Oklahoma State University
Stillwater, OK

Oklahoma Alfalfa
Oklahoma Cooperative Extension Service
Oklahoma Agricultural Experiment Station

Horseweed

COMMON NAME: Horseweed
SCIENTIFIC NAME: Conyza canadensis L. Cronq.
TYPE: Summer Annual Warm-season Broadleaf Weed
DESCRIPTION                                                                 
Germination: March-May.
Reproduction: By seed, July -October.
Stems: Simple, erect, unbranched below, coarsely hairy to hairless.
Leaves: Alternate, simple, numerous, crowded on stem.
Flowers/
Inflorescence:
Small heads at top of plant with small white-pinkish ray flowers and greenish-yellow disk flowers.
Fruit: Achene about 1/32 inch long, tapered from base to apex with numerous slender white bristles at apex.

FOUND:

Throughout the state, only sparsely in thinning stands.

CONTROL:

Control usually not needed since timely mowing for hay drastically reduces its growth. No selective herbicide recommended for control in alfalfa.
In Alfalfa tn_horseweed-15_jpg.jpg (1149 bytes)
Plant
tn_horseweed-13_jpg.jpg (2281 bytes)
Leaf
tn_horseweed-18_jpg.jpg (3019 bytes)
Flower
tn_horseweed-09_jpg.jpg (1375 bytes)
Seed Head
Additional Horseweed Images
Jim Stritzke
Former Alfalfa Weed Control Specialist
Department of Plant and Soil Sciences
Oklahoma State University

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