Effect of elevated temperature on growth and glyphosate susceptibility of Chloris truncata R.Br., Sonchus oleraceus L., and Conyza bonariensis (L.) Cronq.

The relationship between vegetation and soil supporting the habitats in 4 new industrial cities were assessed. Five main habitats were distinguished from inner city toward outskirts: lawns, home gardens, public gardens, waste lands and desert outskirts. After application of Twinspan, 26 vegetation groups were identified in the 5 recognized habitats, demonstrating that some groups are chatracteristic of a certain city, e.g. Asphodelus aestivus - Deverra tortuosa - Thymelaea hirsuta group was confined to the desert habitat of Burg El-Arab city; Thymelaea hirsuta - Linaria albifrons and Atriplex halimus - Atriplex lindleyi subsp. inflata - Suaeda vermiculata - Typha domingensis groups were found in the waste lands of Burg El-Arab city; Conyza bonariensis - Cynodon dactylon - Sonchus oleraceus group in the home garden habitat of 10th Ranadan city; Cynodon dactylon group in the lawns of Burg El-Arab city; Bassia indica - Plantago major group in the public gardens of Burg El-Arab city; Oxalis corniculata - Plantago lagopus group in the public gardens of 10th Ramadan city; Sonchus oleraceus - Cynodon dactylon and Dactyloctenium aegyptium - Leptochloa fusca - Phragmites australis groups in the public gardens of 6th October city. Silt, clay, organic matter, carbonates and carbon contents showed significant diffrences among the 5 habitats.

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Effectiveness of glufosinate, dicamba, and clethodim on glyphosate-resistant and susceptible populations of five key weeds in Australian cotton systems

Weed Technology ◽

10.1017/wet.2021.59 ◽

2021 ◽

pp. 1-20

Author(s):

Jeff Werth ◽

David Thormby ◽

Michelle Keenan ◽

James Hereward ◽

Bhagirath Singh Chauhan

Keyword(s):

Herbicide Resistance ◽

Weed Management ◽

Resistance Management ◽

Sonchus Oleraceus ◽

Conyza Bonariensis ◽

Resistant Population ◽

Susceptible Populations ◽

Chloris Virgata ◽

Effective Treatments

XtendFlexTM cotton with resistance to glyphosate, glufosinate and dicamba may become available in Australia. Resistance to these herbicides enables two additional modes of action to be applied in crop. The double knock strategy, typically glyphosate followed by paraquat, has been a successful tactic for control of glyphosate-resistant in fallow situations in Australia. Glufosinate is a contact herbicide, and may be useful as the second herbicide in a double knock for use in XtendFlexTM cotton crops. We tested the effectiveness of glufosinate applied at intervals of 1, 3, 7, and 10 d after initial applications of glyphosate, dicamba, clethodim and glyphosate mixtures with dicamba or clethodim on glyphosate-resistant and susceptible populations of Conyza bonariensis, Sonchus oleraceus, Chloris virgata, Chloris truncata and Echinochloa colona. Effective treatments for Conyza bonariensis with 100% control were dicamba and glyphosate+dicamba followed by glufosinate independent of the interval between applications. Sonchus oleraceus was effectively controlled in Experiment 1 by all treatments. However, in Experiment 2 effective treatments were dicamba and glyphosate+dicamba followed by glufosinate (99.3 – 100% control). Timing of the follow-up glufosinate did not affect the control achieved. Consistent control of Chloris virgata was achieved with glyphosate, clethodim or glyphosate+clethodim followed by glufosinate at 7 and 10 d intervals (99.7 – 100% control). Control of Chloris truncata was inconsistent. The best treatment for C. truncata was glyphosate+clethodim followed by glufosinate 10 d later (99.8 – 100% control). Echinochloa colona was effectively controlled with all treatments except for glyphosate on the glyphosate-resistant population. Additional in-crop use of glufosinate and dicamba should be beneficial for weed management in XtendFlexTM cotton crops, when utilising the double knock tactic with glufosinate. For effective herbicide resistance management, it is important that these herbicides be used in addition to, rather than substitution for, existing weed management tactics.

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Changes in weed species since the introduction of glyphosate-resistant cotton

Crop and Pasture Science ◽

10.1071/cp13167 ◽

2013 ◽

Vol 64 (8) ◽

pp. 791 ◽

Cited By ~ 31

Author(s):

Jeff Werth ◽

Luke Boucher ◽

David Thornby ◽

Steve Walker ◽

Graham Charles

Keyword(s):

Weed Management ◽

Management Practices ◽

Weed Species ◽

Sonchus Oleraceus ◽

Cropping Season ◽

Conyza Bonariensis ◽

Major Species ◽

Chloris Virgata ◽

A Minor ◽

Over The Top

Weed management practices in cotton systems that were based on frequent cultivation, residual herbicides, and some post-emergent herbicides have changed. The ability to use glyphosate as a knockdown before planting, in shielded sprayers, and now over-the-top in glyphosate-tolerant cotton has seen a significant reduction in the use of residual herbicides and cultivation. Glyphosate is now the dominant herbicide in both crop and fallow. This reliance increases the risk of shifts to glyphosate-tolerant species and the evolution of glyphosate-resistant weeds. Four surveys were undertaken in the 2008–09 and 2010–11 seasons. Surveys were conducted at the start of the summer cropping season (November–December) and at the end of the same season (March–April). Fifty fields previously surveyed in irrigated and non-irrigated cotton systems were re-surveyed. A major species shift towards Conyza bonariensis was observed. There was also a minor increase in the prevalence of Sonchus oleraceus. Several species were still present at the end of the season, indicating either poor control and/or late-season germinations. These included C. bonariensis, S. oleraceus, Hibiscus verdcourtii and Hibiscus tridactylites, Echinochloa colona, Convolvulus sp., Ipomea lonchophylla, Chamaesyce drummondii, Cullen sp., Amaranthus macrocarpus, and Chloris virgata. These species, with the exception of E. colona, H. verdcourtii, and H. tridactylites, have tolerance to glyphosate and therefore are likely candidates to either remain or increase in dominance in a glyphosate-based system.

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Effect of Soil Moisture Regimes on the Glyphosate Sensitivity and Morpho-Physiological Traits of Windmill Grass (Chloris truncata R.Br.), Common Sowthistle (Sonchus oleraceus L.), and Flaxleaf Fleabane [Conyza bonariensis (L.) Cronq.]

Plants ◽

10.3390/plants10112345 ◽

2021 ◽

Vol 10 (11) ◽

pp. 2345

Author(s):

Arslan Masood Peerzada ◽

Alwyn Williams ◽

Chris O’Donnell ◽

Steve Adkins

Keyword(s):

Soil Moisture ◽

Lethal Dose ◽

Physiological Traits ◽

Weed Species ◽

Sonchus Oleraceus ◽

Moisture Availability ◽

Conyza Bonariensis ◽

Moisture Regimes ◽

Soil Moisture Availability ◽

Biomass Reduction

The glasshouse study was conducted with the objectives of (i) investigating the effect of soil moisture variations on the control efficiency of glyphosate on windmill grass (Chloris truncata R.Br.), common sowthistle (Sonchus oleraceus L.), and flaxleaf fleabane [Conyza bonariensis (L.) Cronq.], (ii) evaluating the tolerance of tested weed species under soil moisture variations, and (iii) determining the morphological and physiological characteristics of these species to partially explain herbicide tolerance under periods of reduced soil moisture availability (RSM). The species’ tolerance to glyphosate increased significantly under reduced soil moisture availability (p < 0.001). The lethal dose to cause herbicide injury or biomass reduction by 50% (LD50) and 80% (LD80) in relation to untreated control for water-stressed plants [i.e., moderate soil moisture availability (MSM) and RSM] was significantly higher than that of plants grown under high soil moisture availability (HSM). The tolerance factor (TF) for C. truncata, S. oleraceus, and C. bonariensis, in terms of biomass reduction under RSM, was 2.6, 2.4, and 2.6, respectively, as compared to HSM. The results showed that the glyphosate sensitivity, especially at the sub-lethal rates, of the three weed species under study decreased as soil moisture availability reduced (p < 0.01). Overall glyphosate efficacy, in relation to the recommended rate, was unaffected, except for C. truncata; the weed survived the highest tested glyphosate rate [750 g active ingredient (a.i.) ha−1] under RSM. There was significant interaction between weed species and soil moisture regimes for weed morpho-physiological traits (p < 0.001), with reduced soil moisture having a more influential impact on the growth of C. bonariensis and S. oleraceus compared to C. truncata. Changes in the leaf characteristics, such as increased leaf thickness, higher leaf chlorophyll content, reduced leaf area, and limited stomatal activity for all the tested weed species under MSM and RSM in relation to HSM, partially explain the tolerance of species to glyphosate at sublethal rates.

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CONTROLE QUÍMICO DE PLANTAS DANINHAS UTILIZANDO DIFERENTES PONTAS DE PULVERIZAÇÃO

Scientia Agraria ◽

10.5380/rsa.v15i1.41097 ◽

2014 ◽

Vol 15 (1) ◽

Cited By ~ 1

Author(s):

Mario NIEWEGLOWSKI FILHO ◽

Adelino PELISSARI ◽

Henrique Soares KOEHLER ◽

José Carlos BASSETTI ◽

Márcio MURARO ◽

...

Keyword(s):

Parthenium Hysterophorus ◽

Raphanus Raphanistrum ◽

Bidens Pilosa ◽

Stellaria Media ◽

Metsulfuron Methyl ◽

Rumex Obtusifolius ◽

Sonchus Oleraceus ◽

Conyza Bonariensis

A tecnologia de aplicação de um produto pode influenciar a eficácia de controle no alvo desejado. Assim, a determinação do tipo de ponta de pulverização a ser usada, bem como o volume de calda aplicado são fatores que determinam a qualidade de uma aplicação. Para tanto, este trabalho teve como objetivo avaliar a qualidade da aplicação de herbicidas utilizando diferentes pontas de pulverização (jato plano - SF 110 015 e jato cônico - JA 1,5) e diferentes volumes de calda (100 e 150 L ha-1) visando o controle de plantas daninhas. Assim, utilizou-se o delineamento em blocos casualizados e os tratamentos dispostos em esquema fatorial 2x2x4 (volume de calda x tipo de ponta de pulverização x herbicida), totalizando 16 tratamentos com três blocos. A unidade experimental compreendeu uma área de 700 m2, aonde foi avaliado o controle das plantas daninhas presentes. Os herbicidas utilizados foram: glyphosate, metsulfuron methyl, 2,4 - D e paraquat. As espécies Conyza bonariensis, Sonchus oleraceus, Parthenium hysterophorus, Bidens pilosa, Galinsoga parviflora, Soliva pterosperma, Raphanus raphanistrum, Stellaria media, Spergula arvensis, Stachys arvensis e Rumex obtusifolius foram as plantas daninhas presentes na área. O controle de C. bonariensis, B. pilosa, G. parviflora, R. raphanistrum, S. media e Stachys arvensis não foi influenciado pelo volume de calda aplicado. Entretanto, maiores porcentagens de controle nas espécies S. oleraceus, P. hysterophorus, Spergula arvensis e R. obtusifolius foram obtidas na aplicação de 150 L ha-1 e para S. pterosperma 100 L ha-1. Algumas espécies não apresentaram redução de controle em função do tipo de ponta de pulverização usado, como observado em B. pilosa, S. media e Stachys arvensis. Todavia, o controle de P. hysterophorus foi mais eficiente quando se utilizou a ponta de jato plano. Já as outras sete espécies avaliadas tiveram maior controle com a ponta de jato cônico. Dentre os herbicidas utilizados, o glyphosate foi mais eficiente no controle das plantas daninhas, com exceção das espécies B. pilosa e Stachys arvensis.

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Evidence for a shear mechanism for the precipitation of γ-zirconium hydride in zirconium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011043x ◽

1978 ◽

Vol 36 (1) ◽

pp. 658-659

Author(s):

G.J.C. Carpenter

Keyword(s):

Elevated Temperature ◽

Strain Field ◽

Zirconium Hydride ◽

Zirconium Atom ◽

Atom Diffusion ◽

Solvus Temperature ◽

Hexagonal Close Packed ◽

Partial Dislocations ◽

The Face

In zirconium-hydrogen alloys, rapid cooling from an elevated temperature causes precipitation of the face-centred tetragonal (fct) phase, γZrH, in the form of needles, parallel to the close-packed <1120>zr directions (1). With low hydrogen concentrations, the hydride solvus is sufficiently low that zirconium atom diffusion cannot occur. For example, with 6 μg/g hydrogen, the solvus temperature is approximately 370 K (2), at which only the hydrogen diffuses readily. Shears are therefore necessary to produce the crystallographic transformation from hexagonal close-packed (hep) zirconium to fct hydride.The simplest mechanism for the transformation is the passage of Shockley partial dislocations having Burgers vectors (b) of the type 1/3<0110> on every second (0001)Zr plane. If the partial dislocations are in the form of loops with the same b, the crosssection of a hydride precipitate will be as shown in fig.1. A consequence of this type of transformation is that a cumulative shear, S, is produced that leads to a strain field in the surrounding zirconium matrix, as illustrated in fig.2a.

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Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104819 ◽

1988 ◽

Vol 46 ◽

pp. 550-551

Author(s):

R. E. Franck ◽

J. A. Hawk ◽

G. J. Shiflet

Keyword(s):

High Temperature ◽

Elevated Temperature ◽

Grain Growth ◽

Volume Fraction ◽

Microstructural Characterization ◽

Second Phase ◽

Microstructural Stability ◽

Elevated Temperature Strength ◽

Temperature Applications

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.

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