Effect of Soil pH and Previous Atrazine Use History on Atrazine Degradation in a Tennessee Field Soil

Weed Science ◽  
2010 ◽  
Vol 58 (4) ◽  
pp. 478-483 ◽  
Author(s):  
Thomas C. Mueller ◽  
Lawrence E. Steckel ◽  
Mark Radosevich
Keyword(s):  
Surface Water ◽  
Weed Control ◽  
Soil Ph ◽  
Marked Effect ◽  
Field Studies ◽  
Field Soil ◽  
Effect Of Ph ◽  
Plot Area ◽  
Previously Treated ◽  
Atrazine Degradation

Field studies examined the interaction of soil pH with differing levels of atrazine exposure over 4 yr. Soil pH was 5.2 to 7.1 with atrazine exposures ranging from none (0) to eight applications over a 4-yr period (for each year, one application at planting and one early postemergence). The entire plot area was uniformly managed to reduce potential confounding effects due to cropping history, tillage, and other factors. Soil from all plots previously treated with atrazine displayed rapid atrazine dissipation, with half-lives under laboratory conditions being less than 4 d in plots of pH 5.5 or greater and less than 8 d in the field. Soil pH had a marked effect, with slower atrazine dissipation in those plots that had a pH 5.5 or less. This effect of pH and previous atrazine history was consistent in laboratory and field environments. Implications of these findings include probable reduction in weed control due to more rapid atrazine dissipation and potentially reduced loadings into surface water due to this phenomenon.

Effect of pH, Nitrogen, and Tillage on Weed Control and Corn (Zea mays) Yield

Weed Science ◽  
1980 ◽  
Vol 28 (6) ◽  
pp. 719-722 ◽  
Author(s):  
J. J. Kells ◽  
R. L. Blevins ◽  
C. E. Rieck ◽  
W. M. Muir
Keyword(s):  
Zea Mays ◽  
Weed Control ◽  
Soil Ph ◽  
Soil Surface ◽  
Field Studies ◽  
Conventional Tillage ◽  
Corn Yield ◽  
No Tillage ◽  
Linear Effect ◽  
Surface Soil Ph

Field studies were conducted to determine the effect of soil surface (upper 5 cm) pH and tillage on weed control and corn (Zea maysL.) yield using simazine [2-chloro-4,6-bis-(ethylamino)-s-triazine] as the herbicide for weed control. Soil pH, weed control, and corn yield were examined under no-tillage and conventional tillage systems with and without added lime and different rates of nitrogen. Increased soil pH significantly increased weed control as compared with added lime vs. no added lime, where the surface soil pH influenced the effectiveness of the applied simazine. Soil pH had a greater effect on weed control under no-tillage than under conventional tillage. Conventional tillage significantly (P<.01) increased weed control, yield, and soil pH over no-tillage. Additions of lime as compared to unlimed treatments resulted in significantly increased weed control (83% vs. 63%), yield (5,930 vs. 5,290 kg/ha) and soil pH (5.91 vs. 5.22). The poorest weed control was observed with no-tillage on unlimed plots. A significant tillage by linear effect of nitrogen interaction for all variables resulted from a greater decrease (P<.01) in weed control and soil pH and a greater increase in yield with increased nitrogen under no-tillage than with conventional tillage.

Atrazine Dissipation as Affected by Surface pH and Tillage

Weed Science ◽  
1980 ◽  
Vol 28 (1) ◽  
pp. 101-104 ◽  
Author(s):  
J. J. Kells ◽  
C. E. Rieck ◽  
R. L. Blevins ◽  
W. M. Muir
Keyword(s):  
Weed Control ◽  
Soil Ph ◽  
Field Studies ◽  
Conventional Tillage ◽  
Field Conditions ◽  
No Tillage ◽  
Tillage Systems ◽  
Surface Ph ◽  
Factors Affecting ◽  
Decreasing Ph

Field studies and laboratory analyses were conducted to examine factors affecting degradation of14C-atrazine [2-chloro-4-(ethylamine)-6-(isopropylamino)-s-triazine] under field conditions. The effects of these factors on weed control under no-tillage and conventional tillage systems were also examined. The amount of radioactivity which was unextractable in 90% methanol increased with time following treatment with14C-atrazine. The rate of formation of unextractable14C compounds was greater under no-tillage and increased with decreasing pH. After 14 to 18 days, a greater amount of extractable atrazine was present in areas receiving lime. The degradation of atrazine occurred more rapidly when surface pH was less than 5.0 compared with a pH greater than 6.5. The effect of lime on the amount of parent atrazine present in the soil was directly correlated to its effect on soil pH. Extractable atrazine in the soil 45 days after treatment was significantly correlated with weed control with the greatest effect under no-tillage.

Field Dissipation of Atrazine and Metribuzin in Organic Soils in Florida

2014 ◽  
Vol 28 (4) ◽  
pp. 578-586 ◽  
Author(s):  
Dennis C. Odero ◽  
Dale L. Shaner
Keyword(s):  
Weed Control ◽  
Residual Activity ◽  
Field Studies ◽  
South Florida ◽  
Field Conditions ◽  
Agricultural Area ◽  
Organic Soils ◽  
Bioavailable Fraction ◽  
Rate Of Dissipation ◽  
Atrazine Degradation

Sugarcane growers have observed reduced residual activity of atrazine on organic soils in the Everglades Agricultural Area (EAA) of south Florida. Field studies were conducted between 2011 and 2012 to determine the rate of dissipation of atrazine at 2.24, 4.48, and 8.96 kg ha−1and metribuzin at 0.56, 1.12, and 2.24 kg ha−1in the top 10 cm of soil in sugarcane fields in the EAA. The bioavailable fraction of atrazine dissipated more rapidly than the total amount of atrazine in the soil. Half-lives of the total and bioavailable fraction of atrazine ranged between 3.9 to 12.1 d and 1.0 to 7.5 d, respectively. Metribuzin dissipated much more slowly than atrazine on organic soils. Similarly, dissipation of the bioavailable fraction of metribuzin was more rapid than was the dissipation of the total amount of metribuzin in the soil. Half-lives of the total and bioavailable fraction of metribuzin ranged between 16.2 and 24.8 d and 6.0 and 14.3 d, respectively. These results indicate that enhanced atrazine degradation occurs on organic soils under field conditions in the EAA, resulting in shorter residual atrazine activity. This implies that metribuzin is a better option for weed control in sugarcane grown on organic soils of the EAA exhibiting enhanced atrazine degradation.

Efficacy and Dissipation of Pyroxasulfone and Three Chloroacetamides in a Tennessee Field Soil

Weed Science ◽  
2011 ◽  
Vol 59 (4) ◽  
pp. 574-579 ◽  
Author(s):  
Thomas C. Mueller ◽  
Lawrence E. Steckel
Keyword(s):  
Weed Control ◽  
Half Life ◽  
Dissipation Rate ◽  
Resistance Management ◽  
Growing Season ◽  
Field Studies ◽  
Poor Correlation ◽  
Field Soil ◽  
Rainfall Patterns ◽  
Residual Control

Field studies were conducted in Knoxville, TN, over a 2-yr period (2007 and 2008) to determine the field dissipation rate and efficacy of pyroxasulfone, acetochlor, dimethenamid, ands-metolachlor to broadleaf signalgrass. Depending on rainfall patterns, pyroxasulfone at 209 g ai ha−1provided broadleaf signalgrass control of > 75%, which was equal to or superior to acetochlor at 1,740 g ai ha−1, dimethenamid at 1,500 g ai ha−1ands-metolachlor at 1,420 g ai ha−1. Pyroxasulfone provided residual control into the growing season and provides a tool for resistance management of later-emerging weeds. Herbicide dissipation was rapid in all soils (half-life usually < 20 d), although it was slower in a dry year. The order of herbicide dissipation and half-life in days in the 2 yr was acetochlor (3.5, 5 d) > dimethenamid (5, 9 d) >s-metolachlor (8.8, 27 d) > pyroxasulfone (8.2, > 71 d). There was poor correlation between observed weed control at 45 d after treatment and chemically determined herbicide concentrations at that same time, with ∼ 40% difference in 2007 and ∼ 50% difference in 2008.

CONVISO® SMART – an innovative approach of weed control in sugar beet

2016 ◽  
pp. 517-524 ◽  
Author(s):  
Martin Wegener ◽  
Natalie Balgheim ◽  
Maik Klie ◽  
Carsten Stibbe ◽  
Bernd Holtschulte
Keyword(s):  
Sugar Beet ◽  
Weed Control ◽  
Field Studies ◽  
Essential Amino Acids ◽  
Global Market ◽  
Sugar Beets ◽  
Dose Rates ◽  
Innovative System ◽  
Bayer Cropscience ◽  
Als Inhibitor

KWS SAAT SE and Bayer CropScience AG are jointly developing and commercializing an innovative system of weed control in sugar beet for the global market under the name of CONVISO SMART. The technology is based on the breeding of sugar beet cultivars that are tolerant to herbicides of the ALS-inhibitor-class with a broad-spectrum weed control. This will give farmers a new opportunity to make sugar beet cultivation easier, more flexible in its timing and more efficient. The use of CONVISO, as new herbicide in sugar beet, will make it possible to control major weeds with low dose rates of product and reduced number of applications in the future. The tolerance is based on a change in the enzyme acetholactate synthase, which is involved in the biosynthesis of essential amino acids. This variation can occur spontaneously during cell division. During the development, sugar beets with this spontaneously changed enzyme were specifically selected and used for further breeding of CONVISO SMART cultivars. As such, these varieties are not a product of genetic modification. Field studies with CONVISO SMART hybrids showed complete crop selectivity and a broad and reliable efficacy against a large range of major weeds. The bio-dossier for an EU-wide registration of CONVISO was submitted in April in 2015. The variety inscription process is in preparation in different countries. The system CONVISO SMART is scheduled to be available to farmers in 2018 at the earliest.

Safety and efficacy of linuron with or without an adjuvant or S-metolachlor for POST control of Palmer amaranth (Amaranthus palmeri) in sweetpotato

2021 ◽  
pp. 1-18
Author(s):  
Levi D. Moore ◽  
Katherine M. Jennings ◽  
David W. Monks ◽  
Ramon G. Leon ◽  
David L. Jordan ◽  
...  
Keyword(s):  
Nonionic Surfactant ◽  
Weed Control ◽  
Critical Period ◽  
Total Yield ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Foliar Injury ◽  
Protoporphyrinogen Oxidase ◽  
Safety And Efficacy

Abstract Field studies were conducted to evaluate linuron for POST control of Palmer amaranth in sweetpotato to minimize reliance on protoporphyrinogen oxidase (PPO)-inhibiting herbicides. Treatments were arranged in a two by four factorial where the first factor consisted of two rates of linuron (420 and 700 g ai ha−1), and the second factor consisted of linuron applied alone or in combinations of linuron plus a nonionic surfactant (NIS) (0.5% v/v), linuron plus S-metolachlor (800 g ai ha−1), or linuron plus NIS plus S-metolachlor. In addition, S-metolachlor alone and nontreated weedy and weed-free checks were included for comparison. Treatments were applied to ‘Covington’ sweetpotato 8 d after transplanting (DAP). S-metolachlor alone provided poor Palmer amaranth control because emergence had occurred at applications. All treatments that included linuron resulted in at least 98 and 91% Palmer amaranth control 1 and 2 wk after treatment (WAT), respectively. Including NIS with linuron did not increase Palmer amaranth control compared to linuron alone, but increased sweetpotato injury and subsequently decreased total sweetpotato yield by 25%. Including S-metolachlor with linuron resulted in the greatest Palmer amaranth control 4 WAT, but increased crop foliar injury to 36% 1 WAT compared to 17% foliar injury from linuron alone. Marketable and total sweetpotato yield was similar between linuron alone and linuron plus S-metolachlor or S-metolachlor plus NIS treatments, though all treatments resulted in at least 39% less total yield than the weed-free check resulting from herbicide injury and/or Palmer amaranth competition. Because of the excellent POST Palmer amaranth control from linuron 1 WAT, a system including linuron applied 7 DAP followed by S-metolachlor applied 14 DAP could help to extend residual Palmer amaranth control further into the critical period of weed control while minimizing sweetpotato injury.

Postemergence Control of Italian Ryegrass in Hazelnut Orchards

2021 ◽  
pp. 1-22
Author(s):  
Marcelo L. Moretti
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Field Studies ◽  
Early Spring ◽  
Italian Ryegrass ◽  
Specific Response ◽  
Record Keeping ◽  
Effective Option ◽  
Contrast Analysis ◽  
Herbicide Use

Abstract Italian ryegrass has become a problematic weed in hazelnut orchards of Oregon because of the presence of herbicide-resistant populations. Resistant and multiple-resistant Italian ryegrass populations are now the predominant biotypes in Oregon; there is no information on which herbicides effectively control Italian ryegrass in hazelnut orchards. Six field studies were conducted in commercial orchards to evaluate Italian ryegrass control with POST herbicides. Treatments included flazasulfuron, glufosinate, glyphosate, paraquat, rimsulfuron, and sethoxydim applied alone or in selected mixtures during early spring when plants were in the vegetative stage. Treatment efficacy was dependent on the experimental site. The observed range of weed control 28 d after treatment was 13 to 76 % for glyphosate, 1 to 72% for paraquat, 58 to 88% for glufosinate, 16 to 97 % for flazasulfuron, 8 to 94% for rimsulfuron, and 25 to 91% for sethoxydim. Herbicides in mixtures improved control of Italian ryegrass compared to single active ingredients based on contrast analysis. Herbicides in mixture increased control by 27% compared to glyphosate, 18% to rimsulfuron, 15% to flazasulfuron, 19% to sethoxydim, and 12% compared to glufosinate when averaged across all sites, but mixture not always improved ground coverage of biomass reduction. This complex site-specific response highlights the importance of record-keeping for efficient herbicide use. Glufosinate is an effective option to manage Italian ryegrass. However, the glufosinate-resistant biotypes documented in Oregon may jeopardize this practice. Non-chemical weed control options are needed for sustainable weed management in hazelnuts.

scholarly journals Effect of Clay, Soil Organic Matter, and Soil pH on Initial and Residual Weed Control with Flumioxazin

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1326
Author(s):  
Calvin F. Glaspie ◽  
Eric A. L. Jones ◽  
Donald Penner ◽  
John A. Pawlak ◽  
Wesley J. Everman
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Weed Control ◽  
Soil Ph ◽  
Organic Matter Content ◽  
Amaranthus Retroflexus ◽  
Matter Content ◽  
Weed Species ◽  
Soil Organic Matter Content ◽  
Field Soils

Greenhouse studies were conducted to evaluate the effects of soil organic matter content and soil pH on initial and residual weed control with flumioxazin by planting selected weed species in various lab-made and field soils. Initial control was determined by planting weed seeds into various lab-made and field soils treated with flumioxazin (71 g ha−1). Seeds of Echinochloa crus-galli (barnyard grass), Setaria faberi (giant foxtail), Amaranthus retroflexus (redroot pigweed), and Abutilon theophrasti (velvetleaf) were incorporated into the top 1.3 cm of each soil at a density of 100 seeds per pot, respectively. Emerged plants were counted and removed in both treated and non-treated pots two weeks after planting and each following week for six weeks. Flumioxazin control was evaluated by calculating percent emergence of weeds in treated soils compared to the emergence of weeds in non-treated soils. Clay content was not found to affect initial flumioxazin control of any tested weed species. Control of A. theophrasti, E. crus-galli, and S. faberi was reduced as soil organic matter content increased. The control of A. retroflexus was not affected by organic matter. Soil pH below 6 reduced flumioxazin control of A. theophrasti, and S. faberi but did not affect the control of A. retroflexus and E. crus-galli. Flumioxazin residual control was determined by planting selected weed species in various lab-made and field soils 0, 2, 4, 6, and 8 weeks after treatment. Eight weeks after treatment, flumioxazin gave 0% control of A. theophrasti and S. faberi in all soils tested. Control of A. retroflexus and Chenopodium album (common lambsquarters) was 100% for the duration of the experiment, except when soil organic matter content was greater than 3% or the soil pH 7. Eight weeks after treatment, 0% control was only observed for common A. retroflexus and C. album in organic soil (soil organic matter > 80%) or when soil pH was above 7. Control of A. theophrasti and S. faberi decreased as soil organic matter content and soil pH increased. Similar results were observed when comparing lab-made soils to field soils; however, differences in control were observed between lab-made organic matter soils and field organic matter soils. Results indicate that flumioxazin can provide control ranging from 75–100% for two to six weeks on common weed species.

scholarly journals Determining the critical period for weed control in high-yielding cotton using common sunflower as a mimic weed

2019 ◽  
Vol 33 (6) ◽  
pp. 800-807 ◽  
Author(s):  
Graham W. Charles ◽  
Brian M. Sindel ◽  
Annette L. Cowie ◽  
Oliver G. G. Knox
Keyword(s):  
Weed Control ◽  
Critical Period ◽  
Yield Loss ◽  
Field Studies ◽  
Growing Degree Days ◽  
Degree Days ◽  
Weed Density ◽  
High Level ◽  
The Cost ◽  
Planting Season

AbstractField studies were conducted over six seasons to determine the critical period for weed control (CPWC) in high-yielding cotton, using common sunflower as a mimic weed. Common sunflower was planted with or after cotton emergence at densities of 1, 2, 5, 10, 20, and 50 plants m−2. Common sunflower was added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 growing degree days (GDD) after planting. Season-long interference resulted in no harvestable cotton at densities of five or more common sunflower plants m−2. High levels of intraspecific and interspecific competition occurred at the highest weed densities, with increases in weed biomass and reductions in crop yield not proportional to the changes in weed density. Using a 5% yield-loss threshold, the CPWC extended from 43 to 615 GDD, and 20 to 1,512 GDD for one and 50 common sunflower plants m−2, respectively. These results highlight the high level of weed control required in high-yielding cotton to ensure crop losses do not exceed the cost of control.

Evaluation of weed control in acetyl coA carboxylase-resistant rice with mixtures of quizalofop and auxinic herbicides

2019 ◽  
Vol 34 (4) ◽  
pp. 498-505
Author(s):  
Tameka L. Sanders ◽  
Jason A. Bond ◽  
Benjamin H. Lawrence ◽  
Bobby R. Golden ◽  
Thomas W. Allen ◽  
...  
Keyword(s):  
Weed Control ◽  
Rice Yield ◽  
Field Studies ◽  
Growth Stages ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Herbicide Treatments ◽  
Herbicide Mixture ◽  
Sequential Treatments ◽  
And Control

AbstractRice with enhanced tolerance to herbicides that inhibit acetyl coA carboxylase (ACCase) allows POST application of quizalofop, an ACCase-inhibiting herbicide. Two concurrent field studies were conducted in 2017 and 2018 near Stoneville, MS, to evaluate control of grass (Grass Study) and broadleaf (Broadleaf Study) weeds with sequential applications of quizalofop alone and in mixtures with auxinic herbicides applied in the first or second application. Sequential treatments of quizalofop were applied at 119 g ai ha−1 alone and in mixtures with labeled rates of auxinic herbicides to rice at the two- to three-leaf (EPOST) or four-leaf to one-tiller (LPOST) growth stages. In the Grass Study, no differences in rice injury or control of volunteer rice (‘CL151’ and ‘Rex’) were detected 14 and 28 d after last application (DA-LPOST). Barnyardgrass control at 14 and 28 DA-LPOST with quizalofop applied alone or with auxinic herbicides EPOST was ≥93% for all auxinic herbicide treatments except penoxsulam plus triclopyr. Barnyardgrass control was ≥96% with quizalofop applied alone and with auxinic herbicides LPOST. In the Broadleaf Study, quizalofop plus florpyrauxifen-benzyl controlled more Palmer amaranth 14 DA-LPOST than other mixtures with auxinic herbicides, and control with this treatment was greater EPOST compared with LPOST. Hemp sesbania control 14 DA-LPOST was ≤90% with quizalofop plus quinclorac LPOST, orthosulfamuron plus quinclorac LPOST, and triclopyr EPOST or LPOST. All mixtures except quinclorac and orthosulfamuron plus quinclorac LPOST controlled ivyleaf morningglory ≥91% 14 DA-LPOST. Florpyrauxifen-benzyl or triclopyr were required for volunteer soybean control >63% 14 DA-LPOST. To optimize barnyardgrass control and rice yield, penoxsulam plus triclopyr and orthosulfamuron plus quinclorac should not be mixed with quizalofop. Quizalofop mixtures with auxinic herbicides are safe and effective for controlling barnyardgrass, volunteer rice, and broadleaf weeds in ACCase-resistant rice, and the choice of herbicide mixture could be adjusted based on weed spectrum in the treated field.

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