Time of Application Influences Translocation of Auxinic Herbicides in Palmer Amaranth (Amaranthus palmeri)

The efficacy of WSSA Group 4 herbicides has been reported to vary with dependence on the time of day the application is made, which may affect the value of this mechanism of action as a control option and resistance management tool for Palmer amaranth. The objectives of this research were to evaluate the effect of time of day for application on 2,4-D and dicamba translocation and whether or not altering translocation affected any existing variation in phytotoxicity seen across application time of day. Maximum translocation (Tmax) of [14C]2,4-D and [14C]dicamba out of the treated leaf was significantly increased 52% and 29% to 34% in one of two repeated experiments for each herbicide, respectively, with application at 7:00 AM compared with applications at 2:00 PM and/or 12:00 AM. Applications at 7:00 AM increased [14C]2,4-D distribution to roots and increased [14C]dicamba distribution above the treated leaf compared with other application timings. In phytotoxicity experiments, dicamba application at 8 h after exposure to darkness (HAED) resulted in significantly lower dry root biomass than dicamba application at 8 h after exposure to light (HAEL). Contrasts indicated that injury resulting from dicamba application at 8 HAEL, corresponding to midday, was significantly reduced with a root treatment of 5-[N-(3,4-dimethoxyphenylethyl)methylamino]-2-(3,4-dimethoxyphenyl)-2-isopropylvaleronitrile hydrochloride (verapamil) compared with injury observed with dicamba application and a root treatment of verapamil at 8 HAED, which corresponded to dawn. Overall, time of application appears to potentially influence translocation of 2,4-D and dicamba. Furthermore, inhibition of translocation appears to somewhat influence variation in phytotoxicity across times of application. Therefore, translocation may be involved in the varying efficacy of WSSA Group 4 herbicides due to application time of day, which has implications for the use of this mechanism of action for effective control and resistance management of Palmer amaranth.

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Relating initial paraquat injury to final efficacy in selected weed species influenced by environmental conditions

Weed Technology ◽

10.1017/wet.2020.109 ◽

2020 ◽

pp. 1-10

Author(s):

Nick T. Harre ◽

Garth W. Duncan ◽

Julie M. Young ◽

Bryan G. Young

Keyword(s):

Environmental Factors ◽

Negative Relationship ◽

Injury Rate ◽

Time Of Day ◽

Palmer Amaranth ◽

Shoot Biomass ◽

Lag Phase ◽

Progression Rate ◽

Weed Species ◽

Time Of Application

Abstract Weed control of paraquat can be erratic and may be attributable to differing species sensitivity and/or environmental factors for which minor guidance is available on commercial labels. Therefore, the objectives of this research were to quantify selectivity of paraquat across select weed species and the influence of environmental factors. Experiments were performed under controlled conditions in the greenhouse and growth chamber. Compared with purple deadnettle (dose necessary to reduce shoot biomass by 50% = 39 g ai ha−1), waterhemp, Palmer amaranth, giant ragweed, and horseweed were 4.9, 3.3, 1.9, and 1.3 times more sensitive to paraquat, respectively. The injury progression rate over 3 d after treatment (DAT) was a more accurate predictor of final efficacy at 14 DAT than the lag phase until symptoms first appeared. For example, at the 17.5 g ha−1 dose, the injury rate of waterhemp and Palmer amaranth was, on average, 3.6 times greater than that of horseweed and purple deadnettle. The influence of various environmental factors on paraquat efficacy was weed specific. Applications made at sunrise improved control of purple deadnettle over applications at solar noon or sunset. Lower light intensities (200 or 600 μmol m−2 s−1) surrounding the time of application improved control of waterhemp and horseweed more than 1,000 μmol m−2 s−1. Day/night temperatures of 27/16 C improved horseweed and purple deadnettle control compared with day/night temperatures of 18/13 C. Though control was positively associated with injury rates in the application time of day and temperature experiments, a negative relationship was observed for waterhemp in the light-intensity experiment. Thus, although there are conditions that enhance paraquat efficacy, the specific target species must also be considered. These results advocate paraquat dose recommendations, currently based on weed height, be expanded to address sensitivity differences among weeds. Moreover, these findings contrast with paraquat labels stating temperatures of 13 C or lower do not reduce paraquat efficacy.

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Response of Soil Applied Herbicides at Different Application Timings on The Weed Control Efficacy and Phytotoxicity to Rice In Dry-seeded Condition

Bangladesh Agronomy Journal ◽

10.3329/baj.v22i1.44927 ◽

2020 ◽

Vol 22 (1) ◽

pp. 15-25

Author(s):

Sharif Ahmed ◽

Akbar Hossain ◽

Abu Abdullah Miajy ◽

Tahir H Awan

Keyword(s):

Weed Control ◽

Rice Plant ◽

Plant Density ◽

Control Measure ◽

Effective Control ◽

Application Time ◽

Control Efficacy ◽

Time Of Application ◽

Significant Difference ◽

Weeds Control

Dry-seeded rice (DSR) is a labor and water saving emerging production system. The use of pre-emergence herbicides was found to be the most effective weeds control measure under the DSR system. Although several herbicides are now available in market, the selection of right herbicides with a time of application is crucial for effective control of weeds as well as to reduce the phyto toxicity of crops. A field study in a split-plot design with three replications was conducted to evaluate the effect of application time of soil applied herbicides (viz., 3 times - before crop sowing, after crop sowing but before the first irrigation, and after sowing and first irrigation) and four weeding regimes (viz., weed free, partial-weedy, herbicide oxadiargyl 80 g ai ha-1, and pendimethalin 1000 g ai ha-1) on weed control efficacy, crop performance as well as phytotoxicity of applied herbicides under DSR system. Rice plant stand establishment was highly influenced by application time of herbicides and weeding regimes. Application of pendimethalin at 1000 g ai ha-1 significantly reduced the density of rice plant, more so as sowing was advanced. Compared with the non-treated (partial-weedy) treatment (190 to 195 rice plants m-2), pendimethalin application before sowing, after sowing but before irrigation, and after sowing and irrigation reduced rice plant density by 48, 25 and 12%, respectively. While no significant difference was observed on plant density due to the application of oxadiargyl 80 g ai ha-1, regardless of application time. In case of weed control efficacy for individual herbicides, pendimethalin effectively controlled weeds even spraying before sowing and irrigation; but comparatively less effective than spraying after irrigation. In controlling weeds, oxadiargyl was only effective when spraying after sowing and irrigation, but not before irrigation. Grain yield was significantly increased as the time of herbicide was delayed from before sowing (2.2-2.4 t ha-1), after sowing but before irrigation (2.5-2.6 t ha-1), and after sowing and irrigation (4.0-4.1 tha-1). The results suggest that pre-emergence herbicides should be applied after sowing and irrigation for controlling weeds effectively and also reduce crop toxicity under the DSR system. Bangladesh Agron. J. 2019, 22(1): 15-25

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Evaluation of the time-of-day effect of herbicides applied POST on protoporphyrinogen IX oxidase–resistant and –susceptible Palmer amaranth (Amaranthus palmeri)

Weed Technology ◽

10.1017/wet.2019.43 ◽

2019 ◽

Vol 33 (5) ◽

pp. 651-657

Author(s):

J. Drake Copeland ◽

Garret B. Montgomery ◽

Lawrence E. Steckel

Keyword(s):

Early Morning ◽

Time Of Day ◽

Palmer Amaranth ◽

Amaranthus Palmeri ◽

Application Time ◽

Herbicide Resistant ◽

Consistent Performance ◽

Sites Of Action ◽

And Control

AbstractStudies to evaluate the effect of application time of day (TOD) and protoporphyrinogen IX oxidase (PPO)-inhibiting herbicide–resistant Palmer amaranth on the efficacy of commonly used herbicides was conducted in Tennessee in 2017 and 2018. Treatments of fomesafen, lactofen, acifluorfen, paraquat, glufosinate, glufosinate plus fomesafen, paraquat plus fomesafen, and paraquat plus metribuzin were applied to PPO-resistant (PPO-R) and PPO-susceptible (PPO-S) Palmer amaranth at sunrise and midday. Control of Palmer amaranth with acifluorfen, glufosinate, and glufosinate plus fomesafen was greater with the midday application. However, control of Palmer amaranth with paraquat-based treatments was greater with the sunrise application. TOD effects on PPO-inhibiting herbicides and paraquat-based treatments were more prominent for the PPO-R Palmer amaranth biotype. The TOD effect observed when applying glufosinate in early morning hours on PPO-S Palmer amaranth can be minimized by adding fomesafen to the tank mix. However, this strategy did not provide consistent performance on PPO-R Palmer amaranth. The percentages of living Palmer amaranth plants and control were greater when paraquat plus metribuzin was applied to both biotypes. These results highlight the necessity of at least two effective herbicide sites of action for POST applications intended for controlling PPO-R Palmer amaranth. In addition, the timing of herbicide applications can affect their activity in both PPO-R and PPO-S Palmer amaranth populations.

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Application Time of Day Influences Glyphosate Efficacy

Weed Technology ◽

10.1614/wt-04-251.1 ◽

2007 ◽

Vol 21 (1) ◽

pp. 7-13 ◽

Cited By ~ 19

Author(s):

Keith Mohr ◽

Brent A. Sellers ◽

Reid J. Smeda

Keyword(s):

Weed Control ◽

Field Trials ◽

Time Of Day ◽

Leaf Angle ◽

Diurnal Changes ◽

Leaf Movement ◽

Application Time ◽

Soybean Yield ◽

Time Of Application ◽

Greenhouse Study

Variability in glyphosate efficacy has been observed following late day field applications, but the influence of this “time-of-day effect” on weed control and soybean yield is unknown. Additionally, the basis for differences in weed control due to application time of day has not been fully elucidated. In field trials, broadleaf weed biomass was ≥5-fold greater when glyphosate was applied at 6:00 A.M. compared to 6:00 P.M. in three of four site–years. No consistent time-of-day effect was observed on treated grass weeds. Soybean yield was unaffected by treatments, and was similar to the weed-free control. In a greenhouse study, both barnyardgrass and velvetleaf biomass were as much as 25 to 80% greater when glyphosate was applied at 8:00 P.M. vs. 2:00 P.M. Examination of individual components of the time-of-day effect for velvetleaf indicated that leaf angle and time of application accounted for 82 and 18%, respectively, of the biomass change. This research suggests that diurnal changes in leaf movement of velvetleaf account for much of the time-of-day effect, with the remainder likely due to an unknown physiological component.

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KIH-485 and S-metolachlor Efficacy Comparisons in Conventional and No-Tillage Corn

Weed Technology ◽

10.1614/wt-05-048r2.1 ◽

2006 ◽

Vol 20 (3) ◽

pp. 622-626 ◽

Cited By ~ 38

Author(s):

Patrick W. Geier ◽

Phillip W. Stahlman ◽

John C. Frihauf

Keyword(s):

Weed Control ◽

Field Experiments ◽

Conventional Tillage ◽

Palmer Amaranth ◽

Effective Control ◽

No Tillage ◽

Green Foxtail

Field experiments were conducted during 2003 and 2004 to compare the effectiveness of KIH-485 and S-metolachlor for PRE weed control in no-tillage and conventional-tillage corn. Longspine sandbur control increased as KIH-485 or S-metolachlor rates increased in conventional-tillage corn, but control did not exceed 75% when averaged over experiments. Both herbicides controlled at least 87% of green foxtail with the exception of no-tillage corn in 2004, when KIH-485 was more effective than S-metolachlor at lower rates. Palmer amaranth control ranged from 85 to 100% in 2003 and 80 to 100% in 2004, with the exception of only 57 to 76% control at the lowest two S-metolachlor rates in 2004. Puncturevine control exceeded 94% with all treatments in 2003. In 2004, KIH-485 controlled 86 to 96% of the puncturevine, whereas S-metolachlor controlled only 70 to 81%. Mixtures of atrazine with KIH-485 or S-metolachlor generally provided the most effective control of broadleaf weeds studied.

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Managing Herbicide Resistance: Listening to the Perspectives of Practitioners. Procedures for Conducting Listening Sessions and an Evaluation of the Process

Weed Technology ◽

10.1017/wet.2018.53 ◽

2018 ◽

Vol 32 (4) ◽

pp. 489-497 ◽

Cited By ~ 2

Author(s):

Jill Schroeder ◽

Michael Barrett ◽

David R. Shaw ◽

Amy B. Asmus ◽

Harold Coble ◽

...

Keyword(s):

Small Group ◽

Herbicide Resistance ◽

Planning Process ◽

Resistance Management ◽

Time Of Day ◽

Full Group ◽

Group Discussions ◽

Small Group Discussions ◽

The Subject ◽

Selection Of

AbstractSeven half-day regional listening sessions were held between December 2016 and April 2017 with groups of diverse stakeholders on the issues and potential solutions for herbicide-resistance management. The objective of the listening sessions was to connect with stakeholders and hear their challenges and recommendations for addressing herbicide resistance. The coordinating team hired Strategic Conservation Solutions, LLC, to facilitate all the sessions. They and the coordinating team used in-person meetings, teleconferences, and email to communicate and coordinate the activities leading up to each regional listening session. The agenda was the same across all sessions and included small-group discussions followed by reporting to the full group for discussion. The planning process was the same across all the sessions, although the selection of venue, time of day, and stakeholder participants differed to accommodate the differences among regions. The listening-session format required a great deal of work and flexibility on the part of the coordinating team and regional coordinators. Overall, the participant evaluations from the sessions were positive, with participants expressing appreciation that they were asked for their thoughts on the subject of herbicide resistance. This paper details the methods and processes used to conduct these regional listening sessions and provides an assessment of the strengths and limitations of those processes.

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Evaluation of Florpyrauxifen-benzyl on Herbicide-Resistant and Herbicide-Susceptible Barnyardgrass Accessions

Weed Technology ◽

10.1017/wet.2017.100 ◽

2017 ◽

Vol 32 (2) ◽

pp. 126-134 ◽

Cited By ~ 3

Author(s):

M. Ryan Miller ◽

Jason K. Norsworthy ◽

Robert C. Scott

Keyword(s):

Plant Height ◽

Mechanism Of Action ◽

Control Plant ◽

Resistance Management ◽

Acetolactate Synthase ◽

Management Tool ◽

Alternative Mechanism ◽

Alternative Mode ◽

Herbicide Resistant ◽

Biomass Reduction

AbstractFlorpyrauxifen-benzyl is a new herbicide under development in rice that will provide an alternative mode of action to control barnyardgrass. Multiple greenhouse experiments evaluated florpyrauxifen-benzyl efficacy on barnyardgrass accessions collected in rice fields across Arkansas, and to evaluate its efficacy on herbicide-resistant biotypes. In one experiment, florpyrauxifen-benzyl was applied at the labeled rate of 30 g ai ha−1to 152 barnyardgrass accessions collected from 21 Arkansas counties. Florpyrauxifen-benzyl at 30 g ai ha−1effectively controlled barnyardgrass and subsequently reduced plant height and aboveground biomass. In a dose-response experiment, susceptible-, acetolactate synthase (ALS)-, propanil-, and quinclorac-resistant barnyardgrass biotypes were subjected to nine rates of florpyrauxifen-benzyl ranging from 0 to 120 g ai ha−1. The effective dose required to provide 90% control, plant height reduction, and biomass reduction of the susceptible and resistant biotypes fell below the anticipated labeled rate of 30 g ai ha−1. Based on these results, quinclorac-resistant barnyardgrass as well as other resistant biotypes can be controlled with florpyrauxifen-benzyl at 30 g ai ha−1. Overall, results from these studies indicate that florpyrauxifen-benzyl can be an effective tool for controlling susceptible and currently existing herbicide-resistant barnyardgrass biotypes in rice. Additionally, the unique auxin chemistry of florpyrauxifen-benzyl will introduce an alternative mechanism of action in rice weed control thus acting as an herbicide-resistance management tool.

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Melon fruit yield and quality as a function of doses and times of biostimulant application

Research Society and Development ◽

10.33448/rsd-v9i7.3911 ◽

2020 ◽

Vol 9 (7) ◽

pp. e130973911

Author(s):

Roberto Cleiton Fernandes de Queiroga ◽

Zaqueu Lopes da Silva ◽

Odair Honorato Oliveira de ◽

Elidayane da Nóbrega Santos ◽

Higínio Luan Oliveira Silva ◽

...

Keyword(s):

Block Design ◽

Fruit Production ◽

Soluble Solids ◽

Application Time ◽

Time Of Application ◽

Yield And Quality ◽

Randomized Block Design ◽

Semi Arid Region ◽

Fruit Mass

The objective of this study was to evaluate the productivity and quality of melon fruits as a function of the dose and time of application of biostimulant in the conditions of the semi-arid region of Paraíba. The experiment was carried out at the Federal University of Campina Grande, campus of Pombal - PB, Brazil, in a randomized block design in a 4 x 5 split plot scheme, with doses of biostimulant (0; 0.5; 1.0; 1, 5 and 2.0 L ha-1) and in the subset of the biostimulant application times (15; 20; 25 and 30 days before harvest - DAC), in four replications. Characteristics related to fruit production and quality were evaluated. There was no interaction between the factors of dose and application time of the biostimulant in any of the evaluated characteristics. Thus, the highest estimated values of number of fruits per plant, fruit mass and total melon production were obtained with the application of doses ranging from 0.9 to 1.5 L ha-1 and at the time of application it varied from 22,5 to 23.6 DAC. The content of soluble solids increased 5.5% when the biostimulant dose of 2.0 L ha-1 was used and 4.4% when the product was applied 15 days before harvest.

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Effect of Noni Fruit Extract (Morinda citrifolia L.) And Application Time To Control Crocidolomia binotalis Zell. On Cabbage Plant

Akta Agrosia ◽

10.31186/aa.22.1.13-21 ◽

2019 ◽

Vol 22 (1) ◽

pp. 13-21

Author(s):

Dewi Rahmawati ◽

Djamilah Djamilah ◽

Bilman W Simanihuruk

Keyword(s):

Morinda Citrifolia ◽

Vegetable Crops ◽

Application Time ◽

Fruit Extract ◽

Time Of Application ◽

Crocidolomia Binotalis ◽

Randomized Design ◽

Important Pest ◽

Potential Alternative ◽

Wet Weight

Crocidolomia binotalis Zell is an important pest in Brassicaceae vegetable crops. Vegetable insecticide is one potential alternative to controlling the pest. This study aims to determine the application time of noni fruit extract and to determine the effective concentration of noni fruit extract as a vegetable insecticide in controlling C. binotalis larva on cabbage plants in the field. this study used a Completely Randomized Design (RAL) consisting of two treatment factors and four replications. The first factor is the concentration of extract (5 ppm, 10 ppm, 15 ppm and 20 ppm) and the second factor is the time of application of vegetable pesticide before the pest is invested (W1) and after the pest is invested (W2). So there are 32 units of experiments and 4 units of experiments added as control. The results showed, noni fruit extract had no significant effect on mortality of C. binotalis larvae. The highest mortality rate is at 100% K2 (10ppm) concentration at the time of application before the pest is invested (W1). The interaction had significant effect on the wet weight of the plant canopy but had no significant effect on the mortality of the pest, the intensity of the attack, the percentage of pupa formed, and the present percentage of imago.

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Palmer Amaranth (Amaranthus palmeri) Control by Glufosinate plus Fluometuron Applied Postemergence to WideStrike®Cotton

Weed Technology ◽

10.1614/wt-d-12-00158.1 ◽

2013 ◽

Vol 27 (2) ◽

pp. 291-297 ◽

Cited By ~ 14

Author(s):

Kelly A. Barnett ◽

A. Stanley Culpepper ◽

Alan C. York ◽

Lawrence E. Steckel

Keyword(s):

United States ◽

Weed Control ◽

Acetolactate Synthase ◽

The United States ◽

Palmer Amaranth ◽

Effective Control ◽

Yield Response ◽

Amaranthus Palmeri ◽

Cotton Yield ◽

Cotton Cultivar

Glyphosate-resistant (GR) weeds, especially GR Palmer amaranth, are very problematic for cotton growers in the Southeast and Midsouth regions of the United States. Glufosinate can control GR Palmer amaranth, and growers are transitioning to glufosinate-based systems. Palmer amaranth must be small for consistently effective control by glufosinate. Because this weed grows rapidly, growers are not always timely with applications. With widespread resistance to acetolactate synthase-inhibiting herbicides, growers have few herbicide options to mix with glufosinate to improve control of larger weeds. In a field study using a WideStrike®cotton cultivar, we evaluated fluometuron at 140 to 1,120 g ai ha−1mixed with the ammonium salt of glufosinate at 485 g ae ha−1for control of GR Palmer amaranth 13 and 26 cm tall. Standard PRE- and POST-directed herbicides were included in the systems. Glufosinate alone injured the WideStrike® cotton less than 10%. Fluometuron increased injury up to 25% but did not adversely affect yield. Glufosinate controlled 13-cm Palmer amaranth at least 90%, and there was no improvement in weed control nor a cotton yield response to fluometuron mixed with glufosinate. Palmer amaranth 26 cm tall was controlled only 59% by glufosinate. Fluometuron mixed with glufosinate increased control of the larger weeds up to 28% and there was a trend for greater yields. However, delaying applications until weeds were 26 cm reduced yield 22% relative to timely application. Our results suggest fluometuron mixed with glufosinate may be of some benefit when attempting to control large Palmer amaranth. However, mixing fluometuron with glufosinate is not a substitute for a timely glufosinate application.

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