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Horseweed (marestail)
SunflowerFamily
Key identifying traits
An upright winter or summer annual with inconspicuous, small, white
flowers
Flowers from June to September
Grows anywhere from 1 to 5 feet tall
The leaves are alternate and narrowly lance-shape
Grows on one erect stalk, only the upper part branching
Biology and ecology
An annual plant, reproducing by seed only
It tends to germinate along roadsides in late spring and continues
until frost; a native of the U.S.
Found in range land, pastures, gardens, waste areas, and disturbed
sites
Horseweed contains oils that may cause skin and mucosal irritation
in humans and animals, especially horses
Control
Prevention –
Learn to
identify plants; know your property, plant a cover crop or pasture mix
on disturbed ground
Biological – No known biological agents yet
Cultural – Good vegetative cover helps greatly-not a highly
invasive plant but will take advantage of disturbed or open areas
Mechanical – Cutting, tilling, or mowing is very helpful as a
tool to prevent spread if done before flowering
Chemical – Several effective at label rates;
refer to the
PNW Weed Management Handbook for specific chemical recommendations
Found
scattered throughout Stevens County, heaviest concentrations are along
the road shoulders and in overgrazed pastures.
MSdoc
pdf
