|Scientific Name||Conyza canadensis (L.) Cronquist|
|Common Names||English: Horseweed, Canadian Fleabane; German: Kanadisches Berufkraut; French: Vergerette du Canada; Spanish: Erígero del Canadá, hierba carnicera|
|Description||Annual or over-wintering (facultative biennial), stinking, seed-propagated weed, often forming only one leaf rosette in the first year.|
Leaves with toothed margins whereas the upper leaves will tend to have smooth margins, exudes a "carrot-like" odor.
Round-oval, rounded at the top, petiolate.
Erect, heavily foliated, ramified in the flower area, also bristly ciliate, 30-100 cm (11.81 - 39.37 inch) high.
Undivided, linear-lanceolate, dark-green, bristly ciliate. The lower leaves tapered into the stem, the upper leaves sessile.
Capitulums numerous, small, in paniculiform inflorescence.
Disk florets tube-like, yellowish, several rows of ray florets, filamentous, usually dirty white.
Summer - autumn.
Achenes flattened, 2-ribbed, ivory to light brown, 1-1.2 mm (0.039 - 0.047 inch) long, appressed-puberulent. Pappus of numerous, dull white capillary bristles.
Germination from spring-autumn.
Viability of Seeds
Wind-dispersed seed, transportation of seeds over more than 100 km (62.13 miles).
Invades shorelines and drawdown zones, roadsides, fields, waste places.
Dry, warm, sandy, loamy, and stony soils.
C. canadiensis is slightly poisonous. It contains volatile oils, tannic acids and gallic acid that cause skin irritation in humans and livestock. The weed originates from North America and has become a troublesome weed in North America due to resistance to glyphosate.
Useful non-chemical contribution to Integrated Weed Management
Tillage or a pre-plant burndown will provide season long control. A dense crop canopy prevents severe infestations.
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