Weed Control, Environmental Impact and Profitability of Two-Pass Weed Management Strategies in Glyphosate-Resistant Corn

Abstract

Twelve field trials were conducted over a three-year period (2010, 2011, 2012) at different locations in southwestern Ontario, Canada to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury, weed control, environmental impact, corn yield and profit margin. No visible injury resulted from the herbicide treatments evaluated. One early postemergence (EPOST) application of glyphosate provided good full season control of pigweed species and lady's thumb and fair control of velvetleaf, common ragweed, lamb's-quarters, barnyard grass and green foxtail. One late postemergence (LPOST) application of glyphosate provided excellent control of all weed species evaluated but corn yield was reduced due to early weed interference. The sequential application of glyphosate (EPOST fb LPOST) provided excellent control of all weed species evaluated with no adverse effect on corn yield. The sequential application of a preemergence residual herbicide followed by an application of glyphosate LPOST provided excellent full season control of all weed species evaluated and corn yield was equal to the weed free control. Among the sequential herbicide programs the lowest environmental impact was glyphosate EPOST fb LPOST and saflufenacil/dimethenamid-p, isoxaflutole + atrazine or rimsulfuron + s-metolachlor + dicamba applied PRE fb glyphosate LPOST. Based on this study, the most efficacious and profitable weed management programs in glyphosate-resistant corn are a sequential application of glyphosate or a two-pass program of a preemergence residual herbicide followed by glyphosate LPOST. The two-pass programs have glyphosate stewardship benefits.

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The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.

Claims 13

Intervention effectobservedoriginal resultno effectmeasured

Claim · model-written summary

No visible crop injury resulted from the herbicide treatments in corn.

Taxon: cornZea mays subsp. mayse1
Treatment: herbicide treatmentse2
Outcome: No visible injurye2

Not reportedComparatorDirection

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

*Zea mays subsp. mays* · TaxonDominicus Johannes Bergsma · CC BY-SA 4.0 · Wikimedia Commons ↗

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e2
“No visible injury resulted from the herbicide treatments evaluated”
✓ located verbatim in the source · abstract, characters 301–367 · show in text ↑

Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

One EPOST glyphosate application gave good full-season control of pigweed species and lady's thumb in corn.

Taxon: cornZea mays subsp. mayse1
Treatment: One early postemergence (EPOST) application of glyphosatee3
Interactor: pigweed speciese3weed
Second interactor: lady's thumbPersicaria maculosae3weed
Outcome: full season control of pigweed species and lady's thumbe3
Direction: goode3

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

*Persicaria maculosa* · Second interactorBjoertvedt · CC BY-SA 3.0 · Wikimedia Commons ↗

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e3
“One early postemergence (EPOST) application of glyphosate provided good full season control of pigweed species and lady's thumb and fair control of velvetleaf, common ragweed, lamb's-quarters, barnyard grass and green foxtail”
✓ located verbatim in the source · abstract, characters 369–594 · show in text ↑

Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

One EPOST glyphosate application gave fair control of velvetleaf and common ragweed, and lamb's-quarters, in corn.

Taxon: cornZea mays subsp. mayse1
Treatment: One early postemergence (EPOST) application of glyphosatee3
Interactor: velvetleafAbutilon theophrastie3weed
Second interactor: common ragweedAmbrosia artemisiifoliae3weed
Outcome: fair control of velvetleaf, common ragweed, lamb's-quarterse3
Direction: faire3

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

*Abutilon theophrasti* · InteractorI.Sáček, senior · Public domain · Wikimedia Commons ↗

*Ambrosia artemisiifolia* · Second interactorDalgial · CC BY-SA 3.0 · Wikimedia Commons ↗

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e3
“One early postemergence (EPOST) application of glyphosate provided good full season control of pigweed species and lady's thumb and fair control of velvetleaf, common ragweed, lamb's-quarters, barnyard grass and green foxtail”
✓ located verbatim in the source · abstract, characters 369–594 · show in text ↑

Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

One EPOST glyphosate application gave fair control of barnyard grass and green foxtail in corn.

Taxon: cornZea mays subsp. mayse1
Treatment: One early postemergence (EPOST) application of glyphosatee3
Interactor: barnyard grassEchinochloa crus-gallie3weed
Second interactor: green foxtaile3weed
Outcome: barnyard grass and green foxtaile3
Direction: faire3

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

*Echinochloa crus-galli* · InteractorMichael Becker · CC BY-SA 3.0 · Wikimedia Commons ↗

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e3
“One early postemergence (EPOST) application of glyphosate provided good full season control of pigweed species and lady's thumb and fair control of velvetleaf, common ragweed, lamb's-quarters, barnyard grass and green foxtail”
✓ located verbatim in the source · abstract, characters 369–594 · show in text ↑

Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

One LPOST glyphosate application gave excellent control of all weed species evaluated in corn.

Taxon: cornZea mays subsp. mayse1
Treatment: One late postemergence (LPOST) application of glyphosatee4
Outcome: control of all weed species evaluatede4
Direction: excellente4

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e4
“One late postemergence (LPOST) application of glyphosate provided excellent control of all weed species evaluated but corn yield was reduced due to early weed interference”
✓ located verbatim in the source · abstract, characters 596–767 · show in text ↑

Intervention effectobservedoriginal resultnegativemeasured

Claim · model-written summary

One LPOST glyphosate application reduced corn yield due to early weed interference.

Taxon: cornZea mays subsp. mayse1
Treatment: One late postemergence (LPOST) application of glyphosatee4
Outcome: corn yielde4
Direction: reducede4
Qualifier: due to early weed interferencee4

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e4
“One late postemergence (LPOST) application of glyphosate provided excellent control of all weed species evaluated but corn yield was reduced due to early weed interference”
✓ located verbatim in the source · abstract, characters 596–767 · show in text ↑

Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

Sequential EPOST fb LPOST glyphosate gave excellent control of all weed species evaluated in corn.

Taxon: cornZea mays subsp. mayse1
Treatment: The sequential application of glyphosate (EPOST fb LPOST)e5
Outcome: control of all weed species evaluatede5
Direction: excellente5

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e5
“The sequential application of glyphosate (EPOST fb LPOST) provided excellent control of all weed species evaluated with no adverse effect on corn yield”
✓ located verbatim in the source · abstract, characters 769–920 · show in text ↑

Intervention effectobservedoriginal resultno effectmeasured

Claim · model-written summary

Sequential EPOST fb LPOST glyphosate had no adverse effect on corn yield.

Taxon: cornZea mays subsp. mayse1
Treatment: The sequential application of glyphosate (EPOST fb LPOST)e5
Outcome: corn yielde5
Direction: no adverse effecte5

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e5
“The sequential application of glyphosate (EPOST fb LPOST) provided excellent control of all weed species evaluated with no adverse effect on corn yield”
✓ located verbatim in the source · abstract, characters 769–920 · show in text ↑

Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

PRE residual herbicide followed by LPOST glyphosate gave excellent full-season control of all weed species evaluated in corn.

Taxon: cornZea mays subsp. mayse1
Treatment: a preemergence residual herbicide followed by an application of glyphosate LPOSTe6
Outcome: full season control of all weed species evaluatede6
Direction: excellente6

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e6
“The sequential application of a preemergence residual herbicide followed by an application of glyphosate LPOST provided excellent full season control of all weed species evaluated and corn yield was equal to the weed free control”
✓ located verbatim in the source · abstract, characters 922–1151 · show in text ↑

Intervention effectobservedoriginal resultno effectmeasured

Claim · model-written summary

PRE residual herbicide followed by LPOST glyphosate gave corn yield equal to the weed-free control.

Taxon: cornZea mays subsp. mayse1
Treatment: a preemergence residual herbicide followed by an application of glyphosate LPOSTe6
Outcome: corn yielde6
Direction: equale6
Comparator: weed free controle6

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e6
“The sequential application of a preemergence residual herbicide followed by an application of glyphosate LPOST provided excellent full season control of all weed species evaluated and corn yield was equal to the weed free control”
✓ located verbatim in the source · abstract, characters 922–1151 · show in text ↑

Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

Sequential EPOST fb LPOST glyphosate had the lowest environmental impact among the sequential herbicide programs.

Taxon: cornZea mays subsp. mayse1
Treatment: glyphosate EPOST fb LPOSTe7
Outcome: environmental impacte7
Direction: loweste7
Comparator: the sequential herbicide programse7

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e7
“Among the sequential herbicide programs the lowest environmental impact was glyphosate EPOST fb LPOST”
✓ located verbatim in the source · abstract, characters 1153–1254 · show in text ↑

Recommendationauthor interpretationoriginal resultpositivebasis n/a

Claim · model-written summary

The most efficacious and profitable weed management programs in glyphosate-resistant corn are sequential glyphosate or PRE residual followed by LPOST glyphosate.

Taxon: glyphosate-resistant corne2
Outcome: most efficacious and profitable weed management programse2

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e2
“the most efficacious and profitable weed management programs in glyphosate-resistant corn are a sequential application of glyphosate or a two-pass program of a preemergence residual herbicide followed by glyphosate LPOST”
✓ located verbatim in the source · abstract, characters 1407–1627 · show in text ↑

Recommendationauthor interpretationoriginal resultpositivebasis n/a

Claim · model-written summary

The two-pass programs have glyphosate stewardship benefits in corn.

Taxon: cornZea mays subsp. mayse1
Outcome: glyphosate stewardship benefitse2

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim

e1
“to compare various two-pass weed management strategies in glyphosate-resistant corn for crop injury”
✓ located verbatim in the source · abstract, characters 134–233 · show in text ↑

e2
“The two-pass programs have glyphosate stewardship benefits”
✓ located verbatim in the source · abstract, characters 1629–1687 · show in text ↑

glyphosate · yield · Zea mays (maize)Results differ

77 papers: 42 positive, 35 negative or no effect

34 papers in the same direction as this paper · 42 in the opposite direction

no effect
Corn yield matched the weed-free control with glyphosate applied to weeds 10 to 15 cm tall in 2002.
Glyphosate Application Timings in Twin- and Single-row Corn and Soybean Spacings · 2007 · compared with weed-free control
Same directionCited by this paper
positive
Two glyphosate applications gave higher corn grain yields than a single application when weeds were 5 cm tall or less.
Effect of Postemergence Glyphosate Application Timing on Weed Control and Grain Yield in Glyphosate-Resistant Corn: Results of a 2-Yr Multistate Study¹ · 2003 · compared with a single application
Opposite direction
positive
Adding glyphosate to atrazine sometimes improved corn yields when applied after wheat harvest, compared with atrazine alone.
Herbicide Applications on Wheat and Stubble for No‐Tillage Corn¹ · 1986 · compared with atrazine alone
Opposite direction

73 papers more in this group

See all 77 papers →

glyphosate · weed · Zea mays (maize)Positive and negative results

41 papers: 33 positive, 8 negative or no effect

32 papers in the same direction as this paper · 5 in the opposite direction · 3 reporting no difference from an alternative

positive
Two glyphosate applications improved weed control over one application, especially for weeds no taller than 10 cm in early-planted corn.
Effect of Planting Date, Residual Herbicide, and Postemergence Application Timing on Weed Control and Grain Yield in Glyphosate-Tolerant Corn (Zea mays)¹ · 2002 · compared with a single application
Same directionCited by this paper
negative
Weed densities were greater under the minimum treatment than under the IWM or conventional treatments in all crops.
Evaluation of alternative weed management systems in a modified no-tillage corn–soybean–winter wheat rotation: weed densities, crop yield, and economics · 2002 · compared with IWM or conventional treatment
Opposite direction
negative
Glyphosate alone reduced weed control in crimson clover.
Control of Legume Cover Crops in No-Till Corn (Zea mays) and Cotton (Gossypium hirsutum) · 1990
Opposite direction

37 papers more in this group

See all 41 papers →

glyphosate · control · Zea mays (maize)Positive and negative results

41 papers: 36 positive, 5 negative or no effect

35 papers in the same direction as this paper · 5 in the opposite direction

no effect
Glyphosate applied postemergence gave similar control of common waterhemp in 2001 and giant foxtail in both years.
Weed Management in Strip Tillage Corn · 2004
Opposite direction
negative
Adding glyphosate to clethodim-A mixtures at the 35 g ai ha −1 clethodim dose reduced control by 62% to 75%.
Influence of 2,4-D, dicamba, and glyphosate on clethodim efficacy of volunteer glyphosate-resistant corn · 2019
Opposite direction
negative
The Balance Flexx followed by Diflexx, atrazine and glyphosate sequence gave less than 89% late-season crabgrass control.
Split Applications of Acuron, Halex GT, Resicore, Balance Flexx, and Armezon Pro for Weed Control in Irrigated Corn · 2018
Opposite direction

37 papers more in this group

See all 41 papers →

glyphosate · Echinochloa crus-galli · Zea mays (maize)Results agree

3 papers: 3 positive, 0 negative or no effect

2 papers in the same direction as this paper

positive
Barnyardgrass visual control increased with glyphosate rate from 0 to 450 g/ha.
Response of Barnyardgrass (Echinochloa crus-galli) to Glyphosate Application Timing and Rate in Glyphosate-Resistant Corn (Zea mays)¹ · 2005 · compared with 0 to 450 g/ha
Same direction
positive
At 450 g ae ha-1, adjuvant improved barnyardgrass control by as much as 7%.
Effect of Class Act NG Adjuvant on Glyphosate Efficacy in Corn · 2023
Same direction

See all 3 papers →

glyphosate · Abutilon theophrasti · Zea mays (maize)Results agree

6 papers: 6 positive, 0 negative or no effect

5 papers in the same direction as this paper

2 papers more in this group

See all 6 papers →

herbicide · Echinochloa crus-galli · Zea mays (maize)Positive and negative results

12 papers: 9 positive, 3 negative or no effect

8 papers in the same direction as this paper · 2 in the opposite direction · 1 reporting no difference from an alternative

negative
Delaying herbicide application until 50 days after wheat harvest, compared with 5, 20 or 35 days, gave the highest barnyardgrass populations before and after corn planting.
Herbicide Applications on Wheat and Stubble for No‐Tillage Corn¹ · 1986 · compared with 5,20, or 35 days
Opposite direction
no effect
VLCFA inhibitor herbicides did not differ in barnyard grass control.
Weed Control in Corn and Soybean with Group 15 (VLCFA Inhibitor) Herbicides Applied Preemergence · 2019
Opposite direction
no effect
Reduced rates of herbicide with additives gave weed control of Echinochloa crus-galli similar to mesotrione used alone in maize.
Evaluation of the Efficacy of Mesotrione Plus Nicosulfuron with Additives as Tank Mixtures Used for Weed Control in Maize (Zea Mays L.) · 2011 · compared with mesotrione used alone
No difference from an alternative

8 papers more in this group

See all 12 papers →

herbicide · Abutilon theophrasti · Zea mays (maize)Positive and negative results

13 papers: 9 positive, 4 negative or no effect

8 papers in the same direction as this paper · 3 in the opposite direction · 1 reporting no difference from an alternative

negative
Fertilizer impregnation gave less velvetleaf and lambsquarters control than spraying.
Efficacy of Corn (Zea mays) Herbicides Applied at Reduced Rates Impregnated in Dry Fertilizer · 1994 · compared with applied as sprays
Opposite direction
negative
Velvetleaf control was generally below 80% with soil-applied herbicides.
Application Timing Affects Weed Control with Metolachlor Plus Atrazine in No-Till Corn (Zea mays) · 1997
Opposite direction
negative
Preemergence atrazine failed to control velvetleaf in corn.
Atrazine and Non-Atrazine Herbicide Comparisons in Conventional Till Corn · 2002
Opposite direction

9 papers more in this group

See all 13 papers →

herbicide · crop injury · Zea mays (maize)Positive and negative results

61 papers: 26 positive, 35 negative or no effect

34 papers in the same direction as this paper · 26 in the opposite direction

positive
Preemergence mesotrione caused no injury in sweet corn.
Sweet Corn (Zea mays) Cultivar Sensitivity to Mesotrione^* · 2002
Opposite direction
positive
Corn injury was minimal (≤3%) with all herbicides tested.
Weed Control in Corn (Zea maysL.) as Influenced by Preemergence Herbicides · 2016
Opposite direction
positive
Melatonin priming with paraquat reduced herbicide injury by 4.6 times versus non-priming.
The effect of seed priming with melatonin on improving the tolerance of Zea mays L. var saccharata to paraquat-induced oxidative stress through photosynthetic systems and enzymatic antioxidant activities · 2023 · compared with D treatments
Opposite direction

57 papers more in this group

See all 61 papers →

8 of 11 groups shown: named compounds and organisms first, then groups whose results differ (checked claim by claim), then those with positive and negative results, then the smaller groups.

Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.

Abstract

Claims 13

The same questions in other papers

glyphosate · yield · Zea mays (maize)Results differ

glyphosate · weed · Zea mays (maize)Positive and negative results

glyphosate · control · Zea mays (maize)Positive and negative results

glyphosate · Echinochloa crus-galli · Zea mays (maize)Results agree

glyphosate · Abutilon theophrasti · Zea mays (maize)Results agree

herbicide · Echinochloa crus-galli · Zea mays (maize)Positive and negative results

herbicide · Abutilon theophrasti · Zea mays (maize)Positive and negative results

herbicide · crop injury · Zea mays (maize)Positive and negative results