Green foxtail (Setaria viridis) resistance to acetolactate synthase inhibitors

Volenberg, Dean S.; Stoltenberg, David E.; Boerboom, Chris M.

doi:10.7202/706232ar

Cited by 7 publications

(3 citation statements)

References 43 publications

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“…The results of this study revealed that although all fluridone-resistant hydrilla biotypes behaved differently in response to fluridone concentrations over time, EC 50 values for phytoene and b-carotene content followed almost identical trends in response to varying fluridone concentrations in all biotypes. Factors that accelerate the selection of resistant biotypes include repeated use of a single herbicide in large areas, the failure to alternate different modes of action, and long residual herbicide activity (Maxwell and Mortimer 1994;Volenberg et al 2002). Fluridone has been the primary herbicide used in hydrilla control programs in Florida for over two decades.…”

Section: Resultsmentioning

confidence: 99%

Stability of Fluridone-Resistant Hydrilla (Hydrilla verticillata) Biotypes over Time

2007

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Hydrilla is one of the most serious aquatic weed problems in the United States, and fluridone is the only herbicide approved by the U.S. Environment Protection Agency that provides systemic control. Recently, hydrilla biotypes with varying levels of fluridone resistance have been documented in Florida. Hydrilla biotypes of varying fluridone resistance levels were maintained in 900-L tanks under natural atmospheric conditions from September 2004 to September 2005 in the absence of fluridone. Hydrilla shoot tips were collected from each biotype during September 2004 (at planting), December 2004 (3 mo after planting [MAP]), March 2005 (6 MAP), June 2005 (9 MAP), and September 2005 (12 MAP) and exposed to 5, 10, 15, 20, 30, and 50 µg L−1fluridone to assess changes in susceptibility to this herbicide over time. Nonlinear regression analysis was used to calculate EC50values for phytoene and β-carotene (effective fluridone concentration to increase/decrease the phytoene/β-carotene content in hydrilla plant tissue by 50% over the untreated control) at each time interval. EC50values did not change in the susceptible hydrilla biotype over time. The EC50values for phytoene and β-carotene for the susceptible biotype were 7.5 and 8.9 µg L−1, respectively, at planting and 7.6 and 9.4 µg L−1, respectively, at 12 MAP. Resistant hydrilla biotypes (R1–R5) also showed no change in EC50phytoene values over time. Although, EC50β-carotene values in resistant biotypes R1, R3, R4, and R5 did not change over time, R2 recorded a reduction in EC50β-carotene at 12 MAP. Also, a 0.5-point decrease in resistance factor was observed for all resistant biotypes. Future long-term studies are needed to evaluate stability of resistant hydrilla biotypes in the absence of fluridone selection pressure.

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Section: Resultsmentioning

confidence: 99%

Stability of Fluridone-Resistant Hydrilla (Hydrilla verticillata) Biotypes over Time

2007

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“…Several studies have shown that some herbicides can have initial phytotoxic effects, although seedlings usually recover without severe damage, and yield loss are not observed (Díaz et al 1992;Ivany et al 2002;Thomas et al 1994;Tonks et al 1991;Volenberg et al 2002;Young et al 2003). In other studies, however, various clover species were exposed and evaluated for tolerance to different herbicides including pendimethalin and metolachlor (Tharp and Kells 2000), bentazon and 2,4-D (Evers et al 1993), 2,4-D and dicamba (Griffin et al 1984), and MCPA and 2,4-DB (Conrad and Stritzke 1980); in all cases, yield and persistence of the legume were markedly reduced.…”

Section: Introductionmentioning

confidence: 99%

Effect of five postemergence herbicides on red clover shoot and root growth in greenhouse studies

Ceballos

Palma

Brevis

et al. 2005

phyto

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Société de protection des plantes du Québec (SPPQ)ISSN 0031-9511 (imprimé) 1710-1603 (numérique) Découvrir la revue Citer cet article Ceballos, R., Palma, G., Brevis, H., Ortega, F. & Quiroz, A. (2004). Effect of five postemergence herbicides on red clover shoot and root growth in greenhouse studies. Phytoprotection, 85(3), 153-160. doi:10.7202 MCPA, 2,4-DB, flumetsulam, bentazon, haloxyfop-methyl, flumetsulam/2,4-DB and bentazon/MCPA were studied in greenhouse experiments in order to evaluate their primary effects on red clover (Trifolium pratense) growth and root injury. The influence of these herbicides on root length, plant height, crown diameter, shoot and root dry weights, shoot phytotoxicity and root injury were studied at two application rates. Variable responses in the growth parameters were observed throughout the experimental period. Herbicides did not affect root length. By the end of experiment, plant height was increased by all herbicides except MCPA and bentazon/MCPA. Crown diameter was increased only with MCPA and 2,4-DB, whereas it was not affected by the other herbicides. Bentazon reduced root dry weight while the other herbicides had no effect. In general, MCPA, bentazon, and bentazon/MCPA reduced shoot dry weight. Although all herbicides caused early foliar damage, the plants recovered by the end of experiment comparable to the control plants. Bentazon and bentazon/MCPA produced the greatest shoot damage. Roots were injured from all herbicides, yet they usually recovered over time. However, bentazon/MCPA induced more severe root injury, up to 17% of the plants, causing seedlings died. These results suggest that some herbicides used to protect red clover against weeds may also affect red clover development, increasing its vulnerability to disease. [Effet de cinq herbicides de postlevée sur la croissance de tiges et de racines du trèfle rouge lors d'essais en serre]Le MCPA, le 2,4-DB, le flumetsulam, le bentazone, le haloxyfop-méthyl, le flumetsulam/2,4-DB et le bentazone/MCPA ont été étudiés lors d'expériences en serre afin d'évaluer leurs principaux effets sur la croissance du trèfle rouge (Trifolium pratense) ainsi que sur les dommages racinaires qu'ils pourraient lui causer. Les conséquences qu'ont ces herbicides sur la longueur des racines, la taille de la plante, le diamètre du collet, les poids secs des tiges et des racines, ainsi que leur phytotoxicité pour les tiges et les dommages aux racines ont été étudiés pour deux doses d'application. Les paramètres de croissance ont eu des résultats indépendants les uns des autres tout au long de la durée des expériences. Les herbicides n'ont pas eu d'effet sur la longueur des racines. À la fin des expériences, la taille de la plante avait été augmentée par tous les herbicides sauf le MCPA et le bentazone/MCPA. Le diamètre du collet n'avait été augmenté que par le MCPA et le 2,4-DB, alors que les autres herbicides n'avaient pas eu d'effet. Le bentazone a fait diminuer le poids sec des racines alors que les autres herbicides n'ont pas eu d'ef...

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“…As an example see the results for a study in which the untreated control of two Setaria viridis (green foxtail) populations had similar shoot biomass but produced different biomass at the highest dose of imazethapyr or imazamox. 21 This situation can be compared to a competition between two downhill skiers where they start at the same altitude (similar upper limit u) but finish at different altitudes. Again, it makes no sense to compare the time to reach the midway point (relative ED 50 in a dose-response context) as the end points differ.…”

Section: Error #2: Comparing Ed 50 Values and Calculating The Ri Of Nonparalleled Curvesmentioning

confidence: 99%

Perspective: common errors in dose–response analysis and how to avoid them

Keshtkar

Kudsk

Mesgaran

2021

Pest Management Science

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Dose–response experiments are conducted to determine the toxicity of chemicals on organisms. The relationship between dose and response is described by different statistical models. The four‐parameter log‐logistic model is widely used in pesticide sciences to derive biologically relevant parameters such as ED50 and resistance index (RI). However, there are some common errors associated with the calculation of ED50 and RI that can lead to erroneous conclusions. Here we discuss five common errors and propose guidance to avoid them. We suggest (i) all response curves must be fitted simultaneously to allow for proper comparison of parameters across curves, (ii) in the case of nonparallel curves absolute ED50 must be used instead of relative ED50, (iii) standard errors or confidence intervals of the parameters must be reported, (iv) the e parameter in asymmetrical models is not equal to ED50 and hence absolute ED50 must be estimated, and (v) when the four‐parameter log‐logistic model returns a negative value for the lower asymptote, which is biologically meaningless in most cases, the model should be reduced to its three‐parameter version or other types of model should be applied. The mixed‐effects model and the meta‐analytic approach are suggested as appropriate to average the parameters across repeated dose–response experiments. © 2021 Society of Chemical Industry

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Green foxtail (Setaria viridis) resistance to acetolactate synthase inhibitors

Cited by 7 publications

References 43 publications

Stability of Fluridone-Resistant Hydrilla (Hydrilla verticillata) Biotypes over Time

Stability of Fluridone-Resistant Hydrilla (Hydrilla verticillata) Biotypes over Time

Effect of five postemergence herbicides on red clover shoot and root growth in greenhouse studies

Perspective: common errors in dose–response analysis and how to avoid them

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