Download Common Chickweed

Featured Pest: Common Chickweed
(Stellaria media)
Common chickweed is widespread across Canada forming
dense patches or mats where left uncontrolled. Known for
multiple flushes of emregence it can a persistent agricultural
problem which is complicated by herbicide resistant biotypes.
Biology: An annual or winter annual reproducing by seed. The
stems are prostrate, branched, and horizontally spreading with
swollen nodes. Chickweed can root from any nodes in contact
with the soil.
The leaves are variable in size but oval with a pointed tip,
stalkless and opposite with two leaves per node. The leave
margins are entire and lower leaves are stalked while upper
leaves are sessile (attached directly to the stem). The small
white flowers have 5 petals and are 2-lobed.The seed-pod is
egg-shaped and produces small 1.2 mm, reddish-brown seeds.
Common chickweed is also a prolific seed producer.
conditions such as moisture are favourable and therefore
significant populations can appear after scouting has already
occurred.
Weed Act Status: Common chickweed and its relatives, field
chickweed, mouse-eared chickweed and long-stalked
chickweed are all considered as noxious weeds in Manitoba.
Common chickweed is a non-regulated nuisance weed in
British Columbia.
Herbicide Resistance: Common chickweed is resistant to Group
2 (ALS inhibitors) in Alberta, Saskatchewan and Manitoba as
well as in the United States, South Africa, New Zealand, and
Europe. It also has shown resistance to Group 5 (atrazine) in
Germany and Group 4 (auxins) in China and the United
Kingdom. However; resistance has not be found in any of the
other chickweed species.
Figure 1. Chickweed stand actively growing on November 30th
Figure 2. Single flower at node (left) and Seedling(right)
Identification: Common chickweed is easily identified by its
bright green colour, combined with the ovate-pointed leaves
and the distinctive stem hairs. The stems are smooth except for
a row of fine hairs which alternates from one side of the stem
to the other.
Scouting Techniques:Since it is an annual or winter annual
weed, the emergence can extend from the fall throughout the
next season. Chickweed can be very cold tolerant and will
continually flower until fall frost; hence scouting must be done
repeatedly over the season (see Figure1). Chickweed is a
flushing weed so mutiple waves of emergence will occur if
Issue Date: January 7, 2016
Similar Weeds: Mouse-eared chickweed Cerastium fontanum is
a perennial distinguished by a hairy stem, stalkless leaves with
long hairs on both leaf surfaces and small flowers with 5 styles.
Field chickweed Cerastium arvense is a perennial which also
has narrow leaves but has larger showy flowers with petals two
to three times longer than the sepals.
Narrow-leaved chickweed Stellaria graminea also known as
grass-leaved stitchwort is a perennial with narrow grass-like
leaves. It has square stems, narrow stalkless leaves, three
styles and petals longer than the sepals which distinguishes it
from common chickweed.