the model over-estimated rates of loss. It is suggested that the reason for this was the difficulty of obtaining a correct measure of soil moisture content to use in the simulation program.     

The effect of herbicides on respiration and transformation of nitrogen in two soils III. Lenacil, terbacil, chlorthiamid and 2,4,5-T

The effects of lenacil, terbacil, chlorthiamid and 2,4,5-T at 100 ppm on carbon dioxide evolution, oxygen uptake and nitrogen transformation in two soils have been investigated for several months in the laboratory. The herbicides had no effect on CO₂ output from either Boddington Barn soil (organic carbon content 1.6%, pH 6.1) or Triangle soil (organic carbon content 3.7%, pH 4.8) apart from 2,4,5-T which reduced it sometimes. All the herbicides caused temporary reductions in O₂. uptake, but in Triangle soil treated with 2,4,5-T a significant reduction was observed during the second half of the incubation. 2,4,5-T and to a lesser extent chlorthiamid, reduced nitrification in Triangle soil. All the herbicides slightly increased mineralization of nitrogen except 2,4,5-T which had variable effects in Triangle soil.     

The movement of 2,4,5-trichlorophenoxyacetic acid into the leaves of Rubus procerus P.J. Muell and its effect on chloroplast ultrastructure

Examination of the fine structure of Rubus procerus leaves following application of 2.4.5-trichlorophenoxyacetic acid a field does shows that the chloroplast is a side of herbicide action and that by 1 week after spraying the leaves show changes indicative of accelerated senescence. Both aqueous and non-aqueous methods were used to isolate chloroplasts following treatment of leaves with radioactive 2.4.5-T. Chloroplast isolation using the non-aqueous method indicated an accmulation of radioactivity in that organelle.     

A review of foliar absorption and translocation of 2,4-D and 2,4,5-T

This review is restricted to an examination of the literature on the environmental and chemical factors that affect foliar absorption and translocation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichloro-phenoxyacetic acid (2,4,5-T) by plants. Most of the papers covered by this review have been published since 1965. Earlier works have been reviewed elsewhere by other authors (Currier & Dybing, 1959; Sargent, 1965; Franke, 1967; Robertson & Kirkwood, 1969; Hull, 1970). Often absorption and translocation of herbicides are considered together; here the two will be considered separately wherever possible.     

The uptake and translocation of 2,4,5-T in gorse (Ulex emopaeus L.)

The uptake of 2,4,5-T by spines of gorse (Ulex europaeus L.) was limited and not enhanced when picloram was added to the application solution. Translocation of 2,4,5-T in 6-month-old cuttings after treatment of a single spine or lateral branch was poor. The most significant accumulation of translocated herbicide occurred in stem tissue, with lesser amounts detected in root tissues, root nodules, stem apices and flowers. Untreated lateral branches or spines accumulated minimal amounts of herbicide. The pattern and extent of distribution of 2,4,5-T was not increased by addition of picloram. The lack of efficient control of gorse by 2,4,5-T can largely be attributed to its inadequate uptake and lack of true systemic translocation.     

Foliar penetration and translocation of 2,4,5-T in blackberry (Rubus procerus P.J. Muell.)

Factors affecting the foliar penetration of 2,4,5-T and the translocation of this herbicide in blackberry (Rubus procerus P.J. Muell). are described. Foliar penetration studies showed that from 38% to 59% of the applied herbicide penetrated into leaves picked respectively in summer and autumn. Leaf uptake of 2,4,5-T was found to be temperature independent in young leaves (Q₁₀, = 1·3) and temperature dependent in older leaves (Q₁₀= 3·5). Some evidence is presented which suggests that this may be caused by the wax content of the cuticle. The herbicide translocated well into the root system of small plants, but probably in sublethal amounts. Penetration foliaire et migration du 2,4,5-T chez la mûre (Rubus procerus P. J. Muell.) L'auteur décrit les facteurs affectant la pénétration du 2,4,5-T et la migration de cet herbicide chez la mûre (Rubus procerus P.J. Muell.). Les recherches sur la pénétration foliaire ont montré que 38%à 59% de l'herbicide appliqué pénétrait dans les feuilles récoltées respectivement enete et en automne. II a été constaté que l'absorption foliaire du 2,4,5-T est indépendante de la température chez les jeunes feuilles (Q₁₀= 1,3) et dépendanle de la température dans les feuilles plus ãgées (Q₁₀= 3,5). Certains faits sont présentés qui suggérent que ce phénoméne peut être cause par la teneur en cire de la cuticule. l'herbicide migre aisément dans le systéme radiculaire des petites plantes, mais probable-ment en quantités sublétales. Blatlpenetration und Translokation von 2,4,5-T in der Brombeere (Rubus procerus P.J. Muell.) Es werden Faktoren beschrieben, die die Blattpenetration von 2,4,5-T und die Translokation dieses Herbizids in der Brombeere (Ruhus procerus P.J. Muell.) beeinflussen. Untersuchungen zur Blattpenetration ergaben, dass 38 bis 59% der angewandten Herbizidmenge in Blätter eindrangen die im Sommer bzw. im Herbst gepflückt wurden. Die Aufnahme von 2,4,5-T über das Blatt war bei jungen Blättern unabhängig von der Temperatur (Q₁₀= 1.3); bei älteren Blättern war sie temperaturabhängig (Q₁₀= 3.5). Es werden einige Befunde dargestellt, die darauf hinweisen, dass dies durch den Wachsgehalt der Kutikula verursacht sein könnte. Das Herbizid wurde gut in das Wurzelsystem kleiner Pflanzen transloziert, wahrscheinlich aber in sublethalen Mengen.     

A simple method for the analysis of picloram and 2,4-D or 2,4,5-T in mixtures and commercial formulations

A method is described for the analysis of mixtures of picloram with 2,4-D or 2,4,5-T in commercial formulations. The method involves the esterification of the acids in sealed tubes at 105°C using boron trifiuoride-methanol reagent, followed by extraction, and then estimation by gas chromatography using flame ionisation detection.     

Foliar absorption and translocation of fosamine and 2,4,5-T in blackberry (Rubus proceras P. J. Muell.)

Fosamine (ammonium ethyl carbamoylphosphonate) formulated as a 1% w/v solution in 0–25%v/v Tween 20 was absorbed slowly by detached leaves of Rubus procerus P.J. Muell., 35% of the applied herbicide being absorbed after 96 h. Fosamine does not appear to be rainfast, as up to 80% of the applied herbicide and 99.9% of the removable herbicide were removed from the leaves by washing for 5 min in distilled water. Translocalion of fosamine was rapid in small R. procerus plants and followed a pattern similar to that taken by assimilates: 2,4,5–T did not translocate to the root system as readily as fosamine or assimilates.     

Mixtures of picloram and 2,4,5-T for the control of blackberry (Rubus fruticosus L. agg.)

The effectiveness of‘Tordon 50-d’(5% a.i. picloram plus 20% a.i. 2,4-D both as the triisopropanolamine salts) and various mixtures of 2,4,5-T and picloram were tested for the control of blackberry (Rubus fruticosus L. agg.) in Victoria, Australia. A high correlation was obtained between the % reduction in live canes and the % kill of crowns 13 months after Rubus procerus P.J. Muell. thickets were sprayed with 2,4,5-T or‘Tordon 50-d'. Counting the number of live canes is, therefore, a convenient method of comparing the efficacy of these herbicides for the control of blackberry. ‘Tordon 50-d’was generally more effective than 2,4,5-T but stimulation of suckering from roots was recorded at one site when low rates of‘Tordon 50-d’were used. It was necessary to add high dose rates of‘Tordon 50-d’to 2,4,5-T before there were worthwhile improvements in weed control.‘Tordon 5–20’(5% a.i. picloram as triisopropanolamine salt plus 20% 2,4,5-T as the ethyl hexyl ester) was only slightly more effective in controlling blackberry than‘Tordon 50-d'. The cost and soil residue problems associated with picloram should limit its use as an additive to 2,4,5-T for the control of blackberry in Australia.     

Determination of sugarbeet herbicides in soil samples by hplc

Determination of sugarbeet herbicides such as chloridazon, metamitron and phenmedipham in soil samples is described. After extraction with acetone, pesticides were determined by HPLC on an RP-18 column using methanol/water as mobile phase. Average recoveries were 82% for chloridazon, 93% for metamitron and 77% for phenmedipham. Quantification limits were 3·5 μg kg^?1 for chloridazon, 6·3 μg kg^?1 for metamitron and 3·6 μg kg^?1 for phenmedipham.     

Effect of concentration on absorption and translocation of 2,4,5-T in blackberry (Rubus procerus P. J. Muell.)

Radioactive 2,4,5-T was applied to the leaves of small Rubus precerus (P. J. Muell.) plants grown in pots in the glasshouse in amounts ranging from 24 μg to 55.8 μg per leaf. The amount of 2,4,5-T absorbed and translocated was measured 6h and 24h later. The herbicide was translocated throughout the plant within 6h and the concentration in the various plant parts increased between 6h and 24h. More 2,4,5-T was absorbed at high concentrations than at low concentrations although the percentage absorbed in 24h decreased from 13% to 6% as the concentration was increased Translocation of 2,4,5-T-1-14C was variable, although the amount translocated inereased as the amount applied was increased, and was closely correlated to the amount of herbicide absorbed by the leaves.     

Determination of residual 2,4,5-T in vegetables by high performance liquid chromatography with ultraviolet and fluorometric detection after derivatization with 2-(2,3-naphthalimino)ethyl trifluoromethanesulfonate (NE-OTf)

2,4,5-T was extracted with acetone at below pH 1·0 and the extract was concentrated. After adding 100 g litre^-1 sodium chloride solution to the residual solution, 2,4,5-T was extracted with ethyl acetate+hexane (20+80 by volume). The extract was evaporated to dryness and the residue was dissolved in acetonitrile. 18-crown-6, potassium fluoride and NE-OTf were added to the acetonitrile solution and then allowed to react at 50°C for 20 min. The product was injected to a HPLC with ultraviolet detection operated at 259 nm and fluorometric detection at 394 nm emission and 259 nm excitation. The determination limits of the 2,4,5-T derivative in the sample were 20 μg litre^-1 with UV detection and 10 μg litre^-1 with fluorometric detection. © 1997 SCI.     

Residues in blackcurrants,fodder peas,spinach and potatoes treated with sublethal doses of 2,4,5-T to simulate wind drift damage

Blackcurrants, treated with 0.1 kg of 2,4,5-T ha^?1 (as esters of mixed C₄–C₆ alcohols; ‘Tormona 80’), contained 0.1 mg of 2,4,5-T residues kg^?1 in the berries at ripeness 29 days after treatment. Total residues in the berries were not reduced during growth and ripening, although the residue concentrations declined in the same period due to growth dilution. In spinach leaves from old plants, treated with 0.1 kg ha^?1, 0.05 mg of 2,4,5-T kg^?1 was found 14 days after treatment. Fodder peas showed no residues (< 0.002 mg kg^?1) at harvest 62 days after treatment with 2,4,5-T esters. After application of 0.1 kg ha^?1 on potato plants, the disappearance of 2,4,5-T was rapid during the first month, but residues were translocated into the tubers and reached a constant level of 0.02 mg kg^?1 after 1 month until harvest at 108 days after treatment. In all crops, visible effects were observed after treatment with 0.1 kg ha^?1. After the application at 0.01 kg ha^?1, phytotoxic effects were observed only in blackcurrants, but negligible residues were found in all the test crops.     

Relative persistence of di-and tri-chlorophenoxyalkanoic acid herbicides in Saskatchewan soils

The persistence of 2,4-D, 2,4-DB, dichlorprop, 2,4,5-T, and fenoprop at the 2 ppm level was studied in the laboratory on three prairie soils at 85% of field capacity and 20°C. Following extraction of the soils with aqueous acetonitrile containing acetic acid, the herbicidal acids remaining were analysed gas chromatographically. Breakdown was rapid on all soils and the average half-lives for 2,4-D, 2,4-DB, dichloroprop, 2,4,5-T, and fenoprop were < 7, < 7, 10, 12, and 12 days respectively. Degradation on air-dried soils (15% of field capacity) was negligible with over 85% of the applied herbicides being recoverable after incubation periods during which the herbicides remaining in the moist soils accounted for less than 30% of the original treatments. Persistance relative des acides di et tri-chlorophénoxy-alkanoï-ques herbicides dans des sols du Saskatchewan. La persistance du 2,4-D, du 2,4-DB, du dichlorprop, du 2,4,5-T et du fénoprop, à la concentration de 2 ppm, a étéétudiée au laboratorire, sur trois sols de prairie, a 85% de la capacité au champ et a 20°C. Après leur extraction des sols par l'acétonitrile aqueux contenant de l'acide acétique, les acides herbicides restants ont été analysés par chromatographie en phase gaseuse. La dégradation a été rapide pour tous les sols et les demi-vies moyennes du 2,4-D, du 2,4-DB, du dichlorprop, du 2,4,5-T, et du fénoprop ont été respectivement de <7, <7, 10, 12 et 12 jours. La dégradation sur des sols séchés a l'air (15% de la capacité au champ), a été négligeable, plus de 85% des quantités d'herbicides appliquées étant récupérables après des périodes d'incubation durant lesquelles les herbicides restant dans les sols humides ne représentaient plus que moins de 30% des quantités apportées à l'origine. Relative Persistenz von Di-und Trichlorphenoxyalkansäure-Her-biziden in Böden Saskatchewan In Laborversuchen wurde die Persistenz von 2,4-D, 2,4-DB, Dichlorprop, 2,4,5-T und Fenoprop in drei Prärieböden festgestellt. Die Versuche wurden bei 20°C, 85 % der Feldkapazität und einem anfänglichen Herbizidgehalt der Böden von 2 ppm durchgeführt. Die Extraktion der Böden erfolgte mit wässerigem Acetonitril mit einem geringen Anteil an Essigsäure. Die Herbizide wurden gaschromatographisch nachgewiesen. In allen Böden wurde ein schneller Abbau festgestellt. Die Halbwertszeiten betrugen für 2,4-D, 2,4-DB, Dichlorprop, 2,4,5-T und Fenoprop < 7, < 7,10, 12 bzw. 12Tage. Der Abbau im lufttrockenen Boden (15% der Feldkapazität) war zu vernachlässigen. Hier waren noch mehr als 85% der ausgebrachten Herbizidmenge vorhanden, wenn in den feuchten Böden die Konzentration bereits weniger als 30% betrug.     

Effect of s-triazine and phenoxyalkanoic acid herbicides on UDP-glucuronosyltransferase in rat liver microsomes

Twelve herbicides, representatives of two chemical groups, substituted phenoxyalkanoic acids and s-triazines, were tested for their inhibitory effect on the glucuronidation of 4-nitrophenol (4-NP), phenolphthalein (PPh) and 4-methylumbelliferone (4-MU) by rat liver microsomes. One millimole MCPA, ametryn and cyanazine significantly decreased PPh UDP-glucuronosyltransferase (UGT) activity, while propazine was found to be a most potent inhibitor of 4-NP glucuronidation. Concentrations of 0.1 mM dichlorprop and cyanazine were still inhibitory against PPh-UGT. The inhibition of 4-MU glucuronidation by the herbicides was low and not specific. As a whole, s-triazine derivatives were more inhibitory than the substituted phenoxyalkanoic acids. Kinetic studies with propazine revealed a non-competitive type of inhibition towards the acceptor substrate 4-NP, with an apparent K_i value of 0.540 mM . With ametryn, an uncompetitive type of inhibition against PPh and a mixed type of inhibition towards UDPGA were found, with apparent K_i values of 0.330 mM and 0.380 mM , respectively. © 1999 Society of Chemical Industry     

Effect of 2,4,5-T and picloram on the regeneration of blackberry (Rubus procerus P.J. Muell) from root segments

The formation of roots and shoots on root segments of Rubus procerus P.J. Muell was prevented by soaking the segments for 24 h in a 10^?4M solution of 2,4,5-T or a 10^?5M solution of picloram. Shoot numbers were significantly increased after treatment with 10^?9M and 10^?10M 2,4,5-T, but picloram did not cause a significant increase in shoot numbers. Measurement of the concentration of 2,4,5-T in the extracambial tissue showed that roots treated with 10^?4M 2,4,5-T contained 5× 10^?8 mmole 2,4,5-T per mg dry weight, and by extrapolation, roots treated with 10^?9M 2,4,5-T contained 2× 10^?10 mmole/mg dry weight. Action du 2,4,5-T et du piclorame sur la régénération de la ronce (Rubus procerus P.J. Muell) è partir de fragments de racines La formation de racines et de tiges è partir de fragments de racines dc Ruhus procerus P.J. Muell a été supprimée par trempage des fragmenls pendant 24 heures dans une solution a 10^?4M et de 2.4,5-T, ou dans une solution 10^?5M de piclorame. Le nombre de pousses s'est accru significativement après traitement avec le 2,4,5.-T è 10^?9M et 10^?10M, mais le piclorame n'a pas provoqué d'accroissemcnt significatif du nombre de pousses. La mesure de la concentration de 2,4,5-T dans le tissu extra-cambial a montré que les racines trailées avec du 2,4,5-T è 10^?4M contenaient 5×10^?8 mmole de 2.4,5-T par mg de poids sec et par extrapolation, quc les racines traitées avec du 2,4,5-T k 10^?9M devaient contenir 2 × 10^?12 mmole/mg de poids sec. Die Wirkiing von 2,4,5-T und Picloram auf den Wuchs der Wurzehegmenten von Bromheeren (Rubus procerus P.J. Muell). Die Bildung von Wurzeln und Sprossen aus Wurzelsegmen-ten von Ruhu.i procerus P.J. Muell wurde durch 24-stündiges Einlegen der Wurzelstücke in 10^?4M 2,4,5-T bzw 10^?5M Picloram verhindert. Die Anzahl neugebiideter Sprosse wurde nach Einlegen in 10^?9M und 10^?10M 2,4,5-T, nicht jedoch durch Picloram, signifikant erhöht. Im extracambialen Gewebe von Wurzeln, die mit 10^?4M 2,4,5-T behand-elt worden waren, wurden 5×10^?8mMol 2,4,5-T je mg Trockengewiclu bestimmt. Durch Extrapolation wurde ermittclt. dass mit 10^?9M 2,4,5-T behandelte Wurzeln 2× 10^?12mMol/mg Trockengewicht cnthielten.     

The action of herbicides on fatty acid biosynthesis and elongation in barley and cucumber

BACKGROUND: Herbicides that affect lipid metabolism have been used commercially for many years. Here, napropamide, diphenamid, dimethachlor and cafenstrole are compared; these have all been classified by the Herbicide Resistance Action Committee (HRAC) as K₃ herbicides and inhibitors of cell division and/or synthesis of very‐long‐chain fatty acids (VLCFAs). In addition, spiro‐decanedione A and pinoxaden dione are compared as inhibitors of lipid synthesis through inhibition of acetyl‐CoA carboxylase (ACCase). RESULTS: Whereas the chloracetamide dimethachlor and the carboxyamide cafenstrole potently inhibited VLCFA synthesis in both barley and cucumber, the acetamides napropamide and diphenamid which are also classified as K₃ herbicides and likewise the unclassified herbicide cinmethylin did not. The graminicide pinoxaden dione inhibited de novo fatty acid synthesis in barley, but not in cucumber, and correspondingly inhibited the plastid form of maize ACCase much more than the cytosolic form (IC₅₀ values of 0.1 and 17 µM ). By contrast, spiro‐decanedione A exhibited herbicidal effects not only on grasses but also on broad leaves, strongly inhibited maize cytosolic ACCase and inhibited synthesis of VLCFAs in cucumber. CONCLUSIONS: The acetamides napropamide and diphenamid, which do not inhibit VLCFA synthesis, should be classified separately from K₃ herbicides that do. Pinoxaden dione and spiro‐decanedione A represent new classes of chemicals acting on plant lipid synthesis. Copyright © 2010 Society of Chemical Industry     

Effect of maleic hydrazide and 2,4,5-trichlorophenoxy propionic acid on ripening and quality of mango fruit

Dipping in hot water accelerated the ripening process and reduced fungal spoilage in Mangifera indica cv. Pairi mangoes. Accelerated ripening was counteracted by incorporation of maleic hydrazide (MH) in the dip water, thereby extending the storage life with minimum fungal spoilage. 2,4,5-Trichlorophenoxy propionic acid (2,4,5-TP) also delayed the ripening process, but did not improve skin colour. Hot water treatment with or without MH and 2,4,5-TP increased the carotene content of the flesh. These compounds did not significantly alter the chemical composition or quality of the fruit.