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Pigweed ID

Joe Armstrong
January 16, 2012

Pigweed ID

Joe Armstrong

January 16, 2012
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  1. WEED ID REFRESHER:
    Pigweed species
    Joe Armstrong
    Oklahoma State University Weed Science
    www.weedscience.okstate.edu
    Twitter: @OSUWeedSci

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  2. Generally speaking, identification of
    individual pigweed species is not
    necessary to choose the correct herbicide
    for maximum control.
    However, due to the development of
    herbicide-resistance in populations of
    waterhemp and Palmer pigweed in
    Oklahoma and the US, it is increasingly
    important to properly identify each weed
    to develop an appropriate management
    strategy.

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  3. All pigweeds, regardless of
    species, typically have a small
    notch in the tip of the true leaves.
    © Joe Armstrong,
    Oklahoma State University

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  4. © Joe Armstrong,
    Oklahoma State University
    Seeds of the various pigweed species are
    small, brown or black, round, and shiny.
    Because of their size, the seeds are easily
    moved in soil, with seed, or on equipment

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  5. redroot pigweed
    Redroot pigweed has
    wide, egg-shaped leaves
    © Joe Armstrong,
    Oklahoma State University

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  6. redroot pigweed
    Note the short hairs on the stem.
    © Joe Armstrong,
    Oklahoma State University

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  7. waterhemp
    Waterhemp has long, slender leaves.
    © Joe Armstrong,
    Oklahoma State University

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  8. waterhemp
    The leaves are very waxy and shiny.
    © Joe Armstrong,
    Oklahoma State University

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  9. Palmer pigweed
    Palmer pigweed has wide,
    egg-shaped leaves. Often, they will
    have a white or purple “V” watermark.
    © Joe Armstrong,
    Oklahoma State University

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  10. Palmer pigweed
    Palmer pigweed also has waxy, shiny leaves.
    Note the absence of the watermark.
    © Joe Armstrong,
    Oklahoma State University

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  11. Palmer pigweed
    Unlike redroot pigweed,
    Palmer pigweed has a
    smooth, hairless stem.
    © Joe Armstrong,
    Oklahoma State University

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  12. Palmer pigweed
    waterhemp
    Palmer pigweed can also be
    identified by the long petiole,
    or the stalk that connects the
    leaf blade to the stem. This
    causes the leaves to hang out
    far away from the main stem.
    © Joe Armstrong,
    Oklahoma State University

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  13. Palmer pigweed
    Seedheads on Palmer pigweed plants
    are usually 1-2 feet in length.
    © Joe Armstrong,
    Oklahoma State University

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  14. tumble pigweed
    Tumble pigweed is usually the easiest
    pigweed species to identify. As the name
    suggests, it grows in a low, round shape.
    © Joe Armstrong,
    Oklahoma State University

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  15. tumble pigweed
    Tumble pigweed also has more
    rounded leaf tips and wrinkled leaf
    margins than the other pigweeds.
    © Joe Armstrong,
    Oklahoma State University

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  16. redroot pigweed
    waterhemp
    Palmer pigweed
    tumble pigweed
    © Joe Armstrong, Oklahoma State University

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  17. All photos, unless noted, were
    taken by Joe Armstrong.
    If you would like high resolution
    versions of these photographs,
    please contact Joe at
    [email protected].

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