Abstract
Field studies using glyphosate‐resistant corn ( Zea mays L.), sugarbeet ( Beta vulgaris L.), and spring wheat ( Triticum aestivum L.) were conducted at Scottsbluff, NE, Torrington, WY, and Fort Collins, CO, over 6 yr to evaluate weed population dynamics under glyphosate‐ and conventional herbicide–based weed control strategies. We report the response of common lambsquarters ( Chenopodium album L.), wild buckwheat ( Polygonum convolvulus L.), and all grasses combined to four management strategies imbedded in two crop rotations. There were no consistent or highly significant benefits from a diverse crop rotation versus continuous corn when weed control was considered. Rotating herbicide mode of action for general weed control provided no benefit above that provided by glyphosate at 0.8 kg acid equivalent (ae) ha −1 applied twice each year. There was no evidence that any weed species developed resistance to glyphosate. The most striking finding of these studies was the buildup of common lambsquarters and wild buckwheat that occurs when glyphosate is applied at 0.4 kg ae ha −1 twice each year. Such a low‐use‐rate approach is to be completely discouraged since it appears to enrich the gene pool for individuals that survive low rates of glyphosate. The continuing decline in the real cost of glyphosate should eliminate any legitimate reason for growers to consider using less than the full labeled rate of glyphosate. All treatments that included glyphosate at all three locations over 6 yr provided significantly better grass control than the nonglyphosate conventional treatments.
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Claims 7
Claim · model-written summary
Diverse crop rotation had no consistent weed-control benefit over continuous corn.
- Taxon
- corn
Zea mays subsp. mayst0 - Treatment
- diverse crop rotatione0
- Outcome
- weed controle0
- Direction
- no consistent or highly significant benefitse0
- Comparator
- continuous corne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There were no consistent or highly significant benefits from a diverse crop rotation versus continuous corn when weed control was considered.”
t0“glyphosate‐resistant corn”
Claim · model-written summary
Rotating herbicide action had no added general weed-control benefit over glyphosate twice yearly.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- Rotating herbicide mode of actione0
- Outcome
- general weed controle0
- Direction
- no benefite0
- Comparator
- glyphosate at 0.8 kg acid equivalent (ae) ha −1 applied twice each yeare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rotating herbicide mode of action for general weed control provided no benefit above that provided by glyphosate at 0.8 kg acid equivalent (ae) ha −1 applied twice each year.”
t0“glyphosate‐resistant corn”
Claim · model-written summary
No weed species showed evidence of glyphosate resistance.
- Taxon
- cornZea mays subsp. mayst0
- Interactor
- weed speciese0weed
- Outcome
- weed species developed resistance to glyphosatee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was no evidence that any weed species developed resistance to glyphosate.”
t0“glyphosate‐resistant corn”
Claim · model-written summary
Low-rate glyphosate use built up common lambsquarters.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- glyphosate is applied at 0.4 kg ae ha −1 twice each yeare0
- Interactor
- common lambsquarters
Chenopodium albume0weed - Outcome
- buildup of common lambsquarterse0
- Direction
- buildupe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the buildup of common lambsquarters and wild buckwheat that occurs when glyphosate is applied at 0.4 kg ae ha −1 twice each year”
t0“glyphosate‐resistant corn”
Claim · model-written summary
Low-rate glyphosate use built up wild buckwheat.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- glyphosate is applied at 0.4 kg ae ha −1 twice each yeare0
- Interactor
- wild buckwheat
Fallopia convolvuluse0weed - Outcome
- buildup of common lambsquarters and wild buckwheate0
- Direction
- buildupe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the buildup of common lambsquarters and wild buckwheat that occurs when glyphosate is applied at 0.4 kg ae ha −1 twice each year”
t0“glyphosate‐resistant corn”
Claim · model-written summary
The authors advise against glyphosate at the low use rate.
- Taxon
- cornZea mays subsp. mayst0
- Outcome
- low‐use‐rate approach is to be completely discouragede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Such a low‐use‐rate approach is to be completely discouraged”
t0“glyphosate‐resistant corn”
Claim · model-written summary
Glyphosate treatments improved grass control relative to conventional treatments across all sites.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- treatments that included glyphosatee0
- Interactor
- grasse0weed
- Outcome
- grass controle0
- Direction
- bettere0
- Comparator
- nonglyphosate conventional treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All treatments that included glyphosate at all three locations over 6 yr provided significantly better grass control than the nonglyphosate conventional treatments.”
t0“glyphosate‐resistant corn”
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