<p><a>In the
United States and Canada, weed interference in corn (<i>Zea mays </i>L.) costs farmers nearly $4 billion per year. Weed control
has been achieved primarily through herbicides and tillage. As no-till corn
acres have increased, dependence on herbicides has also increased.
Herbicide-resistant weed infestations have pressured many growers into other
weed management practices, such as adding winter cover crops into crop
rotations. Field experiments were conducted in 2017 through 2018 and 2018
through 2019 at three locations in Indiana to determine residual herbicide
efficacy applied at cereal rye termination and after corn planting in cereal
rye (<i>Secale cereale</i> L.) and
winter-fallow no-till corn. Weed biomass and density suppression was dependent
on weed species and was influenced by cereal rye biomass at termination. Weed
biomass was suppressed by up to 84% by cereal rye alone. Weed biomass reduction
by a residual herbicide premix was similar in both cereal rye and non-cover
crop treatments in most site-years, however cereal rye and the residual
herbicide premix together resulted in decreased giant ragweed (<i>Ambrosia trifida </i>L.) and summer annual
grass biomass compared to the residual herbicide premix applied alone in one
site year. Late-season grass weed density was reduced by residual herbicides,
but was unaffected by cover crop treatment. Late-season common cocklebur density
and biomass increased in cereal rye treatments compared to non-cover crop
treatments. </a></p>
<p>Other
field experiments were conducted at the same locations in 2017 through 2018 and
2018 through 2019 to determine the effect of cover crop species, termination
timing, and chemical cover crop termination strategies on weed control and corn
yield. Crimson cover (<i>Trifolium
incarnatum </i>L.), cereal rye, and a cereal rye/crimson clover mix were
terminated two weeks before, at, and two weeks after corn planting. All plots
were terminated using glyphosate and atrazine, however others were also
terminated with dicamba and acetochlor. The addition of acetochlor generally
reduced early-season weed biomass or density, but not in cereal rye and cover
crop mix treatments that were terminated at or after corn planting. Late-season
summer annual grass biomass was reduced when cover crop biomass at termination
was over 8000 kg ha<sup>-1</sup>. Late-season common cocklebur density in 2018
was 450% to 800% higher in cover crops containing cereal rye, compared to
crimson clover treatments. Corn yield was reduced by 23% to
67% in cereal rye and cover crop mix treatments in two out of three site-years
in 2018, however corn yield was not reduced by crimson clover in either year,
nor by cereal rye or the cover crop mix in 2019.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12671930 |
| Date | 05 August 2020 |
| Creators | Wyatt Steven Petersen (9133244) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Relation | https://figshare.com/articles/thesis/Weed_Control_in_Cover_Crop_No-Till_Corn_Systems/12671930 |
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