Abstract
Field studies were conducted at 35 sites throughout the north-central United States in 1998 and 1999 to determine the effect of postemergence glyphosate application timing on weed control and grain yield in glyphosate-resistant corn. Glyphosate was applied at various timings based on the height of the most dominant weed species. Weed control and corn grain yields were considerably more variable when glyphosate was applied only once. The most effective and consistent season-long annual grass and broadleaf weed control occurred when a single glyphosate application was delayed until weeds were 15 cm or taller. Two glyphosate applications provided more consistent weed control when weeds were 10 cm tall or less and higher corn grain yields when weeds were 5 cm tall or less, compared with a single application. Weed control averaged at least 94 and 97% across all sites in 1998 and 1999, respectively, with two glyphosate applications but was occasionally less than 70% because of late emergence of annual grass and Amaranthus spp. or reduced control of Ipomoea spp. With a single application of glyphosate, corn grain yield was most often reduced when the application was delayed until weeds were 23 cm or taller. Averaged across all sites in 1998 and 1999, corn grain yields from a single glyphosate application at the 5-, 10-, 15-, 23-, and 30-cm timings were 93, 94, 93, 91, and 79% of the weed-free control, respectively. There was a significant effect of herbicide treatment on corn grain yield in 23 of the 35 sites when weed reinfestation was prevented with a second glyphosate application. When weed reinfestation was prevented, corn grain yield at the 5-, 10-, and 15-cm application timings was 101, 97, and 93% of the weed-free control, respectively, averaged across all sites. Results of this study suggested that the optimum timing for initial glyphosate application to avoid corn grain yield loss was when weeds were less than 10 cm in height, no more than 23 d after corn planting, and when corn growth was not more advanced than the V4 stage.Nomenclature: Glyphosate; Amaranthus spp. #3 AMASS; Ipomoea spp. # IPOSS; corn, Zea mays L. ‘Roundup Ready®’ # SETFA.Additional index words: Herbicide-resistant crops, weed interference.Abbreviation: POST, postemergence.
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Claims 17
Claim · model-written summary
Weed control and corn grain yields were more variable when glyphosate was applied only once.
- Taxon
- corn
Zea mays subsp. mayse0 - Treatment
- glyphosate was applied only oncee0
- Outcome
- Weed control and corn grain yieldse0
- Direction
- more variablee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Weed control and corn grain yields were considerably more variable when glyphosate was applied only once”
Claim · model-written summary
A single glyphosate application delayed until weeds were 15 cm or taller gave the most effective and consistent season-long annual grass and broadleaf weed control in corn.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- a single glyphosate application was delayed until weeds were 15 cm or tallere1
- Interactor
- weedse1weed
- Outcome
- season-long annual grass and broadleaf weed controle1
- Direction
- most effective and consistente1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Glyphosate-Resistant Corn”
e1“The most effective and consistent season-long annual grass and broadleaf weed control occurred when a single glyphosate application was delayed until weeds were 15 cm or taller”
Claim · model-written summary
Two glyphosate applications gave more consistent weed control than a single application when weeds were 10 cm tall or less in corn.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- Two glyphosate applicationse2
- Interactor
- weedse2weed
- Outcome
- weed controle2
- Direction
- more consistente2
- Qualifier
- when weeds were 10 cm tall or lesse2
- Comparator
- a single applicatione2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Glyphosate-Resistant Corn”
e2“Two glyphosate applications provided more consistent weed control when weeds were 10 cm tall or less and higher corn grain yields when weeds were 5 cm tall or less, compared with a single application”
Claim · model-written summary
Two glyphosate applications gave higher corn grain yields than a single application when weeds were 5 cm tall or less.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- Two glyphosate applicationse2
- Interactor
- weedse2weed
- Outcome
- corn grain yieldse2
- Direction
- highere2
- Qualifier
- when weeds were 5 cm tall or lesse2
- Comparator
- a single applicatione2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Glyphosate-Resistant Corn”
e2“Two glyphosate applications provided more consistent weed control when weeds were 10 cm tall or less and higher corn grain yields when weeds were 5 cm tall or less, compared with a single application”
Claim · model-written summary
Two glyphosate applications gave weed control averaging at least 94% in 1998 and 97% in 1999 across all sites.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- two glyphosate applicationse3
- Outcome
- Weed controle3
- Value
- at least 94 and 97%e3
- Qualifier
- across all sites in 1998 and 1999, respectivelye3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Glyphosate-Resistant Corn”
e3“Weed control averaged at least 94 and 97% across all sites in 1998 and 1999, respectively, with two glyphosate applications”
Claim · model-written summary
Weed control with two glyphosate applications was occasionally below 70%, because of late emergence of annual grass and Amaranthus spp. or reduced control of Ipomoea spp.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- two glyphosate applicationse3
- Interactor
- Amaranthus spp.
_with_green_foliage%2C_photographed_in_Tamil_Nadu%2C_India.jpg?width=60)
Amaranthuse4weed - Outcome
- Weed controle3
- Value
- less than 70%e4
- Qualifier
- because of late emergence of annual grass and Amaranthus spp. or reduced control of Ipomoea sppe4
IpomoeaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
_with_green_foliage%2C_photographed_in_Tamil_Nadu%2C_India.jpg?width=500)
Verbatim
t0“Glyphosate-Resistant Corn”
e3“Weed control averaged at least 94 and 97% across all sites in 1998 and 1999, respectively, with two glyphosate applications”
e4“but was occasionally less than 70% because of late emergence of annual grass and Amaranthus spp. or reduced control of Ipomoea spp”
Claim · model-written summary
With a single glyphosate application, corn grain yield was most often reduced when the application was delayed until weeds were 23 cm or taller.
- Taxon
- cornZea mays subsp. mayse5
- Treatment
- the application was delayed until weeds were 23 cm or tallere5
- Interactor
- weedse5weed
- Outcome
- corn grain yielde5
- Direction
- reducede5
- Qualifier
- With a single application of glyphosatee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“With a single application of glyphosate, corn grain yield was most often reduced when the application was delayed until weeds were 23 cm or taller”
Claim · model-written summary
A single glyphosate application at the 5-cm timing gave corn grain yield at 93% of the weed-free control.
- Taxon
- cornZea mays subsp. mayse6
- Treatment
- a single glyphosate application at the 5-, 10-, 15-, 23-, and 30-cm timingse6
- Outcome
- corn grain yieldse6
- Direction
- lowerinferrede6
- Value
- 93e6
- Qualifier
- Averaged across all sites in 1998 and 1999e6
- Comparator
- weed-free controle6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Averaged across all sites in 1998 and 1999, corn grain yields from a single glyphosate application at the 5-, 10-, 15-, 23-, and 30-cm timings were 93, 94, 93, 91, and 79% of the weed-free control, respectively”
Claim · model-written summary
A single glyphosate application at the 10-cm timing gave corn grain yield at 94% of the weed-free control.
- Taxon
- cornZea mays subsp. mayse6
- Treatment
- a single glyphosate application at the 5-, 10-, 15-, 23-, and 30-cm timingse6
- Outcome
- corn grain yieldse6
- Direction
- lowerinferrede6
- Value
- 94e6
- Qualifier
- Averaged across all sites in 1998 and 1999e6
- Comparator
- weed-free controle6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Averaged across all sites in 1998 and 1999, corn grain yields from a single glyphosate application at the 5-, 10-, 15-, 23-, and 30-cm timings were 93, 94, 93, 91, and 79% of the weed-free control, respectively”
Claim · model-written summary
A single glyphosate application at the 15-cm timing gave corn grain yield at 93% of the weed-free control.
- Taxon
- cornZea mays subsp. mayse6
- Treatment
- a single glyphosate application at the 5-, 10-, 15-, 23-, and 30-cm timingse6
- Outcome
- corn grain yieldse6
- Direction
- lowerinferrede6
- Value
- 93e6
- Qualifier
- Averaged across all sites in 1998 and 1999e6
- Comparator
- weed-free controle6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Averaged across all sites in 1998 and 1999, corn grain yields from a single glyphosate application at the 5-, 10-, 15-, 23-, and 30-cm timings were 93, 94, 93, 91, and 79% of the weed-free control, respectively”
Claim · model-written summary
A single glyphosate application at the 23-cm timing gave corn grain yield at 91% of the weed-free control.
- Taxon
- cornZea mays subsp. mayse6
- Treatment
- a single glyphosate application at the 5-, 10-, 15-, 23-, and 30-cm timingse6
- Outcome
- corn grain yieldse6
- Direction
- lowerinferrede6
- Value
- 91e6
- Qualifier
- Averaged across all sites in 1998 and 1999e6
- Comparator
- weed-free controle6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Averaged across all sites in 1998 and 1999, corn grain yields from a single glyphosate application at the 5-, 10-, 15-, 23-, and 30-cm timings were 93, 94, 93, 91, and 79% of the weed-free control, respectively”
Claim · model-written summary
A single glyphosate application at the 30-cm timing gave corn grain yield at 79% of the weed-free control.
- Taxon
- cornZea mays subsp. mayse6
- Treatment
- a single glyphosate application at the 5-, 10-, 15-, 23-, and 30-cm timingse6
- Outcome
- corn grain yieldse6
- Direction
- lowerinferrede6
- Value
- 79%e6
- Qualifier
- Averaged across all sites in 1998 and 1999e6
- Comparator
- weed-free controle6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Averaged across all sites in 1998 and 1999, corn grain yields from a single glyphosate application at the 5-, 10-, 15-, 23-, and 30-cm timings were 93, 94, 93, 91, and 79% of the weed-free control, respectively”
Claim · model-written summary
With weed reinfestation prevented, corn grain yield at the 5-cm timing was 101% of the weed-free control.
- Taxon
- cornZea mays subsp. mayse7
- Treatment
- the 5-, 10-, and 15-cm application timingse7
- Outcome
- corn grain yielde7
- Direction
- higherinferrede7
- Value
- 101e7
- Qualifier
- When weed reinfestation was preventede7
- Comparator
- weed-free controle7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“When weed reinfestation was prevented, corn grain yield at the 5-, 10-, and 15-cm application timings was 101, 97, and 93% of the weed-free control, respectively”
Claim · model-written summary
With weed reinfestation prevented, corn grain yield at the 10-cm timing was 97% of the weed-free control.
- Taxon
- cornZea mays subsp. mayse7
- Treatment
- the 5-, 10-, and 15-cm application timingse7
- Outcome
- corn grain yielde7
- Direction
- lowerinferrede7
- Value
- 97e7
- Qualifier
- When weed reinfestation was preventede7
- Comparator
- weed-free controle7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“When weed reinfestation was prevented, corn grain yield at the 5-, 10-, and 15-cm application timings was 101, 97, and 93% of the weed-free control, respectively”
Claim · model-written summary
With weed reinfestation prevented, corn grain yield at the 15-cm timing was 93% of the weed-free control.
- Taxon
- cornZea mays subsp. mayse7
- Treatment
- the 5-, 10-, and 15-cm application timingse7
- Outcome
- corn grain yielde7
- Direction
- lowerinferrede7
- Value
- 93%e7
- Qualifier
- When weed reinfestation was preventede7
- Comparator
- weed-free controle7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“When weed reinfestation was prevented, corn grain yield at the 5-, 10-, and 15-cm application timings was 101, 97, and 93% of the weed-free control, respectively”
Claim · model-written summary
Herbicide treatment had a significant effect on corn grain yield in 23 of the 35 sites when weed reinfestation was prevented with a second glyphosate application.
- Taxon
- cornZea mays subsp. mayse7
- Treatment
- herbicide treatmente7
- Outcome
- corn grain yielde7
- Qualifier
- in 23 of the 35 sites when weed reinfestation was prevented with a second glyphosate applicatione7
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“There was a significant effect of herbicide treatment on corn grain yield in 23 of the 35 sites when weed reinfestation was prevented with a second glyphosate application”
Claim · model-written summary
The optimum timing for initial glyphosate application to avoid corn grain yield loss was when weeds were less than 10 cm tall, no more than 23 d after corn planting, and before corn passed the V4 stage.
- Taxon
- cornZea mays subsp. mayse6
- Organ / stage
- V4 stagee6
- Outcome
- optimum timing for initial glyphosate applicatione6
- Qualifier
- when weeds were less than 10 cm in height, no more than 23 d after corn planting, and when corn growth was not more advanced than the V4 stagee6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Results of this study suggested that the optimum timing for initial glyphosate application to avoid corn grain yield loss was when weeds were less than 10 cm in height, no more than 23 d after corn planting, and when corn growth was not more advanced than the V4 stage”
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- no effect
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See all 41 papers →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.