Abstract
Corn and soybean were planted in narrow and wide row spacings to determine the effect of glyphosate application timing and row spacing on crop yield. Glyphosate was applied when average weed canopy height reached 5, 10, 15, 23, and 30 cm. Weeds present in these studies included velvetleaf, redroot pigweed, common ragweed, common lambsquarters, jimsonweed, barnyardgrass, fall panicum, giant foxtail, yellow foxtail, green foxtail, and eastern black nightshade. Under highly competitive growing conditions (below normal rainfall and high weed density), corn yield was first reduced when weeds reached 10 and 15 cm in height with corn planted in 38- and 76-cm rows, respectively. Under similar conditions, soybean yield was first reduced when weeds reached 15 and 23 cm with soybean planted in 19- and 38-cm rows, respectively. Yield losses occurred only in the untreated control when soybean was planted in 76-cm rows. When growing conditions were less competitive (adequate rainfall and lower weed density), yield losses occurred only when weeds reached 30 cm or more in corn and only in the untreated control in soybean. Corn and soybean yields were higher when planted in narrow rows in three of 4 yr but were more susceptible to early- season weed interference than corn and soybean in wide rows. Corn yield was affected more by weed interference than was soybean yield. The product of weed height by weed density, as the independent variable, resulted in the best linear fit for both corn and soybean yields. High weed densities increase the risk of yield loss and must be considered when determining the appropriate timing for total postemergence herbicide applications such as glyphosate. Sequential glyphosate applications in corn did not increase yield.Nomenclature: Glyphosate; barnyardgrass, Echinochloa crus-galli (L.) Beauv. #3 ECHCG; common lambsquarters, Chenopodium album L. # CHEAL; common ragweed, Ambrosia artemisiifolia L. # AMBEL; eastern black nightshade, Solanum ptycanthum Dun. # SOLPT; fall panicum, Panicum dichotomilflorum Michx. # PANDI; giant foxtail, Setaria faberi Herrm. # SETFA; green foxtail, Setaria viridis (L.) Beauv. # SETVI; jimsonweed, Datura stramonium L. # DATST; redroot pigweed, Amaranthus retroflexus L. # AMARE; velvetleaf, Abutilon theophroasti Medik. # ABUTH; yellow foxtail, Setaria glauca (L.) Beauv. # SETLU; corn, Zea mays L. ‘DK 493RR’; soybean, Glycine max (L.) Merr. ‘Pioneer 92B71’.Additional index words: Application timing, competitive load, narrow-row corn, narrow-row soybean, weed competition, weed interference.Abbreviations: DAE, days after crop emergence; GDDAE, growing degree days after emergence; POST, postemergence; SAS, Statistical Analysis Systems.
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Claims 14
Claim · model-written summary
Corn yield was first reduced when weeds reached 10 and 15 cm, in 38 cm and 76 cm rows respectively, under highly competitive conditions.
- Taxon
- corn
Zea mays subsp. mayse1 - Treatment
- weeds reached 10 and 15 cm in heighte1
- Interactor
- weedse1weed
- Outcome
- corn yielde1
- Direction
- reducede1
- Qualifier
- below normal rainfall and high weed densitye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Under highly competitive growing conditions (below normal rainfall and high weed density), corn yield was first reduced when weeds reached 10 and 15 cm in height with corn planted in 38- and 76-cm rows, respectively”
Claim · model-written summary
Soybean yield was first reduced when weeds reached 15 and 23 cm, in 19 cm and 38 cm rows respectively.
- Taxon
- soybean
Glycine maxe2 - Treatment
- weeds reached 15 and 23 cme2
- Interactor
- weedse2weed
- Outcome
- soybean yielde2
- Direction
- reducede2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“soybean yield was first reduced when weeds reached 15 and 23 cm with soybean planted in 19- and 38-cm rows, respectively”
Claim · model-written summary
Soybean in 76 cm rows showed yield losses only in the untreated control.
- Taxon
- soybeanGlycine maxe3
- Treatment
- 76-cm rowse3
- Outcome
- Yield lossese3
- Direction
- decreaseinferrede3
- Comparator
- untreated controle3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“Yield losses occurred only in the untreated control when soybean was planted in 76-cm rows”
Claim · model-written summary
Corn showed yield losses only when weeds reached 30 cm or more under less competitive conditions.
- Taxon
- cornZea mays subsp. mayse4
- Treatment
- weeds reached 30 cm or moree4
- Interactor
- weedse4weed
- Outcome
- yield lossese4
- Direction
- decreaseinferrede4
- Qualifier
- less competitivee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“When growing conditions were less competitive (adequate rainfall and lower weed density), yield losses occurred only when weeds reached 30 cm or more in corn and only in the untreated control in soybean”
Claim · model-written summary
Soybean showed yield losses only in the untreated control under less competitive conditions.
- Taxon
- soybeanGlycine maxe4
- Outcome
- yield lossese4
- Direction
- decreaseinferrede4
- Qualifier
- less competitivee4
- Comparator
- untreated controle4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“When growing conditions were less competitive (adequate rainfall and lower weed density), yield losses occurred only when weeds reached 30 cm or more in corn and only in the untreated control in soybean”
Claim · model-written summary
Corn yields were higher when planted in narrow rows in three of four years.
- Taxon
- cornZea mays subsp. mayse5
- Treatment
- narrow rowse5
- Outcome
- yieldse5
- Direction
- highere5
- Qualifier
- in three of 4 yre5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“Corn and soybean yields were higher when planted in narrow rows in three of 4 yr but were more susceptible to early- season weed interference than corn and soybean in wide rows”
Claim · model-written summary
Soybean yields were higher when planted in narrow rows in three of four years.
- Taxon
- soybeanGlycine maxe5
- Treatment
- narrow rowse5
- Outcome
- yieldse5
- Direction
- highere5
- Qualifier
- in three of 4 yre5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“Corn and soybean yields were higher when planted in narrow rows in three of 4 yr but were more susceptible to early- season weed interference than corn and soybean in wide rows”
Claim · model-written summary
Corn in narrow rows was more susceptible to early-season weed interference than corn in wide rows.
- Taxon
- cornZea mays subsp. mayse5
- Treatment
- narrow rowse5
- Interactor
- weede5weed
- Outcome
- weed interferencee5
- Direction
- more susceptiblee5
- Comparator
- wide rowse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“Corn and soybean yields were higher when planted in narrow rows in three of 4 yr but were more susceptible to early- season weed interference than corn and soybean in wide rows”
Claim · model-written summary
Soybean in narrow rows was more susceptible to early-season weed interference than soybean in wide rows.
- Taxon
- soybeanGlycine maxe5
- Treatment
- narrow rowse5
- Interactor
- weede5weed
- Outcome
- weed interferencee5
- Direction
- more susceptiblee5
- Comparator
- wide rowse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“Corn and soybean yields were higher when planted in narrow rows in three of 4 yr but were more susceptible to early- season weed interference than corn and soybean in wide rows”
Claim · model-written summary
Corn yield was affected more by weed interference than soybean yield was.
- Taxon
- cornZea mays subsp. mayse6
- Interactor
- weede6weed
- Outcome
- yielde6
- Direction
- moree6
- Comparator
- soybean yielde6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Corn yield was affected more by weed interference than was soybean yield”
Claim · model-written summary
The product of weed height and weed density gave the best linear fit for corn and soybean yields.
- Taxon
- corn and soybeanGlycine maxZea mays subsp. mayse7
- Treatment
- product of weed height by weed densitye7
- Outcome
- yieldse7
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“The product of weed height by weed density, as the independent variable, resulted in the best linear fit for both corn and soybean yields”
Claim · model-written summary
High weed densities increase the risk of yield loss in corn and soybean.
- Taxon
- Corn and soybeanGlycine maxZea mays subsp. mayse0
- Treatment
- High weed densitiese1
- Outcome
- yield losse1
- Direction
- increasee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Corn and soybean were planted in narrow and wide row spacings to determine the effect of glyphosate application timing and row spacing on crop yield”
e1“High weed densities increase the risk of yield loss and must be considered when determining the appropriate timing for total postemergence herbicide applications such as glyphosate”
Claim · model-written summary
Weed density must be considered when timing total postemergence glyphosate applications in corn and soybean.
- Taxon
- Corn and soybeanGlycine maxZea mays subsp. mayse0
- Treatment
- glyphosatee1
- Outcome
- appropriate timing for total postemergence herbicide applicationse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Corn and soybean were planted in narrow and wide row spacings to determine the effect of glyphosate application timing and row spacing on crop yield”
e1“High weed densities increase the risk of yield loss and must be considered when determining the appropriate timing for total postemergence herbicide applications such as glyphosate”
Claim · model-written summary
Sequential glyphosate applications in corn did not increase yield.
- Taxon
- cornZea mays subsp. mayse2
- Treatment
- Sequential glyphosate applicationse2
- Outcome
- yielde2
- Direction
- did not increasee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“Sequential glyphosate applications in corn did not increase yield”