Cyhalofop Butyl Research Articles

Cross-resistance of barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] to aryloxyphenoxypropionate herbicides

Managing emerged weeds that have evolved resistance to acetyl CoA carboxylase (ACCase)-inhibiting herbicides is a challenging task. A dose-response experiment was conducted on barnyardgrass biotypes resistant (R) and susceptible (S) to three aryloxyphenoxypropionate herbicides cyhalofop-butyl (CyB), fenoxaprop-ethyl (FeE), and quizalofop-ethyl (QuE) along with investigations into the potential resistance mechanism of these biotypes. The tested R barnyardgrass biotypes had strong resistance to CyB and FeE (resistant/susceptible ratio: 7.9–14.4) but weak resistance to QuE (resistant/susceptible ratio: 2.4–3.1). Absorption, translocation, and total metabolism of CyB and QuE were not associated with differences among S and R barnyardgrass biotypes. However, differences between S and R barnyardgrass were observed in production of active acid forms of each herbicide (cyhalofop-acid and quizalofop-acid). Production of cyhalofop-acid was >1.6-fold less in R barnyardgrass (3–8%) for 24 h after herbicide application than in the S barnyardgrass (8–16%). Meanwhile, production of quizalofop-acid was less in R barnyardgrass (< 14%) throughout the study period than in the S barnyardgrass (< 22%). Sequencing results of ACCase gene showed no difference between S and R barnyardgrass. Overall results show that a non-target-site resistance mechanism altering metabolism of CyB and QuE likely contributes to resistance of the barnyardgrass biotypes to these herbicides.

Management of weeds in transplanted rice with XR-848 benzyl ester + cyhalofop-butyl (ready-mix)

A field experiment was conducted during rainy (Kharif) seasons of 2015 and 2016 at Agricultural Research Station, Dhadesugur, University of Agricultural Sciences, Raichur, Karnataka, India to evaluate the efficacy of XR-848 benzyl ester 20 g/l + cyhalofop-butyl 100 g/l EC (ready-mix) on weeds in transplanted rice. The dominant grassy weeds in the experimental field were: Echinochloa colona, Panicum repens, Cynodon dactylon, Brachiaria mutica, Digitaria sanguinalis and Leptochloa chinensis; broad-leaved weeds were: Eclipta alba and Ludwigia parviflora and the sedge was Cyperus rotundus. The post-emergence application (PoE) of XR-848 benzyl ester 20 g/l + cyhalofop butyl 100 g/l EC (ready-mix) 180 g/ha recorded significantly lower weeds biomass, higher weed control efficiency at 30, 45 and 60 days after transplanting (DAT) and higher rice grain yield during both the years and it was at par with XR-848 benzyl ester 20 g/l + cyhalofop butyl 100 g/l EC (ready-mix) 150 g/ha. The hand weeding twice at 20 and 40 DAT recorded significantly higher weed control efficiency and grain yield compared to other herbicide treatments.

Integrated management of tough lovegrass (Eragrostis plana Nees): associating chemical control tools and plant physiology

ABSTRACT: The objective of the study was to evaluate the efficiency of herbicides use in the control of tough lovegrass according to the availability of solar radiation and the presence or absence of flooded. Two experiments were conducted in a completely randomized design, in a 2x2x4 and 2x2x5 factorial scheme, where factor A was equivalent to the environment (natural or reduced radiation); factor B to water condition (with a 2 cm flooded or without); and, factor C the herbicides: cyhalofop butyl (315 g ha-1), glyphosate (1080 g ha-1), cyhalofop butyl + glyphosate (315 g ha-1 + 1080 g ha-1) and control (without application) in the first experiment. In the second experiment, the herbicides used were cyhalofop butyl (315 g ha-1), glyphosate (1080 g ha-1), sethoxydim (184g ha-1), imazethapyr (106 g ha-1) and control (without application). Glyphosate efficiently controls plants of tough lovegrass with four tillers (&gt;90%), being superior to cyhalofop, imazethapyr and sethoxydim; independently, of resource conditions. Reduction in the availability of solar radiation generates less shoot dry mass production from the weed, and improves the control only by imazethapyr and cyhalofop. In general, a flooded condition does not affect tough lovegrass control by herbicides.

Weed control and rice yield stability studies across diverse tillage and crop establishment systems under on-farm environments

In zero-till direct seeded rice (DSR), systematic information pertaining to weed management under on-farm conditions for medium- or long-term is lacking. Therefore, on-farm adaptive trials were conducted to find out the effect of different crop establishment and weed management practices on yield stability and weed dynamics over the years at Faridabad and Sonepat districts of Haryana, India. Results showed that DSR with residue (DSRR) coupled with pretilachlor as pre-emergence (PE) @ 0.75 kg ha−1 followed by bispyribac-sodium as post-emergence (POE) @ 0.025 kg ha-1 (PretBis) or cyhalofop butyl @ 0.060 kg ha-1 (PretCy) resulted in rice grain yield (5.38 t ha-1 and 5.33 t ha-1, respectively) statistically at par with transplanted rice (TPR)-PretBis (5.30 t ha-1) and TPR-PretCy (5.21 t ha-1). PretBis produced 32.3 % higher grain yield as compared to farmers’ practice (FP). Higher broad-leaved weeds (BLWs) biomass was recorded under DSR (8.25 g m-2), followed by DSRR (4.58 g m-2) and TPR (3.99 g m-2). Whereas, among weed management practices, PretBis had least BLWs biomass (4.17 g m-2) followed by PretCy (4.77 g m-2). Biomass of narrow leaved weeds (NLWs) and sedges was found lowest under PretCy (3.63 g m-2 and 3.77 g m-2). GGE biplot analysis of biomass of BLWs and NLWs reveals that PretBis and PretCy, respectively had the highest-ranking owing to their stability across the environments (location x year). In year x location environments, last three years of study were in the same mega environments, which indicated stability in weed biomass and population reduction from third year onwards. Yield stability was highest under DSRR-PretCy followed by DSRR-PretBis. The study highlights that, under north-western Indo-Gangetic plains, if the weeds are managed properly, DSRR can be adopted without significant yield reduction during initial years and comparable yield to TPR and improved soil fertility in the long-term.

Evaluation of bio-efficacy of BAS 625 04 H against grassy weeds in direct seeded rice (Oryza sativa L.)

A field experiment was conducted during the kharif 2021 at Instructional-cum-Research Farm, Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh to evaluate new molecules of on weed control in direct seeded rice. BAS 625 04 H is a member of Cyclohexenone group, post emergence herbicide used for annual grassy weeds in various field crops. Post-emergence (POE) application of BAS 625 04 H @ 75 g a.i. ha-1 with MSO adjuvant gave lower total weed density, weed dry weight and higher weed control efficiency at all the intervals which was at par with Cyhalofop butyl 10 % EC and BAS 625 04 H @ 55 g a.i. ha-1 with MSO adjuvant. Among the different doses of BAS 625 04 H higher grain yield and straw yield recorded under BAS 625 04 H @ 75 g a.i. ha-1 with MSO adjuvant and @ 55 g a.i. ha-1 with MSO adjuvant. Untreated control accounted for lower grain yield, higher weed density and dry weight due to heavy competition of weeds for nutrients, space and light.

Validación de Cihalofop-Butilo + Clomazone para el control de Echinochloa colona (L.) Link en arroz de temporal

&#x0D; &#x0D; &#x0D; Durante los ciclos de temporal 2011 y 2012, se establecieron cuatro parcelas en arrozales del municipio de Tres Valles, Veracruz, con objeto de validar los resultados experimentales de control del zacate pata de pichichi [Echinochloa colona (L.) Link] con cihalofop-butilo + clomazone, comparar su ef iciencia y rentabilidad con el tratamiento regional, y transferir el conocimiento de la nueva tecnología a los productores de arroz del centro del estado de Veracruz. Se compararon dos tratamientos: 1. Cihalofop-butilo + clomazone a 315 + 480 g ha-1 ; y 2. Propanil seguido de propanil (tratamiento regional) en dosis diferentes cada ciclo de acuerdo al tamaño de E. colona. En ambos ciclos se evaluó el control de E. colona y la toxicidad al arroz a los 25, 35 y 60 días después de la aplicación de los tratamientos. También se cuantificó el rendimiento de arroz palay y se determinó la rentabilidad de los tratamientos. Con cihalofop-butilo + clomazone el control final de E. colona fue 91.25%, y el rendimiento promedio de arroz palay de 5 033 kg ha-1, mientras que con el tratamiento regional estos valores fueron de 49.50% y 2 883 kg ha-1, respectivamente. La relación beneficio/costo con cihalofop-butilo + clomazone fue de 1.507, mucho mayor que la del tratamiento tradicional (0.802), principalmente por un mayor rendimiento de grano obtenido y un menor costo de control. La nueva tecnología se transfirió a 71 personas, entre productores de arroz y técnicos, a través de dos demostraciones de campo.&#x0D; &#x0D; &#x0D;

Relative efficacy of different herbicides on Echinochloa accessions

The experiment was conducted in pots to study the effect of five herbicides on different Echinochloa accessions during the year 2014. Six ecotypes viz., E. glabrescens (HAU Farm), E. colona/crusgalli (Ahrewan, Fatehabad), E. crusgalli (Majden, Sirsa), E. colona/crusgalli (Beri Akbarpur, Uklana), E. colona/crusgalli (Chamarkhera, Uklana) and E.glabrescens (Mundhal, Hansi) were sprayed at different days after sowing. Butachlor (1500 g/ha) and pretilachlor (1000 g/ha) were sprayed at three days after sowing (DAS). Recommended doses of herbicides i. e. bispyribac sodium (25 g/ha), penoxsulam (22.5 g/ha) and cyhalofop-butyl (120 g/ha) were sprayed at 25 DAS. Sampling was made after 30 DAS. Hebicides butachlor (1500 g/ha) and pretilachlor (1000 g/ha) were used as preemergence and no germination was observed 30 DAS except control. Mortality increased with increasing doses of different herbicides. Except E. glabrescens (HAU Farm-79.5%) and E. colona/crusgalli (Ahrewan, Fatehabad-80.9%), 100% mortality was noticed in all the accessions at RD of penoxulum, whereas 45–95% mortality was seen in all the ecotypes at RD of bispyribac sodium but 100% mortality was observed in all the accessions of Echinochloa at RD of cyhalofop butyl. Reversibly, dry matter decreased with increasing doses of herbicides (RD of penoxsulam-22.5 g/ha, bispyribac sodium-25 g/ha and cyhalofop butyl-120 g/ha) in all the accessions. Maximum per cent decline was noticed in E.colona/crusgalli (15.1%) (Ahrewan, Fatehabad), E. colona/crusgalli (6.1%) (Ahrewan, Fatehabad) and E. colona/crusgalli (Beri Akbarpur, Uklana) at recommended doses of penoxsulam, bispyribac sodium and cyhalofop butyl, respectively, over their respective control. Conclusively, maximum efficacy was shown by cyhalofob butyl on the basis of per cent mortality and dry matter accumulation in different accessions.

Weed persistence, crop resistance and phytotonic effects of herbicides in direct-seeded rice

Results of experiment conducted during Kharif season of 2010 and 2011 with ten different herbicides and combinations on yield of direct seeded rice revealed that crop resistance index and agronomic management index were maximum in hand weeding treatment followed by fenoxaprop + (chororimuron + metsulfuron) and cyhalofop butyl +(chlorimuron + metsulfuron). Weed persistence index was also maximum in Hand weeding treatment followed by cyhalofopbutyl and pyrazosulfuron. Hand weeding treatment has maximum phytotonic effect followed by fenoxaprop + (chororimuron + metsulfuron) and cyhalofop butyl + (chlorimuron + metsulfuron). Fenoxaprop + (chororimuron + metsulfuron) and cyhalofop butyl + (chlorimuron + metsulfuron) were best herbicides for direct seeded rice from economics and environmental point of view. Fenoxaprop + (chororimuron + metsulfuron) and cyhalofop butyl + (chlorimuron + metsulfuron) have recorded lower persistence of escaped weeds indicating broad spectrum effect in controlling the weeds

Effect of water regimes and weed management practices on nutrient uptake by rice and weeds under the system of rice intensification

A field experiment was conducted in kharif 2012 and 2013 at MRCFC, SKUAST, Khudwani (Kashmir) on a silty clay loam soil to evaluate the impact of water regimes and weed management practices on nutrient uptake in rice and weeds under SRI. The soil at experimental site was neutral in reaction, medium in available P, K and organic carbon and low in available N. The treatments comprised of 3 irrigations schedules [alternate wetting and drying (AWD), continuous saturated condition and continuous flooding] and 7 weed management practices viz., 4 herbicidal treatments [pyrazosulfuron ethyl @ 20 g a.i. ha−1 (3 DAT); cyhalofop butyl @ 80 g a.i. ha−1 (15 DAT); pyrazosulfuron ethyl 20 g a.i. followed by cyhalofop butyl 80 g a.i. ha−1 (3 and 15 DAT), and butachlor @ 1.5 kg a.i. ha−1 (3 DAT)]; cono weeding, weedy check and weed-free control. The results revealed that saturated water regime treatment had highest uptake of macronutrients by grain and straw, while highest uptake of macro-nutrients by weeds was in AWD and lowest in continuous flooding. Among weed control measures, the lowest macronutrients uptake by crop was associated with post-emergence application of cyhalofop-butyl and highest amount of NPK depletion by weeds was observed in unweeded control. Minimum NPK uptake by weeds was noticed in sequential application of pyrazosulfuron-ethyl @ 20 g a.i. ha−1 and cyhalofop-butyl @ 60 g a.i. ha−1 treatment.

Bio-efficacy of penoxsulam+cyhalofop butyl 6% OD, a new pre-mix herbicide mixture for weed control in direct seeded puddled irrigated rice (Oryza sativaL.)

The field experiments were conducted during kharif and rabi 2014 to study the efficacy of pre-mix herbicide mixture penoxsulam+cyhalofop butyl for weed control in direct seeded puddled rice. The experiment was laid out in randomized block design with eight treatments and three replications. The treatments comprised four different doses of penoxsulam+cyhalofop butyl 6% OD viz., 120, 125, 130 and 135 g a. i./ha, bispyribac sodium 10% SE 25 g a. i./ha, penoxsulam 24 SC 22.5 g a. i./ha, hand weeding twice and weedy check. On 30 days after sowing (DAS) weed flora comprised sedges (53.91%), broad leaf weeds (37.88%) and grasses (8. 2%) and on 60 DAS weed flora constituted sedges (53.15%), broad leaf weeds (BLW) (34.66%) and grasses (12.19%). The dominant weed species present in the experimental field were Schoenoplectus juncoides (Roxb.) Palla, Cyperus iria L. and Cyperus difformis L. among sedges; Isachne miliaceae Roth among grasses and Ludwigia perennis, Limnocharis flava (L.) Buch., Marsilea quadrifoliata L. and Bergia carpensis L. among broad leaf weeds. Pre-mix herbicide mixture, penoxsulam+cyhalofop butyl was found to be effective in reducing the density and dry weight of weeds at 30, 45 and 60 DAS. Among the doses, higher doses of penoxsulam+cyhalofop butyl (130 and 135 g a. i./ha) were found to be more effective in reducing the dry weight with a weed control efficiency of 97.34 and 98.31%, respectively. Higher growth and better expression of yield attributes were registered for these treatments. Adoption of weed control measures enhanced the grain yield from 4.26 to 8.46 t/ha. All the tested doses of penoxsulam+cyhalofop butyl recorded higher grain yield compared to hand weeding, penoxsulam and bispyribac sodium applied alone. Application of penoxsulam +cyhalofop butyl at its higher dose (135 g a. i./ha) recorded the highest grain yield which was on a par with its lower dose 130 g a. i./ha. The highest gross returns and B: C ratio were also recorded by these treatments. Bispyribac sodium was found to be less effective in reducing the density and dry weight of sedges resulting in lesser yield and B: C ratio compared to penoxsulam in the present study. Hand weeding recorded the lowest gross returns and B: C ratio among the weed control treatments. The study concludes that better broad spectrum control of weeds can be achieved by the post-emergence application of herbicide mixture penoxsulam+cyhalofop butyl on 15 DAS. The selection of herbicide and dose should depend on the target weed species in an area.

Sensibilidade do capim-capivara a herbicidas

Dois experimentos foram conduzidos em casa de vegetação com o objetivo de identificar, através de curvas de dose-resposta, a sensibilidade de plantas jovens e perenizadas de capim-capivara a doses crescentes (0, 25, 50, 75, 100, 125, 150, 175 e 200% da dose recomendada para gramíneas perenes) de cyhalofop-butyl (315 g i.a. ha-1), imazapic + imazapyr (24,5 g e.a. ha-1 + 73,5 g e.a. ha-1), glyphosate (2.160 g e.a. ha-1) e amônio glufosinate (900 g i.a. ha-1). O experimento 1 foi conduzido de janeiro a março de 2010, e o experimento 2, de janeiro de 2010 a janeiro de 2011. Plantas jovens apresentaram maior sensibilidade aos herbicidas amônio glufosinate e cyhalofop-butyl, entretanto, a morte das plantas ocorreu somente quando tratadas com glyphosate e a mistura formulada de imazapic + imazapyr. Em plantas perenizadas, os herbicidas não proporcionaram controle satisfatório.

Degradation of Cyhalofop-butyl (CyB) by Pseudomonas azotoformans Strain QDZ-1 and Cloning of a Novel Gene Encoding CyB-Hydrolyzing Esterase

Cyhalofop-butyl (CyB) is a widely used aryloxyphenoxy propanoate (AOPP) herbicide for control of grasses in rice fields. Five CyB-degrading strains were isolated from rice field soil and identified as Agromyces sp., Stenotrophomonas sp., Aquamicrobium sp., Microbacterium sp., and Pseudomonas azotoformans; the results revealed high biodiversity of CyB-degrading bacteria in rice soil. One strain, P. azotoformans QDZ-1, degraded 84.5% of 100 mg L(-1) CyB in 5 days of incubation in a flask and utilized CyB as carbon source for growth. Strain QDZ-1 could also degrade a wide range of other AOPP herbicides. An esterase gene, chbH, which hydrolyzes CyB to cyhalofop acid (CyA), was cloned from strain QDZ-1 and functionally expressed. A chbH-disrupted mutant dchbH was constructed by insertion mutation. Mutant dchbH could not degrade and utilize CyB, suggesting that chbH was the only esterase gene responsible for CyB degradation in strain QDZ-1. ChbH hydrolyzed all AOPP herbicides tested as well as permethrin. The catalytic efficiency of ChbH toward different AOPP herbicides followed the order quizalofop-P-ethyl ≈ fenoxaprop-P-ethyl > CyB ≈ fluazifop-P-butyl > diclofop-methyl ≈ haloxyfop-P-methyl; the results indicated that the chain length of the alcohol moiety strongly affected the biodegradability of the AOPP herbicides, whereas the substitutions in the aromatic ring had only a slight influence.

Development of Methods for Multiresidue Analysis of Rice Post-Emergence Herbicides in Loam Soil and Their Possible Applications to Soils of Different Composition

Two simple and straightforward sample preparation methods were developed for the multiresidue analysis of post-emergence herbicides in loam soil that are commonly used in rice crop cultivation. A number of strategic soil extraction and cleanup methods were evaluated. The instrumental analysis was performed by HPLC with a diode array detector. The best compromise between the recoveries (69-98%) and good repeatability (RSD < 15%) was obtained using either methanol or methanol-ethyl acetate (70 + 30, v/v) as extraction solvents without any further cleanup. For the first time, residues of metsulfuron methyl, bensulfuron ethyl, bentazone, cyhalofop butyl, pyrazosulfuron ethyl, propanil, and clomazone were analyzed simultaneously. Quinclorac and bispyribac sodium were also assayed, but their recoveries were below 50%. Both methods had an LOD of 0.7 microg/kg and could accurately determine the residues at the 2 microg/kg level. These two methods could not be applied directly to other soil types as the recoveries strongly depended on the soil composition. The developed methodologies were successfully applied in monitoring 87 real-world soil samples, in which only propanil (6 to 12 microg/kg) and clomazone (15 to 20 microg/kg) residues could be detected.

Comparison of extraction solvents and conditions for herbicide residues in milled rice with liquid chromatography-diode array detection analysis (LC-DAD)

Different extraction procedures and clean-up methods were compared in order to develop a sample preparation procedure for the multi-residue analysis of six post-emergence herbicides (metsulfuron methyl, bensulfuron methyl, pyrazosulfuron ethyl, bentazone, bispyribac sodium and cyhalofop butyl) in rice grains followed by liquid chromatography-diode array detection (LC-DAD). Optimum results were obtained dispersing milled rice grain in water, followed by the addition of 1% acetic acid in acetonitrile, MgSO4 and sodium acetate as a modification of the quick, easy, cheap, effective, rugged and safe (QuEChERS) method but no primary and secondary amine (PSA) sorbent was added due to the acidic nature of the herbicides. The method was further expanded to other post-emergence herbicides (quinclorac, clomazone and propanil). Except for quinclorac, which cannot be analysed with this method, the recoveries of the other eight herbicides were in the range 73–111%, with relative standard deviations lower than 12%. Limits of detection (LODs) ranged from 0.03 to 0.08 mg kg−1. A single analyst can extract twelve samples in 4 h. The method presented here allows the simultaneous residue determination of the most common post-emergence herbicides employed in cultivating rice. It is simple, rapid, sensitive, and can be applied routinely to polished rice grain herbicide residue analysis.

Basis of selectivity of cyhalofop-butyl in Oryza sativa L.

Cyhalofop-butyl (CB), 2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid, butyl ester (R), is an aryloxyphenoxypropionate (AOPP) herbicide for postemergence use in rice to control grasses, mainly Echinochloa spp. Similar to other AOPP and cyclohexanedione herbicides, the site of action of CB is acetyl-coenzyme A carboxylase (ACCase), an enzyme in fatty acid biosynthesis. The mechanisms involved in the selectivity of CB in rice (Oryza sativa L.)-absorption, translocation, metabolism, and ACCase susceptibility-were studied. Studies of in vitro inhibition of ACCase in E. oryzoides and O. sativa L. species discounted any differential active site sensitivity as the basis of tolerance to CB. The O. sativa L. cuticle was uniformly covered by waxes, with predominantly unshaped large waxes randomly distributed, obtaining absorption values of under 30%, 24 h after application (HAA). The E. oryzoides cuticle formed a non-uniform covered reticule, with less wax density and areas lacking in waxes reaching maximum values of absorption rising to 73%, 24 HAA. Translocation studies revealed no significant differences, either between species, or between times, remaining in the treated leaf. There was a good correlation between the rate of metabolism and plant tolerance. Plant metabolism studies demonstrated that tolerant rice inactivated the esterases producing a lack of functionality thus reducing the conversion of CB to cyhalofop acid, which is the active form of the herbicide. Moreover, it increased the metabolism of the herbicide forming non toxic metabolites much faster than E. oryzoides. It was concluded that the basis of rice tolerance to CB was a lack of esterase functionality, a reduced absorption through the cuticle and an increase in cyhalofop acid metabolism.

Efficacy of cyhalofop butyl in controlling weeds in transplanted rice (Oryza sativa)

A field experiment was conducted during the rainy season (Kharif) of 1994 and 1995 at Palampur, to find out the effective dose of cyhalofop butyl and surfaclant (PG 26 2) to control weeds in transplanted rice (Oryza sativa L.). Cyhalofop butyl was applied 15 days after rice transplanting. Cyhalofop butyl 90 glha surfactant 0.3% being at par with cyhalofop butyl 90 glha surfactant 0.2%, cyhalofop butyl 75 ha surfactant 0.3, cyhalofop butyl 90 glha without surfactant and butachlor 1.5 kglha resulted in significantly lower dry matter accumulation of weeds compared with remaining treatments. Cyhalofop butyl 90 glha surfactant 0.3% resulted in significantly higher rice yield attributes and yield however, it was at par with cyhalofop butyl 90 g/ha surfactant 0.2% and butachlor 1.5 k ha at 5 days after transplanting during both years and also with cyhalofop butyl75 ha surfactant 0.3% during first year. Key words : Cyhalofop butyl, Surfactant 0.3%, Transplanted, Butachlor, Attributes, Tillers, Weedy check.

水稲用除草剤シハロホップブチルの開発と製剤化技術の確立

水稲用除草剤シハロホップブチルの開発と製剤化技術の確立

水稲用除草剤シハロホップブチルの開発と製剤化技術の確立

水稲用除草剤シハロホップブチルの開発と製剤化技術の確立

Selectivity of Cyhalofop-butyl in Poaceae Species.

Responses to foliar-applied cyhalof op-butyl of the seedlings of 29 Poaceae species at about 3- to 4-leaf stage were examined. Species belonging to subfamilies of Panicoideae, except for Imperata cylindrica, and Eragrostoideae were all susceptible, being completely controlled at 100g ha-1. Most of these species are important summer weeds in crops. Alopecurus aequalis (Pooideae) and Agrostis alba (Pooideae) were also susceptible. Six of 10 other Pooideae species and the two Oryzoideae species tested, as well as I. cylindrica, in which all treated plants survived at 300g ha-1, were shown to have tolerance to cyhalofop-butyl. The other four Pooideae species were less susceptible and incompletely controlled at 100g ha-1. Oryza sativa displayed the highest tolerance; plants treated at 300g ha-1 did not show any significant differences from untreated plants. The typical visual symptom common through all plants of affected species was withering of the emerging leaves. The critical response that led to plant death, however, appeared to be the suspension of new growth. Plant survival after this phase seemed to depend on whether new development was restored before unaffected leaves lost their activity, by resumption of healthy leaf emergence mainly by formation of tillers or rhizomatous shoots.

The Extruded Granule Formulation of Selective Rice Herbicide Cyhalofop Butyl.

Cyhalofop butyl, [R-(+)-n-butyl-2-(4-(2-fluoro-4-cyanophenoxy) phenoxy) propionate] is a selective rice graminicide which can control up to the 5-6 leaf stage of Echinochloa crus-galli by foliar application. The development of granule formulations for rice herbicides is important to strengthen agricultural practices in Japan. One granule system of cyhalofop butyl employs KCl core granules and di-tridecyl phthalate to maximize its bioefficacy. As described in a previous report, this system can enhance plant uptake of the graminicide when a high concentration of cyhalofop butyl plus di-tridecyl phthalate comes into direct contact with a plant. The system does, however, limit the flexibility of one shot granule formulations depending on the KCl core granule compatibility with the partner with which it is combined. Therefore, an extruded granule of cyhalofop butyl is preferable to a KCl granule of cyhalofop butyl to broaden the potential/possible partners for a one shot granule. Several core granule systems and solvent systems were evaluated to develop an efficacious extruded granule of cyhalofop butyl. Among them, the employment of maleic acid polymer type surfactant for the extruded core granule system and di-tridecyl phthalate plus isoparaffin as solvent system showed the best bioefficacy to control the 3 leaf stage of Echinochloa crus-galli than did the KCl granule of cyhalofop butyl. Granules extruded by this system also showed a high release rate of the graminicide in the upper layer of the water.