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Alfalfa
> Year-Round IPM Program > Preplanting > Weed
Identification
Alfalfa
Problematic Weeds in Alfalfa
On this page
- Burclover
- Curly dock
- Goosegreass
- Persian speedwell
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- Poison hemlock
- Swinecress
- Thymeleaf speedwell
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- Bermudgrass
- Dandelion
- Dodder species
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- Field bindweed
- Johnsongrass
- Nutsedge
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The following weeds may cause stand establishment
problems or be problematic long term due to ineffective herbicide
control options. If your proposed alfalfa site is infested with
any of these weeds, you should either consider managing these
weeds before you plant or choose a different site. If you observe
infestations of these weeds in your current alfalfa field, you
can rotate to a different crop for
more successful management. Names link to more information on
identification and biology.
Click
on photos to enlarge
Avoiding
fields with weed infestations—Fall
planting |
Seedlings/young plant |
Mature plant |
Burclover
(Medicago polymorpha): Pea family; summer annual. Seed
leaves oblong; first true leaf rounded with single leaflet;
later leaves with characteristic clover-like shape.
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Burclover
(Medicago polymorpha): Pea family; summer annual. Trifoliate
leaves resemble those of clover and usually have reddish-tinged
midveins. Small, bright-yellow flowers form in clusters at
the end of stems.
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Curly
dock
(Rumex crispus): Buckwheat family; perennial. Seed
leaves succulent and 3 times longer than wide; young seedlings
vary in color, from entirely green
to red-tinged in cooler months; petioles of young seedlings
ribbed with bases extending onto stem. |
Curly dock
(Rumex crispus): Buckwheat family; perennial.
Mature plant with characteristic jointed stems, a membranous
sheath at the leaf base, and usually swollen nodes; can
be 2 to 5 feet tall. |
Goosegrass
(Eleusine indica): Grass family; summer annual. Ligule
thin, membranous and appears torn; collar region with a few
sparse hairs; no auricles; leaf blades smooth and folded. |
Goosegrass
(Eleusine indica): Grass family; summer annual. Appears
as a whitish, silvery mat, forming a pale green clump with
flattened stems in a low rosette; leaves with a short membranous
ligule—blades are flat or folded and 1/8
to 1/3 inch wide. |
No photo available
Persian speedwell
(Veronica persica): Figwort family; winter annual; seed leaves are oval
to triangular in shape and almost as long as they are broad; although similarly
shaped, the first true leaves are larger and either shallowly toothed or smooth
around the edges. |
Persian speedwell
(Veronica persica): Figwort family; winter annual; leaves are roundish
or oval; upper leaves arranged alternately along the stem; lower leaves arranged
in pairs; small, deep blue flowers with white centers are borne on stalks, 3/8
to 1 inch long; entire plant is covered with hairs; mature plants low growing
when mowed frequently.
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Poison hemlock
(Conium maculatum): Carrot family;
biennial. Seed leaves light green, 3 to 5 times as long as
wide, with prominent veins underneath; first true leaves
smooth and deeply cut 2 to 3 times like a parsley leaf; when
crushed has parsnip-like odor.
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Poison hemlock
(Conium maculatum): Carrot family; biennial. Leaves are divided 2 to 3
times into deep lobes or toothed segments; lower leaves have short stalks, flattened
at the base that partially envelop stems; stems have purple
markings upper leaves have short stalks or are stalkless; white sepaless
flowers are borne on umbrella shaped clusters.
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Swinecress
(Coronopus didymus): Mustard family; winter annual; seed leaves light
green, narrow, long, widest at tip; first true leaves club shaped with two notches
(teeth) around margin; leaves and stems slightly hairy; distinct skunk-like odor.
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Swinecress
(Coronopus didymus): Mustard family; winter annual; leaves divided into
narrow segments, somewhat hairy, and may be toothed; lower leaves grow on short
stalks; upper leaves sessile; stems branching and prostrate; flowers white and
tiny; seed pods deeply wrinkled and develop 2 lobes when mature.
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Thymeleaf speedwell
(Veronica serpyllifolia): Figwort
family; perennial; seed leaves spatulate to oblong; first true leaves opposite,
entire, sessile, and lack hairs; older leaves can be more elliptic or ovate in
shape and regularly dentate.
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Thymeleaf speedwell
(Veronica serpyllifolia): Figwort
family; perennial.
Lower leaves opposite, oval to roundish,
on short petiole, with smooth or fine-toothed margin and
often 3-veined from the base; upper leaves alternate, sessile,
and smaller, oval to elliptic; stems almost entirely creeping;
small white to pale-blue flowers with darker blue lines,
borne on stalks. |
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Avoiding
fields with weed infestations—Spring planting |
Seedlings/young plant |
Mature plant |
Bermudagrass
(Cynodon dactylon): Grass family, perennial. First
leaves with somewhat rough surface; ligule present; tuft
of long hairs on either side of ligule; stem flat, wiry,
and without hairs.
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Bermudagrass
(Cynodon dactylon): Grass family, perennial. Look
for dense mats with spreading and branching stolons that
root at nodes.
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Dandelion
(Taraxacum officinale): Perennial. Seed leaves green-yellow, smooth, ranging
from circular to oval to spatulate; young leaves without hairs and
usually gray-green on lower surface, alternate, form
basal rosette, and spatulate or oval with long petiole;
margins of third true leaf wavy with irregular, widely
spaced teeth.
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Dandelion
(Taraxacum officinale): Perennial.
No visible stem; leaves with deeply serrated margins,
cluster in rosette at plant base; flowering
stalks 6 to 24 inches long and terminate in a compound
inflorescence; seeds enclosed singly within fruiting bodies,
attached to a long slender stalk that terminates in a parachute-like
structure. |
Dodder species
(Cuscuta spp.): Morningglory family, summer annual. Leafless
or with small scalelike triangular leaves about 1/16-inch
in length; stems slender, twining or threadlike; vary in
color from pale green to yellow or bright orange.
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Dodder species
(Cuscuta spp.): Morningglory family, summer annual.
Flowers bell-shaped, cream colored and small (about 1/8-inch
long); usually occur in clusters but occasionally borne singly.
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Field bindweed
(Convolvulus arvensis): Morningglory family; perennial; seed leaves nearly
square, with shallow notch at tip; early true leaves spade shaped; petioles flattened.
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Field bindweed
(Convolvulus arvensis): Morningglory family; perennial; leaves are spade
or bell-shaped, lobed at base, and attached to flattened petioles; stems trail
on ground or climb on upright plants; trumpet-shaped white to purplish flowers
close each afternoon and reopen the following day.
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Johnsongrass
(Sorghum halepense): Grass family; perennial; first leaves with white
midvein, 8 times longer than wide and rolled in bud; ligule membranous below
and fringed or toothed above; no auricles.
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Johnsongrass
(Sorghum halepense): Grass family; perennial; leaves
have prominent whitish midvein, which snaps readily when
folded over; flower head is large, open, well-branched,
and often reddish tinged; grows in spreading, leafy patches
that may be as tall as 6 to 7 feet.
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Nutsedge
(Cyperus spp.): Sedge family; perennial.
First leaves inconspicuous and grasslike; grow
mainly from tubers or "nutlets" formed on rhizomes,
mostly in upper foot of soil.
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Nutsedge
(Cyperus spp.): Sedge family; perennial.
In cross section, leaves V-shaped, arranged in
sets of three at base, and stems triangular.
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