Abstract
Challenges in weed management include occurrence of multiple weed species in the field, variable emergence among weed species, different spatial distribution and weed densities, which leads to the persistence of weed patches.The overall objective of this research was to understand the interaction of weed emergence, weed density, herbicide choice, and herbicide rate in soybean.Specific objectives were 1) to characterize the seedbank and emergence patterns of shattercane (Sorghum bicolor L.), prickly sida (Sida spinosa L.), and ivyleaf morningglory (Ipomoea hederacea Jacq.) including initial, peak, end, and duration of emergence in response to crop and herbicide treatments in soybean, and 2) to evaluate large crabgrass (Digitaria sanguinalis L.), shattercane, Palmer amaranth (Amaranthus palmeri S.), and velvetleaf (Abutilon theophrasti Medik.)mortality and dry weight reduction in response to herbicide rates across varying weed densities as well as to determine the influence of velvetleaf growth stage and density on herbicide efficacy.In the emergence study of 2006 to 2008, four treatments were nocrop, no-residual herbicide, half-rate of residual herbicide and full-rate of residual herbicide.Reduction in weed emergence was observed over the years in the same species patch.Species emerged in mid-May in both years, coinciding with soybean planting.Extended emergence was observed for shattercane when moisture was low and temperature high, while for prickly sida and ivyleaf morningglory, extended emergence was observed when moisture was high and temperature low.Applying residual herbicide decreased weed emergence.Herbicide choice was the whole plot, herbicide rates were subplots and weed densities were sub-subplots in field experiments conducted in 2006 and 2007.Shattercane was more susceptible to both glyphosate and clethodim than large crabgrass.Increasing large crabgrass density reduced percent mortality with clethodim, while with glyphosate, density did not affect both species mortality.Shattercane dry weight was reduced to 0 g per plot with 0.1X labeled rate of clethodim or glyphosate while 0.5X of the labeled rate reduced dry weight of large crabgrass to 0 g per plot.For broadleaf weeds, higher percent mortality was observed with glyphosate than with lactofen at high densities.Palmer amaranth was more susceptible than velvetleaf.Velvetleaf response was density dependent, such that increasing density did not increase dry weight.Velvetleaf growth stage was of importance, as stage affected herbicide efficacy, with higher mortality achieved at the two-leaf stage than the four-and six-leaf stages.For glyphosate, 0.125X of labeled rate on velvetleaf density of 5 seedlings per pot achieved more than 90% mortality when applied at the two-leaf stage, but dropped to 60 and 50% mortality when applied at the four-and six-leaf stage, respectively.The trend was the same for velvetleaf at a density of 30 seedlings per pot, which had 80, 60, and 55% mortality for the two-, four-, and six-leaf stages, respectively.Weed managers and farmers have the opportunity to better select herbicide choice and rate based on weed species, weed emergence patterns, and weed density.
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Claims 17
Claim · model-written summary
Shattercane was more susceptible to glyphosate and clethodim than large crabgrass.
- Taxon
- SOYBEAN
Glycine maxt0 - Treatment
- glyphosate and clethodime1
- Interactor
- Shattercane
Sorghum ×drummondiie1weed - Outcome
- susceptiblee1
- Direction
- more susceptiblee1
- Comparator
- large crabgrasse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e1“Shattercane was more susceptible to both glyphosate and clethodim than large crabgrass”
Claim · model-written summary
Increasing large crabgrass density reduced percent mortality with clethodim.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- Increasing large crabgrass densitye2
- Interactor
- large crabgrasse2weed
- Outcome
- percent mortalitye2
- Direction
- reducede2
- Qualifier
- with clethodime2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e2“Increasing large crabgrass density reduced percent mortality with clethodim, while with glyphosate, density did not affect both species mortality”
Claim · model-written summary
With glyphosate, density did not affect weed mortality.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- glyphosatee2
- Outcome
- mortalitye2
- Direction
- did not affecte2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e2“Increasing large crabgrass density reduced percent mortality with clethodim, while with glyphosate, density did not affect both species mortality”
Claim · model-written summary
Shattercane dry weight was reduced to 0 g per plot with 0.1X labeled rate of clethodim or glyphosate.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- 0.1X labeled rate of clethodim or glyphosatee3
- Interactor
- ShattercaneSorghum ×drummondiie3weed
- Outcome
- dry weighte3
- Direction
- reducede3
- Value
- 0 g per plote3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e3“Shattercane dry weight was reduced to 0 g per plot with 0.1X labeled rate of clethodim or glyphosate”
Claim · model-written summary
The 0.5X labeled rate reduced large crabgrass dry weight to 0 g per plot.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- 0.5X of the labeled ratee4
- Interactor
- large crabgrasse4weed
- Outcome
- dry weighte4
- Direction
- reducede4
- Value
- 0 g per plote4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e4“0.5X of the labeled rate reduced dry weight of large crabgrass to 0 g per plot”
Claim · model-written summary
For broadleaf weeds at high densities, glyphosate gave higher percent mortality than lactofen.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- glyphosatee5
- Interactor
- broadleaf weedse5weed
- Outcome
- percent mortalitye5
- Direction
- highere5
- Qualifier
- at high densitiese5
- Comparator
- lactofene5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e5“For broadleaf weeds, higher percent mortality was observed with glyphosate than with lactofen at high densities”
Claim · model-written summary
Palmer amaranth was more susceptible than velvetleaf.
- Taxon
- SOYBEANGlycine maxt0
- Interactor
- Palmer amaranthe6weed
- Second interactor
- velvetleaf
Abutilon theophrastie6weed - Outcome
- susceptiblee6
- Direction
- more susceptiblee6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e6“Palmer amaranth was more susceptible than velvetleaf”
Claim · model-written summary
Increasing velvetleaf density did not increase its dry weight; the response was density dependent.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- increasing densitye7
- Interactor
- VelvetleafAbutilon theophrastie7weed
- Outcome
- dry weighte7
- Direction
- did not increasee7
- Qualifier
- density dependente7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e7“Velvetleaf response was density dependent, such that increasing density did not increase dry weight”
Claim · model-written summary
For glyphosate at 0.125X labeled rate on velvetleaf at 5 seedlings per pot, mortality was more than 90% when applied at the two-leaf stage.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- For glyphosate, 0.125X of labeled ratee1
- Interactor
- velvetleafAbutilon theophrastie1weed
- Outcome
- mortalitye1
- Value
- more than 90%e1
- Qualifier
- velvetleaf density of 5 seedlings per pote1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e1“For glyphosate, 0.125X of labeled rate on velvetleaf density of 5 seedlings per pot achieved more than 90% mortality when applied at the two-leaf stage”
Claim · model-written summary
Mortality dropped to 60 and 50% when glyphosate was applied at the four- and six-leaf stages instead of the two-leaf stage.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- four-and six-leaf stagee3
- Interactor
- velvetleafAbutilon theophrastie2weed
- Outcome
- mortalitye3
- Direction
- droppede3
- Value
- 60 and 50%e3
- Comparator
- two-leaf stagee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e1“higher mortality achieved at the two-leaf stage than the four-and six-leaf stages”
e2“For glyphosate, 0.125X of labeled rate on velvetleaf density of 5 seedlings per pot achieved more than 90% mortality when applied at the two-leaf stage”
e3“but dropped to 60 and 50% mortality when applied at the four-and six-leaf stage, respectively”
Claim · model-written summary
At 30 seedlings per pot, velvetleaf mortality was 80, 60 and 55% for the two-, four- and six-leaf stages.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- two-, four-, and six-leaf stagese1
- Interactor
- velvetleafAbutilon theophrastie1weed
- Outcome
- mortalitye1
- Value
- 80, 60, and 55%e1
- Qualifier
- at a density of 30 seedlings per pote1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e1“The trend was the same for velvetleaf at a density of 30 seedlings per pot, which had 80, 60, and 55% mortality for the two-, four-, and six-leaf stages, respectively”
Claim · model-written summary
Weed managers and farmers can better select herbicide choice and rate based on weed species, emergence patterns and density.
- Taxon
- SOYBEANGlycine maxt0
- Outcome
- herbicide choice and ratee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e1“Weed managers and farmers have the opportunity to better select herbicide choice and rate based on weed species, weed emergence patterns, and weed density”
Claim · model-written summary
Weed emergence was reduced over the years in the same species patch in soybean.
- Taxon
- SOYBEANGlycine maxt0
- Outcome
- weed emergencee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e1“Reduction in weed emergence was observed over the years in the same species patch”
Claim · model-written summary
Weed species emerged in mid-May in both years, coinciding with soybean planting.
- Taxon
- SOYBEANGlycine maxt0
- Outcome
- Species emergede1
- Qualifier
- mid-Maye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e1“Species emerged in mid-May in both years, coinciding with soybean planting”
Claim · model-written summary
Shattercane emergence was extended when moisture was low and temperature high.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- moisture was low and temperature highe1
- Interactor
- shattercaneSorghum ×drummondiie1weed
- Outcome
- extended emergencee1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e1“Extended emergence was observed for shattercane when moisture was low and temperature high”
Claim · model-written summary
Prickly sida and ivyleaf morningglory emergence was extended when moisture was high and temperature low.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- moisture was high and temperature lowe1
- Interactor
- prickly sidae1weed
- Second interactor
- ivyleaf morningglory
Ipomoea hederaceae1weed - Outcome
- extended emergencee1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e1“while for prickly sida and ivyleaf morningglory, extended emergence was observed when moisture was high and temperature low”
Claim · model-written summary
Residual herbicide decreased weed emergence in soybean.
- Taxon
- SOYBEANGlycine maxt0
- Treatment
- residual herbicidee1
- Outcome
- weed emergencee1
- Direction
- decreasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“HERBICIDE RATE IN SOYBEAN”
e1“Applying residual herbicide decreased weed emergence”
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