CAS No. 59756-60-4
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ACTIVITY: Herbicide (unclassified)

CAS Name: 1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone



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Pest Manag Sci. 2005 Mar;61(3):258-68.

Molecular evolution of herbicide resistance to phytoene desaturase inhibitors in Hydrilla verticillata and its potential use to generate herbicide-resistant crops.

Arias RS, Netherland MD, Scheffler BE, Puri A, Dayan FE.

USDA/ARS, Natural Products Utilization Research Unit, PO Box 8048, University, Mississippi 38677, USA.

Hydrilla [Hydrilla verticillata (Lf) Royle] is one of the most serious invasive aquatic weed problems in the USA. This plant possesses numerous mechanisms of vegetative reproduction that enable it to spread very rapidly. Management of this weed has been achieved by the systemic treatment of water bodies with the herbicide fluridone. At least three dioecious fluridone-resistant biotypes of hydrilla with two- to fivefold higher resistance to the herbicide than the wild-type have been identified. Resistance is the result of one of three independent somatic mutations at the arginine 304 codon of the gene encoding phytoene desaturase, the molecular target site of fluridone. The specific activities of the three purified phytoene desaturase variants are similar to the wild-type enzyme. The appearance of these herbicide-resistant biotypes may jeopardize the ability to control the spread of this non-indigenous species to other water bodies in the southern USA. The objective of this paper is to provide general information about the biology and physiology of this aquatic weed in relation to its recent development of resistance to the herbicide fluridone, and to discuss how this discovery might lead to a new generation of herbicide-resistant crops. Copyright 2005 Society of Chemical Industry

PMID: 15668922 [PubMed - in process]


Mol Ecol. 2004 Oct;13(10):3229-37.
Somatic mutation-mediated evolution of herbicide resistance in the nonindigenous invasive plant hydrilla (Hydrilla verticillata).

Michel A, Arias RS, Scheffler BE, Duke SO, Netherland M, Dayan FE.

USDA/ARS, Natural Products Utilization Research Unit, PO Box 8048, University, Mississippi 38677, USA.

Hydrilla (Hydrilla verticillata L.f. Royle) was introduced to the surface water of Florida in the 1950s and is today one of the most serious aquatic weed problems in the USA. As a result of concerns associated with the applications of pesticides to aquatic systems, fluridone is the only USEPA-approved chemical that provides systemic control of hydrilla. After a decrease in fluridone's efficacy at controlling hydrilla, 200 Florida water bodies were sampled to determine the extent of the problem and the biological basis for the reduced efficacy. Our studies revealed that hydrilla phenotypes with two- to six-fold higher fluridone resistance were present in 20 water bodies. Since fluridone is an inhibitor of the enzyme phytoene desaturase (PDS), the gene for PDS (pds) was cloned from herbicide-susceptible and -resistant hydrilla plants. We report for the first time in higher plants three independent herbicide-resistant hydrilla biotypes arising from the selection of somatic mutations at the arginine 304 codon of pds. The three PDS variants had specific activities similar to the wild-type enzyme but were two to five times less sensitive to fluridone. In vitro activity levels of the enzymes correlated with in vivo resistance of the corresponding biotypes. As hydrilla spread rapidly to lakes across the southern United States in the past, the expansion of resistant biotypes is likely to pose significant environmental challenges in the future.

PMID: 15367135 [PubMed - in process]

Applied Clay Science Volume 24, Issues 3-4 , February 2004, Pages 167-175

Third Mediterranean Clay Meeting

Fluridone adsorption–desorption on organo-clays

Dana Yaron-Marcovich, Shlomo Nir and Yona Chen

Department of Soil and Water Sciences, Faculty of Agricultural Food and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel

The adsorption–desorption of the herbicide fluridone on Na-montmorillonite and several organo-montmorillonite complexes was studied at a variety of loadings of the organic cation and pH levels. The aim was to find the organo-clay complex, which would be an optimal adsorbent for the hydrophobic fluridone. The organic cations studied were hexadecyltrimethylammonium (HDTMA), benzyltriethylammonium (BTEA), benzyltrimethylammonium (BTMA) and methylene blue (MB) at loadings equal to 25%, 50% and 100% of the cation exchange capacity (CEC) of the clay-mineral. The adsorbed amount of fluridone increased several-fold when montmorillonite was preadsorbed by the organic cation HDTMA up to its CEC and with BTMA at a loading of 5/8 of the CEC. BTEA and MB did not improve the adsorption capacity of the clay for fluridone. The results suggest that interactions between the phenyl rings of the herbicide and that of a small organic cation are geometrically easier to establish than with a larger organic cation. A reduced interaction between the phenyl rings of MB and those of fluridone may account for the low affinity of fluridone adsorption on montmorillonite-MB. In all cases, fluridone adsorption increased with decreasing pH and reached 100% for pH 2.7. Protonation of fluridone molecules with decreasing pH would result in increased adsorption through cation exchange. Thus, by regulating the pH, complete fluridone adsorption can be achieved. Desorption isotherms demonstrate high degree of irreversibility of the adsorption–desorption process and suggest that strong binding mechanisms dominate the fluridone-clay and organo-clay interactions. The results for fluridone adsorption–desorption demonstrate that, for similar molecules, a clay-based slow release formulation can be designed by first lowering the pH.

Pesticide Biochemistry and Physiology Volume 78, Issue 3 , March 2004, Pages 127-139

Death mechanisms caused by carotenoid biosynthesis inhibitors in green and in undeveloped plant tissues

Jin-Seog Kim (a), Byung-Wook Yun (b), Jung Sup Choi (a), Tae-Joon Kim (a), Sang-Soo Kwak (b) and Kwang-Yun Cho (a)

(a) Biofunction Research Team, Bioorganic Science Division, Korea Research Institute of Chemical Technology (KRICT), P.O. Box 107, Yuseong, Taejeon 305-600, Republic of Korea
(b) Laboratory of Environmental Biotechnology, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Yuseong, Taejeon 305-333, Republic of Korea

This study was carried out to investigate the difference in physiological processes leading to two different responses of albinism and necrosis to the phytoene desaturase inhibitor fluridone, which is dependent on the developmental state of tissue at the time of fluridone treatment. A soil-drench of fluridone solution at the 40% growth of the 3rd leaf of maize (Zea mays L.) caused the leaf to grow into a white/green mixed leaf; completely white in the basal part (W), pale green in the middle part (PG), and green in apical part of the leaf blade (G). In the PG and G, the effective quantum yield of electron transport through photosystem II (Yield) was significantly inhibited, Fv/Fm was decreased but Fo increased, hydrogen peroxide was more accumulated than untreated control, and cellular leakage was faster and more pronounced than in the white tissue (W). In the W, however, all of Fo, Fm, and Yield values were near zero due to loss of chlorophyll. Moreover, there was a relatively low content of hydrogen peroxide, slower cellular leakage and longer survival of tissue in the W. On the other hand, the level of antioxidants such as carotenoids, tocopherols, and ascorbic acid was lower in the W than untreated control. However, the specific activities of antioxidant enzymes were elevated in the W; 3.47 times in superoxide dismutase (SOD), 3.21 times in peroxidase (POD), 1.59 times in catalase and 1.21 times in glutathione reductase. In particular, SOD and POD activities had a tendency to be increased during senescence. In the kinetics experiment carried out during a senescence of the 2nd white leaf, increase of wilting and browning began to occur prior to any significant change in MDA-equivalents, and high reduction of carbohydrate contents occurred prior to increase of wilting and necrosis. Carbohydrate supplement significantly delayed the death of white leaves. Taken together, the above results indicated that in the developed tissue, whose greening has already taken place at the time of herbicide treatment, its death was related to the cell destruction by excessive oxidative stress induced through photosynthetic electron transport blockade. Conversely, in the developing or undifferentiated tissue at the time of herbicide treatment, that eventually grown into a white tissue, its death seemed to be more dependent on a loss of photosystem function followed by carbohydrate deficiency.


Plant Cell Environ. 2003 Jun;26(6):867-874.

Role of abscisic acid in cadmium tolerance of rice (Oryza sativa L.) seedlings.

Hsu YT, Kao CH.

Department of Agronomy, National Taiwan University, Taipei, Taiwan, Republic of China.

Changes in abscisic acid (ABA) contents in Cd-treated rice (Oryza sativa L.) seedlings of two cultivars were investigated. On treatment with CdCl2, the ABA content rapidly increased in the leaves and roots of Cd-tolerant cultivar (cv. Tainung 67, TNG67) but not in the Cd-sensitive cultivar (cv. Taichung Native 1, TN1). The reduction of transpiration rate of TN1 caused by Cd was less than that of TNG67. Exogenous application of ABA reduced transpiration rate, decreased Cd content, and enhanced Cd tolerance of TN1 seedlings. Exogenous application of the ABA biosynthesis inhibitor, fluridone, reduced ABA accumulation, increased transpiration rate and Cd content, and decreased Cd tolerance of TNG67 seedlings. Fluridone effect on Cd toxicity of TNG67 seedlings was reversed by the application of ABA. The roles of endogenous ABA in Cd tolerance of rice seedlings are discussed and suggested.

PMID: 12803614 [PubMed - as supplied by publisher]


Z Naturforsch [C]. 2002 Jul-Aug;57(7-8):671-9.

Bansformation of tobacco with a mutated cyanobacterial phytoene desaturase gene confers resistance to bleaching herbicides.

Wagner T, Windhovel U, Romer S.

Lehrstuhl fur Physiologie und Biochemie der Pflanzen, Universitat Konstanz, Germany.

Carotenoids are constituents of the photosynthetic apparatus and essential for plant survival because of their involvement in protection of chlorophylls against photooxidation. Certain classes of herbicides are interfering with carotenoid biosynthesis leading to pigment destruction and a bleached plant phenotype. One important target site for bleaching herbicides is the enzyme phytoene desaturase catalysing the desaturation of phytoene in zeta-carotene. This enzymatic reaction can be inhibited by norflurazon or fluridone. We have transformed tobacco with a mutated cyanobacterial phytoene desaturase gene (pds) derived from the Synechococcus PCC 7942 mutant NFZ4. Characterization of the resulting transformants revealed an up to 58 fold higher norflurazon resistance in comparison to wild type controls. The tolerance for fluridone was also increased 3 fold in the transgenics. Furthermore, the transformed tobacco maintained a higher level of D1 protein of photosystem II indicating a lower susceptibility to photooxidative damage in the presence of norflurazon. In contrast, the genetic manipulation did not confer herbicide resistance against zeta-carotene desaturase inhibitors.

PMID: 12240995 [PubMed - indexed for MEDLINE]

Full report available at http://sgnis.org/publicat/papers/getsma02.pdf

Lake and Reservoir Management (2002) 18(3): 181-190

Whole Lake Fluridone Treatments for Selective Control of Eurasian Watermilfoil: I. Application Strategy and Herbicide Residues

Getsinger, K.D., J.D. Madsen, T.J. Koschnick, and M.D. Netherland

The herbicide fluridone is being used in northern lakes and reservoirs to control the exotic species Eurasian watermilfoil (Myriophyllum spicatum L.). Since quantitative information linking changes in plant communities following fluridone applications is limited, particularly with respect to water residue records, a study was conducted to investigate the effect of low-dose treatments on the submersed plant communities in four Michigan lakes. The overall study objective was to determine whether plant species diversity and frequency of occurrence were affected by low-dose fluridone applications in the year of treatment. The primary objective of this portion of the overall study was to provide an application strategy that would maintain a threshold dose of fluridone, 5 mug.L-1 declining to 2 mug.L-1, in the treated lakes to selectively control Eurasian watermilfoil. Study lakes were 55 to 220 ha in size and contained an average of nine species of submersed plants. Big Crooked, Camp, Lobdell, and Wolverine lakes were treated in mid-May 1997 with the formulation Sonar(R) AS, to yield an initial concentration of 5 mug.L-1 fluridone in the upper 3.05 m of each lake. A sequential application of Sonar(R)AS was conducted on each lake at 16 to 21 days after initial treatment (DAIT), intended to re-establish a fluridone concentration of 5 mug.L-1 in the upper 3.05 m of each lake. Bass, Big Seven, Clear, and Heron lakes received no fluridone applications and served as untreated reference sites. Water residue samples were collected at prescribed intervals on each fluridone-treated lake from pretreatment up to 81 DAIT. Samples were collected from six littoral stations and from two deep locations throughout each take, and temperature profiles were measured at the deep stations. Fluridone residues were analyzed using two separate techniques, the newly developed enzyme-linked immunosorbent assay and the standard high performance liquid chromatography method. Fluridone levels on three Of the treated lakes met the laboratory-derived criteria for achieving good control of Eurasian watermilfoil by providing a peak concentration of approximately 5 mug.L-1 during the first 2 weeks posttreatment, and by maintaining a concentration >2 mug.L-1 through 60 DAIT. Residues became well mixed in the water column under isothermal conditions, and thermal stratification prevented mixing of fluridone into deeper and colder waters. Residue data indicated that thermal stratification, or the lack thereof, at the time of herbicide application can affect target herbicide concentrations. Using the volume of a pre-selected depth zones to calculate the amount of fluridone needed to achieve a particular target concentration can result in an over- or under-dosing of a water body.

Plant Science Volume 126, Issue 2 , 8 August 1997, Pages 211-218

 Androgenesis in Hordeum vulgare L.: Effects of mannitol, calcium and abscisic acid on anther pretreatment

S. Hoekstra (a), S. van Bergen (a), I. R. van Brouwershaven (a), R. A. Schilperoort (b) and M. Wang (a)

(a) Center for Phytotechnology RUL/TNO, Department of Plant Biotechnology, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands
(b) Center for Phytotechnology, Institute of Molecular Plant Sciences, Leiden University, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands

Pretreatment-induced androgenesis of Hordeum vulgare L. cv. Igri was investigated in order to find factors which control optimal plant production. The influence of what is called pre-medium and of the concentration of both mannitol and calcium were studied. Increasing concentrations of each of the compounds, also resulting in a higher osmolality, improved both embryo like structure (ELS) and plant productions. Optimal ELS production was obtained upon anther pretreatment in about 20 mM CaCl2 while optimal plant production was obtained with anther pretreatment in about 30 mM CaCl2. In addition, it was observed that calcium could be replaced by potassium ions. Since abscisic acid (ABA) is involved in several developmental processes and is known to be induced by various stresses, we studied the effects of ABA and the ABA biosynthesis inhibitor fluridone on the induction of androgenesis. Although external addition of ABA did not significantly affect both ELS and plant productions during pretreatment, addition of fluridone could dramatically reduce the production of plants. The possible mechanism of pretreatment in induction of androgenesis is discussed.

Soil Biology and Biochemistry Volume 26, Issue 6 , June 1994, Pages 689-694

Reduced fluridone efficacy in soil: A possible case for reversible microbial inactivation

Miriam Freund (a), Oded Yarden (b), Rina Varsano (a) and Baruch Rubin (a),

(a) Department of Field Crops, Vegetables and Genetics, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel
(b) Department of Plant Pathology and Microbiology, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel

A reduction in efficacy of the persistent herbicide fluridone has been observed in soils with fluridone application history (FH soils). Fluridone activity, as monitored by bioassay, persisted in FH soils for ca 1 week, whereas in fluridone non-history (FNH) soils phytotoxicity could be observed even after 3 months of exposure. Incorporation of small volumes of FH soil were sufficient to confer rapid loss of herbicidal activity on larger, autoclaved FNH soil volumes. In FH soils exposed to intensive antimicrobial treatments the activity of fluridone was restored to levels similar to those observed in FNH soils. Autoclaving and to a lesser extent, other disinfestation or antimicrobial measures ( irradiation, methyl bromide, several fungicides) used to treat FH soils, exposed test plants to phytotoxic compounds even though the herbicide was not re-applied to the soil. Fluridone adsorption coefficients (Ka) in FH and FNH soils were similar, suggesting that physical adsorption of the herbicide does not play a key role in the observed inactivation of fluridone in FH soil. The possibility of reversible microbial inactivation of fluridone is discussed.

Phytochemistry Volume 30, Issue 3 , 1991, Pages 815-821

Carotenoid metabolism and the biosynthesis of abscisic acid

Andrew D. Parry and Roger Horgan

Department of Biological Sciences, The University College of Wales, Aberystwyth, Dyfed, SY23 3DA, U.K.

The conversion of all-trans-violaxanthin to 9?-cis-neoxanthin was shown to occur in fluridone-treated etiolated Lycopersicon and Phaseolus seedlings, following exposure to light. The results of deuterium oxide labelling experiments supported this precursor/product relationship, and provided further evidence for the origin of abscisic acid. Several apo-carotenoids, putative by-products of abscisic acid biosynthesis, were synthesised by chemical oxidation but were not detected in plant extracts. In vitro, lipoxygenase cleaved neoxanthin and violaxanthin down to small (C13) fragments. It may be that in vivo any apo-carotenoids formed by the specific cleavage of 9?-cis-neoxanthin, during abscisic acid biosynthesis, are rapidly metabolized by lipoxygenase or similar enzymes.


J Assoc Off Anal Chem. 1986 Sep-Oct;69(5):856-9.

Liquid chromatographic determination of fluridone aquatic herbicide and its metabolite in fish and crayfish.

West SD, Day EW Jr.

A residue method is described for determination of the aquatic herbicide fluridone (1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone) and its metabolite (1-methyl-3-(4-hydroxyphenyl)-5-[3-(trifluoromethyl) phenyl]-4(1H)-pyridinone) in fish and crayfish tissues. Both compounds are extracted from tissues with methanol, and the extracts are subjected to acidic hydrolysis to release conjugated forms of fluridone and the metabolite. Sample extracts are purified by liquid-liquid partitioning and Florisil Sep-Pak column chromatography. Both compounds are separated and measured by reverse phase liquid chromatography with UV detection at 313 nm. In the absence of interfering peaks, the method has a detection limit of approximately 0.04 ppm of either compound. Overall, recoveries averaged 96% for fluridone and 78% for the metabolite for all tissue types combined.

PMID: 3771457 [PubMed - indexed for MEDLINE]


Bull Environ Contam Toxicol. 1985 May;34(5):696-701.

No Abstract available

Toxicity of fluridone in algal bioassays.

Trevors JT, Vedelago H.

PMID: 4005449 [PubMed - indexed for MEDLINE]

Pesticide Biochemistry and Physiology Volume 17, Issue 1 , February 1982, Pages 68-75

Degradation of fluridone in submersed soils under controlled laboratory conditions*

[*Published in cooperation with the College of Agriculture Research Center, Washington State University, as Scientific Paper No. 6061.]

L. Y. Marquis, R. D. Comes and C. P. Yang

U.S. Department of Agriculture, Agricultural Research Service, Irrigated Agriculture Research and Extension Center, Prosser, Washington 99350, USA

The experimental, aquatic herbicide fluridone (1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone) was degraded in two submersed soils and in the water above those soils to one acidic metabolite (identified as 1,4-dihydro-1-methyl-4-oxo-5-[3-(trifluoromethyl)phenyl]-3-pyridinecarboxylic acid by mass spectrometry). A sandy and a silt loam soil were treated with [14C]fluridone, immersed in water, and analyzed after 1, 3, 5, 7, 9, and 12 months. Seven to fifteen percent of the 14C applied to the soils was recovered in the water on each of the various collection dates. The acidic metabolite accounted for 86 to 93% of the radioactivity in the water fraction 7 months after treatment. The metabolite was absorbed strongly by both soils and comprised about 60% of the total 14C in each soil after 12 months. The remainder of the 14C in the soils after 12 months was either the parent compound (~30%) or an undefined insoluble residue (~10%).


J Assoc Off Anal Chem. 1980 Nov;63(6):1304-9.

Gas chromatographic determination of fluridone aquatic herbicide and its major metabolite in fish.

West SD, Burger RO.

A gas-liquid chromatographic (GLC) method is described for determining residues of the aquatic herbicide fluridone (1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone) and its major metabolite (1-methyl-3-(4-hydroxyphenyl)-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone) in fish. Both compounds are extracted from fish tissue with methanol, and the extracts are subjected to acidic hydrolysis to release conjugated forms of fluridone and the metabolite. After purification by liquid-liquid partitioning, sample extracts are reacted with methyl iodide to methylate the metabolite, and then both fluridone and the metabolite are brominated with phosphorus tribromide. After purification by Florisil column chromatography, the derivatives are separated and measured by electron capture GLC. The method is capable of determining approximately 0.01 ppm of both compounds in fish, and recoveries have averaged 84 +/- 14.7% for fluridone and 83 +/- 13.4% for the metabolite.

PMID: 7451395 [PubMed - indexed for MEDLINE]


J Agric Food Chem. 1979 Sep-Oct;27(5):1067-72.

No Abstract available

Dissipation of the experimental aquatic herbicide fluridone from lakes and ponds.

West SD, Day EW Jr, Burger RO.

PMID: 575721 [PubMed - indexed for MEDLINE]

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