First report of Amaranthus viridis resistance to herbicides

Due to the limited number of herbicides registered for the control of dicot weeds in cotton crops, ALS inhibitors have been used on an intensive and recurrent basis. Given that, cases of poor weed control have been described after application of these herbicides in the main cotton producing areas in Brazil, the purpose of the present work was to evaluate the occurrence of resistance to ALS herbicides in Amaranthus viridis biotypes from those areas. Dose-response curves were prepared after pre-emergence applications of trifloxysulfuron-sodium (0; 1.8; 3.7; 7.5; 15 and 30 g ha-1) and pyrithiobac-sodium (0; 35; 70; 140; 280 and 560 g ha-1), equivalent to 0, ¼, ½, 1, 2 and 4 times the recommended commercial rates. The selection of trifloxysulfuron-sodium resistant biotypes of A. viridis was confirmed in samples from Bahia (BA 7, BA 8, BA 9 and BA 11). However, no resistance to pyrithiobac-sodium was found for biotypes either from Bahia or from Mato Grosso do Sul.

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INFLUENCE OF IMMUNIZATION PROCEDURES ON THE TITER, AFFINITY AND SPECIFICITY OF ANTISERA TO GLYCOPOLYPEPTIDES

Acta Endocrinologica ◽

10.1530/acta.0.062s054 ◽

1969 ◽

Vol 62 (1_Suppl) ◽

pp. S54-S76 ◽

Cited By ~ 20

Author(s):

William D. Odell ◽

Guy Abraham ◽

H. Randar Raud ◽

Ronald S. Swerdloff ◽

Delbert A. Fisher

Keyword(s):

Dose Response ◽

Cross Reaction ◽

Response Curves ◽

Immunological Properties ◽

Molecular Weights ◽

High Affinity ◽

Rate Of Increase ◽

Specific Antisera ◽

Dose Response Curves ◽

Selection Of

ABSTRACT HLH, HTSH, HCG and HFSH are glycopolypeptides with similar molecular weights and immunological properties. Production of antisera useful in specific radioimmunoassays has been difficult. Immunization of rabbits with each of these hormones homogenized in complete Freund's adjuvant is routinely followed by antiserum production. Titers rise progressively with repeated immunizations for ten weeks or more and then the rate of increase falls. Rabbits producing higher titers of antiserum after two immunizations generally continue to produce higher titers during additional immunizations, thus selection of animals early during immunization is possible. Affinity of the antisera against all four hormones generally also increases during the course of immunization. Several ways of estimating affinity of antisera are presented. Specificity of antisera is variable, particularly against HFSH. Review of published techniques and our own experience reveals that all specific anti HFSH has been obtained after two to four immunizations; those after five or more immunizations have shown complete cross reaction with HLH, HTSH, and HFSH. These observations may explain the failure of some investigators to obtain specific antisera. For HFSH antisera, affinity progressively increases, but specificity appears to decrease with frequency of immunization. For HTSH and HCG antisera, specificity is retained or increases with repeated immunizations, and specific high affinity antisera are more regularly produced. Antisera capable of use to produce specific radioimmunoassays need not necessarily contain only antibodies against the hormone to be measured. Thus antisera against LH might be present in an antiserum used to quantify HFSH, if the anti HLH did not bind HFSH in either radioactive or nonradioactive form. Specificities of antisera vary a great deal and consideration of the nature of cross reacting substances would be effective in producing specificity. Thus when HLH reacted completely and equally with HFSH in an HFSH assay, absorbtion would completely neutralize all anti HFSH antibodies. If HLH and HFSH had dose response curves with quite different slopes (and hence different affinities for the anti HFSH), absorbtion is possible. When two or more populations of antibodies against HFSH are demonstrable by the presence of biphasic dose response curves in the assay, and if one population is specific, absorbtion of the nonspecific population may be possible.

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Adjuvants Influenced Saflufenacil Efficacy on Fall-Emerging Weeds

Weed Technology ◽

10.1614/wt-08-174.1 ◽

2009 ◽

Vol 23 (3) ◽

pp. 340-345 ◽

Cited By ~ 21

Author(s):

Stevan Z. Knezevic ◽

Avishek Datta ◽

Jon Scott ◽

Leo D. Charvat

Keyword(s):

Weed Control ◽

Dose Response ◽

Field Experiments ◽

Weed Species ◽

Response Curves ◽

Wheat Field ◽

Field Pennycress ◽

Field Bindweed ◽

Label Dose ◽

Dose Response Curves

Saflufenacil is a new herbicide being developed for preplant burndown and PRE broadleaf weed control in field crops, including corn, soybean, sorghum, and wheat. Field experiments were conducted in 2006 and 2007 at Concord, in northeast Nebraska, with the objective to describe dose–response curves of saflufenacil applied with several adjuvants for broadleaf weed control. Dose–response curves based on log-logistic model were used to determine the effective dose that provides 90% weed control (ED90) values for six broadleaf weeds (field bindweed, prickly lettuce, henbit, shepherd's-purse, dandelion, and field pennycress). Addition of adjuvants greatly improved efficacy of saflufenacil. For example, the ED90values for field bindweed control at 28 d after treatment were 71, 20, 11, and 7 g/ha for saflufenacil applied alone, or with nonionic surfactant (NIS), crop oil concentrate (COC), or methylated seed oil (MSO), respectively. MSO was the adjuvant that provided the greatest enhancement of saflufenacil across all species tested. COC was the second-best adjuvant and provided control similar to MSO on many weed species. NIS provided the least enhancement of saflufenacil. These results are very similar to the proposed label dose of saflufenacil for burndown weed control, which will range from 25 to 100 g/ha with MSO or COC. We believe that such a dose would provide excellent burndown control of most broadleaf weed species that emerge in the fall in Nebraska.

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Linear DNA Elution Dose Response Curves Obtained in CHO Cells with Non-unwinding Filter Elution after Appropriate Selection of the Lysis Conditions

International Journal of Radiation Biology ◽

10.1080/09553008914550621 ◽

1989 ◽

Vol 55 (4) ◽

pp. 569-581 ◽

Cited By ~ 66

Author(s):

Ryuichi Okayasu ◽

George Iliakis

Keyword(s):

Dose Response ◽

Cho Cells ◽

Response Curves ◽

Linear Dna ◽

Dose Response Curves ◽

Selection Of

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Resistance of Amaranthus retroflexus to acetolactate synthase inhibitor herbicides in Brazil

Planta Daninha ◽

10.1590/s0100-83582014000200022 ◽

2014 ◽

Vol 32 (2) ◽

pp. 437-446 ◽

Cited By ~ 8

Author(s):

A.C. Francischini ◽

J. Constantin ◽

R.S. Oliveira Jr. ◽

G. Santos ◽

L.H.M. Franchini ◽

...

Keyword(s):

Dose Response ◽

Acetolactate Synthase ◽

Amaranthus Retroflexus ◽

High Yield ◽

Cross Resistance ◽

Yield Losses ◽

Mato Grosso ◽

Als Inhibitors ◽

Synthase Inhibitor ◽

Mato Grosso Do Sul

When in competition with cotton, Amaranthus retroflexus can cause high yield losses. Due to the limited availability of selective herbicides registered for post emergence control of this weed, the same herbicides have been used repeated times over the last few years, which may have selected resistant biotypes. Biotypes of A. retroflexus collected from the main areas of cotton cultivation in Brazil were submitted to dose-response trials, by applying the herbicides trifloxysulfuron-sodium and pyrithiobac-sodium in doses equivalent to 0, ¼, ½, 1, 2 and 4 times the recommended rates. Resistance to ALS inhibitors was confirmed in biotypes of A. retroflexus. Biotype MS 2 from Mato Grosso do Sul, was cross-resistant to both trifloxysulfuron-sodium and pyrithiobac-sodium, while biotype MS 1 was resistant to trifloxysulfuron-sodium only. Likewise, singular and cross resistance was also confirmed in biotypes from Goiás (GO 3, GO 4 and GO 6), in relation to trifloxysulfuronsodium and pyrithiobac-sodium. One biotype from Mato Grosso (MT 13) was not resistant to any of the ALS inhibitors evaluated in this work.

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Response of Sweet Corn to Pyroxasulfone in High-Organic-Matter Soils

Weed Technology ◽

10.1614/wt-d-12-00133.1 ◽

2013 ◽

Vol 27 (2) ◽

pp. 341-346 ◽

Cited By ~ 5

Author(s):

Dennis C. Odero ◽

Alan L. Wright

Keyword(s):

Organic Matter ◽

Weed Control ◽

Dose Response ◽

Sweet Corn ◽

Corn Yield ◽

Response Curves ◽

Common Lambsquarters ◽

High Organic Matter ◽

Dose Response Curves ◽

Common Purslane

Field experiments were conducted in 2011 and 2012 in Belle Glade, FL to evaluate the response of sweet corn and weed control to pyroxasulfone on high-organic-matter soils in the Everglades Agricultural Area (EAA) of southern Florida with the use of dose-response curves. Pyroxasulfone was applied PRE at 31.25, 62.5, 125, 250, 500, and 1,000 g ai ha−1 on soil with 80% organic matter. Dose-response curves based on a three-parameter log-logistic model were used to determine pyroxasulfone rate required to provide 90% control (ED90) of spiny amaranth, common lambsquarters, and common purslane in sweet corn. The ED90 values for spiny amaranth, common lambsquarters, and common purslane control were 209, 215, and 194 g ha−1 of pyroxasulfone, respectively, at 21 d after treatment (DAT). At 42 DAT, the ED90 values for spiny amaranth, common lambsquarters, and common purslane control were 217, 271, and 234 g ha−1 of pyroxasulfone, respectively. Sweet corn yield increased with increasing rates of pyroxasulfone. An estimated 214 g ha−1 of pyroxasulfone was required to maintain sweet corn yield at 90% level of the weed-free yield. In addition, pyroxasulfone did not result in sweet corn injury. These results indicate that pyroxasulfone can provide effective weed control in sweet corn on high-organic-matter soils of the EAA.

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Dose–Response Curves of KIH-485 for Preemergence Weed Control in Corn

Weed Technology ◽

10.1614/wt-08-097.1 ◽

2009 ◽

Vol 23 (1) ◽

pp. 34-39 ◽

Cited By ~ 41

Author(s):

Stevan Z. Knezevic ◽

Avishek Datta ◽

Jon Scott ◽

Peter J. Porpiglia

Keyword(s):

Weed Control ◽

Dose Response ◽

Field Experiments ◽

Response Curves ◽

Tolerance Dose ◽

Green Foxtail ◽

Excellent Control ◽

Dose Response Curves ◽

Different Levels ◽

Large Crabgrass

Field experiments were conducted in Nebraska with the experimental herbicide KIH-485 on soils with three different levels of organic matter (OM) to ascertain a dose response for weed control and corn tolerance. Dose–response curves based on the log-logistic model were used to determine the effective dose that provides 90% weed control (ED90 values) for three grasses (green foxtail, field sandbur, large crabgrass) and two broadleaf weeds (velvetleaf, tall waterhemp). The ED90 values for green foxtail control were 143, 165, and 202 g ai/ha for soils with 1, 2, and 3% OM, respectively at 28 d after treatment (DAT). The highest dose of 371 g ai/ha was needed for field sandbur control at 28 DAT, compared with 141 g ai/ha for large crabgrass, 152 g ai/ha for tall waterhemp, and 199 g ai/ha for velvetleaf. There was no significant corn injury observed. Grain yield increased with increasing doses of KIH-485; optimum yield was achieved at about 195 g ai/ha. From the dose–response curves it is clear that the proposed label rate of KIH-485 of 200 to 300 g ai/ha will provide excellent control of most grasses and certain broadleaf weeds in corn for at least the first 4 wk of the growing season on soils up to 3% OM in the state of Nebraska.

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Dose-response Curves in the Fibrin Plate Assay Fibrinolytic Activity of Proteases

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647705 ◽

1974 ◽

Vol 32 (02/03) ◽

pp. 356-365 ◽

Cited By ~ 12

Author(s):

F Haverkate ◽

D. W Traas

Keyword(s):

Dose Response ◽

Fibrinolytic Activity ◽

Enzyme Concentration ◽

Response Curves ◽

Agar Gel ◽

Porcine Tissue ◽

Plate Assay ◽

Fibrin Plate ◽

Different Types ◽

Dose Response Curves

SummaryIn the fibrin plate assay different types of relationships between the dose of applied proteolytic enzyme and the response have been previously reported. This study was undertaken to determine whether a generally valid relationship might exist.Trypsin, chymotrypsin, papain, the plasminogen activator urokinase and all of the microbial proteases investigated, including brinase gave a linear relationship between the logarithm of the enzyme concentration and the diameter of the circular lysed zone. A similar linearity of dose-response curves has frequently been found by investigators who used enzyme plate assays with substrates different from fibrin incorporated in an agar gel. Consequently, it seems that this linearity of dose-response curves is generally valid for the fibrin plate assay as well as for other enzyme plate bioassays.Both human plasmin and porcine tissue activator of plasminogen showed deviations from linearity of semi-logarithmic dose-response curves in the fibrin plate assay.

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BIOASSAY OF THYROID HORMONE USING HYPOTHYROID TADPOLES

Acta Endocrinologica ◽

10.1530/acta.0.0410143 ◽

1962 ◽

Vol 41 (1) ◽

pp. 143-153 ◽

Cited By ~ 2

Author(s):

U. Henriques

Keyword(s):

Thyroid Hormone ◽

Dose Response ◽

Developmental Rate ◽

Response Curves ◽

Sodium Salts ◽

Dose Response Curves

ABSTRACT A bioassay of thyroid hormone has been developed using Xenopus larvae made hypothyroid by the administration of thiourea. Only tadpoles of uniform developmental rate were used. Thiourea was given just before the metamorphotic climax in concentrations that produced neoteni in an early metamorphotic stage. During maintained thiourea neotoni, 1-thyroxine and 1-triiodothyronine were added as sodium salts to the water for three days and at the end of one week the stage of metamorphosis produced was determined. In this way identical dose-response curves were obtained for the two compounds. No qualitative differences between their effects were noted except that triiodothyronine seemed more toxic than thyroxine in equivalent doses. Triiodothyronine was found to be 7–12 times as active as thyroxine.

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