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Latin name: Cyperus esculentus
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Family: Cyperaceae
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Common name: Yellow nutsedge
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Life cycle: perennial
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Habit: Upright with grass-like foliage
(but nutsedge is not a grass!!!!!).
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Foliage: Long, glossy, 3-ranked,
linear leaves. At a glance, leaves appear similar to grass. Nutsedge
leaves are angular, with a cross-sectional view appearing like the letter
'W'.
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Flower:
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Cotyledon or seedling: Nutsedge
plants most often emerge from tubers. Foliage emerging from tubers
appears similar to mature foliage, just smaller.
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Roots: Fibrous root system. Nutlets
(tubers, really) develop within the root system, from which new
plants develop.
New plants emerging from nutlets are difficult to control with preemergence
herbicides, and generally only products containing the active ingredient metolachlor
(such as Pennant) will provide acceptable preemergence control. Plants
also
spread
by rhizomes.
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Emergence: Yellow nutsedge emerges when soil temperatures
are sufficiently high, usually in mid-April. |
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Special considerations: In Oregon,
only yellow nutsedge is problematic. Some growers have reported seeing
purple nutsedge, but also stated that it did not persist year after year.
This may be due to winter climate (temperatures), though I'm not
certain. Nonetheless, yellow nutsedge (Cyperus esculentus)
is the species Oregon growers should be most concerned with.
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Control: Neither tilling nor cultivation
are effective, and both practices often make the problem worse. Hoeing
is not effective. Translocated postemergence herbicides are necessary
for complete control of root system and tubers, otherwise, new plants will
emerge. Contact herbicides are not effective (for long-term control).
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Look alikes: purple nutsedge (Cyperus
rotunda) and liriope (it takes a well trained eye to see and weed
nutsedge from 'Big Blue' liriope).
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