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Fomesafen. TOXNET profile from Hazardous Substances Data Base.


See for Updates: http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB

FORMESAFEN
CASRN: 72178-02-0
For other data, click on the Table of Contents

Human Health Effects:

Skin, Eye and Respiratory Irritations:

Mild skin irritant; mild to moderate eye irritant (rabbits).
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 521]**PEER REVIEWED**


Probable Routes of Human Exposure:

Occupational exposure to fomesafen may occur through inhalation of spray mists and aerosols and dermal contact with this herbicide during or after its application or at workplaces where fomesafen is produced. (SRC)
**PEER REVIEWED**


Emergency Medical Treatment:

Animal Toxicity Studies:

Non-Human Toxicity Excerpts:

In the present paper we describe needle-shaped and granular cytoplasmic inclusions in the liver cells of mice and rats with experimental porphyria biochemically resembling human porphyria cutanea tarda. The inclusions were inconspicuous in routine histological slides. The ferric ferricyanide reduction reaction, however, enabled us to demonstrate their shape and location within the hepatic lobule. Needle-shaped inclusions are considered to represent a structure specifically seen in experimental porphyrias resembling porphyria cutanea tarda. These structures are similar to the inclusions seen in human porphyria cutanea tarda.
[Fakan F et al; Exp Toxicol Pathol 49 (3-4): 289-93 (1997)]**PEER REVIEWED**

The results of quantitative structure-activity relationship (QSAR) analysis on a structurally diverse group of peroxisome proliferators are reported. The relative potencies of 11 peroxisome proliferators (with respect) to clofibric acid) for induction of palmitoyl-CoA oxidation in rat hepatocyte cultures appear to be determined by a combination of lipophilicity (logP descriptor) and calculated binding affinity (logK) to a model of the mouse liver peroxisome proliferator-activated receptor alpha (mPPARalpha) ligand-binding domain. It is possible that desolvation of the putative binding site and ligand ionization may also play a role in activation of the mouse liver peroxisome proliferator-activated receptor alpha.
[Lewis D FV and BG Lake; Toxicology In Vitro 11 (1-2): 99-105 (1997)]**PEER REVIEWED**

Field studies were conducted to determine rhizomatous johnsongrass and barnyardgrass control with clethodim, quizalofop-P-ethyl, fluazifop-P, sethoxydim, fenoxaprop-ethyl, and quizalofop-P-tefuryl applied alone and with lactofen, imazaquin, chlorimuron, and formesafen. Graminicides applied alone controlled johnsongrass and barnyardgrass 83 to 99%. Of the graminicides evaluated, clethodium was the most antagonistic of the broadleaf herbicides toward the activity of graminicides. Clethodim mixed with imazaquin reduced johnsongrass control as much as 64% and mixed with chlorimuron reduced barnyardgrass control as much as 52%. Quizalofop-P-tefuryl was least affected by broadleaf herbicides and formesafen was least antagonistic in mixtures with graminicides.
[Vidrine PR et al; Weed Technology 9 (1): 68-72 (1995)]**PEER REVIEWED**

The effect of the protoporphyrinogen oxidase-inhibiting herbicide formesafen on liver porphyrin accumulation was studied in long-term high-dose experiments. Formesafen caused liver accumulation of uroporphyrin and heptacarboxylic porphyrin when fed at 0.25% in the diet to male ICR mice for 5 mos. (Formesafen-treated mice: 52 nmol uroporphyrin, 21 nmol heptacarboxylic porphyrin/g liver; control mice: traces of uroporphyrin, heptacarboxylic porphyrin not detected). Uroporphyrinogen decarboxylase activity was depressed to about 25% of control values. Iron treatment accelerated the development of this porphyria cutanea tarda-like experimental porphyria both in ICR and C57B1/6J mice. In contrast to other uroporphyrinogen decarboxylase inhibitors, formesafen treatment did not increase the cytochrome P450IA-related activities and the amount of P450IA2 protein was shown to be significantly decreased by Western immunoblotting. Thus, formesafen is a unique chemical that inhibits both the oxidation of protoporphyrinogen as well as the conversion of uroporphyrinogen to caproporphyrinogen. However, the accumulation of highly carboxylated porphyrins is evident only after prolonged treatment with high doses of the herbicide.
[Krijt J et al; Food and Chemical Toxicology 32 (7): 641-649 (1994)]**PEER REVIEWED**

One important factor which may influence the extent and rate of percutaneous absorption is the dosing vehicle. The purpose of the experiments described was to compare the effect of dosing vehicles of different polarities on the absorption of two herbicides across rat skin in vivo. Rats were dosed dermally with either fluazifop-butyl (logP(oct) 4.5) or formesafen sodium salt (logP(oct) -1.2) in propylene glycol (PG), octanol (OCT), or ethyl decanoate(ED), and the amount of radioactivity excreted in urine was determined. Absorption rates were estimated from the urinary excretion data and from blood kinetic data derived from intravenously dose rats. For fluazifop-butyl the average rate of absorption (x10(-2) ug/hr-1 +/- SE) was not greatly influenced by the dosing vehicle (octanol, 2.94 +/- 0.08; ethyl decanoate 3.66 +/- 0.10; propylene glycol, 3.95 +/- 0.32) despite relatively large differences in solubility (propylene glycol, 38 mg/ml; octanol,and ethyl decanoate, > 600 mg/ml). These results were consistent with the finding that there was at most only a twofold difference in the epidermal membrane:vehicle partition coefficients (km). In contrast, the absorption rate of formesafen from propylene glycol (1.98 +/- 0.04) was approximately half that of ethyl decanoate (3.98 +/- 0.06) and octanol (4.49 +/- 0.08) for the first 30 hr after application and was in keeping with solubility data (propylene glycol, 638 mg/ml; octanol, 12 mg/ml; ethyl decanoate, < 10 mg/ml). At later time points the absorption of formesafen from propylene glycol increased; this is discussed in relation to the penetration-enhancing properties of propylene glycol.
[Rawlings JM et al; Fundam Appl Toxicol 23 (1): 93-100 (1994)]**PEER REVIEWED**

Carryover potential of imazaquin (0.14 kg ai/ha), chlorimuron plus metribuzin (0.06 + 0.36 kg/ha), and formesafen (0.28 kg/ha) to snap bean, watermelon, cucumber, mustard, and sunflower was evaluated in Arkansas in 1987 to 1989. Crops were direct-seeded into treated plots at various times after application. Imazaquin and chlorimuron plus metribuzin injured sunflower, watermelon, cucumber, and mustard when planted 16 wk following application in one of two years. Formesafen injured all crops initially but did not injure snap bean, sunflower, watermelon, and cucumber planted 16 wk after application. In experiments in which herbicides were applied to soybean, fall-planted spinach and mustard were injured in one of two years.
[Johnson DH and RE Talbert; Weed Technology 7 (3): 573-577 (1993)]**PEER REVIEWED**

The effects of the herbicides formesafen oxyfluorfen, oxadiazon, and fluazifop-butyl on porphyrin accumulation in mouse liver, rat primary hepatocyte culture and HepG2 cells were investigated. Ten days of herbicide feeding (0.25% in the diet) increased the liver porphyrine in male C57B1/6J mice from 1.4 +/- 0.6 to 4.8 +/- 2.1 (formesafen) 16.9 +/- 2.9 (oxyfluorfen) and 25.9 +/- 3.1 (oxadiazon) nmol/g wet weight, respectively. Fluazifop-butyl had no effect on liver porphyrin metabolism. Formesafen, oxyfluorfen and oxadiazon increased the cellular porphyrin content of rat hepatocytes after 24 hr of incubation (control, 3.2 pmol/mg protein, formesafen, oxyfluorfen and oxadiazon at 0.125 mM concentration 51.5, 54.3 and 44.0 pmol/mg protein, respectively). The porphyrin content of HepG2 cells increase from 1.6 to 18.2, 10.6 to 9.2 pmol/mg protein after 24 hr incubation with the three herbicides. Fluazifop-butyl increased hepatic cytochrome P450 levels and ethoxy- and pentoxyresorufin O-dealkylase (EROD and PROD) activity, oxyfluorfen increased pentoxyresorufin O-dealkylase activity. Peroxisomal palmitoyl CoA oxidation increased after formesafen and fluazifop treatment to about 500% of control values both in mouse liver and rat hepatocytes. Both rat hepatocytes and HepG2 cells can be used as a test system for the porphyrogenic potential of photobleaching herbicides.
[Krijt J et al; Arch Toxicol 67 (4): 255-261 (1993)]**PEER REVIEWED**

1. The three-dimensional structure of a portion of the ligand-binding domain of the mouse liver peroxisome proliferator-activated receptor (PPAR) described by Issemann and Green (1990) has been modelled from amino acid sequence data. 2. By inspection of the three-dimensional structure of the portion of the peroxisome proliferator-activated receptor ligand-binding domain, a putative binding site for peroxisome proliferation, consisting of one isoleucine, one lysine and two phenylalanine moieties (residues 354, 358, 359 and 361, respectively), has been identified. 3. The interaction of 12 peroxisome proliferators with the putative peroxisome proliferator-activated receptor binding site has been investigated and energetics of binding calculated from ligand-bound and ligand-free receptor geometries. 4. The interaction data have been used to establish quantitative structure-activity relationships (QSARs) between peroxisome proliferator binding and either peroxisome proliferator-activated receptor activation in COS1 cells or induction of palmitoyl-CoA oxidation in rat hepatocyte cultures. 5. The results are discussed in terms of the role of peroxisome proliferator-activated receptor in the mechanism of initiation of peroxisome proliferation in rodent liver.
[Lewis D FV and BG Lake; Xenobiotica 23 (1): 79-96 (1993)]**PEER REVIEWED**

Two field experiments were established in 1988 and 1989 in southeast Missouri to evaluate several herbicides and herbicide combinations for giant ragweed control in soybean. In 1988, a timely rainfall was not received for soil-applied herbicides and giant ragweed control was less than 75%. However, in 1989 soil moisture was sufficient for uptake of soil-applied herbicides and early season giant ragweed control was generally greater than 80%. Chlorimuron, chlorimuron plus 2,4-DB, (4-(2,4-dichlorophenoxy)butanoic acid) imazaquin plus 2,4-DB, acifluorfen followed by naptalam plus 2,4-DB, formesafen, and imazethapyr applied to 2.5 to 5 cm giant ragweed controlled more than 85% in 1988. In 1989, all POST treatments except imazaquin controlled more than 8.1% of giant ragweed 2 wk after treatments. Imazethapyr controlled seedling giant ragweed at heights up to 12-25 cm. Giant ragweed regrowth and/or reinfestation and giant ragweed seed production occurred with all herbicide treatments.
[Baysinger JA and BD Sims; Weed Technol 6 (1): 13-18 (1992)]**PEER REVIEWED**

Field studies were conducted from 1986 through 1988 to evaluate various herbicides for yellow nutsedge control and peanut yields. Three applications of pyridate provided control comparable to two applications of bentazon with yellow nutsedge regrowth beginning 3 to 4 wk after application depending on moisture conditions. Crop oil concentrate did not improve the activity of pyridate. Flurtamone provided control comparable with that of metolachlor. Nutsedge control with formesafen was erratic with peanut injury noted. peanut yields did not reflect the competitive nature of nutsedge.
[Grichar WJ; Weed Technol 6 (1): 108-112 (1992)]**PEER REVIEWED**

Field studies were conducted at three locations in Louisiana (USA) over two years to evaluate mid-season, foliar-applied acifluorfen, formesafen, and lactofen for hemp sesbania control in soybean. Acifluorfen and formesafen were applied POST at 30, 40, 50, 60, 70, 140, and 280 g ai/ha. The data fit a quadratic model and log transformations were made to determine differences between treatments. Hemp sesbania control was highly correlated with herbicide rate for each herbicide. Averaged over rates of application, acifluorfen, and formesafen provided equivalent control of hemp sesbania, which was greater than that achieved with lactofen. The minimum effective rate of acifluorfen or formesafen for 80 and 100% control of 50- to 60-cm hemp sesbania was 50 and 140 g ai/ha, respectively. The minimum effective alctofen rate to provide at least 80% control was 220 g/ha.
[Vidrine, PR et al; Weed Technol 6 (2): 374-377 (1992)]**PEER REVIEWED**

Field studies were conducted to identify herbicides suitable for improved control of hairy nightshade, redroot pigweed, and common lambsquarters in pinto beans. Formesafen at 0.25 kg ai/ha did not adequately control these weeds. Clomazone at 0.5 kg ai/ha controlled common lambsquarters but only suppressed the growth of redroot pigweed and hairy nightshade. Ethalflurlin at 0.8 to 1.1 kg ai/ha gave excellent initial control of these weeds but did not control later flushes of hairy nightshade. Imazethapyr applied PPI or POST at 50 to 75 g ai/ha controlled hairy nightshade, redroot pigweed, and common lambsquarters throughout the growing season. Imazethapyr combined with ethalfluralin gave superior weed control and resulted in greater yields than the most commonly used herbicides in pinto beans in western Canada.
[Blackshaw RE and R Esau; Weed Technol 5 (3): 532-538 (1991)]**PEER REVIEWED**

Research was conducted to determine the tolerance of flue-cured tobacco to formesafen and the potential for weed control in tobacco with formesafen. Treatments consisted of formesafen at 0.4 or 0.6 kg ai/ha applied pretransplant incorporated (PTI), pretransplant (PRE-T), post-transplant (POS-T), postemergence over-top (POT), or post-directed (PD). Tobacco injury within 30 days of application was as high as 30%, but tobacco recovered and few significant differences in tobacco yield, grade index, or prices were observed except where formesafen was applied pretransplant incorporated at 0.6 kg/ha. Tobacco tolerance relative to time of application was generally pretransplant = postemergence over-top > post-transplant = pretransplant incorporated. Florida pusley and large crabgrass control was > 80% for all formesafen treatments. Yellow and purple nutsedge control was approximately 30% before cultivation.
[Bridges DC and MG Stephenson; Weed Technol 5 (4): 868-872 (1991)]**PEER REVIEWED**

The postemergence-active herbicides lactofen, formesafen, and acifluorfen were applied to established matted-row strawberry plants (Fragaris x annanassa) and evaluated for broadleaf weed control and foliar phytotoxicity. Strawberries were evaluated for yield and fruit quality. Treatments were applied following June renovation. All herbicide treatments resulted in acceptable control of broadleaf weeds present at the time of application; however, sicklepod (Cassia obtusifolia) germinated after herbicide application. All treatments caused foliar development. Formesafen and acifluorfen were the only herbicides to suppress runner count. Yield the following year were not reduced by herbicide treatments.
[Caylor AW et al; J Am Soc Hortic Sci 116 (4): 669-671 (1991)]**PEER REVIEWED**

The response of crop and weed species to herbicides within the same family may vary considerably. The detrimental effect of late seedling of soybeans (Glycine max (L.) Merr.) is expressed as a reduction in individual plant yield components. Any temporary suppression in plant growth due to herbicides may cause additional yield reductions. Field studies were conducted to determine the response of 15 weed species and soybeans to acifluorfen, formesafen, and lactofen, and the effect of these herbicides on foliar injury and seed yields of determinate soybeans when seeded at post-optimal dates. Herbicides were applied to weeds and soybeans at 3 wk after seeding and to soybeans in the V4 to V5 stage when grown under weed-free conditions. Weed control was similar with all three herbicides. Differences observed in weed control among herbicides appeared to be of little practical importance. Soybeans exhibited differential herbicides tolerance (formesafen > acifluorfen > lactofen ). Soybean injury increased as rates of acifluorfen and lactofen increased, but was not affected by increasing rates of formesafen. Soybean seed yields were not reduced by herbicides. Determinate soybeans seed at post-optimal dates appear to recover from foliar injury caused by these herbicides and seed yields are not affected.
[Harris JR et al; J Prod Agric 4 (3): 407-411 (1991)]**PEER REVIEWED**


Non-Human Toxicity Values:

LD50 Rat (male) oral 1250-2000 mg/kg
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 521]**PEER REVIEWED**

LD50 Rat (female) oral 1600 mg/kg
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 521]**PEER REVIEWED**


Ecotoxicity Values:

LD50 Mallard ducks oral >5000 mg/kg
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 521]**PEER REVIEWED**

LC50 Salmo gairdneri (rainbow trout) 680 mg/l/96 hr
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 521]**PEER REVIEWED**

LC50 Lepomis macrochirus (bluegill sunfish) 6030 mg/l/96 hr
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 521]**PEER REVIEWED**


Metabolism/Pharmacokinetics:

Absorption, Distribution & Excretion:

The use of organofluorine compounds has increased throughout this century, and they are now ubiquitous environmental contaminants. Although generally viewed as recalcitrant because of their lack of chemical reactivity, many fluorinated organics are biologically active. Several questions surround their distribution, fate, and effects. Of particular interest is the fate of perfluoroalkyl substituents, such as the trifluoromethyl group. Most evidence to date suggest that such groups resist defluorination, yet they can confer significant biological activity. Certain volatile fluorinated compounds can be oxidized in the troposphere yielding nonvolatile compounds, such as trifluoroacetic acid. In addition, certain nonvolatile fluorinated compounds can be transformed in the biosphere to volatile compounds. Research is needed to assess the fluorinated impurities present in commercial formulations, and the transformation products generated by biochemical processes and/or oxidation in the troposphere.
[Key BD et al; Environmental Science & Technology 31 (9): 2445-2454 (1997)]**PEER REVIEWED**


Mechanism of Action:

Using extracts from suspension-cultured cells of soybean (Glycine max cv. Mandarin) as a source of active enzymes, the activities of glutathione transferases (GSTs) catalyzing the conjugation of 1-chloro-2,4-dinitrobenzene (CDNB) and selective herbicides were determined to be in the order 1-chloro-2,4-dinitrobenzene-ethyl. glutathione transferase activities showed a thiol dependence in a substrate-specific manner. Thus, glutathione transferase activities toward acifluorfen and formesafen were greater when homoglutathione (hGSH), the endogenously occurring thiol in soybean, was used as the co-substrate rather than glutathione (GSH). Compared with glutathione, homoglutathione addition either reduced or had no effect on glutathione transferase activities toward other substrates. In the absence of enzyme, the rates of homoglutathione conjugation with acifluorfen, chlorimuron-ethyl and formesafen were negligible, suggesting that rapid homoglutathione conjugation in soybean must be catalyzed by glutathione transferases. glutathione transferase activities were subsequently determined in 14-day-old plants of soybean and a number of annual grass and broadleaf weeds. glutathione transferase activities of the plants were then related to observed sensitivities to post-emergence applications of the four herbicides. When enzyme activity was expressed on a mg-1 protein basis, all grass weeds and Abutilon theophrasti contained considerably higher glutathione transferase activity toward CDNB than soybean. With formesafen as the substrate, glutathione transferase activities were determined to be in the order soybean Digitaria sanguinalis > Sorghum halepense = Setaria faberi with none of the broadleaf weeds showing any activity. This order related well to the observed selectivity of formesafen, with the exception of A. theophrasti, which was partially tolerant to the herbicide. Using metolachlor as the substrate the order of the glutathione transferase activities was soybean > A. theophrasti Amaranthus retroflexus > Ipomoea hederacea, with the remaining species showing no activity. glutathione transferase activities toward metolachlor correlated well with the selectivity of the herbicide toward the broadleaf weeds but not toward the grass weeds. Acifluorfen and chlorimuron-ethyl were selectively active on these species, but glutathione transferase activities toward these herbicides could not be detected in crude extracts from whole plants.
[Andrews CJ et al; Pesticide Science 51 (2): 213-222 (1997)]**PEER REVIEWED**

Field studies were conducted in 1994 and 1995 to examine the effects of soybean (Glycine max (L.) Merr.) row spacing and application rate and timing of four postemergence herbicide tank mixtures on weed control and soybean yield. Weed control and soybean yield were greater in narrow rows (7.5 in) than wide rows (30 in). Herbicide tank mixtures applied at 25% of the full recommended rate at an early postemergence timing followed by a second 25% application at a standard postemergence timing (1/4x E Post + 1/4x Post) resulted in weed control and soybean yield equal to that of herbicide tank mixtures applied at the full recommended rate at a standard postemergence timing (1x Post). Three of four tank mixtures in 1994 and two of four in 1995, applied at 50% of the full rate applied at a standard postemergence timing (1/2x Post) resulted in weed control and soybean yield equal to that of 1x Post applications. All tank mixtures applied at 50% of the full rate at an early postemergence timing (1/2x E Post) resulted in poor weed control and low soybean yield. In most cases it was more profitable to plant soybean in narrow rows than wide rows regardless of application rate or timing, based on economic gross margin calculations. Gross margins of tank mixtures applied at 1/4x E Post + 1/4x Post were similar to or greater than the gross margin of the same tank mixtures applied at the full rate in 13 of 16 cases. Gross margins of tank mixtures applied at 1/2x Post were similar to or greater than the gross margin of the same tank mixture applied at the full rate in eight of 16 cases.
[Mickelson JA, Renner KA; Journ Product Agricult 10 (3): 431-437 (1997)]**PEER REVIEWED**


Interactions:

Field studies were conducted in 1994 and 1995 in central and southern Illinois to compare several total postemergence weed control programs in soybean (Glycine max (L.) Merr.). Herbicide programs evaluated were imazethapyr (an acetolactate synthase (ALS) inhibiting herbicide) applied alone or in combination with lactofen and two non-acetolactate synthase herbicide programs consisting of combinations of bentazon, acifluorfen, and sethoxydima and combinations of formesafen, fluazifop, and fenoxyprop. These treatments were applied early postemergence (EPOST, V-1 soybean-first trifoliate) and postemergence (POST, V-2 soybean-second trifoliate). Non-acetolactate synthase herbicide programs generally provide more effective weed control postemergence, while weed control with imazethapyr tended to be greater early postemergence. Non-acetolactate synthase herbicide programs applied postemergence provided weed control levels that were equal to imazethapyr in three out of four experiments. In 1994 at Brownstown, broadleaf weed control was poor with non-acetolactate synthase herbicide programs when weed growth stages were larger and environmental conditions more extreme than other experiments. Adding lactofen to imazethapyr increased broadleaf weed control in some instances but decreased giant foxtail (Setaria faberil L.) control. Imazethapyr plus lactofen tended to produce the greatest degree of soybean injury.
[Hart SE et al; Journal of Production Agriculture 10 (1): 136-141 (1997)]**PEER REVIEWED**

Broadleaf weed and yellow nutsedge control with herbicide programs containing pendimethalin and combinations of formesafen, fluometuron, and norflurazon applied alone or with POST-directed applications of MSMA or fluometuron plus MSMA was evaluated. Soil-applied herbicide combination containing formesafen controlled yellow nutsedge better than combinations of norflurazon and fluometuron but did not provide better entireleaf, ivyleaf, pitted, and tall morningglory or sicklepod control. Fluometuron plus MSMA controlled morningglories and sicklepod more effectively than MSMA. Seed cotton yield was greater in one of two years when formesafen was applied and was associated with better yellow nutsedge control.
[Wilcut JW et al; Weed Technology 11 (2): 221-226 (1997)]**PEER REVIEWED**

The objective of on-farm herbicide screening experiment sin soybean was to assess the efficacy of new herbicides and herbicide combinations for weed control in two tillage systems in Lusaka Province, Zambia weed control treatments consisted of two control treatments (no-weeding and clean weeding with a hand hoe), two standard treatments (metribuzin + metolachlor and formesafen + fluazifop-butyl) and seven test herbicides/herbicide combinations (oxadiazon, oxadiazon + metolachlor, imazethapyr, acifluorfen + fluazifop-butyl, bentazone + fluazifop-butyl, bentazone + fenoxaprop-ethyl and bentazone + acifluorfen). Loss of potential yield owing to uncontrolled weeds was 66% and 40% under conventional and minimum tillage, respectively. All herbicide treatments performed well wider conventional tillage, whereas none of the treatments was able to satisfactorily control weeds under minimum tillage, especially Euphorbia heterophylla and late weeds. Standard herbicide treatments performed well under both tillage systems.
[Schmid W et al; Applied Plant Science 10 (1): 16-20 (1996)]**PEER REVIEWED**

Field studies were conducted to determine rhizomatous johnsongrass and barnyardgrass control with clethodim, quizalofop-P-ethyl, fluazifop-P, sethoxydim, fenoxaprop-ethyl, and quizalofop-P-tefuryl applied alone and with lactofen, imazaquin, chlorimuron, and formesafen. Graminicides applied alone controlled johnsongrass and barnyardgrass 83 to 99%. Of the graminicides evaluated, clethodium was the most antagonistic of the broadleaf herbicides toward the activity of graminicides. Clethodim mixed with imazaquin reduced johnsongrass control as much as 64% and mixed with chlorimuron reduced barnyardgrass control as much as 52%. Quizalofop-P-tefuryl was least affected by broadleaf herbicides and formesafen was least antagonistic in mixtures with graminicides.
[Vidrine PR et al; Weed Technology 9 (1): 68-72 (1995)]**PEER REVIEWED**

Field experiments were conducted to determine interactions of chlorimuron or imazaquin with formesafen, lactofen, or acifluorfen on three-leaf and eight-leaf common cocklebur, hemp sesbania, pitted morningglory, and prickly sida. Antagonism was the most common interaction with common cocklebur, and was most severe with chlorimuron combined with formesafen or acifluorfen, whereas lactofen did not antagonize common cocklebur control. Reductions in control were greater when ow rates of chlorimuron were used. On three-leaf prickly sida, control synergistically increased when imazaquin was combined with formesafen or acifluorfen, but the majority of these combinations were additive on eight-leaf prickly sida. Three-leaf pitted morningglory control synergistically increased when 36 g ai/ha imazaquin was combined with 210 g ai/ha formesafen or 110 or 220 g ai/ha lactofen. With eight-leaf pitted morningglory, synergism occurred when 2 g ai/ha chlorimuron was combined with the high rate of any diphenylether herbicide tested, and when 36 g/ha imazaquin was combined with 11- g/ha lactofen or 210 g ai/ha acifluorfen; however, at higher rates of chlorimuron or imazequin, several antagonistic interactions occurred. Hemp sesbania was controlled over 90% by all combinations, and no interactions occurred.
[Wesley MT and DR Shaw; Weed Technol 6 (2): 345-351 (1992)]**PEER REVIEWED**

Experiments were conducted to investigate the interactions of tank-mix combinations of sethoxydim plus the sodium salt of bentazon, the sodium salt of acifluorfen, formesafen, imazaquin, or the ethyl ester of chlorimuron. Antagonistic interactions were observed with tank-mixes of sethoxydim plus bentazon, imazaquin, or chlorimuron applied for fall pancium (Pancium dichotomiflorum), large crabgrass (Digitaria sanguinalis) and goosegrass (Eleusine indica) control in field experiments. Antagonism was observed in greenhouse experiments with tank-mixes of sethoxydim plus bentazon or imazaquin applied to goosegrass. Bentazon, acifluorfen, and formesafen reduced 14C-sethoxydim uptake by large crabgrass. However, imazaquin and chlorimuron did not affect 14C-sethoxydim uptake. In field experiments, no interactions occurred with tank-mixes of sethoxydim plus any of the broadleaf weed control herbicides applied to entire leaf or tall morningglory (Ipomoea hederacea var. Integriuscula and I. purpurea, respectively).
[Holshouser DL and HD Coble; Weed Technol 4 (1): 128-133 (1990)]**PEER REVIEWED**


Pharmacology:

Interactions:

Field studies were conducted in 1994 and 1995 in central and southern Illinois to compare several total postemergence weed control programs in soybean (Glycine max (L.) Merr.). Herbicide programs evaluated were imazethapyr (an acetolactate synthase (ALS) inhibiting herbicide) applied alone or in combination with lactofen and two non-acetolactate synthase herbicide programs consisting of combinations of bentazon, acifluorfen, and sethoxydima and combinations of formesafen, fluazifop, and fenoxyprop. These treatments were applied early postemergence (EPOST, V-1 soybean-first trifoliate) and postemergence (POST, V-2 soybean-second trifoliate). Non-acetolactate synthase herbicide programs generally provide more effective weed control postemergence, while weed control with imazethapyr tended to be greater early postemergence. Non-acetolactate synthase herbicide programs applied postemergence provided weed control levels that were equal to imazethapyr in three out of four experiments. In 1994 at Brownstown, broadleaf weed control was poor with non-acetolactate synthase herbicide programs when weed growth stages were larger and environmental conditions more extreme than other experiments. Adding lactofen to imazethapyr increased broadleaf weed control in some instances but decreased giant foxtail (Setaria faberil L.) control. Imazethapyr plus lactofen tended to produce the greatest degree of soybean injury.
[Hart SE et al; Journal of Production Agriculture 10 (1): 136-141 (1997)]**PEER REVIEWED**

Broadleaf weed and yellow nutsedge control with herbicide programs containing pendimethalin and combinations of formesafen, fluometuron, and norflurazon applied alone or with POST-directed applications of MSMA or fluometuron plus MSMA was evaluated. Soil-applied herbicide combination containing formesafen controlled yellow nutsedge better than combinations of norflurazon and fluometuron but did not provide better entireleaf, ivyleaf, pitted, and tall morningglory or sicklepod control. Fluometuron plus MSMA controlled morningglories and sicklepod more effectively than MSMA. Seed cotton yield was greater in one of two years when formesafen was applied and was associated with better yellow nutsedge control.
[Wilcut JW et al; Weed Technology 11 (2): 221-226 (1997)]**PEER REVIEWED**

The objective of on-farm herbicide screening experiment sin soybean was to assess the efficacy of new herbicides and herbicide combinations for weed control in two tillage systems in Lusaka Province, Zambia weed control treatments consisted of two control treatments (no-weeding and clean weeding with a hand hoe), two standard treatments (metribuzin + metolachlor and formesafen + fluazifop-butyl) and seven test herbicides/herbicide combinations (oxadiazon, oxadiazon + metolachlor, imazethapyr, acifluorfen + fluazifop-butyl, bentazone + fluazifop-butyl, bentazone + fenoxaprop-ethyl and bentazone + acifluorfen). Loss of potential yield owing to uncontrolled weeds was 66% and 40% under conventional and minimum tillage, respectively. All herbicide treatments performed well wider conventional tillage, whereas none of the treatments was able to satisfactorily control weeds under minimum tillage, especially Euphorbia heterophylla and late weeds. Standard herbicide treatments performed well under both tillage systems.
[Schmid W et al; Applied Plant Science 10 (1): 16-20 (1996)]**PEER REVIEWED**

Field studies were conducted to determine rhizomatous johnsongrass and barnyardgrass control with clethodim, quizalofop-P-ethyl, fluazifop-P, sethoxydim, fenoxaprop-ethyl, and quizalofop-P-tefuryl applied alone and with lactofen, imazaquin, chlorimuron, and formesafen. Graminicides applied alone controlled johnsongrass and barnyardgrass 83 to 99%. Of the graminicides evaluated, clethodium was the most antagonistic of the broadleaf herbicides toward the activity of graminicides. Clethodim mixed with imazaquin reduced johnsongrass control as much as 64% and mixed with chlorimuron reduced barnyardgrass control as much as 52%. Quizalofop-P-tefuryl was least affected by broadleaf herbicides and formesafen was least antagonistic in mixtures with graminicides.
[Vidrine PR et al; Weed Technology 9 (1): 68-72 (1995)]**PEER REVIEWED**

Field experiments were conducted to determine interactions of chlorimuron or imazaquin with formesafen, lactofen, or acifluorfen on three-leaf and eight-leaf common cocklebur, hemp sesbania, pitted morningglory, and prickly sida. Antagonism was the most common interaction with common cocklebur, and was most severe with chlorimuron combined with formesafen or acifluorfen, whereas lactofen did not antagonize common cocklebur control. Reductions in control were greater when ow rates of chlorimuron were used. On three-leaf prickly sida, control synergistically increased when imazaquin was combined with formesafen or acifluorfen, but the majority of these combinations were additive on eight-leaf prickly sida. Three-leaf pitted morningglory control synergistically increased when 36 g ai/ha imazaquin was combined with 210 g ai/ha formesafen or 110 or 220 g ai/ha lactofen. With eight-leaf pitted morningglory, synergism occurred when 2 g ai/ha chlorimuron was combined with the high rate of any diphenylether herbicide tested, and when 36 g/ha imazaquin was combined with 11- g/ha lactofen or 210 g ai/ha acifluorfen; however, at higher rates of chlorimuron or imazequin, several antagonistic interactions occurred. Hemp sesbania was controlled over 90% by all combinations, and no interactions occurred.
[Wesley MT and DR Shaw; Weed Technol 6 (2): 345-351 (1992)]**PEER REVIEWED**

Experiments were conducted to investigate the interactions of tank-mix combinations of sethoxydim plus the sodium salt of bentazon, the sodium salt of acifluorfen, formesafen, imazaquin, or the ethyl ester of chlorimuron. Antagonistic interactions were observed with tank-mixes of sethoxydim plus bentazon, imazaquin, or chlorimuron applied for fall pancium (Pancium dichotomiflorum), large crabgrass (Digitaria sanguinalis) and goosegrass (Eleusine indica) control in field experiments. Antagonism was observed in greenhouse experiments with tank-mixes of sethoxydim plus bentazon or imazaquin applied to goosegrass. Bentazon, acifluorfen, and formesafen reduced 14C-sethoxydim uptake by large crabgrass. However, imazaquin and chlorimuron did not affect 14C-sethoxydim uptake. In field experiments, no interactions occurred with tank-mixes of sethoxydim plus any of the broadleaf weed control herbicides applied to entire leaf or tall morningglory (Ipomoea hederacea var. Integriuscula and I. purpurea, respectively).
[Holshouser DL and HD Coble; Weed Technol 4 (1): 128-133 (1990)]**PEER REVIEWED**


Environmental Fate & Exposure:

Environmental Fate/Exposure Summary:

Fomesafen's production and use as a contact broadleaf herbicide is expected to result in its direct release to the environment. If released to air, a vapor pressure of <7.5X10-7 mm Hg at 50 deg C indicates that fomesafen will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase fomesafen will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 10 days. Particulate- phase fomesafen may be removed from the atmosphere by wet and dry deposition. Fomesafen will photodecompose readily under relatively low intensities of sunlight. If released to soil, measured Koc values ranging from 150 to 1200 indicate fomesafen is expected to have low to high mobility. Fomesafen is not expected to volatilize from wet or dry soil surfaces based on an estimated Henry's Law constant of 7.5X10-13 atm-cu m/mole and this compound's vapor pressure, respectively. Biodegradation of fomesafen in soil is expected to be an important fate process under anaerobic conditions, with a half-life of generally less than 3 weeks. If released into water, some adsorption of fomesafen to suspended solids and sediment in the water column is expected based upon the measured Koc values. A pKa of 2.7 indicates fomesafen will exist almost entirely in the ionized form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate process. An estimated BCF of 17 suggests the potential for bioconcentration in aquatic organisms is low. Occupational exposure to fomesafen may occur through inhalation of spray mists and aerosols and dermal contact with this herbicide during or after its application or at workplaces where fomesafen is produced. (SRC)
**PEER REVIEWED**


Probable Routes of Human Exposure:

Occupational exposure to fomesafen may occur through inhalation of spray mists and aerosols and dermal contact with this herbicide during or after its application or at workplaces where fomesafen is produced. (SRC)
**PEER REVIEWED**


Artificial Pollution Sources:

Fomesafen's production and use as a contact broadleaf herbicide(1) is expected to result in its direct release to the environment(SRC).
[(1) Farm Chemicals Handbook 1997. Willoughby, OH: Meister p. C177 (1997)]**PEER REVIEWED**


Environmental Fate:

TERRESTRIAL FATE: Based on a classification scheme(1), soil Koc values ranging from 150 to 1200(2), indicate that fomesafen is expected to have low to high mobility in soil(SRC). Volatilization of fomesafen from moist soil surfaces is not expected to be important(SRC) given an estimated Henry's Law constant of 7.5X10-13 atm-cu m/mole(SRC), using a fragment constant estimation method(4). Fomesafen is not expected to volatilize from dry soil surfaces based on a vapor pressure of <7.5X10-7 mm Hg(5). Biodegradation of fomesafen is expected to be an important fate process in soil(SRC): a half- life of less than 3 weeks is expected under anaerobic conditions; under aerobic conditions, half-lives range from about 6 months to greater than 12 months depending on soil type(6).
[(1) Swann RL et al; Res Rev 85: 23 (1983) (2) Weber JB; Pestic Sci 39: 31-8 (1993) (3) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington,DC: Amer Chem Soc pp. 4-9 (1990) (4) Meylan WM, Howard PH; Environ Toxicol Chem 10: 1283-93 (1991) (5) Tomlin C ed; The Pesticide Manual. A World Compendium. Incorporating the Agrochemicals Handbook. 10th ed. Bath,UK: The Bath Press. p. 520 (1994) (6) Humburg NE; Herbicide Handbook of the Weed Science Society of America. 6th ed. Champaign,IL: Weed Science Society of America p. 143 (1989)]**PEER REVIEWED**

AQUATIC FATE: Based on a classification scheme(1), soil Koc values ranging from 150 to 1200(2), indicate that some adsorption of fomesafen to suspended solids and sediment in water is expected(SRC). Fomesafen's pKa of 2.7(6) indicates that this compound will exist almost entirely in the ionized form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate process(SRC). According to a classification scheme(5), an estimated BCF of 17(3,SRC), from a water solubility of >600 mg/l at pH 7(6), suggests that bioconcentration in aquatic organisms is low(SRC). Biodegradation of fomesafen in aquatic systems may be important(SRC) based upon its biodegradation in soil under anaerobic conditions(7). Fomesafen will photodecompose readily under relatively low intensities of sunlight(7).
[(1) Swann RL et al; Res Rev 85: 23 (1983) (2) Weber JB; Pestic Sci 39: 31-8 (1993) (3) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington,DC: Amer Chem Soc pp. 4- 9, 5-4, 5-10, 15-1 to 15-29 (1990) (4) Meylan WM, Howard PH; Environ Toxicol Chem 10: 1283-93 (1991) (5) Franke C et al; Chemosphere 29: 1501-14 (1994) (6) Tomlin CDS ed; The Pesticide Manual. A World Compendium. 11th ed. The British Crop Protection Council. p. 616 (1997) (7) Humburg NE; Herbicide Handbook of the Weed Science Society of Amererica. 6th ed. Champaign,IL: Weed Sci Soc Amer p. 143 (1989)]**PEER REVIEWED**

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), fomesafen, which has a vapor pressure of <7.5X10-7 mm Hg at 50 deg C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase fomesafen is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be about 10 days(3,SRC). Particulate-phase fomesafen may be physically removed from the air by wet and dry deposition(SRC). Fomesafen will photodecompose readily under relatively low intensities of sunlight(4).
[(1) Bidleman TF; Environ Sci Technol 22: 361-367 (1988) (2) Tomlin C ed; The Pesticide Manual. A World Compendium. Incorporating the Agrochemicals Handbook. 10th ed. Bath, UK: The Bath Press. p. 520 (1994) (3) Meylan WM, Howard PH; Chemosphere 26: 2293-99 (1993) (4) Humburg NE; Herbicide Handbook of the Weed Science Society of America. 6th ed. Champaign, IL: Weed Science Society of America p. 143 (1989)]**PEER REVIEWED**


Environmental Biodegradation:

In soil, fomesafen is rapidly decomposed under anaerobic conditions, with a half-life of less than 3 weeks(1). In laboratory soil studies under aerobic conditions, half-lives range from about 6 months to greater than 12 months depending on soil type(1).
[(1) Humburg NE; Herbicide Handbook of the Weed Science Society of America. 6th ed. Champaign, IL: Weed Science Society of America p. 143 (1989)]**PEER REVIEWED**


Environmental Abiotic Degradation:

The rate constant for the vapor-phase reaction of fomesafen with photochemically-produced hydroxyl radicals has been estimated as 1.6X10-12 cu cm/molecule-sec at 25 deg C(SRC) using a structure estimation method(1,SRC). This corresponds to an atmospheric half-life of about 10 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1,SRC). Fomesafen will photodecompose readily under relatively low intensities of sunlight(2). The UV absorption spectrum of fomesafen in aqueous solution consists of a single smooth peak at 300 nm(3) indicating fomesafen may be susceptible to direct photolysis(SRC).
[(1) Meylan WM, Howard PH; Chemosphere 26: 2293-99 (1993) (2) Humburg NE; Herbicide Handbook of the Weed Science Society of America. 6th ed. Champaign, IL: Weed Science Society of America p. 143 (1989) (3) Weber JB; Pestic Sci 39: 31-8 (1993)]**PEER REVIEWED**


Environmental Bioconcentration:

An estimated BCF of 17 was calculated for fomesafen(SRC), using a water solubility of >600 mg/l at pH 7(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests that bioconcentration in aquatic organisms is low.
[(1) Tomlin CDS ed; The Pesticide Manual. A World Compendium. 11th ed. The British Crop Protection Council. p. 616 (1997) (2) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington,DC: Amer Chem Soc pp. 5-4, 5-10 (1990) (3) Franke C et al; Chemosphere 29: 1501-14 (1994)]**PEER REVIEWED**


Soil Adsorption/Mobility:

Kom values of 86 and 700 were determined for fomesafen in Drummer silt loam and Norfolk sandy loam, respectively(1). These values correspond to Koc values of 150 and 1200, respectively(2,SRC). According to a classification scheme(3), these measured Koc values suggest that fomesafen is expected to have low to high mobility in soil(SRC). Sorption of fomesafen by both soils increased greatly as pH decreased: on the Drummer soil it increased from 14% at pH 6.3 to 42 and 95% at pH 4.7 and 2.0, respectively; on the Norfolk soil, fomesafen sorption increased from 5% at pH 5.3 to 15 and 55% at pH 4.0 and 2,0, respectively(1). 4% of fomesafen was sorbed by Ca-montmorillonite(1). In laboratory soil studies, fomesafen's mobility was similar to that of atrazine, moderately mobile(4).
[(1) Weber JB; Pestic Sci 39: 31-8 (1993) (2) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington,DC: Amer Chem Soc pp. 4-3 (1990) (3) Swann RL et al; Res Rev 85: 23 (1983) (4) Humburg NE; Herbicide Handbook of the Weed Science Society of America. 6th ed. Champaign, IL: Weed Science Society of America p. 143 (1989)]**PEER REVIEWED**


Volatilization from Water/Soil:

The Henry's Law constant for fomesafen is estimated as 7.5X10-13 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that fomesafen is expected to be essentially nonvolatile from water surfaces(2,SRC). A pKa of 2.7 for fomesafen(3) also indicates that it will not significantly volatilize from water or soil surfaces as it will exist predominately in the ionized form under environmental pHs(SRC).
[(1) Meylan WM, Howard PH; Environ Toxicol Chem 10: 1283-93 (1991) (2) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington,DC: Amer Chem Soc pp. 15-1 to 15-29 (1990) (3) Tomlin CDS ed; The Pesticide Manual. A World Compendium. 11th ed. The British Crop Protection Council. p. 616 (1997)]**PEER REVIEWED**


Environmental Standards & Regulations:

FIFRA Requirements:

Tolerances are established for the residues of sodium salt of fomesafen, 5-(2-chloro-4-(trifluoromethyl)phenoxy)-N-(methylsulfonyl)-2-nitrobenzamide, in or on soybeans.
[40 CFR 180.433 (7/1/97)]**PEER REVIEWED**


Allowable Tolerances:

Tolerances are established for the residues of sodium salt of fomesafen, 5-(2-chloro-4-(trifluoromethyl)phenoxy)-N-(methylsulfonyl)-2-nitrobenzamide, in or on soybeans at 0.05 ppm.
[40 CFR 180.433 (7/1/97)]**PEER REVIEWED**


Chemical/Physical Properties:

Molecular Formula:

C15-H10-Cl-F3-N2-O6-S
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Molecular Weight:

438.8
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Color/Form:

Colorless crystals.
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**

White crystalline solid.
[Humburg, N.E. (ed.). Herbicide Handbook of the Weed Science Society of America. 6th ed. Champaign, IL: Weed Science Society of America, 1989. 143]**PEER REVIEWED**


Melting Point:

220 to 221 deg C
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Corrosivity:

Noncorrosive under normal use conditions.
[Humburg, N.E. (ed.). Herbicide Handbook of the Weed Science Society of America. 6th ed. Champaign, IL: Weed Science Society of America, 1989. 143]**PEER REVIEWED**


Density/Specific Gravity:

1.28 g/ml at 20 deg C
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Dissociation Constants:

pKa approx. 2.7 at 20 deg C
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Octanol/Water Partition Coefficient:

log Kow = 2.9 at pH 1
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Solubilities:

Soluble in water 50 mg/l at 25 deg C and pH 7; less than 1 mg/l at pH 1.
[Farm Chemicals Handbook 1997. Willoughby, OH: Meister Publishing Co., 1997.,p. C177]**PEER REVIEWED**

Soluble in a range of organic solvents. /Technical material/
[Humburg, N.E. (ed.). Herbicide Handbook of the Weed Science Society of America. 6th ed. Champaign, IL: Weed Science Society of America, 1989. 143]**PEER REVIEWED**


Vapor Pressure:

<7.5X10-7 mm Hg at 50 deg C
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Other Chemical/Physical Properties:

Stable in storage for at least 6 months at 50 deg C. Decomposed by light. Resistant to hydrolysis under both acidic and alkaline conditions. Forms water-soluble salts.
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Chemical Safety & Handling:

Skin, Eye and Respiratory Irritations:

Mild skin irritant; mild to moderate eye irritant (rabbits).
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 521]**PEER REVIEWED**


Hazardous Decomposition:

Decomposed by light.
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Preventive Measures:

SRP: The scientific literature for the use of contact lenses in industry is conflicting. The benefit or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.
**PEER REVIEWED**


Stability/Shelf Life:

Stable in storage for at least 6 months at 50 degrees C
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Storage Conditions:

Stable in storage for at least 6 months at 50 deg C. Decomposed by light. Resistant to hydrolysis under both acidic and alkaline conditions. Forms water-soluble salts.
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Disposal Methods:

SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.
**PEER REVIEWED**


Occupational Exposure Standards:

Manufacturing/Use Information:

Major Uses:

Herbicide. Selective annual broadleaf weed killer and has activity on some grass and sedge species.
[Humburg, N.E. (ed.). Herbicide Handbook of the Weed Science Society of America. 6th ed. Champaign, IL: Weed Science Society of America, 1989. 143]**PEER REVIEWED**

Contact broadleaf herbicide. Postemergence, over the top, on soybeans.
[Farm Chemicals Handbook 1997. Willoughby, OH: Meister Publishing Co., 1997.,p. C177]**PEER REVIEWED**

Fomesafen was used on crops during the 1990 to 1993 crop years.
[Gianessi LP, Anderson JE; Pesticide Use in U.S. Crop Production. National Center Food Agric Policy National Data Report (1995)]**PEER REVIEWED**

Field experiments were conducted from 1991 to 1993 to evaluate eclipta, Eclipta prostrate L., control and peanut, Arachis hypogaea L., response to herbicide treatments. Formesafen (5-(2-chloro-4-(trifluoromethyl)phenoxy)-N-(methylsulfonyl)-2-nitrobenzamide) applied at cracking was the only preemergence-applied herbicide which provided season-long control (>84%). Herbicides applied postemergence were more effective when the eclipta was less than 5 cm in height. The most consistent early postemergence treatments were bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), bentazone (3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide), and bentazon + acifluorfen (5-2-chloro-4-(trifluoromethyl)phenoxy)-2-nitrobenzoic acid) + 2,4-DB (4-(2,4-dichloro-phenoxy)butanoic acid). Various other early postemergence followed by late postemergence sequential treatments also were equally effective. Minor peanut injury was observed at the early season rating from several herbicides; however, all injury had disappeared by the late season rating. Eclipta control did not consistently improve peanut pod yield.
[Altom JV et al; Peanut Science 22 (2): 114-120 (1995)]**PEER REVIEWED**


Methods of Manufacturing:

Acifluorfen + ammonia + methanesulfonyl chloride (amide formation/sulfonamide formation).
[Ashford, R.D. Ashford's Dictionary of Industrial Chemicals. London, England: Wavelength Publications Ltd., 1994. 438]**PEER REVIEWED**


General Manufacturing Information:

Fomesafen was used on the following crops during the 1990 to 1993 crop years (from federal and state pesticide use surveys), by crop (State, % of crop acreage treated based on estimates of the crop's 1992 planted acreage): green beans (AR, 70%; IL, 50%) and soybeans (AL, 10%; AR, 13%; FL, 2%; GA, 2%; IL, 2%; IN, 2%; KY, 16%; LA, 15%; MI, 3%; MS, 10%; MO, 2%; NC, 6%; OH, 3%; SC, 6%; and TN, 9%).
[Gianessi LP, Anderson JE; Pesticide Use in U.S. Crop Production. National Center Food Agric Policy National Data Report (1995)]**PEER REVIEWED**


Formulations/Preparations:

Aqueous concentration, liquid concentration.
[Farm Chemicals Handbook 1997. Willoughby, OH: Meister Publishing Co., 1997.,p. C177]**PEER REVIEWED**

Soluble concentrate.
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Consumption Patterns:

In 1989, the national usage of formesafen was 227,000 lbs AI/year in U.S. agriculture.
[Gianessi LP; US Pesticide Use Trends: 1966-1989. Resources for the Future, Washington, DC (1992)]**PEER REVIEWED**


Laboratory Methods:

Analytic Laboratory Methods:

Product analysis by HPLC with UV detection. Residue analysis in soil by HPLC; in crops by TLC, HPLC or NMR. Details available from Zeneca.
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Special References:

Special Reports:

Retzinger E J Jr and C Mallory-Smith; Weed Technology 11 (2): 384-393 1997. Classification of herbicides by site of action for weed resistance management strategies.

Tsuda T et al; Journal of Pesticide Science 22 (3): 218-221 1997. Synthesis of N-alkyl-2,3-dimethyl-5-N'-5-halo-2-methylphenylcarbamoyl-6-pyrazinecarboxamides and their herbicidal activity.

Chamberlain K et al; Pesticide Science 47 (3): 265-271 1996. 1-Octanol/water partitition coefficient (Kow) and pKa for ionizable pesticides measured by a pH-metric method.

Elcombe CR et al; Ann NY Acad Sci 804: 628-35 1996. Peroxisome proliferators: species differences in response of primary hepatocyte cultures.

Georgiev G TS; Dokladi Na B"Lgarskata Akademiya Na Naukite 49 (3): 83-86 1996. Effect of combined application of certain herbicides and phenylurea cytokinin 4-Pu-30 on soybean growth and productivity.

Knott CM; Annals of Applied Biology 128 (Suppl.): 38-39 1996. Evaluation of herbicides for weed control in runner beans phaseolus coccineus.

Knott CM; Annals of Applied Biology 128 (Suppl.): 54-55 1996. Tolerance of spring-sown lupins lupinus albus to herbicides.

Shad RA and SU Siddiqui; Experimental Agriculture 32 (2): 151-160 1996. Problems associated with Phalaris minor and other grass weeds in India and Pakistan.

South DB and JB Zwolinski; Southern Journal of Applied Forestry 20 (3): 127-135 1996. Chemicals used in southern forest nurseries.

Talbert NE et al; Arkansas Agricultural Experiment Station Research Series 0 (452): I-IV, 1-38 1996. Field evaluations of herbicides on small fruit vegetable and ornamental crops 1995.

Mahmoud S MM et al; Egyptian Journal of Phytopathology 22 (1): 39-57 1994. Some aspects affecting preplanting management of cotton seedling disease caused by Rhizoctonia solani.

Mayer AS et al; Water Environment Research 66 (4): 532-585 1994. Fate and effects of pollutants groundwater quality.

Mineau P et al; Ecotoxicology and Environmental Safety 29 (3): 304-329 1994. An analysis of avian reproduction studies submitted for pesticide registration.

Orfila L and M Salazar-Bookaman; Rev Fac Farm Univ Cent Venez 57 (1): 6-11 1994. Cytotoxic activity of the herbicide formesafen in rat hepatocytes treated in vitro.

Eyherabide JJ; Tests Agrochem Cultiv 0 (13): 56-57 1992. Evaluation of pre-emergence applications of formesafen and acetochlor against weeds in soybeans.

Zanin G et al; Crop Prot 11 (2): 174-180 1992. Economics of herbicide use on arable crops in north-central Italy.

Lalova M and L Tyankova; C R Acad Bulg Sci 44 (9): 89-91 1991. Influence of herbicides on soybean fatty acids.

Beal DD; Progress in Clinical and Biological Research 331: 5-18 1990. Use of mouse liver tumor data in risk assessments performed by the USA EPA.

Rana MA et al; Crop Res 3 (1): 40-50 1990. Effect of maturity stages and desiccant application on seed yield and oil quality of sunflower (Helianthus annuus L.).

Rovesti L and KV Deseo; Nematologica 36 (2): 237-245 1990. Compatibility of chemical pesticides with the entomopathogenic nematodes: Steinernema carpocapsae Weiser and Steinernema feltiae Filipjev (Nematoda: Steinernematidae).


Synonyms and Identifiers:

 

Synonyms:

5-[2-chloro-4-(trifluoromethyl)phenoxy]-N-(methylsulfonyl)-2-nitrobenzamide
**PEER REVIEWED**

5(2-chloro-alpha,alpha,alpha-trifluoro-p-tolyloxy)-N-mesyl-2-nitrobenzamide
**PEER REVIEWED**

5(2-chloro-alpha,alpha,alpha-trifluoro-p-tolyloxy)-N-methylsulfonyl-2-nitrobenza mide
**PEER REVIEWED**


Formulations/Preparations:

Aqueous concentration, liquid concentration.
[Farm Chemicals Handbook 1997. Willoughby, OH: Meister Publishing Co., 1997.,p. C177]**PEER REVIEWED**

Soluble concentrate.
[Tomlin, C.D.S. (ed.). The Pesticide Manual - World Compendium. 10th ed. Surrey, UK: The British Crop Protection Council, 1994. 520]**PEER REVIEWED**


Administrative Information:

Hazardous Substances Databank Number: 6660

Last Revision Date: 20000929

Last Review Date: Reviewed by SRP on 5/7/1998

Update History:

Complete Update on 09/11/1998, 49 fields added/edited/deleted.