timeline for japanese knotweed identification
DESCRIPTION
Japanese Knotweed, Timeline, IdentificationTRANSCRIPT
October (mid-end) October (beginning)
Autumn
September (beginning) September (end)
Timeline for Japanese Knotweed
Identification
Sarah Sutcliffe
During Autumn,
typically October, the
leaves turn orange/
yellow and drop off,
the stem peels and
sheds its purple
speckles to reveal
orange/brown
coloured woody stems
which can remain for
several years. Above
ground it may be
possible to see the top
of the crown stump,
from which next year’s
new growth will
emanate.
November (beginning)
November (end)
Timeline for Japanese Knotweed
Identification
Autumn
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Timeline for Japanese Knotweed
Identification
(be
gin
nin
g)
(m
id)
(
en
d)
Winter
January
(be
gin
nin
g)
(m
id)
(
en
d)
December
Sarah Sutcliffe
Timeline for Japanese Knotweed
Identification
All vegetation has died
back leaving smooth,
hollow woody canes.
Energy from the above
ground material is
trans-located back into
the rhizome system,
stored and lies
dormant throughout
winter.
(be
gin
nin
g)
(m
id)
(
en
d)
February
Winter
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Timeline for Japanese Knotweed
Identification
Spring
March (beginning)
March (end)
April (beginning)
Sarah Sutcliffe
Timeline for Japanese Knotweed
Identification
Spring
April (end)
May
Purple- green shoots
start to emerge in
Spring (March/April)
with rolled up leaves.
When the new leaves
unfurl these tend to
Have a reddish tinge
which soon turns
green.
New shoots from well-
established crowns
have thicker
asparagus-like stalks
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Timeline for Japanese Knotweed
Identification
Summer
June
July
Growth up to around 3m
high, with dense, hollow
jointed stems reminiscent
of bamboo. Stems are
green with purple speckles.
Dense green leaf coverage,
mature leaves measure up
to 120mm in length with
flattened base and pointed
tip, overall are shovel
shaped in appearance.
Sarah Sutcliffe
Timeline for Japanese Knotweed
Identification
Summer
Leaves are arranged
alternately along the stem in
a zig zag pattern. White
flowers appear in August/
September- October in
hanging clusters which are
attached to the end of the
leaf stem. The underground
rhizomes are thick and
woody with a knotty
appearance. When snapped
reveal a bright orange
coloured centre. The rhizome
system may extend to, and
beyond, a depth of 2m and
in worst case scenario,
extend a maximum of 7m,
but more usually extends 2-
4m laterally from a parent
plant. Growth rate can be up
to 40mm per day.
August (beginning)
August (end)
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