Yellow Flag Iris (Iris pseudacorus)
• Reproduces quickly through seed
dispersal and horizontal root
systems
• Create thickets in standing water
and wetlands.
• Fragments of the yellow flag can
form new plants when they break
off
• Density poses a threat to native
wetland species as it excludes
plant and animal diversity.
• The removal of yellow flag
requires labour intensive removal
of root systems.
Giant Hogweed (Heracleum mantegazzianum)
• Highly competitive plant: vigorous early
season growth, abundance in full shade,
tolerance of seasonal flooding.
• Up to 100,000 winged seeds (per plant),
remain for up to 15 years.
• Removal of mature plants=manual removal
of the first 8-12 cm of the central root.
• Immature plants= cutting the plants at
ground level and covering the soil with
black plastic.
• After removal, mow the site every two
weeks to exhaust the seed bank in the soil
(for 3-5 years)
Himalayan Blackberry (Rubus discolor)
•Spreads by root and stem fragments.
•Birds and omnivorous mammals
consume berries and disperse seeds,
which can lay dormant for years.
•This invasive specie favors disturbed
sites such as streambeds, roadways
and forest edges.
•The Himalayan Blackberry is a threat
to riverbanks, because it outcompetes
deep rooted native shrubs by limiting
light exposure, resulting in increased
erosion of the banks.
English Ivy (Hedera helix)
Goutweed/Bishop’s
Weed
Policemans Helmet
Effective control methods- Giant hogweed
1) Manual removal of the taproot.
Taproot removal is most effective from early spring (April) to early summer (July). Be
sure to do this more than once as year, as plant can re-sprout.
2) Removal of flowering heads.
Cut all flowering heads with garden clippers or scissors just below the bloom. The
collected flowers should be contained and disposed in a landfill. Giant hogweed
flowers from late June to mid September.
3) Repeated mowing.
Useful when a lot of giant hogweed plants are present on large, flat sites. Mowing
should be repeated continuously, on three-week intervals, throughout the growing
season (April-November).
4) Application of diluted glyphosate.
Herbicide that should be used sparingly to control giant hogweed. It can be applied
directly to the leaf surface with a paintbrush or inserted into the stem. Herbicide
application is most effective in early spring (April). A second application later on in
the growing season (approx. June) is often required.
Effective Control methods –Yellow Flag
Iris
1)Manual removal of the plant and rhizome:
Requires pickaxes or crowbars. Easiest immediately after the pond water level
has fallen, but the soil is still wet (late June-early July) Done annually. Reduce
amount of disturbed soil. Replant with native or non‐invasive vegetation to
stabilize against erosion. The collected plants should be contained and
disposed in a landfill.
2)Removal of flowering heads and leaves:
April-June, flowering head removal is effective. Removing flowering heads does
not kill the plants; however it will help prevent seed dispersal. These actions
will only be possible if SCG volunteers are willing and equipped with waders.
3) Repeated Mowing:
May keep yellow‐flag iris contained and can potentially kill it by depleting the
energy in the rhizomes after several years of intensive mowing. In SCG pond,
this is only practical during times when the pond is dry (late July-early
September).