Stevens County Noxious Weed Control
Board This web site will help
you identify & control noxious weeds. Conventional & biological control
(BioControl) information and photographs are here. Maps & related
information are included.
Flowers are small and white consisting of 5 petals and borne in
numerous umbrella like clusters
Stems are erect, stout, and purple spotted with distinct ridges and
extensively branched
Leaves are fern like and have a musty odor
Has a large white fleshy tap root
Seeds are paired, 1/8 inch long, brown, ribbed and concave
Biology and ecology
A biennial, occasionally growing up to 10 feet tall
Tolerates poorly drained soils and often found along streams and
ditch banks
Also found on roadsides and gradually invading perennial crops and
pastures
All plant parts including the white fleshy root are poisonous to
humans and livestock
It was the liquid extracted from this plant that Socrates
reportedly used to kill himself in 399BC
Control
Prevention –
Learn to
identify plants; know your property; beware of parsley type plants
invading along waterways or wet roadsides
Biological – The poison hemlock moth has been a very effective
defoliator of Poison hemlock plants where introduced on large
infestations in Washington state.
Cultural – Good vegetative cover lessens likelihood of initial
infestations
Mechanical – Tillage, digging and pulling are all effective
controls but care must be used in handling
Chemical – Several effective at label rates but must use care
near water;
refer to the
PNW Weed Management Handbook for specific chemical recommendations
purple spotted stem
fern-like leaf
flowers
Where found –
Occasionally
found in Stevens County, generally in wet, poorly drained areas
including ditch banks, bogs and wet pastures.
